import { Signal } from "@char/aftercare";
import { audition, play, playing, stop } from "../audio/transport.ts";
import { fetchTheoryTab, theoryTabPath, theoryTabProject } from "../import/theorytab.ts";
import { sounding, voiceTrack } from "../project/harmony.ts";
import {
  type ChordTrack,
  type ChordClip,
  findTrack,
  fitView,
  insertLeadIn,
  type NoteClip,
  pasteChords,
  pasteNotes,
  newChordTrack,
  newId,
  newNoteTrack,
  canonBeat,
  placeChord,
  type Project,
  type Track,
  projectKey,
} from "../project/model.ts";
import { commit, openNewProject, project } from "../project/store.ts";
import {
  type Chord,
  chordMatches,
  chordSymbol,
  isKeyRelative,
  parseChord,
} from "../theory/chord.ts";
import { romanOf } from "../theory/analysis.ts";
import { type Key, stepInScale } from "../theory/key.ts";
import { voiceChord } from "../theory/voicing.ts";
import { projectMidi } from "../midi/export.ts";
import { parseMidi } from "../midi/smf.ts";
import { chordsOf } from "../midi/chords.ts";
import { activeTrackId, cursor, selectedIds, selection } from "./state.ts";
import { chooseSections } from "./theorytab-dialog.tsx";
import { choosePartKinds } from "./midi-dialog.tsx";
import { saveFile } from "./dom.tsx";
import { projectFromFile, projectToFile } from "../project/persist.ts";

export const togglePlay = (): void => (playing.get() ? stop() : play(cursor.get()));

const chordTrack = (p: Project, id: string) => findTrack(p, id, "chords");

const voiced = (trackId: string, id: string) => {
  const p = project.get();
  const track = chordTrack(p, trackId);
  return track && voiceTrack(track, projectKey(p)).find(v => v.event.id === id);
};

/** hear some of a chord track's notes as the track would play them */
const auditionIn = (trackId: string, notes: readonly number[], dur: number, delay = 0) => {
  const track = chordTrack(project.get(), trackId);
  audition(track ? sounding(track, notes) : notes, dur, delay);
};

const auditionChord = (trackId: string, id: string) =>
  auditionIn(trackId, voiced(trackId, id)?.notes ?? [], 0.9);

/** length of a new chord at `start`: the default, unless it'd run into the next chord */
function newChordLength(p: Project, track: ChordTrack, start: number) {
  const next = track.chords.find(c => c.start > start)?.start ?? Infinity;
  return Math.min(p.chordLength, next - start);
}

/** write a chord symbol at the cursor, replacing the chord there, then step past it */
export function writeChord(trackId: string, symbol: string, { quiet = false } = {}): void {
  const p = project.get();
  const track = chordTrack(p, trackId);
  if (!track) return;
  const start = cursor.get();
  const existing = track.chords.find(c => c.start === start);
  const dur = existing?.dur ?? newChordLength(p, track, start);
  const id = existing?.id ?? newId();
  commit(d => placeChord(chordTrack(d, trackId)!, { id, start, dur, symbol }));
  cursor.set(start + dur);
  if (!quiet) auditionChord(trackId, id);
}

/** the chord track the palette writes to: the active one, or else the first */
export function paletteTrack(p: Project): ChordTrack | undefined {
  const active = p.tracks.find(t => t.id === activeTrackId.get());
  return active?.kind === "chords" ? active : p.tracks.find(t => t.kind === "chords");
}

/**
 * where to write a chord that follows on from the current one: just after the chord at the
 * cursor, if nothing's there yet; or else at the cursor, as the palette does
 */
export function nextChordAt(): number {
  const track = paletteTrack(project.get());
  const here = track?.chords.find(c => c.start === cursor.get());
  if (!here) return cursor.get();
  const end = canonBeat(here.start + here.dur);
  return track!.chords.some(c => c.start === end) ? here.start : end;
}

