use serde::{Deserialize, Serialize};
use serde_json::{Value, json};
use tokio::io::{AsyncReadExt, AsyncWriteExt};

#[derive(Serialize, Deserialize, Debug, Clone)]
pub struct JsonRpcRequest {
    pub jsonrpc: String,
    pub id: Option<Value>,
    pub method: String,
    pub params: Option<Value>,
}

#[derive(Serialize, Debug, Clone)]
pub struct JsonRpcResponse {
    pub jsonrpc: String,
    pub id: Value,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub result: Option<Value>,
    #[serde(skip_serializing_if = "Option::is_none")]
    pub error: Option<Value>,
}

pub async fn send_response(response: JsonRpcResponse) {
    let msg = serde_json::to_string(&response).unwrap_or_else(|_| "{}".to_string());
    tracing::info!(
        "Sending JSON-RPC response (id: {:?}): {}{}",
        response.id,
        &msg[..msg.floor_char_boundary(500)],
        if msg.len() > 500 { "..." } else { "" }
    );
    // CRITICAL ARCHITECTURAL DECISION:
    // The MCP StdioTransport MUST use Newline-Delimited JSON (NDJSON).
    // Do NOT use LSP-style HTTP headers (e.g. Content-Length).
    // See MCP protocol spec (SEP-2575) and mcp-go-sdk bufio.Scanner implementation.
    let mut stdout = tokio::io::stdout();
    let _ = stdout.write_all(msg.as_bytes()).await;
    let _ = stdout.write_all(b"\n").await;
    let _ = stdout.flush().await;
}

macro_rules! handle_lua_result {
    ($id:expr, $result:expr) => {
        match $result.await {
            Ok(res) => send_text_result!($id.clone(), res),
            Err(e) => send_error($id, -32603, &e).await,
        }
    };
}

pub async fn send_error(id: Value, code: i32, message: &str) {
    send_response(JsonRpcResponse {
        jsonrpc: "2.0".to_string(),
        id,
        result: None,
        error: Some(serde_json::json!({"code": code, "message": message})),
    })
    .await;
}

#[cfg(windows)]
async fn get_socket_path() -> Result<String, String> {
    let profile =
        std::env::var("USERPROFILE").unwrap_or_else(|_| "C:\\Users\\reazul.ashraf".into());
    let path = format!("{profile}\\.gemini\\active_nvim.txt");

    if let Ok(content) = tokio::fs::read_to_string(&path).await {
        let p = content.trim().to_string();
        if !p.is_empty() {
            if p.starts_with(r"\\.\pipe\") {
                return Ok(p);
            } else if p.starts_with("nvim.") {
                return Ok(format!(r"\\.\pipe\{p}"));
            }
            return Ok(p);
        }
    }

    tracing::warn!("active_nvim.txt missing or invalid, falling back to pipe discovery");
    if let Ok(mut dir) = tokio::fs::read_dir(r"\\.\pipe\").await {
        while let Ok(Some(entry)) = dir.next_entry().await {
            let name = entry.file_name();
            let name_str = name.to_string_lossy();
            if name_str.starts_with("nvim.") {
                return Ok(format!(r"\\.\pipe\{name_str}"));
            }
        }
    }
    Err("Could not find active Windows Neovim named pipe".to_string())
}

#[cfg(unix)]
async fn get_socket_path() -> Result<String, String> {
    if let Ok(home) = std::env::var("HOME") {
        let path = format!("{}/.gemini/active_nvim.txt", home);
        if let Ok(content) = tokio::fs::read_to_string(&path).await {
            let p = content.trim().to_string();
            if !p.is_empty() {
                return Ok(p);
            }
        }
    }

    if let Ok(mut entries) = tokio::fs::read_dir("/tmp").await {
        while let Ok(Some(entry)) = entries.next_entry().await {
            if let Ok(name) = entry.file_name().into_string() {
                if name.starts_with("nvim.") {
                    let path = entry.path().join("0");
                    if tokio::fs::try_exists(&path).await.unwrap_or(false) {
                        return Ok(path.to_string_lossy().to_string());
                    }
                }
            }
        }
    }
    Err("Could not find Neovim socket".to_string())
}
use std::collections::HashMap;
use std::sync::Arc;
use std::sync::LazyLock;
use tokio::sync::{mpsc, oneshot};

pub struct NvimRequest {
    pub msgid: u64,
    pub req: rmpv::Value,
    pub reply: oneshot::Sender<Result<rmpv::Value, String>>,
}

use std::sync::atomic::{AtomicU64, Ordering};
static NEXT_MSGID: AtomicU64 = AtomicU64::new(1);
static NVIM_CONN: LazyLock<Arc<std::sync::Mutex<Option<mpsc::Sender<NvimRequest>>>>> =
    LazyLock::new(|| Arc::new(std::sync::Mutex::new(None)));

async fn get_nvim_connection() -> Result<mpsc::Sender<NvimRequest>, String> {
    {
        let conn_lock = NVIM_CONN.lock().unwrap_or_else(|e| e.into_inner());
        if let Some(sender) = conn_lock.as_ref()
            && !sender.is_closed()
        {
            return Ok(sender.clone());
        }
    }

    tracing::info!("Establishing new persistent connection to Neovim");
    let socket_path = get_socket_path().await?;

