use std::path::PathBuf;
use std::sync::atomic::{AtomicBool, AtomicI64, AtomicU32, AtomicU64, Ordering};
use std::sync::Arc;

use crossbeam_channel::Receiver;
use doux::EngineMetrics;

use crate::app::App;
use crate::engine::{
    build_stream, spawn_sequencer, AnalysisHandle, AudioStreamConfig, LinkState, MidiCommand,
    PatternChange, ScopeBuffer, SequencerConfig, SequencerHandle, SpectrumBuffer,
};
use crate::midi;
use crate::model;
use crate::settings::Settings;
use crate::state::audio::RefreshRate;
use crate::state::StagedChange;
use crate::theme;

pub struct InitArgs {
    pub samples: Vec<PathBuf>,
    pub output: Option<String>,
    pub input: Option<String>,
    pub channels: Option<u16>,
    pub buffer: Option<u32>,
}

pub struct Init {
    pub app: App,
    pub link: Arc<LinkState>,
    pub sequencer: SequencerHandle,
    pub playing: Arc<AtomicBool>,
    pub nudge_us: Arc<AtomicI64>,
    pub metrics: Arc<EngineMetrics>,
    pub scope_buffer: Arc<ScopeBuffer>,
    pub spectrum_buffer: Arc<SpectrumBuffer>,
    pub audio_sample_pos: Arc<AtomicU64>,
    pub sample_rate_shared: Arc<AtomicU32>,
    pub stream: Option<cpal::Stream>,
    pub analysis_handle: Option<AnalysisHandle>,
    pub midi_rx: Receiver<MidiCommand>,
    #[cfg(feature = "desktop")]
    pub settings: Settings,
    #[cfg(feature = "desktop")]
    pub mouse_x: Arc<AtomicU32>,
    #[cfg(feature = "desktop")]
    pub mouse_y: Arc<AtomicU32>,
    #[cfg(feature = "desktop")]
    pub mouse_down: Arc<AtomicU32>,
}

pub fn init(args: InitArgs) -> Init {
    let settings = Settings::load();

    let link = Arc::new(LinkState::new(settings.link.tempo, settings.link.quantum));
    if settings.link.enabled {
        link.enable();
    }

    let playing = Arc::new(AtomicBool::new(true));
    let nudge_us = Arc::new(AtomicI64::new(0));

    let mut app = App::new();

    app.playback.queued_changes.push(StagedChange {
        change: PatternChange::Start {
            bank: 0,
            pattern: 0,
        },
        quantization: model::LaunchQuantization::Immediate,
        sync_mode: model::SyncMode::Reset,
    });

    app.audio.config.output_device = args.output.or(settings.audio.output_device.clone());
    app.audio.config.input_device = args.input.or(settings.audio.input_device.clone());
    app.audio.config.channels = args.channels.unwrap_or(settings.audio.channels);
    app.audio.config.buffer_size = args.buffer.unwrap_or(settings.audio.buffer_size);
    app.audio.config.max_voices = settings.audio.max_voices;
    app.audio.config.sample_paths = args.samples;
    app.audio.config.refresh_rate = RefreshRate::from_fps(settings.display.fps);
    app.ui.runtime_highlight = settings.display.runtime_highlight;
    app.audio.config.show_scope = settings.display.show_scope;
    app.audio.config.show_spectrum = settings.display.show_spectrum;
    app.ui.show_completion = settings.display.show_completion;
    app.ui.color_scheme = settings.display.color_scheme;
    app.ui.hue_rotation = settings.display.hue_rotation;
    app.audio.config.layout = settings.display.layout;

    let base_theme = settings.display.color_scheme.to_theme();
    let rotated =
        cagire_ratatui::theme::transform::rotate_theme(base_theme, settings.display.hue_rotation);
    theme::set(rotated);

    // MIDI connections
    let outputs = midi::list_midi_outputs();
    let inputs = midi::list_midi_inputs();
    for (slot, name) in settings.midi.output_devices.iter().enumerate() {
        if !name.is_empty() {
            if let Some(idx) = outputs.iter().position(|d| &d.name == name) {
                let _ = app.midi.connect_output(slot, idx);
            }
        }
    }
    for (slot, name) in settings.midi.input_devices.iter().enumerate() {
        if !name.is_empty() {
            if let Some(idx) = inputs.iter().position(|d| &d.name == name) {
                let _ = app.midi.connect_input(slot, idx);
            }
        }
    }

    let metrics = Arc::new(EngineMetrics::default());
    let scope_buffer = Arc::new(ScopeBuffer::new());
    let spectrum_buffer = Arc::new(SpectrumBuffer::new());

    let audio_sample_pos = Arc::new(AtomicU64::new(0));
    let sample_rate_shared = Arc::new(AtomicU32::new(44100));
    let mut initial_samples = Vec::new();
    for path in &app.audio.config.sample_paths {
        let index = doux::sampling::scan_samples_dir(path);
        app.audio.config.sample_count += index.len();
        initial_samples.extend(index);
    }
    let preload_entries: Vec<(String, std::path::PathBuf)> = initial_samples
        .iter()
        .map(|e| (e.name.clone(), e.path.clone()))
        .collect();

