use std::process::Command;
use std::io::{BufRead, BufReader};
use std::time::{Duration, Instant};
use std::thread;
use std::sync::{Arc, Mutex};
use std::sync::mpsc;
use serde::{Deserialize, Serialize};
use tauri::{AppHandle, Emitter};

/// Generic progress information from Python processes
#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct PythonProgress {
    pub step: String,
    pub progress: f64,  // -1 for indeterminate, 0-100 for percentage
    pub message: String,
    pub details: Option<serde_json::Value>,
    pub timestamp: f64,
}

/// Progress callback trait for handling Python process progress
pub trait ProgressCallback: Send + Sync {
    fn on_progress(&self, progress: PythonProgress);
}

/// Simple function-based progress callback
pub struct FunctionCallback<F>
where
    F: Fn(PythonProgress) + Send + Sync,
{
    callback: F,
}

impl<F> FunctionCallback<F>
where
    F: Fn(PythonProgress) + Send + Sync,
{
    #[allow(dead_code)]
    pub fn new(callback: F) -> Self {
        Self { callback }
    }
}

impl<F> ProgressCallback for FunctionCallback<F>
where
    F: Fn(PythonProgress) + Send + Sync,
{
    fn on_progress(&self, progress: PythonProgress) {
        (self.callback)(progress);
    }
}

/// Tauri event-based progress callback
pub struct TauriEventCallback {
    app: AppHandle,
    event_name: String,
}

impl TauriEventCallback {
    pub fn new(app: AppHandle, event_name: String) -> Self {
        Self { app, event_name }
    }
}

impl ProgressCallback for TauriEventCallback {
    fn on_progress(&self, progress: PythonProgress) {
        let _ = self.app.emit(&self.event_name, &progress);
    }
}

/// Configuration for Python command execution
pub struct PythonExecutorConfig {
    pub timeout_seconds: u64,
    pub working_directory: Option<std::path::PathBuf>,
}

impl Default for PythonExecutorConfig {
    fn default() -> Self {
        Self {
            timeout_seconds: 600, // 10 minutes default
            working_directory: None,
        }
    }
}

/// Execute a Python command with progress callback support
///
/// This function handles:
/// - Multiple Python command attempts (python, python3, py)
/// - UTF-8 encoding setup
/// - Concurrent stdout/stderr reading
/// - JSON-RPC message parsing
/// - Progress notifications via callback
/// - Timeout handling
pub async fn execute_python_command_with_progress<P>(
    app: tauri::AppHandle,
    args: &[String],
    config: Option<PythonExecutorConfig>,
    progress_callback: Option<P>,
) -> Result<String, String>
where
    P: ProgressCallback + 'static,
{
    execute_python_internal(app, args, config, progress_callback).await
}

/// Execute a Python command with the given arguments (legacy interface)
///
/// This function handles:
/// - Multiple Python command attempts (python, python3, py)
/// - UTF-8 encoding setup
/// - Concurrent stdout/stderr reading
/// - JSON-RPC message parsing
/// - Timeout handling
/// - Detailed error reporting
pub async fn execute_python_command(
    app: tauri::AppHandle,
    args: &[String],
    config: Option<PythonExecutorConfig>
) -> Result<String, String> {
    execute_python_internal(app, args, config, None::<FunctionCallback<fn(PythonProgress)>>).await
}

/// Execute Python command with a simple function callback
#[allow(dead_code)]
pub async fn execute_python_with_callback<F>(
    app: tauri::AppHandle,
    args: &[String],
    config: Option<PythonExecutorConfig>,
    callback: F,
) -> Result<String, String>
where
    F: Fn(PythonProgress) + Send + Sync + 'static,
{
    let progress_callback = FunctionCallback::new(callback);
    execute_python_command_with_progress(app, args, config, Some(progress_callback)).await
}

/// Execute Python command with Tauri event emission
pub async fn execute_python_with_events(
    app: tauri::AppHandle,
    args: &[String],
    config: Option<PythonExecutorConfig>,
    event_name: &str,
) -> Result<String, String> {
    let progress_callback = TauriEventCallback::new(app.clone(), event_name.to_string());
    execute_python_command_with_progress(app, args, config, Some(progress_callback)).await
}

/// Python command builder for easier command construction
#[allow(dead_code)]
pub struct PythonCommandBuilder {
    module: String,
    args: Vec<(String, String)>,
}