    #[cfg(windows)]
    let stream = {
        use tokio::net::windows::named_pipe::ClientOptions;
        ClientOptions::new()
            .open(&socket_path)
            .map_err(|e| e.to_string())?
    };

    #[cfg(unix)]
    let stream = {
        use tokio::net::UnixStream;
        UnixStream::connect(socket_path)
            .await
            .map_err(|e| e.to_string())?
    };

    let (mut read_half, mut write_half) = tokio::io::split(stream);
    let (tx, mut rx) = mpsc::channel::<NvimRequest>(32);
    type PendingRequestsMap =
        Arc<std::sync::Mutex<HashMap<u64, oneshot::Sender<Result<rmpv::Value, String>>>>>;
    let pending_requests: PendingRequestsMap = Arc::new(std::sync::Mutex::new(HashMap::new()));

    // Write task
    let pending_clone = Arc::clone(&pending_requests);
    tokio::spawn(async move {
        while let Some(req) = rx.recv().await {
            let mut buf = Vec::new();
            if let Err(e) = rmpv::encode::write_value(&mut buf, &req.req) {
                let _ = req.reply.send(Err(e.to_string()));
                continue;
            }

            pending_clone
                .lock()
                .unwrap_or_else(|e| e.into_inner())
                .insert(req.msgid, req.reply);

            if write_half.write_all(&buf).await.is_err() {
                tracing::error!("Failed to write to Neovim socket");
                break;
            }
        }
    });

    // Read task
    let pending_clone2 = Arc::clone(&pending_requests);
    tokio::spawn(async move {
        let mut resp_buf = Vec::new();
        let mut chunk = vec![0u8; 65536];
        let mut offset = 0;

        loop {
            let mut cursor = std::io::Cursor::new(&resp_buf[offset..]);
            match rmpv::decode::read_value(&mut cursor) {
                Ok(val) => {
                    offset += cursor.position() as usize;

                    if let rmpv::Value::Array(ref arr) = val
                        && arr.len() >= 4
                        && arr[0] == rmpv::Value::Integer(1.into())
                    {
                        let msgid = match &arr[1] {
                            rmpv::Value::Integer(i) => i.as_u64().unwrap_or(0),
                            _ => 0,
                        };

                        if let Some(reply_sender) = pending_clone2
                            .lock()
                            .unwrap_or_else(|e| e.into_inner())
                            .remove(&msgid)
                        {
                            let _ = reply_sender.send(Ok(val));
                        }
                    }
                    if offset == resp_buf.len() {
                        resp_buf.clear();
                        offset = 0;
                    } else if offset > 1024 * 1024 {
                        resp_buf.drain(..offset);
                        offset = 0;
                    }
                    continue;
                }
                Err(e)
                    if match &e {
                        rmpv::decode::Error::InvalidMarkerRead(io_err) => {
                            io_err.kind() == std::io::ErrorKind::UnexpectedEof
                        }
                        rmpv::decode::Error::InvalidDataRead(io_err) => {
                            io_err.kind() == std::io::ErrorKind::UnexpectedEof
                        }
                        _ => false,
                    } =>
                {
                    resp_buf.drain(..offset);
                    offset = 0;

                    let read_future = read_half.read(&mut chunk);
                    match tokio::time::timeout(tokio::time::Duration::from_secs(60), read_future)
                        .await
                    {
                        Ok(Ok(n)) if n > 0 => {
                            resp_buf.extend_from_slice(&chunk[..n]);
                        }
                        _ => {
                            tracing::error!("Neovim socket read loop closed or timeout");
                            break;
                        }
                    }
                }
                Err(_) => {
                    tracing::error!("Failed to parse message from Neovim socket");
                    break;
                }
            }
        }

        // Cleanup pending requests on disconnect
        let mut pending = pending_clone2.lock().unwrap_or_else(|e| e.into_inner());
        for (_, sender) in pending.drain() {
            let _ = sender.send(Err("Connection closed".to_string()));
        }
    });

    // Cleanup task for timed-out requests
    let pending_clone3 = Arc::clone(&pending_requests);
    tokio::spawn(async move {
        let mut interval = tokio::time::interval(tokio::time::Duration::from_secs(10));
        loop {
            interval.tick().await;
            if Arc::strong_count(&pending_clone3) <= 1 {
                break; // Socket closed and other tasks finished, no need to keep cleaning up
            }
            pending_clone3
                .lock()
                .unwrap_or_else(|e| e.into_inner())
                .retain(|_, sender| !sender.is_closed());
        }
    });

    let mut conn_lock = NVIM_CONN.lock().unwrap_or_else(|e| e.into_inner());
    if let Some(existing_sender) = conn_lock.as_ref()
        && !existing_sender.is_closed()
    {
        // Another task established the connection while we were waiting
        return Ok(existing_sender.clone());
    }
    *conn_lock = Some(tx.clone());
    Ok(tx)
}

