//! Sequencer module for playing and timing musical sequences
//!
//! This module provides a sequencer that can play back compositions,
//! handle timing, and coordinate multiple tracks and patterns.

use crate::bpm_to_samples_per_beat;
use crate::config::EffectConfig;
use crate::core::Composition;
use crate::effects::{
    AudioEffect, BitCrusher, Chorus, Delay, Distortion, EffectsChain, HighPassFilter,
    LowPassFilter, Reverb, TapeSaturation, VinylCrackle,
};
use crate::patterns::MelodicPattern;
use crate::synthesis::{PolySynth, Waveform};
use std::collections::VecDeque;

/// Main sequencer for playing compositions
#[derive(Debug)]
pub struct Sequencer {
    pub tempo: f32,
    pub is_playing: bool,
    pub current_position: f32, // Current position in beats
    pub loop_enabled: bool,
    pub loop_start: f32, // Loop start in beats
    pub loop_end: f32,   // Loop end in beats

    // Internal timing
    samples_per_beat: usize,
    current_sample: usize,

    // Event scheduling
    scheduled_events: VecDeque<ScheduledEvent>,

    // Playback state
    tracks: Vec<TrackState>,
    global_volume: f32,
}

/// A scheduled musical event
#[derive(Debug, Clone)]
struct ScheduledEvent {
    pub event_time: f32, // Time in beats
    pub event_type: EventType,
    pub track_index: usize,
}

/// Types of sequencer events
#[derive(Debug, Clone)]
#[allow(dead_code)]
enum EventType {
    NoteOn { midi_note: u8, velocity: f32 },
    NoteOff { midi_note: u8 },
    VolumeChange { volume: f32 },
    TempoChange { new_tempo: f32 },
}

/// State for each track in the sequencer
#[derive(Debug)]
struct TrackState {
    pub synth: PolySynth,
    pub volume: f32,
    pub is_muted: bool,
    pub current_notes: Vec<u8>, // Currently playing MIDI notes
    pub effects: EffectsChain,
}

impl TrackState {
    fn new(waveform: Waveform, max_tracks: usize, effect_configs: &[EffectConfig]) -> Self {
        let effects =
            Self::create_effects_chain(effect_configs).unwrap_or_else(|_| EffectsChain::new());
        Self {
            synth: PolySynth::new(max_tracks, waveform),
            volume: 1.0,
            is_muted: false,
            current_notes: Vec::new(),
            effects,
        }
    }

    /// Create an effects chain from effect configurations
    fn create_effects_chain(effect_configs: &[EffectConfig]) -> Result<EffectsChain, String> {
        let mut effects_chain = EffectsChain::new();

