use crate::audio::AudioEngine;
use crate::config::Config;
use std::io::{Read, Write};
use std::os::unix::net::{UnixListener, UnixStream};
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::{Arc, Mutex};
use std::thread;
use std::time::Duration;

#[derive(Debug, Clone)]
enum ShuffleMode {
    None,
    All,
    Album,
}

struct Queue {
    tracks: Vec<PathBuf>,
    position: usize,
    shuffle: ShuffleMode,
    shuffled_indices: Vec<usize>,
}

impl Queue {
    fn new() -> Self {
        Queue {
            tracks: Vec::new(),
            position: 0,
            shuffle: ShuffleMode::None,
            shuffled_indices: Vec::new(),
        }
    }

    fn add_track(&mut self, path: PathBuf) {
        self.tracks.push(path);
        self.update_shuffle_indices();
    }

    fn set_shuffle(&mut self, mode: ShuffleMode) {
        self.shuffle = mode.clone();
        self.update_shuffle_indices();
    }

    fn update_shuffle_indices(&mut self) {
        self.shuffled_indices = (0..self.tracks.len()).collect();
        if let ShuffleMode::All = self.shuffle {
            use rand::seq::SliceRandom;
            let mut rng = rand::rng();
            self.shuffled_indices.shuffle(&mut rng);
        }
    }

    fn current(&self) -> Option<&PathBuf> {
        if self.tracks.is_empty() {
            None
        } else if let ShuffleMode::All = self.shuffle {
            self.shuffled_indices
                .get(self.position)
                .and_then(|&idx| self.tracks.get(idx))
        } else if let ShuffleMode::Album = self.shuffle {
            // TODO: When database is ready, only shuffle tracks in same album/folder
            // For now, behave like All
            self.shuffled_indices
                .get(self.position)
                .and_then(|&idx| self.tracks.get(idx))
        } else {
            self.tracks.get(self.position)
        }
    }

    fn next(&mut self) -> Option<PathBuf> {
        let max_pos = self.tracks.len().saturating_sub(1);
        if self.position < max_pos {
            self.position += 1;
            self.current().cloned()
        } else {
            None
        }
    }

    fn previous(&mut self) -> Option<PathBuf> {
        if self.position > 0 {
            self.position -= 1;
            self.current().cloned()
        } else {
            None
        }
    }
}

pub fn start_daemon() -> Result<(), Box<dyn std::error::Error>> {
    let config = Config::load()?;
    let socket_path = config.get_socket_path();
    let pid_path = get_pid_path(&config);

    // Check if daemon is already running
    if let Ok(pid) = check_running_daemon(&pid_path) {
        return Err(format!("Daemon already running with PID {}", pid).into());
    }

    // Clean up stale socket file if it exists
    if socket_path.exists() {
        std::fs::remove_file(&socket_path).ok();
    }

    // Create runtime directory
    if let Some(parent) = socket_path.parent() {
        std::fs::create_dir_all(parent)?;
    }
    if let Some(parent) = pid_path.parent() {
        std::fs::create_dir_all(parent)?;
    }

    // Write PID file
    let pid = std::process::id();
    std::fs::write(&pid_path, pid.to_string())?;
    println!("Daemon started with PID {}", pid);

    // Shared shutdown flag - can be triggered by signal or command
    let shutdown_flag = Arc::new(AtomicBool::new(false));
    let shutdown_flag_signal = Arc::clone(&shutdown_flag);

    // Handle SIGTERM and SIGINT
    ctrlc::set_handler(move || {
        println!("Received shutdown signal");
        shutdown_flag_signal.store(true, Ordering::SeqCst);
    })?;

    let listener = UnixListener::bind(&socket_path)?;
    println!("Listening on {:?}", socket_path);

    let audio_engine = Arc::new(AudioEngine::new());
    let queue = Arc::new(Mutex::new(Queue::new()));

    // Load and apply saved settings
    let config = Config::load().unwrap_or_default();
    if let Some(vol) = config.volume {
        audio_engine.set_volume(vol as f32 / 100.0);
    }
    if let Some(ref shuffle_str) = config.shuffle {
        if let Ok(mut q) = queue.lock() {
            match shuffle_str.as_str() {
                "on" | "all" => q.set_shuffle(ShuffleMode::All),
                "album" => q.set_shuffle(ShuffleMode::Album),
                _ => {}
            }
        }
    }