async fn call_nvim(req: rmpv::Value) -> Result<rmpv::Value, String> {
    let msgid = if let rmpv::Value::Array(ref arr) = req {
        if arr.len() > 1 {
            match &arr[1] {
                rmpv::Value::Integer(i) => i.as_u64().unwrap_or(0),
                _ => 0,
            }
        } else {
            0
        }
    } else {
        0
    };

    let tx = get_nvim_connection().await?;
    let (reply_tx, reply_rx) = oneshot::channel();

    tx.send(NvimRequest {
        msgid,
        req,
        reply: reply_tx,
    })
    .await
    .map_err(|_| "Failed to send request to Neovim connection manager")?;

    match tokio::time::timeout(tokio::time::Duration::from_secs(10), reply_rx).await {
        Ok(Ok(res)) => res,
        Ok(Err(_)) => Err("Response channel dropped".to_string()),
        Err(_) => Err("Timeout waiting for Neovim response".to_string()),
    }
}

async fn call_nvim_method(method: &str, args: Vec<rmpv::Value>) -> Result<rmpv::Value, String> {
    use rmpv::Value as RmpValue;
    let msgid = NEXT_MSGID.fetch_add(1, Ordering::SeqCst);
    let req = RmpValue::Array(vec![
        RmpValue::Integer(0.into()),
        RmpValue::Integer(msgid.into()),
        RmpValue::String(method.into()),
        RmpValue::Array(args),
    ]);

    let resp = call_nvim(req).await?;
    if let RmpValue::Array(mut arr) = resp {
        if arr.len() < 4 {
            return Err("Invalid response length".to_string());
        }
        if !arr[2].is_nil() {
            return Err(format!("Neovim error: {:?}", arr[2]));
        }
        return Ok(arr.swap_remove(3));
    }
    Err("Invalid response format".to_string())
}

async fn send_nvim_command(cmd: &str) -> Result<(), String> {
    call_nvim_method("nvim_command", vec![rmpv::Value::String(cmd.into())]).await?;
    Ok(())
}

async fn get_nvim_active_buffer() -> Result<String, String> {
    let result = call_nvim_method(
        "nvim_buf_get_lines",
        vec![
            rmpv::Value::Integer(0.into()),
            rmpv::Value::Integer(0.into()),
            rmpv::Value::Integer((-1).into()),
            rmpv::Value::Boolean(true),
        ],
    )
    .await?;

    if let rmpv::Value::Array(lines) = result {
        let mut text = String::new();
        for line in lines {
            if let rmpv::Value::String(s) = line
                && let Some(s) = s.as_str()
            {
                text.push_str(s);
                text.push('\n');
            }
        }
        return Ok(text);
    }
    Err("Invalid response format".to_string())
}

async fn get_nvim_cursor() -> Result<String, String> {
    let result =
        call_nvim_method("nvim_win_get_cursor", vec![rmpv::Value::Integer(0.into())]).await?;

    if let rmpv::Value::Array(pos) = result
        && pos.len() == 2
        && let (rmpv::Value::Integer(row), rmpv::Value::Integer(col)) = (&pos[0], &pos[1])
    {
        return Ok(format!("Line: {row}, Column: {col}"));
    }
    Err("Invalid response format".to_string())
}

async fn get_nvim_visual_selection() -> Result<String, String> {
    let lua_script = r#"
        local _, csrow, cscol, _ = unpack(vim.fn.getpos("'<"))
        local _, cerow, cecol, _ = unpack(vim.fn.getpos("'>"))
        local lines = vim.fn.getline(csrow, cerow)
        if type(lines) == "table" then
            return table.concat(lines, "\n")
        else
            return lines
        end
    "#;

    let result = call_nvim_method(
        "nvim_exec_lua",
        vec![
            rmpv::Value::String(lua_script.into()),
            rmpv::Value::Array(vec![]),
        ],
    )
    .await?;

    if let rmpv::Value::String(s) = result
        && let Some(text) = s.as_str()
    {
        return Ok(text.to_string());
    }
    Err("Invalid response format".to_string())
}

async fn set_nvim_diagnostics(line: i64, message: &str) -> Result<(), String> {
    let escaped_message = message.replace('\\', "\\\\").replace('"', "\\\"");
    let lua_script = format!(
        r#"
        local ns = vim.api.nvim_create_namespace("gemini_diagnostics")
        local diagnostics = {{{{
            lnum = {line} - 1,
            col = 0,
            severity = vim.diagnostic.severity.WARN,
            message = "{escaped_message}",
        }}}}
        vim.diagnostic.set(ns, 0, diagnostics, {{}})
    "#
    );

    call_nvim_method(
        "nvim_exec_lua",
        vec![
            rmpv::Value::String(lua_script.into()),
            rmpv::Value::Array(vec![]),
        ],
    )
    .await?;