        for effect_config in effect_configs {
            let effect: Box<dyn AudioEffect> = match effect_config.effect_type.as_str() {
                "lowpass" => {
                    let cutoff = effect_config
                        .params
                        .get("cutoff")
                        .and_then(|v| v.as_float())
                        .unwrap_or(1000.0) as f32;
                    let resonance = effect_config
                        .params
                        .get("resonance")
                        .and_then(|v| v.as_float())
                        .unwrap_or(1.0) as f32;
                    Box::new(LowPassFilter::new(cutoff, resonance))
                }
                "highpass" => {
                    let cutoff = effect_config
                        .params
                        .get("cutoff")
                        .and_then(|v| v.as_float())
                        .unwrap_or(1000.0) as f32;
                    let resonance = effect_config
                        .params
                        .get("resonance")
                        .and_then(|v| v.as_float())
                        .unwrap_or(1.0) as f32;
                    Box::new(HighPassFilter::new(cutoff, resonance))
                }
                "delay" => {
                    let time = effect_config
                        .params
                        .get("time")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.3) as f32;
                    let feedback = effect_config
                        .params
                        .get("feedback")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.3) as f32;
                    let mix = effect_config
                        .params
                        .get("mix")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.3) as f32;
                    Box::new(Delay::new(time, feedback, mix))
                }
                "reverb" => {
                    let room_size = effect_config
                        .params
                        .get("room_size")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.5) as f32;
                    let damping = effect_config
                        .params
                        .get("damping")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.5) as f32;
                    let mix = effect_config
                        .params
                        .get("mix")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.3) as f32;
                    Box::new(Reverb::new(room_size, damping, mix))
                }
                "distortion" => {
                    let drive = effect_config
                        .params
                        .get("drive")
                        .and_then(|v| v.as_float())
                        .unwrap_or(2.0) as f32;
                    let tone = effect_config
                        .params
                        .get("tone")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.5) as f32;
                    Box::new(Distortion::new(drive, tone))
                }
                "chorus" => {
                    let rate = effect_config
                        .params
                        .get("rate")
                        .and_then(|v| v.as_float())
                        .unwrap_or(1.0) as f32;
                    let depth = effect_config
                        .params
                        .get("depth")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.5) as f32;
                    let mix = effect_config
                        .params
                        .get("mix")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.3) as f32;
                    let layers = effect_config
                        .params
                        .get("layers")
                        .and_then(|v| v.as_integer())
                        .unwrap_or(3) as usize;
                    Box::new(Chorus::new(rate, depth, mix, layers))
                }
                "vinyl" => {
                    let intensity = effect_config
                        .params
                        .get("intensity")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.5) as f32;
                    let frequency = effect_config
                        .params
                        .get("frequency")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.5) as f32;
                    let mix = effect_config
                        .params
                        .get("mix")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.3) as f32;
                    Box::new(VinylCrackle::new(intensity, frequency, mix))
                }
                "tape" => {
                    let drive = effect_config
                        .params
                        .get("drive")
                        .and_then(|v| v.as_float())
                        .unwrap_or(2.0) as f32;
                    let warmth = effect_config
                        .params
                        .get("warmth")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.7) as f32;
                    let mix = effect_config
                        .params
                        .get("mix")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.5) as f32;
                    Box::new(TapeSaturation::new(drive, warmth, mix))
                }
                "bitcrusher" => {
                    let bit_depth = effect_config
                        .params
                        .get("bit_depth")
                        .and_then(|v| v.as_float())
                        .unwrap_or(8.0) as f32;
                    let sample_rate_reduction = effect_config
                        .params
                        .get("sample_rate_reduction")
                        .and_then(|v| v.as_float())
                        .unwrap_or(2.0) as f32;
                    let mix = effect_config
                        .params
                        .get("mix")
                        .and_then(|v| v.as_float())
                        .unwrap_or(0.5) as f32;
                    Box::new(BitCrusher::new(bit_depth, sample_rate_reduction, mix))
                }
                _ => {
                    return Err(format!(
                        "Unknown effect type: {}",
                        effect_config.effect_type
                    ));
                }
            };

            effects_chain.add_effect(effect);
        }

        Ok(effects_chain)
    }
}

impl Sequencer {
    /// Create a new sequencer
    ///
    /// # Arguments
    /// * `tempo` - Initial tempo in BPM
    pub fn new(tempo: f32) -> Self {
        let samples_per_beat = bpm_to_samples_per_beat(tempo);

        Self {
            tempo,
            is_playing: false,
            current_position: 0.0,
            loop_enabled: false,
            loop_start: 0.0,
            loop_end: 16.0,
            samples_per_beat,
            current_sample: 0,
            scheduled_events: VecDeque::new(),
            tracks: Vec::new(),
            global_volume: 1.0,
        }
    }

    /// Load a composition into the sequencer
    pub fn load_composition(&mut self, composition: &Composition) -> Result<(), String> {
        self.clear();

        // Create track states for each track in the composition
        for track in &composition.tracks {
            let waveform = track.waveform;

            let mut track_state = TrackState::new(waveform, 8, &track.effect_configs);
            track_state.volume = track.volume;
            self.tracks.push(track_state);
        }