    // Accept connections until shutdown
    listener.set_nonblocking(true)?;
    loop {
        // Check for shutdown signal
        if shutdown_flag.load(Ordering::SeqCst) {
            break;
        }

        // Check if track ended and play next
        if audio_engine.poll_track_ended() {
            if let Ok(mut q) = queue.lock() {
                if let Some(next_track) = q.next() {
                    audio_engine.play(next_track);
                } else {
                    audio_engine.stop();
                }
            }
        }

        match listener.accept() {
            Ok((stream, _)) => {
                let audio_clone = Arc::clone(&audio_engine);
                let shutdown_flag_clone = Arc::clone(&shutdown_flag);
                let queue_clone = Arc::clone(&queue);
                thread::spawn(move || {
                    handle_client(stream, audio_clone, shutdown_flag_clone, queue_clone);
                });
            }
            Err(ref e) if e.kind() == std::io::ErrorKind::WouldBlock => {
                thread::sleep(Duration::from_millis(50));
                continue;
            }
            Err(e) => eprintln!("Connection failed: {}", e),
        }

        thread::sleep(Duration::from_millis(50));
    }

    // Cleanup
    cleanup_daemon(&socket_path, &pid_path);
    println!("Daemon stopped");
    Ok(())
}

pub fn stop_daemon() -> Result<(), Box<dyn std::error::Error>> {
    let config = Config::load()?;
    let pid_path = get_pid_path(&config);

    match check_running_daemon(&pid_path) {
        Ok(pid) => {
            // Try to send stop command first for graceful shutdown
            if let Ok(()) = send_command_raw("stop_daemon".to_string()) {
                // Wait for daemon to stop
                for _ in 0..50 {
                    thread::sleep(Duration::from_millis(100));
                    if !is_process_running(pid) {
                        break;
                    }
                }
            }

            // Force kill if still running
            if is_process_running(pid) {
                unsafe {
                    libc::kill(pid as i32, libc::SIGTERM);
                }
                thread::sleep(Duration::from_millis(500));

                // Force kill if still alive
                if is_process_running(pid) {
                    unsafe {
                        libc::kill(pid as i32, libc::SIGKILL);
                    }
                }
            }

            // Clean up files
            let socket_path = config.get_socket_path();
            std::fs::remove_file(&socket_path).ok();
            std::fs::remove_file(&pid_path).ok();

            println!("Daemon stopped");
            Ok(())
        }
        Err(e) => Err(format!("Daemon not running: {}", e).into()),
    }
}

pub fn restart_daemon() -> Result<(), Box<dyn std::error::Error>> {
    // Stop existing daemon
    if let Ok(()) = stop_daemon() {
        // Wait a bit for cleanup
        thread::sleep(Duration::from_millis(500));
    }

    // Start new daemon in background
    let current_exe = std::env::current_exe()?;
    std::process::Command::new(current_exe)
        .arg("start")
        .spawn()?;

    println!("Daemon restarted");
    Ok(())
}

pub fn send_command(cmd: String) -> Result<(), Box<dyn std::error::Error>> {
    send_command_raw(cmd)?;
    Ok(())
}

fn send_command_raw(cmd: String) -> Result<(), Box<dyn std::error::Error>> {
    let config = Config::load()?;
    let socket_path = config.get_socket_path();

    let mut stream = UnixStream::connect(socket_path)?;
    stream.write_all(cmd.as_bytes())?;

    let mut response = String::new();
    stream.read_to_string(&mut response)?;
    print!("{}", response);

    Ok(())
}

fn handle_client(
    mut stream: UnixStream,
    audio: Arc<AudioEngine>,
    shutdown_flag: Arc<AtomicBool>,
    queue: Arc<Mutex<Queue>>,
) {
    let mut buffer = [0; 1024];
    if let Ok(size) = stream.read(&mut buffer) {
        let cmd = String::from_utf8_lossy(&buffer[..size]);
        let response = process_command(cmd.trim(), &audio, &shutdown_flag, &queue);
        let _ = stream.write_all(response.as_bytes());
    }
}