    Ok(())
}

fn rmpv_to_json(val: &rmpv::Value) -> serde_json::Value {
    match val {
        rmpv::Value::Nil => serde_json::Value::Null,
        rmpv::Value::Boolean(b) => serde_json::json!(*b),
        rmpv::Value::Integer(i) => {
            if let Some(n) = i.as_i64() {
                serde_json::json!(n)
            } else if let Some(n) = i.as_u64() {
                serde_json::json!(n)
            } else {
                serde_json::Value::Null
            }
        }
        rmpv::Value::F32(f) => serde_json::json!(f),
        rmpv::Value::F64(f) => serde_json::json!(f),
        rmpv::Value::String(s) => {
            if let Some(str_val) = s.as_str() {
                serde_json::json!(str_val)
            } else {
                serde_json::Value::Null
            }
        }
        rmpv::Value::Array(arr) => {
            let vec: Vec<serde_json::Value> = arr.iter().map(rmpv_to_json).collect();
            serde_json::Value::Array(vec)
        }
        rmpv::Value::Map(map) => {
            let mut obj = serde_json::Map::new();
            for (k, v) in map {
                let key_str = if let rmpv::Value::String(s) = k {
                    s.as_str().unwrap_or("").to_string()
                } else {
                    format!("{k:?}")
                };
                obj.insert(key_str, rmpv_to_json(v));
            }
            serde_json::Value::Object(obj)
        }
        _ => serde_json::json!(format!("{:?}", val)),
    }
}

fn json_to_rmpv(val: &serde_json::Value) -> rmpv::Value {
    match val {
        serde_json::Value::Null => rmpv::Value::Nil,
        serde_json::Value::Bool(b) => rmpv::Value::Boolean(*b),
        serde_json::Value::Number(n) => {
            if let Some(i) = n.as_i64() {
                rmpv::Value::Integer(i.into())
            } else if let Some(u) = n.as_u64() {
                rmpv::Value::Integer(u.into())
            } else if let Some(f) = n.as_f64() {
                rmpv::Value::F64(f)
            } else {
                rmpv::Value::Nil
            }
        }
        serde_json::Value::String(s) => rmpv::Value::String(s.as_str().into()),
        serde_json::Value::Array(arr) => rmpv::Value::Array(arr.iter().map(json_to_rmpv).collect()),
        serde_json::Value::Object(obj) => rmpv::Value::Map(
            obj.iter()
                .map(|(k, v)| (rmpv::Value::String(k.as_str().into()), json_to_rmpv(v)))
                .collect(),
        ),
    }
}

async fn execute_nvim_lua_with_args(code: &str, args: Vec<rmpv::Value>) -> Result<String, String> {
    let result = call_nvim_method(
        "nvim_exec_lua",
        vec![rmpv::Value::String(code.into()), rmpv::Value::Array(args)],
    )
    .await?;
    let json_res = rmpv_to_json(&result);
    // If it's a simple string, return it unquoted, otherwise format it pretty
    if let serde_json::Value::String(s) = json_res {
        Ok(s)
    } else {
        Ok(serde_json::to_string_pretty(&json_res).unwrap_or_default())
    }
}

async fn execute_nvim_lua(code: &str) -> Result<String, String> {
    execute_nvim_lua_with_args(code, vec![]).await
}

macro_rules! send_text_result {
    ($id:expr, $text:expr) => {
        send_response(JsonRpcResponse {
            jsonrpc: "2.0".to_string(),
            id: $id,
            result: Some(serde_json::json!({
                "content": [{
                    "type": "text",
                    "text": $text
                }]
            })),
            error: None,
        }).await
    };
}

pub async fn run_mcp_loop(app_name: &str, app_version: &str) {
    if std::env::args().any(|arg| arg == "--version") {
        println!(
            "{} {} ({})",
            app_name,
            app_version,
            std::env::var("GIT_HASH").unwrap_or_else(|_| "unknown".to_string())
        );
        return;
    }
    let _guard = init_logging(app_name);
    tracing::info!("{} MCP server started", app_name);
    let mut stdin = tokio::io::BufReader::new(tokio::io::stdin());
    loop {
        let raw_msg = if let Some(m) = mcp_stdio::read_mcp_message(&mut stdin).await {
            m
        } else {
            tracing::info!("Stdin closed, exiting loop");
            break;
        };

        let msg = match serde_json::from_str::<JsonRpcRequest>(&raw_msg) {
            Ok(m) => {
                tracing::info!("Received message method: {}", m.method);
                m
            }
            Err(e) => {
                tracing::error!(
                    "Failed to parse JSON-RPC request from JSONL: {}. Payload: {}",
                    e,
                    raw_msg
                );
                continue;
            }
        };

        let app_name = app_name.to_string();
        let app_version = app_version.to_string();

        tokio::spawn(async move {
            let id = msg.id.unwrap_or(json!(null));

            match msg.method.as_str() {
                "initialize" => {
                    let init = rmcp::model::InitializeResult::new(
                        rmcp::model::ServerCapabilities::builder()
                            .enable_tools()
                            .build(),
                    )
                    .with_server_info(rmcp::model::Implementation::new(
                        app_name.clone(),
                        app_version.clone(),
                    ))
                    .with_protocol_version(rmcp::model::ProtocolVersion::V_2024_11_05)
                    .with_instructions(include_str!("instructions.md"));

