use super::audio::{self, Stem};
use super::sync::{SyncData, Syncable};
use crate::synchronization::sync::TimestampMS;
use crate::ui::MaybeProgressBar;
use anyhow::Result;
use indicatif::ProgressBar;
use itertools::Itertools;
use measure_time::debug_time;
use midly::{MetaMessage, MidiMessage, TrackEvent, TrackEventKind};
use rayon::prelude::*;
use std::{collections::HashMap, fmt::Debug, path::PathBuf};

pub struct MidiSynchronizer {
    pub midi_path: PathBuf,
}

trait Averageable {
    fn average(&self) -> f32;
}

impl Averageable for Vec<f32> {
    fn average(&self) -> f32 {
        self.iter().sum::<f32>() / self.len() as f32
    }
}

impl Syncable for MidiSynchronizer {
    fn new(path: impl Into<PathBuf>) -> Self {
        Self {
            midi_path: path.into(),
        }
    }

    fn load(&self, progressbar: Option<&ProgressBar>) -> Result<SyncData> {
        let (now, notes_per_instrument, markers) =
            load_midi_file(&self.midi_path, progressbar)?;

        if let Some(pb) = progressbar {
            pb.set_length(notes_per_instrument.len() as _);
            pb.set_position(0);
        }

        Ok(SyncData {
            markers,
            bpm: Some(tempo_to_bpm(now.tempo)),
            stems: HashMap::from_par_iter(notes_per_instrument.par_iter().map(
                |(name, notes)| {
                    let mut notes_per_ms =
                        HashMap::<usize, Vec<audio::Note>>::new();

                    for note in notes.iter() {
                        notes_per_ms.entry(note.ms as usize).or_default().push(
                            audio::Note {
                                pitch: note.key,
                                tick: note.tick,
                                velocity: note.vel,
                            },
                        );
                    }

                    let duration_ms = *notes_per_ms.keys().max().unwrap_or(&0);

                    let mut amplitudes = Vec::<f32>::new();
                    let mut last_amplitude = 0.0;
                    for i in 0..duration_ms {
                        if let Some(notes) = notes_per_ms.get(&i) {
                            last_amplitude = notes
                                .iter()
                                .map(|n| n.velocity as f32)
                                .collect::<Vec<f32>>()
                                .average();
                        }
                        amplitudes.push(last_amplitude);
                    }

                    progressbar.map(|bar| bar.inc(1));

                    (
                        name.clone(),
                        Stem {
                            amplitude_max: notes
                                .iter()
                                .map(|n| n.vel)
                                .max()
                                .unwrap_or(0)
                                as f32,
                            amplitude_db: amplitudes,
                            duration_ms,
                            notes: notes_per_ms,
                            name: name.clone(),
                        },
                    )
                },
            )),
        })
    }
}

#[derive(Clone)]
struct Note {
    tick: u32,
    ms: u32,
    key: u8,
    vel: u8,
}

struct Now {
    ms: usize,
    tempo: usize,
    ticks_per_beat: u16,
}

type Timeline<'a> = HashMap<u32, HashMap<String, TrackEvent<'a>>>;

type StemNotes = HashMap<u32, HashMap<String, Note>>;

impl Note {
    fn is_off(&self) -> bool {
        self.vel == 0
    }
}

fn tempo_to_bpm(µs_per_beat: usize) -> usize {
    (60_000_000.0 / µs_per_beat as f32).round() as usize
}

// fn to_ms(delta: u32, bpm: f32) -> f32 {
//     (delta as f32) * (60.0 / bpm) * 1000.0
// }

impl Debug for Note {
    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
        write!(
            f,
            "{}{}",
            self.key,
            if self.is_off() {
                "↓".to_string()
            } else if self.vel == 100 {
                "".to_string()
            } else {
                format!("@{}", self.vel)
            }
        )
    }
}

fn load_midi_file(
    source: &PathBuf,
    progressbar: Option<&ProgressBar>,
) -> Result<(
    Now,
    HashMap<String, Vec<Note>>,
    HashMap<TimestampMS, String>,
)> {
    debug_time!("load_midi_notes");

    let mut markers = HashMap::<TimestampMS, String>::new();

