use crate::router::McpTool;
use crate::state::MemoryState;
use crate::tools::{ProcessLogAction, ProcessLogsTool};
use async_trait::async_trait;
use serde_json::Value;
use std::fs::File;
use std::io::{Read, Seek, SeekFrom};
use std::sync::Arc;

pub struct ProcessLogsHandler;

#[async_trait]
impl McpTool for ProcessLogsHandler {
    fn name(&self) -> &'static str {
        "process_logs"
    }

    fn schema(&self) -> Value {
        crate::mcp::tool_def::<ProcessLogsTool>(
            "process_logs",
            "Monitor, tail, and manage process logs: watch a log file, tail recent output, or clear log files.",
        )
    }

    async fn execute(&self, args: Value, _state: Arc<MemoryState>) -> crate::error::Result<String> {
        let tool_args: ProcessLogsTool = serde_json::from_value(args).map_err(|e| e.to_string())?;
        let safe_path = crate::handlers::utils::validate_safe_path(&tool_args.file_path)?;

        match tool_args.action {
            ProcessLogAction::Watch => {
                if !safe_path.exists() {
                    return Err(crate::error::AppError::Internal(format!(
                        "File does not exist: {}",
                        tool_args.file_path
                    )));
                }
                Ok(format!("Started watching logs for {}", tool_args.file_path))
            }
            ProcessLogAction::Get => {
                let max_lines = tool_args.max_lines.unwrap_or(100);
                let result =
                    tokio::task::spawn_blocking(move || -> crate::error::Result<String> {
                        let mut file = File::open(&safe_path).map_err(|e| {
                            crate::error::AppError::Internal(format!("Failed to open file: {}", e))
                        })?;
                        let len = file.metadata().map_err(|e| e.to_string())?.len();

                        let read_size = std::cmp::min(16 * 1024, len);
                        file.seek(SeekFrom::End(-(read_size as i64)))
                            .map_err(|e| e.to_string())?;

                        let mut vec_buf = Vec::new();
                        file.read_to_end(&mut vec_buf).map_err(|e| e.to_string())?;

                        let buffer = String::from_utf8_lossy(&vec_buf).to_string();
                        let lines: Vec<&str> = buffer.lines().collect();
                        let recent_lines = if lines.len() > max_lines {
                            lines[lines.len() - max_lines..].join("\n")
                        } else {
                            buffer
                        };

                        Ok(recent_lines)
                    })
                    .await
                    .map_err(|e| {
                        crate::error::AppError::Internal(format!("Task panic: {}", e))
                    })??;

                Ok(result)
            }
            ProcessLogAction::Clear => {
                if safe_path.exists() {
                    std::fs::write(&safe_path, "").map_err(|e| {
                        crate::error::AppError::Internal(format!("Failed to clear log file: {}", e))
                    })?;
                }
                Ok(format!("Cleared logs in {}", tool_args.file_path))
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use serde_json::json;
    use std::sync::Arc;
    use tempfile::tempdir;

    #[tokio::test]
    async fn test_process_logs_watch() {
        let dir = tempdir().unwrap();
        let state = Arc::new(MemoryState::new(dir.path().to_str().unwrap()));
        let handler = ProcessLogsHandler;

        let log_file = dir.path().join("test.log");
        std::fs::write(&log_file, "line1\nline2").unwrap();

        let args = json!({
            "action": "watch",
            "file_path": log_file.to_str().unwrap()
        });

        let result = handler
            .execute(args, state)
            .await
            .map_err(|e| format!("Failed to watch logs: {}", e))
            .unwrap();
        assert!(result.contains("Started watching logs"));
    }

    #[tokio::test]
    async fn test_process_logs_get() {
        let dir = tempdir().unwrap();
        let state = Arc::new(MemoryState::new(dir.path().to_str().unwrap()));
        let handler = ProcessLogsHandler;

        let log_file = dir.path().join("test_recent.log");
        std::fs::write(&log_file, "line1\nline2\nline3").unwrap();

        let args = json!({
            "action": "get",
            "file_path": log_file.to_str().unwrap()
        });

        let result = handler
            .execute(args, state)
            .await
            .map_err(|e| format!("Failed to get recent logs: {}", e))
            .unwrap();
        assert!(result.contains("line1"));
        assert!(result.contains("line3"));
    }

    #[tokio::test]
    async fn test_process_logs_clear() {
        let dir = tempdir().unwrap();
        let state = Arc::new(MemoryState::new(dir.path().to_str().unwrap()));
        let handler = ProcessLogsHandler;

        let log_file = dir.path().join("test_clear.log");
        std::fs::write(&log_file, "line1\nline2\nline3").unwrap();

        let args = json!({
            "action": "clear",
            "file_path": log_file.to_str().unwrap()
        });

        let result = handler.execute(args, state.clone()).await.unwrap();
        assert!(result.contains("Cleared logs"));

        let content = std::fs::read_to_string(&log_file).unwrap();
        assert_eq!(content, "");
    }

    #[tokio::test]
    async fn test_process_logs_get_with_large_file() {
        let dir = tempfile::tempdir().unwrap();
        let state = Arc::new(MemoryState::new(dir.path().to_str().unwrap()));
        let handler = ProcessLogsHandler;

        let log_file = dir.path().join("large_test.log");
        let mut buffer = String::new();
        for _ in 0..1000 {
            buffer.push_str("line\n");
        }
        std::fs::write(&log_file, buffer).unwrap();

        let args = serde_json::json!({
            "action": "get",
            "file_path": log_file.to_str().unwrap()
        });

        let result = handler
            .execute(args, state)
            .await
            .map_err(|e| format!("Failed to get recent logs: {}", e))
            .unwrap();
        assert!(result.contains("line"));
    }
}