/** hear a chord as it would sound written at a beat, led on from the chord before it */
export function previewChord(symbol: string, at = cursor.get()): void {
  const p = project.get();
  const key = projectKey(p);
  const chord = parseChord(symbol, key);
  if (!chord) return;
  const track = paletteTrack(p);
  const before = track && voiceTrack(track, key).findLast(v => v.event.start < at);
  const notes = voiceChord(chord, before?.notes);
  audition(track ? sounding(track, notes) : notes, 0.9);
}

export function writeChordFromPalette(symbol: string, at = cursor.get()): void {
  cursor.set(at);
  let track = paletteTrack(project.get());
  if (!track) {
    track = newChordTrack();
    const added = track;
    commit(d => void d.tracks.unshift(added));
  }
  activeTrackId.set(track.id);
  // quiet: double-clicking to get here already previewed it
  writeChord(track.id, symbol, { quiet: true });
}

export function createChordWithNote(trackId: string, beat: number, pitch: number): void {
  const p = project.get();
  const track = chordTrack(p, trackId);
  if (!track) return;
  const start = Math.floor(beat / p.grid) * p.grid;
  const chord = { id: newId(), start, dur: newChordLength(p, track, start), notes: [pitch] };
  commit(d => placeChord(chordTrack(d, trackId)!, chord));
  cursor.set(start);
  audition([pitch]);
}

/** hand-voice a chord; its symbol is kept only while it still describes the notes */
function setChordNotes(track: ChordTrack, id: string, notes: number[], key: Key) {
  const c = track.chords.find(c => c.id === id);
  if (!c) return;
  if (!notes.length) {
    track.chords = track.chords.filter(x => x !== c);
    return;
  }
  c.notes = [...new Set(notes)].sort((a, b) => a - b);
  const typed = c.symbol !== undefined ? parseChord(c.symbol, key) : undefined;
  if (!(typed && chordMatches(typed, c.notes))) delete c.symbol;
}

export function revoice(
  trackId: string,
  id: string,
  change: (notes: number[]) => number[],
): void {
  const v = voiced(trackId, id);
  if (!v) return;
  const notes = change(v.notes).filter(n => n >= 0 && n < 128);
  const key = projectKey(project.get());
  commit(d => setChordNotes(chordTrack(d, trackId)!, id, notes, key));
  auditionIn(trackId, notes, 0.9);
}

export const toggleChordNote = (trackId: string, id: string, pitch: number): void =>
  revoice(trackId, id, notes =>
    notes.includes(pitch) ? notes.filter(n => n !== pitch) : [...notes, pitch],
  );

/** throw away a chord's hand-set notes, so it's voiced from its neighbours again */
export function unpin(trackId: string, id: string): void {
  const v = voiced(trackId, id);
  if (!v?.pinned) return;
  const symbol = v.event.symbol ?? (v.chord && chordSymbol(v.chord));
  if (symbol === undefined) return;
  commit(d => {
    const c = chordTrack(d, trackId)!.chords.find(c => c.id === id)!;
    c.symbol = symbol;
    delete c.notes;
  });
  auditionChord(trackId, id);
}

export function resizeChord(trackId: string, id: string, delta: number): void {
  commit(d => {
    const track = chordTrack(d, trackId)!;
    const c = track.chords.find(c => c.id === id);
    if (c) placeChord(track, { ...c, dur: Math.max(d.grid, c.dur + delta) });
  });
}

/** step the cursor to the neighbouring chord boundary */
export function moveChordCursor(track: ChordTrack, direction: 1 | -1): void {
  const at = cursor.get();
  const step = project.get().chordLength;
  const bounds = [
    ...new Set([0, ...track.chords.flatMap(c => [c.start, canonBeat(c.start + c.dur)])]),
  ].sort((a, b) => a - b);
  cursor.set(
    direction > 0
      ? (bounds.find(b => b > at) ?? at + step)
      : (bounds.findLast(b => b < at) ?? Math.max(0, at - step)),
  );
  const here = track.chords.find(c => c.start === cursor.get());
  selection.set(here ? { trackId: track.id, ids: [here.id] } : null);
}