                    send_response(JsonRpcResponse {
                        jsonrpc: "2.0".to_string(),
                        id,
                        result: Some(serde_json::to_value(init).unwrap_or_default()),
                        error: None,
                    })
                    .await;
                }
                "notifications/initialized" => {}
                "tools/list" => {
                    send_response(JsonRpcResponse {
                        jsonrpc: "2.0".to_string(),
                        id,
                        result: Some(json!({
                            "tools": [
                                {
                                    "name": "nvim_goto_line",
                                    "description": "Open a file and jump to a specific line",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "file": { "type": "string" },
                                            "line": { "type": "integer" }
                                        },
                                        "required": ["file", "line"]
                                    }
                                },
                                {
                                    "name": "nvim_get_active_buffer",
                                    "description": "Get the contents of the currently active Neovim buffer",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {}
                                    }
                                },
                                {
                                    "name": "nvim_get_cursor",
                                    "description": "Get the current cursor position (line and column) in the active Neovim buffer",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {}
                                    }
                                },
                                {
                                    "name": "nvim_get_visual_selection",
                                    "description": "Get the text that is currently highlighted or was last highlighted in Visual mode",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {}
                                    }
                                },
                                {
                                    "name": "nvim_set_diagnostics",
                                    "description": "Push a diagnostic message (like an LSP warning) to a specific line in the active buffer",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "line": { "type": "integer" },
                                            "message": { "type": "string" }
                                        },
                                        "required": ["line", "message"]
                                    }
                                },
                                {
                                    "name": "nvim_list_buffers",
                                    "description": "List all open buffers in Neovim",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {}
                                    }
                                },
                                {
                                    "name": "nvim_get_diagnostics",
                                    "description": "Get all diagnostics for the current active buffer",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {}
                                    }
                                },
                                {
                                    "name": "nvim_execute_lua",
                                    "description": "Execute arbitrary Lua code in Neovim and return the result (JSON serialized). CRITICAL: This is the primary tool for editing files. Use `vim.api.nvim_buf_set_lines` to modify buffers. ALWAYS trigger a notification (`require('notify')(...)`). ALWAYS auto-save (`vim.cmd('write')`) after edits. NEVER use interactive commands or 'c' flags in substitutions (e.g. use `vim.cmd('%s/old/new/ge')`).",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "code": { "type": "string" }
                                        },
                                        "required": ["code"]
                                    }
                                },
                                {
                                    "name": "nvim_open_file",
                                    "description": "Safely opens a file in the active Neovim window",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "file": { "type": "string" },
                                            "filetype": { "type": "string" }
                                        },
                                        "required": ["file"]
                                    }
                                },
                                {
                                    "name": "nvim_open_buffer",
                                    "description": "Creates and opens a transient, scratch buffer that is not tied to a file on disk",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "name": { "type": "string" },
                                            "content": { "type": "string" },
                                            "filetype": { "type": "string" }
                                        }
                                    }
                                },
                                {
                                    "name": "nvim_close_buffer",
                                    "description": "Closes the current active buffer (or a specified buffer)",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "buf_id": { "type": "integer" },
                                            "force": { "type": "boolean" }
                                        }
                                    }
                                },
                                {
                                    "name": "nvim_split_window",
                                    "description": "Opens a file or buffer in a split window alongside the current buffer",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "file": { "type": "string" },
                                            "buf_id": { "type": "integer" },
                                            "direction": { "type": "string", "enum": ["vertical", "horizontal"] }
                                        }
                                    }
                                },
                                {
                                    "name": "nvim_reload_buffer",
                                    "description": "Forces Neovim to reload the buffer from the filesystem, picking up external changes",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "buf_id": { "type": "integer" },
                                            "force": { "type": "boolean" }
                                        }
                                    }
                                },
                                {
                                    "name": "nvim_save_buffer",
                                    "description": "Explicitly saves the current active buffer",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {}
                                    }
                                },
                                {
                                    "name": "nvim_set_quickfix",
                                    "description": "Populates Neovim's quickfix list with search results, compile errors, or lint warnings",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "items": {
                                                "type": "array",
                                                "items": {
                                                    "type": "object",
                                                    "properties": {
                                                        "filename": { "type": "string" },
                                                        "lnum": { "type": "integer" },
                                                        "text": { "type": "string" }
                                                    },
                                                    "required": ["filename", "lnum", "text"]
                                                }
                                            },
                                            "action": { "type": "string", "enum": ["replace", "append", "prepend"] }
                                        },
                                        "required": ["items"]
                                    }
                                },
                                {
                                    "name": "nvim_highlight_lines",
                                    "description": "Temporarily or permanently highlights a block of code, or clears existing highlights.",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "buf_id": { "type": "integer" },
                                            "start_line": { "type": "integer" },
                                            "end_line": { "type": "integer" },
                                            "group": { "type": "string" },
                                            "duration_ms": { "type": "integer", "description": "Duration to show highlight in milliseconds. Set to 0 for permanent (until cleared manually)." },
                                            "clear_only": { "type": "boolean", "description": "If true, will only clear existing highlights and ignore start/end lines." }
                                        },
                                        "required": ["start_line", "end_line"]
                                    }
                                },
                                {
                                    "name": "nvim_get_messages",
                                    "description": "Retrieves the recent Neovim command-line messages, including warnings, error popups, and plugin outputs",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {
                                            "tail": { "type": "integer" }
                                        }
                                    }
                                },
                                {
                                    "name": "nvim_get_viewport",
                                    "description": "Retrieves the exact range of lines currently visible on your screen",
                                    "inputSchema": {
                                        "type": "object",
                                        "properties": {}
                                    }
                                }
                            ]
                        })),
                        error: None,
                    }).await;
                }
                "tools/call" => {
                    let params = msg.params.unwrap_or(json!({}));
                    let name = params.get("name").and_then(|n| n.as_str()).unwrap_or("");
                    let default_args = json!({});
                    let args = params.get("arguments").unwrap_or(&default_args);