#[allow(dead_code)]
impl PythonCommandBuilder {
    pub fn new(module: &str) -> Self {
        Self {
            module: module.to_string(),
            args: Vec::new(),
        }
    }

    pub fn arg(mut self, key: &str, value: &str) -> Self {
        self.args.push((key.to_string(), value.to_string()));
        self
    }

    pub fn action(self, action: &str) -> Self {
        self.arg("--action", action)
    }

    pub fn build(self) -> Vec<String> {
        let mut result = vec![
            "-m".to_string(),
            self.module,
        ];

        for (key, value) in self.args {
            result.push(key);
            result.push(value);
        }

        result
    }
}

/// Execute a Python module with progress support
#[allow(dead_code)]
pub async fn execute_python_module_with_progress(
    app: tauri::AppHandle,
    module: &str,
    action: &str,
    params: Vec<(&str, &str)>,
    event_name: &str,
    config: Option<PythonExecutorConfig>,
) -> Result<String, String> {
    let mut builder = PythonCommandBuilder::new(module).action(action);

    for (key, value) in params {
        builder = builder.arg(key, value);
    }

    let args = builder.build();
    execute_python_with_events(app, &args, config, event_name).await
}

/// Helper function to create Python module commands with progress
///
/// # Arguments
/// * `app` - Tauri app handle
/// * `module` - Python module path (e.g., "python_core.services.template_manager")
/// * `action` - Action to perform (e.g., "batch_import")
/// * `params` - Additional parameters as key-value pairs
/// * `event_name` - Event name for progress updates
/// * `config` - Optional executor configuration
#[allow(dead_code)]
pub async fn execute_python_action_with_progress(
    app: tauri::AppHandle,
    module: &str,
    action: &str,
    params: &[(&str, &str)],
    event_name: &str,
    config: Option<PythonExecutorConfig>,
) -> Result<String, String> {
    let mut args = vec![
        "-m".to_string(),
        module.to_string(),
        "--action".to_string(),
        action.to_string(),
    ];

    // Add additional parameters
    for (key, value) in params {
        args.push(key.to_string());
        args.push(value.to_string());
    }

    execute_python_with_events(app, &args, config, event_name).await
}

/// Internal implementation for Python command execution
async fn execute_python_internal<P>(
    _app: tauri::AppHandle,
    args: &[String],
    config: Option<PythonExecutorConfig>,
    progress_callback: Option<P>,
) -> Result<String, String>
where
    P: ProgressCallback + 'static,
{
    let config = config.unwrap_or_default();
    
    println!("Executing Python command with args: {:?}", args);

    // Get project root directory
    let current_dir = std::env::current_dir()
        .map_err(|e| format!("Failed to get current directory: {}", e))?;

    let project_root = if let Some(working_dir) = config.working_directory {
        working_dir
    } else if current_dir.ends_with("src-tauri") {
        current_dir.parent().unwrap_or(&current_dir).to_path_buf()
    } else {
        current_dir
    };

    println!("Working directory: {:?}", project_root);

    // Try multiple Python commands in order of preference
    let python_commands = if cfg!(target_os = "windows") {
        vec!["python", "python3", "py"]
    } else {
        vec!["python3", "python"]
    };

    let mut child = None;
    let mut last_error = String::new();

    for python_cmd in python_commands {
        println!("Trying Python command: {}", python_cmd);
        let mut cmd = Command::new(python_cmd);
        cmd.current_dir(&project_root);
        cmd.args(args);
        cmd.stdout(std::process::Stdio::piped());
        cmd.stderr(std::process::Stdio::piped());

        // Set environment variables for consistent encoding
        cmd.env("PYTHONIOENCODING", "utf-8");
        cmd.env("PYTHONUNBUFFERED", "1");

        // On Windows, ensure UTF-8 console output
        if cfg!(target_os = "windows") {
            cmd.env("PYTHONUTF8", "1");
        }

        match cmd.spawn() {
            Ok(process) => {
                println!("Successfully started Python process with: {}", python_cmd);
                child = Some(process);
                break;
            }
            Err(e) => {
                last_error = format!("Failed to start {} process: {}", python_cmd, e);
                println!("{}", last_error);
                continue;
            }
        }
    }

    let mut child = child.ok_or_else(|| {
        format!("Failed to start Python process with any command. Last error: {}", last_error)
    })?;

    let stdout = child.stdout.take().unwrap();
    let stderr = child.stderr.take().unwrap();