    #[cfg(feature = "desktop")]
    let mouse_x = Arc::new(AtomicU32::new(0.5_f32.to_bits()));
    #[cfg(feature = "desktop")]
    let mouse_y = Arc::new(AtomicU32::new(0.5_f32.to_bits()));
    #[cfg(feature = "desktop")]
    let mouse_down = Arc::new(AtomicU32::new(0.0_f32.to_bits()));

    let seq_config = SequencerConfig {
        audio_sample_pos: Arc::clone(&audio_sample_pos),
        sample_rate: Arc::clone(&sample_rate_shared),
        cc_access: Some(Arc::new(app.midi.cc_memory.clone()) as Arc<dyn model::CcAccess>),
        variables: Arc::clone(&app.variables),
        dict: Arc::clone(&app.dict),
        #[cfg(feature = "desktop")]
        mouse_x: Arc::clone(&mouse_x),
        #[cfg(feature = "desktop")]
        mouse_y: Arc::clone(&mouse_y),
        #[cfg(feature = "desktop")]
        mouse_down: Arc::clone(&mouse_down),
    };

    let (sequencer, initial_audio_rx, midi_rx) = spawn_sequencer(
        Arc::clone(&link),
        Arc::clone(&playing),
        settings.link.quantum,
        Arc::clone(&app.live_keys),
        Arc::clone(&nudge_us),
        seq_config,
    );

    let stream_config = AudioStreamConfig {
        output_device: app.audio.config.output_device.clone(),
        channels: app.audio.config.channels,
        buffer_size: app.audio.config.buffer_size,
        max_voices: app.audio.config.max_voices,
    };

    let (stream, analysis_handle) = match build_stream(
        &stream_config,
        initial_audio_rx,
        Arc::clone(&scope_buffer),
        Arc::clone(&spectrum_buffer),
        Arc::clone(&metrics),
        initial_samples,
        Arc::clone(&audio_sample_pos),
    ) {
        Ok((s, info, analysis, registry)) => {
            app.audio.config.sample_rate = info.sample_rate;
            app.audio.config.host_name = info.host_name;
            app.audio.config.channels = info.channels;
            sample_rate_shared.store(info.sample_rate as u32, Ordering::Relaxed);
            app.audio.sample_registry = Some(Arc::clone(&registry));

            if !preload_entries.is_empty() {
                let sr = info.sample_rate;
                std::thread::Builder::new()
                    .name("sample-preload".into())
                    .spawn(move || {
                        preload_sample_heads(preload_entries, sr, &registry);
                    })
                    .expect("failed to spawn preload thread");
            }

            (Some(s), Some(analysis))
        }
        Err(e) => {
            app.ui.set_status(format!("Audio failed: {e}"));
            app.audio.error = Some(e);
            (None, None)
        }
    };

    app.mark_all_patterns_dirty();

    Init {
        app,
        link,
        sequencer,
        playing,
        nudge_us,
        metrics,
        scope_buffer,
        spectrum_buffer,
        audio_sample_pos,
        sample_rate_shared,
        stream,
        analysis_handle,
        midi_rx,
        #[cfg(feature = "desktop")]
        settings,
        #[cfg(feature = "desktop")]
        mouse_x,
        #[cfg(feature = "desktop")]
        mouse_y,
        #[cfg(feature = "desktop")]
        mouse_down,
    }
}

pub fn preload_sample_heads(
    entries: Vec<(String, std::path::PathBuf)>,
    target_sr: f32,
    registry: &doux::SampleRegistry,
) {
    let mut batch = Vec::with_capacity(entries.len());
    for (name, path) in &entries {
        match doux::sampling::decode_sample_head(path, target_sr) {
            Ok(data) => batch.push((name.clone(), Arc::new(data))),
            Err(e) => eprintln!("preload {name}: {e}"),
        }
    }
    if !batch.is_empty() {
        registry.insert_batch(batch);
    }
}