                    match name {
                        "nvim_goto_line" => {
                            if let (Some(file), Some(line)) = (
                                args.get("file").and_then(|v| v.as_str()),
                                args.get("line").and_then(serde_json::Value::as_i64),
                            ) {
                                let escaped_file = file.replace('\\', "\\\\");
                                let cmd = format!("e {escaped_file} | {line} | normal! zz");
                                match send_nvim_command(&cmd).await {
                                    Ok(()) => {
                                        send_text_result!(
                                            id.clone(),
                                            format!(
                                                "Successfully jumped to {} line {}",
                                                file, line
                                            )
                                        );
                                    }
                                    Err(e) => send_error(id, -32603, &e).await,
                                }
                            } else {
                                send_error(id, -32602, "Missing 'file' or 'line'").await;
                            }
                        }
                        "nvim_get_active_buffer" => match get_nvim_active_buffer().await {
                            Ok(content) => {
                                send_text_result!(id.clone(), content);
                            }
                            Err(e) => send_error(id, -32603, &e).await,
                        },
                        "nvim_get_cursor" => match get_nvim_cursor().await {
                            Ok(content) => {
                                send_text_result!(id.clone(), content);
                            }
                            Err(e) => send_error(id, -32603, &e).await,
                        },
                        "nvim_get_visual_selection" => match get_nvim_visual_selection().await {
                            Ok(content) => {
                                send_text_result!(id.clone(), content);
                            }
                            Err(e) => send_error(id, -32603, &e).await,
                        },
                        "nvim_set_diagnostics" => {
                            if let (Some(line), Some(message)) = (
                                args.get("line").and_then(serde_json::Value::as_i64),
                                args.get("message").and_then(|v| v.as_str()),
                            ) {
                                match set_nvim_diagnostics(line, message).await {
                                    Ok(()) => {
                                        send_text_result!(
                                            id.clone(),
                                            format!("Successfully set diagnostic on line {}", line)
                                        );
                                    }
                                    Err(e) => send_error(id, -32603, &e).await,
                                }
                            } else {
                                send_error(id, -32602, "Missing 'line' or 'message'").await;
                            }
                        }
                        "nvim_list_buffers" => {
                            let lua_code = r"
                                local bufs = vim.api.nvim_list_bufs()
                                local result = {}
                                for _, buf in ipairs(bufs) do
                                    if vim.api.nvim_buf_is_loaded(buf) then
                                        local name = vim.api.nvim_buf_get_name(buf)
                                        table.insert(result, { id = buf, name = name })
                                    end
                                end
                                return vim.fn.json_encode(result)
                            ";
                            handle_lua_result!(id, execute_nvim_lua(lua_code))
                        }
                        "nvim_get_diagnostics" => {
                            let lua_code = r"
                                local bufnr = vim.api.nvim_get_current_buf()
                                local diagnostics = vim.diagnostic.get(bufnr)
                                local result = {}
                                for _, d in ipairs(diagnostics) do
                                    table.insert(result, {
                                        lnum = d.lnum,
                                        col = d.col,
                                        severity = d.severity,
                                        message = d.message,
                                        source = d.source
                                    })
                                end
                                return vim.fn.json_encode(result)
                            ";
                            handle_lua_result!(id, execute_nvim_lua(lua_code))
                        }