        // Schedule all note events
        self.schedule_composition_events(composition)?;

        // Set loop end to composition duration
        self.loop_end = composition.total_duration;

        Ok(())
    }

    /// Schedule events from a composition
    fn schedule_composition_events(&mut self, composition: &Composition) -> Result<(), String> {
        for (track_index, track) in composition.tracks.iter().enumerate() {
            for note in &track.notes {
                // Schedule note on
                let note_on_event = ScheduledEvent {
                    event_time: note.start_time,
                    event_type: EventType::NoteOn {
                        midi_note: note.midi_note,
                        velocity: note.velocity,
                    },
                    track_index,
                };

                // Schedule note off
                let note_off_event = ScheduledEvent {
                    event_time: note.start_time + note.duration,
                    event_type: EventType::NoteOff {
                        midi_note: note.midi_note,
                    },
                    track_index,
                };

                self.scheduled_events.push_back(note_on_event);
                self.scheduled_events.push_back(note_off_event);
            }
        }

        // Sort events by time
        let mut events: Vec<_> = self.scheduled_events.drain(..).collect();
        events.sort_by(|a, b| a.event_time.partial_cmp(&b.event_time).unwrap());
        self.scheduled_events.extend(events);

        Ok(())
    }

    /// Start playback
    pub fn play(&mut self) {
        self.is_playing = true;
    }

    /// Stop playback
    pub fn stop(&mut self) {
        self.is_playing = false;
        self.current_position = 0.0;
        self.current_sample = 0;

        // Stop all playing notes
        for track in &mut self.tracks {
            for &note in track.current_notes.clone().iter() {
                track.synth.stop_note(crate::midi_to_frequency(note));
            }
            track.current_notes.clear();
        }
    }

    /// Pause playback
    pub fn pause(&mut self) {
        self.is_playing = false;
    }

    /// Set the current playback position
    pub fn set_position(&mut self, position: f32) {
        self.current_position = position;
        self.current_sample = (position * self.samples_per_beat as f32) as usize;

        // Stop all current notes when seeking
        for track in &mut self.tracks {
            for &note in track.current_notes.clone().iter() {
                track.synth.stop_note(crate::midi_to_frequency(note));
            }
            track.current_notes.clear();
        }
    }

    /// Set the tempo
    pub fn set_tempo(&mut self, tempo: f32) {
        self.tempo = tempo;
        self.samples_per_beat = bmp_to_samples_per_beat(tempo);
    }

    /// Enable/disable looping
    pub fn set_loop(&mut self, enabled: bool, start: f32, end: f32) {
        self.loop_enabled = enabled;
        self.loop_start = start;
        self.loop_end = end;
    }

    /// Set global volume
    pub fn set_global_volume(&mut self, volume: f32) {
        self.global_volume = volume.clamp(0.0, 1.0);
    }

    /// Mute/unmute a track
    pub fn set_track_mute(&mut self, track_index: usize, muted: bool) {
        if let Some(track) = self.tracks.get_mut(track_index) {
            track.is_muted = muted;
            if muted {
                // Stop all notes in this track
                for &note in track.current_notes.clone().iter() {
                    track.synth.stop_note(crate::midi_to_frequency(note));
                }
                track.current_notes.clear();
            }
        }
    }

    /// Set track volume
    pub fn set_track_volume(&mut self, track_index: usize, volume: f32) {
        if let Some(track) = self.tracks.get_mut(track_index) {
            track.volume = volume.clamp(0.0, 1.0);
        }
    }

    /// Process audio for a given number of samples
    pub fn process_audio(&mut self, buffer: &mut [f32]) -> Result<(), String> {
        if !self.is_playing {
            // Fill with silence
            for sample in buffer.iter_mut() {
                *sample = 0.0;
            }
            return Ok(());
        }

        for i in 0..buffer.len() {
            // Update position
            self.current_position = self.current_sample as f32 / self.samples_per_beat as f32;

