/*
 * This file is a part of RSPlayer
 * Licensed under the GPL-3.0 License
 * Copyright (C) 2026 Salmonik @ salmonik@tuta.io
 * https://codeberg.org/salmonik/RSPlayer
*/

use crate::notification;
use std::io::{Read, Seek, SeekFrom};
use std::path::{Path, PathBuf};
use std::sync::atomic::{AtomicBool, Ordering};
use std::sync::mpsc::{self, Receiver, Sender};
use std::sync::{Arc, Mutex};
use std::thread;

struct HttpMediaSource {
    reader: Mutex<Box<dyn Read + Send>>,
    buffer: Vec<u8>,
    position: usize,
    eof: bool,
}

impl HttpMediaSource {
    fn new(reader: Box<dyn Read + Send>) -> Self {
        HttpMediaSource {
            reader: Mutex::new(reader),
            buffer: Vec::new(),
            position: 0,
            eof: false,
        }
    }
}

impl Read for HttpMediaSource {
    fn read(&mut self, buf: &mut [u8]) -> std::io::Result<usize> {
        if self.position < self.buffer.len() {
            let available = self.buffer.len() - self.position;
            let to_copy = buf.len().min(available);
            buf[..to_copy].copy_from_slice(&self.buffer[self.position..self.position + to_copy]);
            self.position += to_copy;
            return Ok(to_copy);
        }
        if self.eof {
            return Ok(0);
        }
        let n = self.reader.lock().unwrap().read(buf)?;
        if n > 0 {
            self.buffer.extend_from_slice(&buf[..n]);
            self.position += n;
        } else {
            self.eof = true;
        }
        Ok(n)
    }
}

impl Seek for HttpMediaSource {
    fn seek(&mut self, pos: SeekFrom) -> std::io::Result<u64> {
        match pos {
            SeekFrom::Start(offset) => {
                let offset = offset as usize;
                while offset > self.buffer.len() && !self.eof {
                    let mut temp = [0u8; 8192];
                    let n = self.reader.lock().unwrap().read(&mut temp)?;
                    if n == 0 {
                        self.eof = true;
                    } else {
                        self.buffer.extend_from_slice(&temp[..n]);
                    }
                }
                self.position = offset.min(self.buffer.len());
                Ok(self.position as u64)
            }
            SeekFrom::End(_) => Err(std::io::Error::new(
                std::io::ErrorKind::Unsupported,
                "cannot seek from end on a stream",
            )),
            SeekFrom::Current(offset) => {
                let new_pos = if offset >= 0 {
                    self.position.saturating_add(offset as usize)
                } else {
                    self.position.saturating_sub((-offset) as usize)
                };
                while new_pos > self.buffer.len() && !self.eof {
                    let mut temp = [0u8; 8192];
                    let n = self.reader.lock().unwrap().read(&mut temp)?;
                    if n == 0 {
                        self.eof = true;
                    } else {
                        self.buffer.extend_from_slice(&temp[..n]);
                    }
                }
                self.position = new_pos.min(self.buffer.len());
                Ok(self.position as u64)
            }
        }
    }
}

impl symphonia::core::io::MediaSource for HttpMediaSource {
    fn is_seekable(&self) -> bool {
        true
    }

    fn byte_len(&self) -> Option<u64> {
        None
    }
}

#[allow(dead_code)]
pub enum AudioCommand {
    Play(PathBuf),
    Pause,
    Resume,
    Stop,
    SetVolume(f32),
}

pub struct AudioEngine {
    command_tx: Sender<AudioCommand>,
    is_playing: Arc<AtomicBool>,
    pub current_track: Arc<Mutex<Option<std::path::PathBuf>>>,
    track_ended: Arc<AtomicBool>,
    volume: Arc<Mutex<f32>>,
    position: Arc<Mutex<f64>>,
}

#[allow(clippy::new_without_default)]
impl AudioEngine {
    pub fn new() -> Self {
        let (tx, rx) = mpsc::channel();
        let is_playing = Arc::new(AtomicBool::new(false));
        let is_playing_clone = Arc::clone(&is_playing);
        let current_track = Arc::new(Mutex::new(None));
        let current_track_clone = Arc::clone(&current_track);
        let track_ended = Arc::new(AtomicBool::new(false));
        let track_ended_clone = Arc::clone(&track_ended);

        let volume = Arc::new(Mutex::new(1.0f32));
        let volume_clone = Arc::clone(&volume);

        let position = Arc::new(Mutex::new(0.0));
        let position_clone = Arc::clone(&position);

        thread::spawn(move || {
            audio_thread(
                rx,
                is_playing_clone,
                current_track_clone,
                volume_clone,
                track_ended_clone,
                position_clone,
            );
        });