                        "nvim_open_file" => {
                            let args_rmp = json_to_rmpv(args);
                            let code = "
                                local args = ...
                                vim.cmd('edit ' .. vim.fn.fnameescape(args.file))
                                if args.filetype and args.filetype ~= '' then
                                    vim.bo.filetype = args.filetype
                                end
                                return 'Opened file ' .. args.file
                            ";
                            handle_lua_result!(id, execute_nvim_lua_with_args(code, vec![args_rmp]))
                        }
                        "nvim_open_buffer" => {
                            let args_rmp = json_to_rmpv(args);
                            let code = "
                                local args = ...
                                local buf = vim.api.nvim_create_buf(true, true)
                                if args.name and args.name ~= '' then
                                    pcall(vim.api.nvim_buf_set_name, buf, args.name)
                                end
                                if args.content then
                                    local lines = vim.split(args.content, '\\n')
                                    vim.api.nvim_buf_set_lines(buf, 0, -1, false, lines)
                                end
                                if args.filetype and args.filetype ~= '' then
                                    vim.bo[buf].filetype = args.filetype
                                end
                                vim.api.nvim_win_set_buf(0, buf)
                                return 'Opened buffer ' .. tostring(buf)
                            ";
                            handle_lua_result!(id, execute_nvim_lua_with_args(code, vec![args_rmp]))
                        }
                        "nvim_close_buffer" => {
                            let args_rmp = json_to_rmpv(args);
                            let code = "
                                local args = ...
                                local buf = args.buf_id or vim.api.nvim_get_current_buf()
                                local force = args.force or false
                                vim.api.nvim_buf_delete(buf, { force = force })
                                return 'Closed buffer ' .. tostring(buf)
                            ";
                            handle_lua_result!(id, execute_nvim_lua_with_args(code, vec![args_rmp]))
                        }
                        "nvim_split_window" => {
                            let args_rmp = json_to_rmpv(args);
                            let code = "
                                local args = ...
                                local cmd = args.direction == 'horizontal' and 'split' or 'vsplit'
                                vim.cmd(cmd)
                                if args.file and args.file ~= '' then
                                    vim.cmd('edit ' .. vim.fn.fnameescape(args.file))
                                elseif args.buf_id then
                                    vim.api.nvim_win_set_buf(0, args.buf_id)
                                end
                                return 'Split window created'
                            ";
                            handle_lua_result!(id, execute_nvim_lua_with_args(code, vec![args_rmp]))
                        }
                        "nvim_reload_buffer" => {
                            let args_rmp = json_to_rmpv(args);
                            let code = "
                                local args = ...
                                local buf = args.buf_id or vim.api.nvim_get_current_buf()
                                vim.api.nvim_buf_call(buf, function()
                                    if args.force then
                                        vim.cmd('edit!')
                                    else
                                        vim.cmd('edit')
                                    end
                                end)
                                return 'Reloaded buffer ' .. tostring(buf)
                            ";
                            handle_lua_result!(id, execute_nvim_lua_with_args(code, vec![args_rmp]))
                        }
                        "nvim_save_buffer" => {
                            let code = "
                                vim.cmd('write')
                                return 'Saved current buffer'
                            ";
                            handle_lua_result!(id, execute_nvim_lua(code));
                        }
                        "nvim_set_quickfix" => {
                            let args_rmp = json_to_rmpv(args);
                            let code = "
                                local args = ...
                                local items = args.items or {}
                                local action = ' '
                                if args.action == 'append' then action = 'a' end
                                if args.action == 'prepend' then action = 'p' end
                                if args.action == 'replace' then action = 'r' end
                                vim.fn.setqflist(items, action)
                                vim.cmd('copen')
                                return 'Populated quickfix with ' .. tostring(#items) .. ' items'
                            ";
                            handle_lua_result!(id, execute_nvim_lua_with_args(code, vec![args_rmp]))
                        }
                        "nvim_highlight_lines" => {
                            let args_rmp = json_to_rmpv(args);
                            let code = "
                                local args = ...
                                local buf = args.buf_id or vim.api.nvim_get_current_buf()
                                local group = args.group or 'IncSearch'
                                local ns = vim.api.nvim_create_namespace('antigravity_highlight')

                                if args.clear_only then
                                    vim.api.nvim_buf_clear_namespace(buf, ns, 0, -1)
                                    return 'Cleared highlights'
                                end

                                vim.api.nvim_buf_clear_namespace(buf, ns, 0, -1)
                                for i = args.start_line - 1, args.end_line - 1 do
                                    pcall(vim.api.nvim_buf_add_highlight, buf, ns, group, i, 0, -1)
                                end

                                local duration = args.duration_ms or 5000
                                if duration > 0 then
                                    vim.defer_fn(function()
                                        pcall(vim.api.nvim_buf_clear_namespace, buf, ns, 0, -1)
                                    end, duration)
                                end
                                return 'Highlighted lines ' .. tostring(args.start_line) .. ' to ' .. tostring(args.end_line)
                            ";
                            handle_lua_result!(id, execute_nvim_lua_with_args(code, vec![args_rmp]))
                        }
                        "nvim_get_messages" => {
                            let args_rmp = json_to_rmpv(args);
                            let code = "
                                local args = ...
                                local msg = vim.fn.execute('messages')
                                local lines = vim.split(msg, '\\n')
                                if args.tail and args.tail > 0 and #lines > args.tail then
                                    local tail_lines = {}
                                    for i = #lines - args.tail + 1, #lines do
                                        table.insert(tail_lines, lines[i])
                                    end
                                    return table.concat(tail_lines, '\\n')
                                end
                                return msg
                            ";
                            handle_lua_result!(id, execute_nvim_lua_with_args(code, vec![args_rmp]))
                        }
                        "nvim_get_viewport" => {
                            let code = "
                                local first = vim.fn.line('w0')
                                local last = vim.fn.line('w$')
                                local lines = vim.api.nvim_buf_get_lines(0, first - 1, last, false)
                                local res = {}
                                for i, line in ipairs(lines) do
                                    table.insert(res, tostring(first + i - 1) .. ': ' .. line)
                                end
                                return table.concat(res, '\\n')
                            ";
                            match execute_nvim_lua(code).await {
                                Ok(res) => send_text_result!(id.clone(), res),
                                Err(e) => send_error(id, -32603, &e).await,
                            }
                        }