            // Process scheduled events
            self.process_events_at_position(self.current_position);

            // Generate audio sample
            let mut sample = 0.0;

            for track in &mut self.tracks {
                if !track.is_muted {
                    let track_sample = track.synth.next_sample();
                    let processed_sample = track.effects.process_sample(track_sample);
                    sample += processed_sample * track.volume;
                }
            }

            // Apply global volume
            buffer[i] = sample * self.global_volume;

            // Advance sample counter
            self.current_sample += 1;

            // Handle looping
            if self.loop_enabled && self.current_position >= self.loop_end {
                self.set_position(self.loop_start);
            }
        }

        Ok(())
    }

    /// Process events that should occur at the current position
    fn process_events_at_position(&mut self, position: f32) {
        while let Some(event) = self.scheduled_events.front() {
            if event.event_time <= position {
                let event = self.scheduled_events.pop_front().unwrap();
                self.process_event(event);
            } else {
                break;
            }
        }
    }

    /// Process a single event
    fn process_event(&mut self, event: ScheduledEvent) {
        if event.track_index >= self.tracks.len() {
            return;
        }

        let track = &mut self.tracks[event.track_index];

        if track.is_muted {
            return;
        }

        match event.event_type {
            EventType::NoteOn {
                midi_note,
                velocity: _,
            } => {
                let frequency = crate::midi_to_frequency(midi_note);
                track.synth.play_note(frequency);
                track.current_notes.push(midi_note);
            }
            EventType::NoteOff { midi_note } => {
                let frequency = crate::midi_to_frequency(midi_note);
                track.synth.stop_note(frequency);
                track.current_notes.retain(|&n| n != midi_note);
            }
            EventType::VolumeChange { volume } => {
                track.volume = volume;
            }
            EventType::TempoChange { new_tempo } => {
                self.set_tempo(new_tempo);
            }
        }
    }

    /// Clear all scheduled events and reset state
    pub fn clear(&mut self) {
        self.scheduled_events.clear();
        self.tracks.clear();
        self.current_position = 0.0;
        self.current_sample = 0;
        self.is_playing = false;
    }

    /// Get current playback information
    pub fn get_playback_info(&self) -> PlaybackInfo {
        PlaybackInfo {
            is_playing: self.is_playing,
            current_position: self.current_position,
            tempo: self.tempo,
            loop_enabled: self.loop_enabled,
            loop_start: self.loop_start,
            loop_end: self.loop_end,
            track_count: self.tracks.len(),
            active_notes: self.tracks.iter().map(|t| t.current_notes.len()).sum(),
        }
    }

    /// Add a real-time note event
    pub fn trigger_note(&mut self, track_index: usize, midi_note: u8, _velocity: f32) {
        if let Some(track) = self.tracks.get_mut(track_index) {
            if !track.is_muted {
                let frequency = crate::midi_to_frequency(midi_note);
                track.synth.play_note(frequency);
                track.current_notes.push(midi_note);
            }
        }
    }

    /// Release a real-time note
    pub fn release_note(&mut self, track_index: usize, midi_note: u8) {
        if let Some(track) = self.tracks.get_mut(track_index) {
            let frequency = crate::midi_to_frequency(midi_note);
            track.synth.stop_note(frequency);
            track.current_notes.retain(|&n| n != midi_note);
        }
    }

    /// Schedule a pattern to play
    pub fn schedule_pattern(
        &mut self,
        pattern: &MelodicPattern,
        track_index: usize,
        start_time: f32,
    ) {
        let midi_notes = pattern.get_midi_notes(4); // Use octave 4 as base

        for (midi_note, offset_time, duration, velocity) in midi_notes {
            let note_on_event = ScheduledEvent {
                event_time: start_time + offset_time,
                event_type: EventType::NoteOn {
                    midi_note,
                    velocity,
                },
                track_index,
            };

            let note_off_event = ScheduledEvent {
                event_time: start_time + offset_time + duration,
                event_type: EventType::NoteOff { midi_note },
                track_index,
            };