        AudioEngine {
            command_tx: tx,
            is_playing,
            current_track,
            track_ended,
            volume,
            position,
        }
    }

    pub fn play(&self, path: PathBuf) {
        self.track_ended.store(false, Ordering::SeqCst);
        if let Ok(mut track) = self.current_track.lock() {
            *track = Some(path.clone());
        }
        let _ = self.command_tx.send(AudioCommand::Play(path));
    }

    pub fn pause(&self) {
        let _ = self.command_tx.send(AudioCommand::Pause);
    }

    pub fn resume(&self) {
        let _ = self.command_tx.send(AudioCommand::Resume);
    }

    pub fn stop(&self) {
        let _ = self.command_tx.send(AudioCommand::Stop);
    }

    pub fn set_volume(&self, volume: f32) {
        let _ = self.command_tx.send(AudioCommand::SetVolume(volume));
    }

    pub fn get_volume(&self) -> u8 {
        self.volume
            .lock()
            .map(|v| (*v * 100.0) as u8)
            .unwrap_or(100)
    }

    pub fn is_playing(&self) -> bool {
        self.is_playing.load(Ordering::SeqCst)
    }

    pub fn current_track(&self) -> Option<std::path::PathBuf> {
        self.current_track.lock().ok().and_then(|g| g.clone())
    }

    pub fn poll_track_ended(&self) -> bool {
        self.track_ended.swap(false, Ordering::SeqCst)
    }

    pub fn position(&self) -> f64 {
        self.position.lock().map(|p| *p).unwrap_or(0.0)
    }
}

struct AudioData {
    format: Box<dyn symphonia::core::formats::FormatReader>,
    decoder: Box<dyn symphonia::core::codecs::audio::AudioDecoder>,
    sample_rate: u32,
    channels: u16,
    sample_buffer: Vec<f32>,
    buffer_pos: usize,
    resample_ratio: Option<f64>,
}

fn resample_linear(input: &[f32], ratio: f64, channels: usize) -> Vec<f32> {
    if ratio == 1.0 {
        return input.to_vec();
    }
    let input_frames = input.len() / channels;
    let output_frames = (input_frames as f64 * ratio).ceil() as usize;
    let mut output = Vec::with_capacity(output_frames * channels);
    for i in 0..output_frames {
        let input_pos = i as f64 / ratio;
        let idx = input_pos.floor() as usize;
        let frac = input_pos.fract() as f32;
        for ch in 0..channels {
            let cur = if idx * channels + ch < input.len() {
                input[idx * channels + ch]
            } else {
                0.0
            };
            let next = if (idx + 1) * channels + ch < input.len() {
                input[(idx + 1) * channels + ch]
            } else {
                cur
            };
            output.push(cur + frac * (next - cur));
        }
    }
    output
}

fn audio_thread(
    rx: Receiver<AudioCommand>,
    is_playing: Arc<AtomicBool>,
    current_track: Arc<Mutex<Option<std::path::PathBuf>>>,
    volume: Arc<Mutex<f32>>,
    track_ended: Arc<AtomicBool>,
    position: Arc<Mutex<f64>>,
) {
    use cpal::traits::{DeviceTrait, HostTrait, StreamTrait};

    let host = cpal::default_host();
    let device = match host.default_output_device() {
        Some(d) => d,
        None => {
            eprintln!("No output device available");
            return;
        }
    };

    let config = match device.default_output_config() {
        Ok(c) => c,
        Err(e) => {
            eprintln!("Failed to get output config: {}", e);
            return;
        }
    };

    let device_sample_rate = config.sample_rate();
    let channels = config.channels();
    crate::debug_eprintln(format_args!(
        "Default output: {} Hz, {} channels",
        device_sample_rate, channels
    ));

    let mut current_stream: Option<cpal::Stream> = None;
    let audio_data: Arc<Mutex<Option<AudioData>>> = Arc::new(Mutex::new(None));

    while let Ok(cmd) = rx.recv() {
        match cmd {
            AudioCommand::Play(path) => {
                is_playing.store(true, Ordering::SeqCst);
                if let Ok(mut track) = current_track.lock() {
                    *track = Some(path.clone());
                }
                if let Ok(mut pos) = position.lock() {
                    *pos = 0.0;
                }

                // Drop the current stream before creating a new one
                current_stream = None;

                match open_audio_file(&path) {
                    Ok(mut data) => {
                        crate::debug_eprintln(format_args!(
                            "File: {} Hz, {} channels",
                            data.sample_rate, data.channels
                        ));

                        if data.sample_rate != device_sample_rate {
                            crate::debug_eprintln(format_args!(
                                "Resampling from {} Hz to {} Hz",
                                data.sample_rate, device_sample_rate
                            ));
                            data.resample_ratio =
                                Some(device_sample_rate as f64 / data.sample_rate as f64);
                        }