    // Read midi file using midly
    if let Some(pb) = progressbar {
        pb.set_length(1);
        pb.set_prefix("Loading");
        pb.set_message("reading MIDI file");
        pb.set_position(0);
    }

    let raw = std::fs::read(source)?;
    let midifile = midly::Smf::parse(&raw)?;

    let mut timeline = Timeline::new();
    progressbar
        .set_message(format!("MIDI file has {} tracks", midifile.tracks.len()));

    let mut now = Now {
        ms: 0,
        tempo: 0,
        ticks_per_beat: match midifile.header.timing {
            midly::Timing::Metrical(ticks_per_beat) => ticks_per_beat.as_int(),
            midly::Timing::Timecode(fps, subframe) => {
                (1.0 / fps.as_f32() / subframe as f32) as u16
            }
        },
    };

    // Get track names and (initial) BPM
    let mut track_no = 0;
    let mut track_names = HashMap::<usize, String>::new();
    for track in midifile.tracks.iter() {
        track_no += 1;
        let mut track_name = String::new();
        for event in track {
            match event.kind {
                TrackEventKind::Meta(MetaMessage::TrackName(name_bytes)) => {
                    track_name = String::from_utf8(name_bytes.to_vec())?;
                }
                TrackEventKind::Meta(MetaMessage::Tempo(tempo)) => {
                    if now.tempo == 0 {
                        now.tempo = tempo.as_int() as usize;
                    }
                }
                _ => {}
            }
        }
        track_names.insert(
            track_no,
            if !track_name.is_empty() {
                track_name
            } else {
                format!("Track #{}", track_no)
            },
        );
    }

    // Convert ticks to absolute
    let mut track_no = 0;
    for track in midifile.tracks.iter() {
        track_no += 1;
        let mut absolute_tick = 0;
        for event in track {
            absolute_tick += event.delta.as_int();
            timeline
                .entry(absolute_tick)
                .or_default()
                .insert(track_names[&track_no].clone(), *event);
        }
    }

    // Convert ticks to ms
    let mut absolute_tick_to_ms = HashMap::<u32, usize>::new();
    let mut last_tick = 0;
    for (tick, tracks) in timeline.iter().sorted_by_key(|(tick, _)| *tick) {
        for event in tracks.values() {
            if let TrackEventKind::Meta(MetaMessage::Tempo(tempo)) = event.kind {
                now.tempo = tempo.as_int() as usize;
            }
        }
        let delta = tick - last_tick;
        last_tick = *tick;
        now.ms += midi_tick_to_ms(delta, now.tempo, now.ticks_per_beat as usize);
        absolute_tick_to_ms.insert(*tick, now.ms);
    }

    if let Some(pb) = progressbar {
        pb.set_length(
            midifile.tracks.iter().map(|t| t.len() as u64).sum::<u64>(),
        );
        pb.set_prefix("Loading");
        pb.set_message("parsing MIDI events");
        pb.set_position(0);
    }

    // Add notes
    let mut stem_notes = StemNotes::new();
    for (tick, tracks) in timeline.iter().sorted_by_key(|(tick, _)| *tick) {
        for (track_name, event) in tracks {
            if let TrackEventKind::Meta(MetaMessage::Marker(marker)) = event.kind
            {
                markers.insert(
                    absolute_tick_to_ms[tick],
                    String::from_utf8(marker.to_vec())?,
                );
            }

            if let TrackEventKind::Midi {
                channel: _,
                message,
            } = event.kind
            {
                match message {
                    MidiMessage::NoteOn { key, vel }
                    | MidiMessage::NoteOff { key, vel } => {
                        stem_notes
                            .entry(absolute_tick_to_ms[tick] as u32)
                            .or_default()
                            .insert(
                                track_name.clone(),
                                Note {
                                    tick: *tick,
                                    ms: absolute_tick_to_ms[tick] as u32,
                                    key: key.as_int(),
                                    vel: if matches!(
                                        message,
                                        MidiMessage::NoteOff { .. }
                                    ) {
                                        0
                                    } else {
                                        vel.as_int()
                                    },
                                },
                            );
                    }
                    _ => {}
                }
            }
            progressbar.inc(1)
        }
    }

    let mut result = HashMap::<String, Vec<Note>>::new();

    for (_ms, notes) in stem_notes.iter().sorted_by_key(|(ms, _)| *ms) {
        for (track_name, note) in notes {
            result
                .entry(track_name.clone())
                .or_default()
                .push(note.clone());
        }
    }

    Ok((now, result, markers))
}

fn midi_tick_to_ms(tick: u32, tempo: usize, ppq: usize) -> usize {
    let with_floats = (tempo as f32 / 1e3) / ppq as f32 * tick as f32;
    with_floats.round() as usize
}