            // Insert events in the correct position to maintain time order
            self.insert_event_sorted(note_on_event);
            self.insert_event_sorted(note_off_event);
        }
    }

    /// Insert an event maintaining time order
    fn insert_event_sorted(&mut self, event: ScheduledEvent) {
        let mut insert_index = self.scheduled_events.len();

        for (i, existing_event) in self.scheduled_events.iter().enumerate() {
            if event.event_time < existing_event.event_time {
                insert_index = i;
                break;
            }
        }

        self.scheduled_events.insert(insert_index, event);
    }
}

/// Information about current playback state
#[derive(Debug, Clone)]
pub struct PlaybackInfo {
    pub is_playing: bool,
    pub current_position: f32,
    pub tempo: f32,
    pub loop_enabled: bool,
    pub loop_start: f32,
    pub loop_end: f32,
    pub track_count: usize,
    pub active_notes: usize,
}

/// A real-time pattern player for live performance
#[derive(Debug)]
pub struct PatternPlayer {
    pub patterns: Vec<MelodicPattern>,
    pub current_pattern: usize,
    pub is_recording: bool,
    recorded_pattern: MelodicPattern,
    quantization: f32, // Beat quantization (e.g., 0.25 for sixteenth notes)
}

impl PatternPlayer {
    /// Create a new pattern player
    pub fn new() -> Self {
        Self {
            patterns: Vec::new(),
            current_pattern: 0,
            is_recording: false,
            recorded_pattern: MelodicPattern::new(
                crate::scales::Scale::new(crate::scales::ScaleType::Major, 60),
                2,
            ),
            quantization: 0.25,
        }
    }

    /// Add a pattern to the player
    pub fn add_pattern(&mut self, pattern: MelodicPattern) {
        self.patterns.push(pattern);
    }

    /// Select a pattern to play
    pub fn select_pattern(&mut self, index: usize) {
        if index < self.patterns.len() {
            self.current_pattern = index;
        }
    }

    /// Start recording a new pattern
    pub fn start_recording(&mut self) {
        self.is_recording = true;
        self.recorded_pattern.notes.clear();
    }

    /// Stop recording and save the pattern
    pub fn stop_recording(&mut self) -> Option<MelodicPattern> {
        if self.is_recording {
            self.is_recording = false;
            if !self.recorded_pattern.notes.is_empty() {
                return Some(self.recorded_pattern.clone());
            }
        }
        None
    }

    /// Record a note during recording
    pub fn record_note(&mut self, scale_degree: usize, duration: f32, velocity: f32) {
        if self.is_recording {
            let note = crate::patterns::PatternNote::new(scale_degree, 0, duration, velocity);
            self.recorded_pattern.add_note(note);
        }
    }

    /// Get the current pattern
    pub fn get_current_pattern(&self) -> Option<&MelodicPattern> {
        self.patterns.get(self.current_pattern)
    }

    /// Set quantization amount
    pub fn set_quantization(&mut self, quantization: f32) {
        self.quantization = quantization.max(0.0625); // Minimum 64th note quantization
    }
}

impl Default for PatternPlayer {
    fn default() -> Self {
        Self::new()
    }
}

// Fix the typo in the helper function
fn bmp_to_samples_per_beat(bpm: f32) -> usize {
    bpm_to_samples_per_beat(bpm)
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::core::{CompositionBuilder, CompositionStyle};
    use crate::scales::{Scale, ScaleType};

    #[test]
    fn test_sequencer_creation() {
        let sequencer = Sequencer::new(120.0);
        assert_eq!(sequencer.tempo, 120.0);
        assert!(!sequencer.is_playing);
        assert_eq!(sequencer.current_position, 0.0);
    }