fn process_command(
    cmd: &str,
    audio: &AudioEngine,
    shutdown_flag: &Arc<AtomicBool>,
    queue: &Arc<Mutex<Queue>>,
) -> String {
    match cmd {
        "status" => {
            if audio.is_playing() {
                if let Some(track) = audio.current_track() {
                    format!("Playing\nTrack: {}\n", track.display())
                } else {
                    "Playing\n".to_string()
                }
            } else {
                "Stopped\n".to_string()
            }
        }
        "pause" => {
            audio.pause();
            "Paused\n".to_string()
        }
        "resume" => {
            audio.resume();
            "Resumed\n".to_string()
        }
        "stop" => {
            audio.stop();
            // Clear queue on stop
            if let Ok(mut q) = queue.lock() {
                q.tracks.clear();
                q.position = 0;
            }
            "Stopped\n".to_string()
        }
        "stop_daemon" => {
            // Signal the daemon to shut down
            shutdown_flag.store(true, Ordering::SeqCst);
            "Shutting down\n".to_string()
        }
        "next" => {
            if let Ok(mut q) = queue.lock() {
                if let Some(next_track) = q.next() {
                    audio.play(next_track);
                    "Playing next track\n".to_string()
                } else {
                    audio.stop();
                    "Queue empty, stopped\n".to_string()
                }
            } else {
                "Error accessing queue\n".to_string()
            }
        }
        "previous" => {
            if let Ok(mut q) = queue.lock() {
                if let Some(prev_track) = q.previous() {
                    audio.play(prev_track);
                    "Playing previous track\n".to_string()
                } else {
                    "No previous track\n".to_string()
                }
            } else {
                "Error accessing queue\n".to_string()
            }
        }
        "shuffle" => {
            if let Ok(q) = queue.lock() {
                match q.shuffle {
                    ShuffleMode::None => "Shuffle: off\n".to_string(),
                    ShuffleMode::All => "Shuffle: on (all)\n".to_string(),
                    ShuffleMode::Album => "Shuffle: on (album)\n".to_string(),
                }
            } else {
                "Error accessing queue\n".to_string()
            }
        }
        _ if cmd.starts_with("shuffle ") => {
            let mode_str = cmd[8..].trim();
            if let Ok(mut q) = queue.lock() {
                let result = if mode_str == "on" || mode_str == "all" {
                    q.set_shuffle(ShuffleMode::All);
                    "Shuffle: on (all)\n".to_string()
                } else if mode_str == "album" {
                    q.set_shuffle(ShuffleMode::Album);
                    "Shuffle: on (album)\n".to_string()
                } else if mode_str == "off" || mode_str == "none" {
                    q.set_shuffle(ShuffleMode::None);
                    "Shuffle: off\n".to_string()
                } else {
                    "Usage: shuffle [on|off|album]\n".to_string()
                };
                // Save to config
                if let Ok(mut config) = Config::load() {
                    if mode_str == "off" || mode_str == "none" {
                        config.shuffle = None;
                    } else {
                        config.shuffle = Some(mode_str.to_string());
                    }
                    let _ = config.save();
                }
                result
            } else {
                "Error accessing queue\n".to_string()
            }
        }
        _ if cmd.starts_with("play ") => {
            let path_str = &cmd[5..].trim();
            let path = std::path::PathBuf::from(path_str);
            if path.is_file() {
                // Add to queue and play
                if let Ok(mut q) = queue.lock() {
                    q.add_track(path.clone());
                }
                audio.play(path);
                format!("Playing: {}\n", path_str)
            } else if path.is_dir() {
                // Find all audio files in directory
                match find_audio_in_dir(&path) {
                    Some(files) if !files.is_empty() => {
                        if let Ok(mut q) = queue.lock() {
                            for file in &files {
                                q.add_track(file.clone());
                            }
                            // If shuffle is on, shuffled_indices is already set
                            // Play the first track from the shuffled list
                            if let Some(track) = q.current().cloned() {
                                audio.play(track);
                            }
                        }
                        format!("Queued {} tracks from: {}\n", files.len(), path_str)
                    }
                    _ => format!("Error: No audio files found in '{}'\n", path_str),
                }
            } else {
                format!("File not found: {}\n", path_str)
            }
        }
        _ if cmd.starts_with("volume ") => {
            if let Ok(level) = cmd[7..].trim().parse::<u8>() {
                audio.set_volume(level as f32 / 100.0);
                // Save to config
                if let Ok(mut config) = Config::load() {
                    config.volume = Some(level);
                    let _ = config.save();
                }
                format!("Volume set to {}\n", level)
            } else {
                "Usage: volume <0-100>\n".to_string()
            }
        }
        _ if cmd.starts_with("shuffle ") => {
            let mode_str = cmd[8..].trim();
            if let Ok(mut q) = queue.lock() {
                if mode_str == "on" || mode_str == "all" {
                    q.set_shuffle(ShuffleMode::All);
                    "Shuffle: on\n".to_string()
                } else if mode_str == "off" || mode_str == "none" {
                    q.set_shuffle(ShuffleMode::None);
                    "Shuffle: off\n".to_string()
                } else {
                    "Usage: shuffle [on|off]\n".to_string()
                }
            } else {
                "Error accessing queue\n".to_string()
            }
        }
        _ if cmd.starts_with("queue") => {
            if let Ok(q) = queue.lock() {
                if q.tracks.is_empty() {
                    "Queue is empty\n".to_string()
                } else {
                    let mut output = String::new();
                    let current_position = q.position;
                    // Use shuffled_indices for display order if shuffle is on
                    let indices: Vec<usize> = if let ShuffleMode::None = q.shuffle {
                        (0..q.tracks.len()).collect()
                    } else {
                        q.shuffled_indices.clone()
                    };
                    for (display_idx, &track_idx) in indices.iter().enumerate() {
                        if let Some(track) = q.tracks.get(track_idx) {
                            if display_idx == current_position {
                                output.push_str(&format!("> {} (playing)\n", track.display()));
                            } else {
                                output.push_str(&format!("  {}\n", track.display()));
                            }
                        }
                    }
                    // Use pager if output is long (more than 24 lines)
                    if output.lines().count() > 24 {
                        use std::process::{Command, Stdio};
                        let pager = Command::new("less").arg("-R").stdin(Stdio::piped()).spawn();
                        if let Ok(mut child) = pager {
                            use std::io::Write;
                            let _ = child.stdin.as_mut().unwrap().write_all(output.as_bytes());
                            let _ = child.wait();
                            "".to_string()
                        } else {
                            output
                        }
                    } else {
                        output
                    }
                }
            } else {
                "Error accessing queue\n".to_string()
            }
        }
        _ => "Unknown command\n".to_string(),
    }
}