    // Use channels for concurrent reading
    let (stdout_tx, _stdout_rx) = mpsc::channel();
    let (stderr_tx, _stderr_rx) = mpsc::channel();
    let (result_tx, result_rx) = mpsc::channel();

    let progress_messages = Arc::new(Mutex::new(Vec::new()));
    let error_messages = Arc::new(Mutex::new(Vec::new()));
    let final_result = Arc::new(Mutex::new(None::<String>));

    // Wrap progress callback in Arc for thread sharing
    let progress_callback = Arc::new(progress_callback);

    // Spawn thread for reading stdout
    let progress_messages_clone = Arc::clone(&progress_messages);
    let final_result_clone = Arc::clone(&final_result);
    let progress_callback_clone = Arc::clone(&progress_callback);
    thread::spawn(move || {
        let mut reader = BufReader::new(stdout);
        let mut buffer = Vec::new();

        // Read raw bytes and handle encoding issues
        loop {
            buffer.clear();
            match reader.read_until(b'\n', &mut buffer) {
                Ok(0) => break, // EOF
                Ok(_) => {
                    // Convert bytes to string, handling invalid UTF-8
                    let line = String::from_utf8_lossy(&buffer);
                    let line = line.trim_end_matches('\n').trim_end_matches('\r');

                    if line.is_empty() {
                        continue;
                    }
                    println!("Python stdout: {}", line);

                    // Parse JSON-RPC messages
                    if line.starts_with("JSONRPC:") {
                        let json_str = &line[8..]; // Remove "JSONRPC:" prefix
                        if let Ok(json_value) = serde_json::from_str::<serde_json::Value>(json_str) {
                            if let Some(method) = json_value.get("method") {
                                if method == "progress" {
                                    // Store progress message
                                    if let Ok(mut messages) = progress_messages_clone.lock() {
                                        messages.push(json_str.to_string());
                                    }

                                    // Call progress callback if available
                                    if let Some(ref callback) = *progress_callback_clone {
                                        if let Some(params) = json_value.get("params") {
                                            // Try to parse as PythonProgress
                                            if let Ok(progress) = serde_json::from_value::<PythonProgress>(params.clone()) {
                                                callback.on_progress(progress);
                                            } else {
                                                // Fallback: create basic progress from available data
                                                let step = params.get("step")
                                                    .and_then(|v| v.as_str())
                                                    .unwrap_or("unknown")
                                                    .to_string();
                                                let message = params.get("message")
                                                    .and_then(|v| v.as_str())
                                                    .unwrap_or("")
                                                    .to_string();
                                                let progress_val = params.get("progress")
                                                    .and_then(|v| v.as_f64())
                                                    .unwrap_or(-1.0);

                                                let progress = PythonProgress {
                                                    step,
                                                    progress: progress_val,
                                                    message,
                                                    details: Some(params.clone()),
                                                    timestamp: std::time::SystemTime::now()
                                                        .duration_since(std::time::UNIX_EPOCH)
                                                        .unwrap_or_default()
                                                        .as_secs_f64(),
                                                };
                                                callback.on_progress(progress);
                                            }
                                        }
                                    }
                                    println!("Progress: {}", json_str);
                                }
                            } else if json_value.get("result").is_some() || json_value.get("error").is_some() {
                                // This is a final result or error response
                                if let Ok(mut result) = final_result_clone.lock() {
                                    // Extract the result or error content from JSON-RPC
                                    if let Some(result_content) = json_value.get("result") {
                                        *result = Some(result_content.to_string());
                                    } else if let Some(error_content) = json_value.get("error") {
                                        *result = Some(format!("{{\"status\":false,\"error\":{}}}", error_content));
                                    }
                                };
                            }
                        }
                    } else if line.trim().starts_with('{') && line.trim().ends_with('}') {
                        // Fallback: try to parse as direct JSON result
                        if let Ok(json_value) = serde_json::from_str::<serde_json::Value>(line.trim()) {
                            // Check if this looks like a final result (has status field)
                            if json_value.get("status").is_some() {
                                if let Ok(mut result) = final_result_clone.lock() {
                                    *result = Some(line.trim().to_string());
                                }
                                println!("Direct JSON result: {}", line.trim());
                            }
                        }
                    } else {
                        println!("Python other: {}", line);
                    }

                    if stdout_tx.send(line.to_string()).is_err() {
                        break;
                    }
                }
                Err(e) => {
                    println!("Error reading stdout: {}", e);
                    break;
                }
            }
        }
    });