export function deleteNotes(trackId: string, ids: readonly string[]): void {
  commit(d => {
    const track = findTrack(d, trackId, "notes")!;
    track.notes = track.notes.filter(n => !ids.includes(n.id));
  });
  selection.set(null);
}

export function nudgeNotes(
  trackId: string,
  ids: readonly string[],
  by: { beats?: number; pitch?: number; degrees?: number; dur?: number },
): void {
  const p = project.get();
  const key = projectKey(p);
  const pitched = (pitch: number) =>
    (by.degrees ? stepInScale(pitch, key, by.degrees) : pitch) + (by.pitch ?? 0);
  commit(d => {
    for (const n of findTrack(d, trackId, "notes")!.notes) {
      if (!ids.includes(n.id)) continue;
      n.start = Math.max(0, n.start + (by.beats ?? 0));
      n.pitch = Math.min(127, Math.max(0, pitched(n.pitch)));
      n.dur = Math.max(p.grid, n.dur + (by.dur ?? 0));
    }
  });
  if (by.pitch || by.degrees) {
    const track = findTrack(project.get(), trackId, "notes")!;
    audition(
      track.notes.filter(n => ids.includes(n.id)).map(n => n.pitch),
      0.4,
    );
  }
}

export function addTrack(kind: "chords" | "notes"): void {
  const track = kind === "chords" ? newChordTrack() : newNoteTrack();
  commit(d => void d.tracks.push(track));
  activeTrackId.set(track.id);
}

export function removeTrack(id: string): void {
  commit(d => void (d.tracks = d.tracks.filter(t => t.id !== id)));
  if (activeTrackId.get() === id) activeTrackId.set(project.get().tracks[0]?.id ?? null);
}

/** add every part of a midi file as a track of chords or of melody, starting from beat 0 */
export async function importMidi(file: File): Promise<void> {
  let parts;
  try {
    parts = parseMidi(new Uint8Array(await file.arrayBuffer()));
  } catch (e) {
    alert(`couldn't import ${file.name}: ${(e as Error).message}`);
    return;
  }
  if (!parts.length) {
    alert(`${file.name} has no (non-drum) notes in it`);
    return;
  }

  const kinds = await choosePartKinds(file.name, parts);
  if (!kinds) return;

  const base = file.name.replace(/\.midi?$/i, "");
  const tracks = parts.map((part, i): Track => {
    const name = parts.length > 1 ? `${base}: ${part.name}` : base;
    const view = fitView(part.notes.map(n => n.pitch));
    if (kinds[i] === "chords") {
      const chords = chordsOf(part.notes).map(c => ({ id: newId(), ...c }));
      return { ...newChordTrack(name), view, chords };
    }
    return { ...newNoteTrack(name), view, notes: part.notes.map(n => ({ id: newId(), ...n })) };
  });
  commit(d => void d.tracks.push(...tracks));
  activeTrackId.set(tracks[0].id);
  // the header, not the lane: it's pinned to the left, so this won't scroll sideways
  requestAnimationFrame(() =>
    document
      .querySelector(`.track-head[data-track="${tracks[0].id}"]`)
      ?.scrollIntoView({ block: "nearest" }),
  );
}

export const importingTheoryTab = new Signal(false);

/** start a new project from a TheoryTab: every section's chords and melody */
export async function importTheoryTab(url: string): Promise<void> {
  const path = theoryTabPath(url);
  if (!path) {
    alert("that doesn't look like a TheoryTab link (hooktheory.com/theorytab/view/…)");
    return;
  }
  if (importingTheoryTab.get()) return;
  importingTheoryTab.set(true);
  let tab;
  try {
    tab = await fetchTheoryTab(path);
  } catch (e) {
    alert(`couldn't import that TheoryTab: ${(e as Error).message}`);
    return;
  } finally {
    importingTheoryTab.set(false);
  }

  const sections = tab.sections.length > 1 ? await chooseSections(tab) : tab.sections;
  if (!sections) return;
  const part = sections.length === 1 && tab.sections.length > 1 ? ` (${sections[0].name})` : "";
  try {
    openNewProject(theoryTabProject({ title: tab.title + part, sections }));
  } catch (e) {
    alert(`couldn't import that TheoryTab: ${(e as Error).message}`);
  }
}