    #[test]
    fn test_playback_control() {
        let mut sequencer = Sequencer::new(120.0);

        sequencer.play();
        assert!(sequencer.is_playing);

        sequencer.pause();
        assert!(!sequencer.is_playing);

        sequencer.stop();
        assert!(!sequencer.is_playing);
        assert_eq!(sequencer.current_position, 0.0);
    }

    #[test]
    fn test_position_setting() {
        let mut sequencer = Sequencer::new(120.0);
        sequencer.set_position(4.0);
        assert_eq!(sequencer.current_position, 4.0);
    }

    #[test]
    fn test_tempo_change() {
        let mut sequencer = Sequencer::new(120.0);
        sequencer.set_tempo(140.0);
        assert_eq!(sequencer.tempo, 140.0);
    }

    #[test]
    fn test_loop_settings() {
        let mut sequencer = Sequencer::new(120.0);
        sequencer.set_loop(true, 0.0, 8.0);
        assert!(sequencer.loop_enabled);
        assert_eq!(sequencer.loop_start, 0.0);
        assert_eq!(sequencer.loop_end, 8.0);
    }

    #[test]
    fn test_composition_loading() {
        let mut sequencer = Sequencer::new(120.0);
        let mut composition = CompositionBuilder::new()
            .style(CompositionStyle::Electronic)
            .measures(4)
            .build();

        let _ = composition.generate();
        let result = sequencer.load_composition(&composition);

        assert!(result.is_ok());
        assert_eq!(sequencer.tracks.len(), composition.tracks.len());
    }

    #[test]
    fn test_pattern_player() {
        let mut player = PatternPlayer::new();
        let scale = Scale::new(ScaleType::Major, 60);
        let mut pattern = MelodicPattern::new(scale, 1);
        pattern.generate_ascending(1);

        player.add_pattern(pattern);
        assert_eq!(player.patterns.len(), 1);

        player.select_pattern(0);
        assert_eq!(player.current_pattern, 0);
        assert!(player.get_current_pattern().is_some());
    }

    #[test]
    fn test_pattern_recording() {
        let mut player = PatternPlayer::new();

        player.start_recording();
        assert!(player.is_recording);

        player.record_note(1, 1.0, 0.8);
        player.record_note(3, 1.0, 0.7);

        let recorded = player.stop_recording();
        assert!(recorded.is_some());
        assert_eq!(recorded.unwrap().notes.len(), 2);
    }

    #[test]
    fn test_real_time_notes() {
        let mut sequencer = Sequencer::new(120.0);

        // Create a simple composition to have tracks
        let mut composition = CompositionBuilder::new().measures(1).build();
        let _ = composition.generate();
        let _ = sequencer.load_composition(&composition);

        // Only test if we have tracks
        if sequencer.tracks.len() > 0 {
            // Test real-time note triggering
            sequencer.trigger_note(0, 60, 0.8);
            assert!(sequencer.tracks[0].current_notes.contains(&60));

            sequencer.release_note(0, 60);
            assert!(!sequencer.tracks[0].current_notes.contains(&60));
        } else {
            // If no tracks, just verify the sequencer doesn't crash
            sequencer.trigger_note(0, 60, 0.8);
            sequencer.release_note(0, 60);
        }
    }

    #[test]
    fn test_track_control() {
        let mut sequencer = Sequencer::new(120.0);

        // Create a composition with multiple tracks
        let mut composition = CompositionBuilder::new().measures(2).build();
        let _ = composition.generate();
        let _ = sequencer.load_composition(&composition);

        if sequencer.tracks.len() > 0 {
            // Test muting
            sequencer.set_track_mute(0, true);
            assert!(sequencer.tracks[0].is_muted);

            // Test volume control
            sequencer.set_track_volume(0, 0.5);
            assert_eq!(sequencer.tracks[0].volume, 0.5);
        }
    }
}