fn find_audio_in_dir(dir: &Path) -> Option<Vec<std::path::PathBuf>> {
    use std::ffi::OsStr;

    let mut results = Vec::new();

    if let Ok(entries) = std::fs::read_dir(dir) {
        let mut entries: Vec<_> = entries.filter_map(|e| e.ok()).collect();
        entries.sort_by_key(|e| e.file_name());

        for entry in entries {
            let path = entry.path();
            if path.is_file() {
                if let Some(ext) = path.extension().and_then(OsStr::to_str) {
                    if matches!(
                        ext.to_lowercase().as_str(),
                        "mp3" | "flac" | "ogg" | "m4a" | "wav" | "opus"
                    ) {
                        results.push(path);
                    }
                }
            } else if path.is_dir() {
                if let Some(mut found) = find_audio_in_dir(&path) {
                    results.append(&mut found);
                }
            }
        }
    }

    if results.is_empty() {
        None
    } else {
        Some(results)
    }
}

/// Get the PID file path for the daemon
fn get_pid_path(_config: &Config) -> std::path::PathBuf {
    let runtime_dir = std::env::var("XDG_RUNTIME_DIR")
        .map(std::path::PathBuf::from)
        .unwrap_or_else(|_| std::path::PathBuf::from("/tmp"));
    runtime_dir.join("rsplayer").join("rsplayer.pid")
}

/// Check if a process with the given PID is running
fn is_process_running(pid: u32) -> bool {
    unsafe {
        // send signal 0 to check if process exists
        libc::kill(pid as i32, 0) == 0
    }
}

/// Check if daemon is running by reading PID file
fn check_running_daemon(pid_path: &std::path::Path) -> Result<u32, Box<dyn std::error::Error>> {
    if !pid_path.exists() {
        return Err("PID file not found".into());
    }

    let contents = std::fs::read_to_string(pid_path)?;
    let pid = contents.trim().parse::<u32>()?;

    if is_process_running(pid) {
        Ok(pid)
    } else {
        // Stale PID file, clean it up
        std::fs::remove_file(pid_path).ok();
        Err("Stale PID file, daemon not running".into())
    }
}

/// Clean up daemon resources (socket and PID file)
fn cleanup_daemon(socket_path: &std::path::Path, pid_path: &std::path::Path) {
    std::fs::remove_file(socket_path).ok();
    std::fs::remove_file(pid_path).ok();
}