                        // Pre-decode some samples before starting playback to prevent buffer underrun
                        let channels = data.channels as usize;
                        for _ in 0..100 {
                            match data.format.next_packet() {
                                Ok(Some(packet)) => match data.decoder.decode(&packet) {
                                    Ok(decoded) => {
                                        let num_samples = decoded.samples_interleaved();
                                        let mut samples = vec![0.0f32; num_samples];
                                        decoded.copy_to_slice_interleaved(&mut samples);

                                        let resampled = if let Some(ratio) = data.resample_ratio {
                                            resample_linear(&samples, ratio, channels)
                                        } else {
                                            samples
                                        };

                                        data.sample_buffer.extend(resampled);
                                    }
                                    Err(_) => break,
                                },
                                _ => break,
                            }
                        }
                        data.buffer_pos = 0;

                        let stream_config: cpal::StreamConfig =
                            device.default_output_config().unwrap().into();

                        let audio_data_clone = Arc::clone(&audio_data);
                        let vol = Arc::clone(&volume);
                        let ended = Arc::clone(&track_ended);
                        let is_playing_clone = Arc::clone(&is_playing);
                        let position_clone = Arc::clone(&position);

                        if let Ok(mut d) = audio_data.lock() {
                            *d = Some(data);
                        }

                        match device.build_output_stream(
                            &stream_config,
                            move |data: &mut [f32], _: &cpal::OutputCallbackInfo| {
                                let vol = vol.lock().map(|v| *v).unwrap_or(1.0);

                                if let Ok(mut audio_data) = audio_data_clone.lock() {
                                    let mut should_clear = false;

                                    if let Some(ref mut state) = *audio_data {
                                        let channels = state.channels as usize;
                                        let mut offset = 0usize;

                                        // Keep decoding until we fill the buffer or run out of data
                                        while offset < data.len() {
                                            // First, copy any buffered samples
                                            if state.buffer_pos < state.sample_buffer.len() {
                                                let remaining =
                                                    &state.sample_buffer[state.buffer_pos..];
                                                let to_copy =
                                                    remaining.len().min(data.len() - offset);
                                                data[offset..offset + to_copy]
                                                    .copy_from_slice(&remaining[..to_copy]);
                                                state.buffer_pos += to_copy;
                                                offset += to_copy;

                                                // If we've consumed all buffered samples, clear the buffer
                                                if state.buffer_pos >= state.sample_buffer.len() {
                                                    state.sample_buffer.clear();
                                                    state.buffer_pos = 0;
                                                }
                                                continue; // Try to fill more of the buffer
                                            }

                                            // Decode more data
                                            match state.format.next_packet() {
                                                Ok(Some(packet)) => {
                                                    match state.decoder.decode(&packet) {
                                                        Ok(decoded) => {
                                                            let num_samples =
                                                                decoded.samples_interleaved();
                                                            let mut samples =
                                                                vec![0.0f32; num_samples];
                                                            decoded.copy_to_slice_interleaved(
                                                                &mut samples,
                                                            );

                                                            // Resample if needed
                                                            let resampled = if let Some(ratio) =
                                                                state.resample_ratio
                                                            {
                                                                resample_linear(
                                                                    &samples, ratio, channels,
                                                                )
                                                            } else {
                                                                samples
                                                            };

                                                            // Copy what we can to output
                                                            let to_copy = resampled
                                                                .len()
                                                                .min(data.len() - offset);
                                                            data[offset..offset + to_copy]
                                                                .copy_from_slice(
                                                                    &resampled[..to_copy],
                                                                );
                                                            offset += to_copy;

                                                            // Buffer the rest
                                                            if to_copy < resampled.len() {
                                                                state.sample_buffer.clear();
                                                                state
                                                                    .sample_buffer
                                                                    .extend_from_slice(
                                                                        &resampled[to_copy..],
                                                                    );
                                                                state.buffer_pos = 0;
                                                            }
                                                        }
                                                        Err(_) => break,
                                                    }
                                                }
                                                _ => break,
                                            }
                                        }

                                        // Apply volume
                                        for sample in data.iter_mut().take(offset) {
                                            *sample *= vol;
                                        }

                                        // Fill remaining with silence
                                        for sample in data.iter_mut().skip(offset) {
                                            *sample = 0.0;
                                        }

                                        // Track playback position
                                        if offset > 0
                                            && let Ok(mut pos) = position_clone.lock()
                                        {
                                            *pos += offset as f64
                                                / (device_sample_rate as f64 * channels as f64);
                                        }

                                        // If no more data and offset is 0, track ended
                                        if offset == 0 && state.sample_buffer.is_empty() {
                                            ended.store(true, Ordering::SeqCst);
                                            is_playing_clone.store(false, Ordering::SeqCst);
                                            should_clear = true;
                                        }
                                    } else {
                                        for sample in data.iter_mut() {
                                            *sample = 0.0;
                                        }
                                    }