                        "nvim_execute_lua" => {
                            if let Some(code) = args.get("code").and_then(|v| v.as_str()) {
                                // BAKE IN: Block interactive prompts that cause server deadlocks
                                let lower_code = code.to_lowercase();
                                if lower_code.contains("vim.fn.input")
                                    || lower_code.contains("vim.ui.select")
                                    || lower_code.contains("vim.fn.confirm")
                                    || lower_code.contains("vim.ui.input")
                                {
                                    send_error(id, -32600, "CRITICAL ERROR: Interactive Lua functions (input, select, confirm) are strictly forbidden via MCP as they will hang the headless server.").await;
                                    return;
                                }
                                // Block the 'c' confirm flag in vim.cmd substitutions
                                if (code.contains("vim.cmd")
                                    || code.contains("vim.api.nvim_command"))
                                    && code.contains("%s")
                                    && (code.contains("gc'")
                                        || code.contains("gc\"")
                                        || code.contains("gc\n")
                                        || code.contains("c'")
                                        || code.contains("c\""))
                                {
                                    send_error(id, -32600, "CRITICAL ERROR: The 'c' (confirm) flag in Neovim substitutions is strictly forbidden via MCP as it triggers an interactive prompt that hangs the headless server. Use '/g' or '/ge' instead.").await;
                                    return;
                                }

                                handle_lua_result!(id, execute_nvim_lua(code));
                            } else {
                                send_error(id, -32602, "Missing 'code'").await;
                            }
                        }
                        _ => send_error(id, -32601, "Method not found").await,
                    }
                }
                _ => {
                    if id.is_null() {
                        // Ignore notifications silently
                    } else {
                        send_error(id, -32601, "Method not found").await;
                    }
                }
            }
        });
    }
}

fn init_logging(app_name: &str) -> tracing_appender::non_blocking::WorkerGuard {
    let log_dir = dirs::home_dir()
        .unwrap_or_default()
        .join(".gemini/mcp_memory/logs");
    std::fs::create_dir_all(&log_dir).unwrap_or_default();

    let file_appender = tracing_appender::rolling::daily(log_dir, format!("{app_name}.log"));
    let (non_blocking, guard) = tracing_appender::non_blocking(file_appender);

    let _ = tracing_subscriber::fmt()
        .with_writer(non_blocking)
        .with_ansi(false)
        .with_max_level(tracing::Level::INFO)
        .try_init();

    guard
}

#[cfg(test)]
mod tests {
    use super::*;
    use tokio::io::BufReader;

    #[test]
    fn test_rmpv_to_json_primitives() {
        assert_eq!(rmpv_to_json(&rmpv::Value::Nil), serde_json::Value::Null);
        assert_eq!(rmpv_to_json(&rmpv::Value::Boolean(true)), json!(true));
        assert_eq!(rmpv_to_json(&rmpv::Value::Integer(42.into())), json!(42));
        assert_eq!(
            rmpv_to_json(&rmpv::Value::String("hello".into())),
            json!("hello")
        );
    }

    #[test]
    fn test_rmpv_to_json_array() {
        let arr = rmpv::Value::Array(vec![
            rmpv::Value::Integer(1.into()),
            rmpv::Value::String("test".into()),
        ]);
        assert_eq!(rmpv_to_json(&arr), json!([1, "test"]));
    }

    #[test]
    fn test_rmpv_to_json_map() {
        let map = vec![(
            rmpv::Value::String("key1".into()),
            rmpv::Value::Integer(100.into()),
        )];
        let rmp_map = rmpv::Value::Map(map);

        let json_map = rmpv_to_json(&rmp_map);
        assert_eq!(json_map, json!({ "key1": 100 }));
    }

    #[tokio::test]
    async fn test_read_message_jsonl() {
        let input = "{\"jsonrpc\": \"2.0\", \"id\": 1, \"method\": \"test\"}\n";
        let mut reader = BufReader::new(input.as_bytes());
        let raw = mcp_stdio::read_mcp_message(&mut reader).await.unwrap();
        let req: JsonRpcRequest = serde_json::from_str(&raw).unwrap();
        assert_eq!(req.method, "test");
    }

    #[tokio::test]
    async fn test_read_message_http_headers() {
        let payload = "{\"jsonrpc\": \"2.0\", \"id\": 2, \"method\": \"test2\"}";
        let input = format!("Content-Length: {}\r\n\r\n{}", payload.len(), payload);
        let mut reader = BufReader::new(input.as_bytes());
        let raw = mcp_stdio::read_mcp_message(&mut reader).await.unwrap();
        let req: JsonRpcRequest = serde_json::from_str(&raw).unwrap();
        assert_eq!(req.method, "test2");
    }

    #[tokio::test]
    async fn test_read_message_malformed() {
        let input = "Content-Length: abc\r\n\r\n{}";
        let mut reader = BufReader::new(input.as_bytes());
        let req = mcp_stdio::read_mcp_message(&mut reader).await;
        assert!(req.is_none());
    }
}