    // Spawn thread for reading stderr
    let error_messages_clone = Arc::clone(&error_messages);
    thread::spawn(move || {
        let mut reader = BufReader::new(stderr);
        let mut buffer = Vec::new();

        // Read raw bytes and handle encoding issues
        loop {
            buffer.clear();
            match reader.read_until(b'\n', &mut buffer) {
                Ok(0) => break, // EOF
                Ok(_) => {
                    // Convert bytes to string, handling invalid UTF-8
                    let line = String::from_utf8_lossy(&buffer);
                    let line = line.trim_end_matches('\n').trim_end_matches('\r');

                    if line.is_empty() {
                        continue;
                    }

                    println!("Python stderr: {}", line);
                    if let Ok(mut messages) = error_messages_clone.lock() {
                        messages.push(line.to_string());
                    }
                    if stderr_tx.send(line.to_string()).is_err() {
                        break;
                    }
                }
                Err(e) => {
                    println!("Error reading stderr: {}", e);
                    break;
                }
            }
        }
    });

    // Spawn thread to wait for process completion
    thread::spawn(move || {
        match child.wait() {
            Ok(status) => {
                let _ = result_tx.send(Ok(status));
            }
            Err(e) => {
                let _ = result_tx.send(Err(format!("Failed to wait for process: {}", e)));
            }
        }
    });

    // Wait for process to complete with timeout
    println!("Waiting for Python process to complete...");
    let timeout_duration = Duration::from_secs(config.timeout_seconds);
    let start_time = Instant::now();

    let exit_status = loop {
        match result_rx.try_recv() {
            Ok(Ok(status)) => break status,
            Ok(Err(e)) => return Err(e),
            Err(mpsc::TryRecvError::Empty) => {
                if start_time.elapsed() > timeout_duration {
                    return Err(format!("Python process timed out after {} seconds", config.timeout_seconds));
                }
                thread::sleep(Duration::from_millis(100));
                continue;
            }
            Err(mpsc::TryRecvError::Disconnected) => {
                return Err("Process monitoring thread disconnected".to_string());
            }
        }
    };

    println!("Python process terminated with code: {:?}", exit_status.code());

    // Extract final results from shared state
    let final_result_value = {
        final_result.lock().unwrap().clone()
    };
    let progress_messages_value = {
        progress_messages.lock().unwrap().clone()
    };
    let error_messages_value = {
        error_messages.lock().unwrap().clone()
    };

    // Return the final result if we found one
    if let Some(result) = final_result_value {
        println!("Extracted JSON-RPC result: {}", result);
        return Ok(result);
    }

    // If no JSON-RPC result found, provide detailed error information
    if exit_status.success() {
        // Process succeeded but no output - this is unusual
        let error_msg = if progress_messages_value.is_empty() {
            "Python script completed successfully but produced no output"
        } else {
            "Python script completed but did not return a valid JSON result"
        };
        Err(error_msg.to_string())
    } else {
        // Process failed - provide detailed error based on exit code
        let error_msg = if let Some(code) = exit_status.code() {
            let unsigned_code = code as u32;
            match code {
                1 => "Python script failed with general error. Check if all dependencies are installed.".to_string(),
                120 => "Python module import failed or function not supported. This may be due to missing dependencies or incompatible Python environment. Please run the environment test first.".to_string(),
                -1073741510 => "Python process was terminated by antivirus or system security. Please add the application to your antivirus whitelist.".to_string(),
                _ if unsigned_code == 3221225786 => "Python process was terminated by antivirus or system security. Please add the application to your antivirus whitelist.".to_string(),
                _ => format!("Python script failed with exit code: {}. This may indicate a system or environment issue.", code)
            }
        } else {
            "Python process was killed by external signal. This may be caused by antivirus software or system security policies.".to_string()
        };

        // Include any error output we captured
        let mut full_error = error_msg;

        if !progress_messages_value.is_empty() {
            full_error.push_str(&format!("\n\nLast stdout: {}", progress_messages_value.join("\n")));
        }

        if !error_messages_value.is_empty() {
            full_error.push_str(&format!("\n\nStderr: {}", error_messages_value.join("\n")));
        }

        Err(full_error)
    }
}