/** a new chord written the way `like` was: roman if it was, so it keeps following the key */
const writtenLike = (like: string | undefined, chord: Chord, key: Key) =>
  like !== undefined && isKeyRelative(like) ? romanOf(chord, key) : chordSymbol(chord);

/** replace a chord with a variation of it, auto-voiced */
export function transformChord(
  trackId: string,
  id: string,
  change: (chord: Chord, key: Key) => Chord | undefined,
): void {
  const v = voiced(trackId, id);
  const key = projectKey(project.get());
  const next = v?.chord && change(v.chord, key);
  if (!next) return;
  const symbol = writtenLike(v.event.symbol, next, key);
  commit(d => {
    const c = chordTrack(d, trackId)!.chords.find(c => c.id === id)!;
    c.symbol = symbol;
    delete c.notes;
  });
  auditionChord(trackId, id);
}

/** put chords before this one that lead into it, then play them into it */
export function leadInto(trackId: string, id: string, chords: Chord[]): void {
  const v = voiced(trackId, id);
  const p = project.get();
  const key = projectKey(p);
  if (!v) return;
  const symbols = chords.map(c => writtenLike(v.event.symbol, c, key));
  if (!insertLeadIn(structuredClone(chordTrack(p, trackId)!), id, symbols, p.grid)) return;
  commit(d => void insertLeadIn(chordTrack(d, trackId)!, id, symbols, p.grid));
  const after = voiceTrack(chordTrack(project.get(), trackId)!, key);
  const target = after.findIndex(c => c.event.id === id);
  const sequence = after.slice(target - chords.length, target + 1);
  sequence.forEach((c, i) => auditionIn(trackId, c.notes, 0.5, i * 0.45));
  cursor.set(after[target].event.start);
}

/** download the project as a midi file */
export function exportMidi(): void {
  const p = project.get();
  saveFile(p.name, ".mid", projectMidi(p), "audio/midi");
}

export function exportProject(): void {
  const p = project.get();
  saveFile(p.name, ".chordpad", projectToFile(p), "application/cbor");
}

export async function importProject(file: File): Promise<void> {
  try {
    openNewProject(projectFromFile(new Uint8Array(await file.arrayBuffer())));
  } catch (e) {
    alert(`couldn't open ${file.name}: ${(e as Error).message}`);
  }
}

/** the chords an edit applies to: those selected in the track, or else the one at the cursor */
export function chordsToEdit(track: ChordTrack): string[] {
  const selected = selectedIds(track.id).filter(id => track.chords.some(c => c.id === id));
  if (selected.length) return selected;
  const here = track.chords.find(c => c.start === cursor.get());
  return here ? [here.id] : [];
}

export function deleteChords(trackId: string, ids: readonly string[]): void {
  if (!ids.length) return;
  commit(d => {
    const track = chordTrack(d, trackId)!;
    track.chords = track.chords.filter(c => !ids.includes(c.id));
  });
  selection.set(null);
}

/** put chords in at the cursor, over whatever's there, and select them */
export function pasteClip(trackId: string, clip: ChordClip): void {
  const at = cursor.get();
  let ids: string[] = [];
  commit(d => void (ids = pasteChords(chordTrack(d, trackId)!, clip, at)));
  selection.set({ trackId, ids });
  cursor.set(at + clip.span);
}

/** add notes at the cursor and select them, moving the cursor past them to paste again after */
export function pasteNoteClip(trackId: string, clip: NoteClip): void {
  const at = cursor.get();
  let ids: string[] = [];
  commit(d => void (ids = pasteNotes(findTrack(d, trackId, "notes")!, clip, at)));
  selection.set({ trackId, ids });
  cursor.set(at + clip.span);
}