                                    if should_clear {
                                        *audio_data = None;
                                    }
                                }
                            },
                            |err| {
                                eprintln!("Stream error: {}", err);
                            },
                            None,
                        ) {
                            Ok(stream) => {
                                if let Err(e) = stream.play() {
                                    eprintln!("Failed to start stream: {}", e);
                                    notification::notify_error("Failed to start audio stream");
                                    is_playing.store(false, Ordering::SeqCst);
                                } else {
                                    current_stream = Some(stream);
                                }
                            }
                            Err(e) => {
                                eprintln!("Failed to create stream: {}", e);
                                notification::notify_error("Failed to create audio stream");
                                is_playing.store(false, Ordering::SeqCst);
                            }
                        }
                    }
                    Err(e) => {
                        eprintln!("Failed to open audio: {}", e);
                        notification::notify_error("Failed to open audio file");
                        is_playing.store(false, Ordering::SeqCst);
                    }
                }
            }
            AudioCommand::Pause => {
                if let Some(ref stream) = current_stream {
                    if let Err(e) = stream.pause() {
                        eprintln!("Failed to pause stream: {}", e);
                    }
                    is_playing.store(false, Ordering::SeqCst);
                }
            }
            AudioCommand::Resume => {
                if let Some(ref stream) = current_stream {
                    if let Err(e) = stream.play() {
                        eprintln!("Failed to resume stream: {}", e);
                    } else {
                        is_playing.store(true, Ordering::SeqCst);
                    }
                }
            }
            AudioCommand::Stop => {
                current_stream = None;
                if let Ok(mut d) = audio_data.lock() {
                    *d = None;
                }
                is_playing.store(false, Ordering::SeqCst);
                if let Ok(mut track) = current_track.lock() {
                    *track = None;
                }
            }
            AudioCommand::SetVolume(vol) => {
                if let Ok(mut volume_ref) = volume.lock() {
                    *volume_ref = vol;
                }
            }
        }
    }
}

fn open_audio_file(path: &PathBuf) -> Result<AudioData, Box<dyn std::error::Error>> {
    use symphonia::core::audio::layouts::CHANNEL_LAYOUT_STEREO;
    use symphonia::core::codecs::audio::AudioDecoderOptions;
    use symphonia::core::formats::probe::Hint;
    use symphonia::core::io::MediaSourceStream;

    let path_str = path.to_string_lossy();
    let is_url = path_str.starts_with("http://") || path_str.starts_with("https://");

    let mss: MediaSourceStream = if is_url {
        let client = reqwest::blocking::Client::builder()
            .user_agent("RSPlayer/0.8.2")
            .connect_timeout(std::time::Duration::from_secs(10))
            .build()
            .map_err(|e| format!("Failed to create HTTP client: {}", e))?;
        let response = client
            .get(path_str.as_ref())
            .send()
            .map_err(|e| format!("HTTP request failed: {}", e))?;
        let status = response.status();
        if !status.is_success() {
            return Err(format!("HTTP error {} for URL", status).into());
        }
        let reader = HttpMediaSource::new(Box::new(response));
        MediaSourceStream::new(Box::new(reader), Default::default())
    } else {
        let file = std::fs::File::open(path)?;
        MediaSourceStream::new(Box::new(file), Default::default())
    };

    let mut hint = Hint::new();
    if is_url
        && let Some(ext) = Path::new(path_str.as_ref())
            .extension()
            .and_then(|e| e.to_str())
    {
        hint.with_extension(ext);
    }
    let format = symphonia::default::get_probe().probe(
        &hint,
        mss,
        Default::default(),
        Default::default(),
    )?;

    let track = format
        .tracks()
        .iter()
        .find(|t| {
            t.codec_params
                .as_ref()
                .and_then(|p| p.audio())
                .and_then(|a| a.sample_rate)
                .is_some()
        })
        .ok_or("No suitable track found")?;

    let codec_params = track
        .codec_params
        .as_ref()
        .ok_or("No codec parameters")?
        .audio()
        .ok_or("Not an audio track")?;

    let sample_rate = codec_params.sample_rate.unwrap_or(44100);
    let channels = codec_params
        .channels
        .clone()
        .unwrap_or(CHANNEL_LAYOUT_STEREO)
        .count() as u16;

    let decoder = symphonia::default::get_codecs()
        .make_audio_decoder(codec_params, &AudioDecoderOptions::default())?;

    Ok(AudioData {
        format,
        decoder,
        sample_rate,
        channels,
        sample_buffer: Vec::new(),
        buffer_pos: 0,
        resample_ratio: None,
    })
}