import type { JSX } from "@char/aftercare/jsx-runtime";
import { voiceTrack } from "../project/harmony.ts";
import { canonBeat, insertLeadIn, projectKey } from "../project/model.ts";
import { project } from "../project/store.ts";
import { prettyRoman } from "../theory/analysis.ts";
import { type Chord, chordName, chordSymbol } from "../theory/chord.ts";
import { connections } from "../theory/connect.ts";
import { parallel, relative, suspend, toggleSeventh, tritoneSub } from "../theory/transform.ts";
import { invertVoicing } from "../theory/voicing.ts";
import { leadInto, revoice, transformChord, unpin } from "./actions.ts";
import { disclosure, watch } from "./dom.tsx";
import { activeTrackId, chordPanelOpen, cursor } from "./state.ts";

const button = (label: string, result: string | undefined, run: () => void, title = "") => (
  <button
    type="button"
    class="chord-panel-action"
    disabled={result === undefined}
    title={title}
    _onclick={run}
  >
    {label}
    {result ? <b>{result}</b> : undefined}
  </button>
);

const group = (label: string, buttons: JSX.Element[]) => (
  <div class="chord-panel-group">
    <span class="chord-panel-label">{label}</span>
    <div class="chord-panel-buttons">{buttons}</div>
  </div>
);

const names = (chords: Chord | Chord[] | undefined) =>
  chords && [chords].flat().map(chordName).join(" ");

/** tools for the chord at the cursor: its voicing, variations on it, and ways into it */
export function ChordPanel(): JSX.Element {
  const panel = (<div class="chord-panel-body" />) as HTMLElement;
  const name = (<div class="chord-panel-name" />) as HTMLElement;

  watch(panel, [project, cursor, activeTrackId, chordPanelOpen], () => {
    if (!chordPanelOpen.get()) {
      name.replaceChildren();
      return panel.replaceChildren();
    }
    const p = project.get();
    const track = p.tracks.find(t => t.id === activeTrackId.get());
    const key = projectKey(p);
    const voiced = track?.kind === "chords" ? voiceTrack(track, key) : [];
    const v = voiced.find(v => v.event.start === cursor.get());
    if (!v || track?.kind !== "chords") {
      name.replaceChildren();
      panel.replaceChildren(<span class="chord-panel-empty">select a chord to change it</span>);
      return;
    }

    const [trackId, id, c] = [track.id, v.event.id, v.chord];
    const voicing = (label: string, change: (notes: number[]) => number[]) =>
      button(label, "", () => revoice(trackId, id, change));
    const octave =
      (by: number) =>
      ([bass, ...upper]: number[]) => [bass, ...upper.map(n => n + by)];
    const change = (label: string, f: (c: Chord) => Chord | undefined, title?: string) =>
      button(label, names(c && f(c)), () => transformChord(trackId, id, f), title);
    // the ways in from the chord before, where there's room for them before this one
    const i = voiced.indexOf(v);
    const prev = voiced[i - 1];
    const before = prev && canonBeat(prev.event.start + prev.event.dur) === v.event.start;
    const routes = c ? connections(before ? prev.chord : undefined, c) : [];
    const fits = (chords: Chord[]) =>
      insertLeadIn(structuredClone(track), id, chords.map(chordSymbol), p.grid);
    const connect = routes
      .filter(r => fits(r.chords))
      .slice(0, 6)
      .map(r => button(r.name, names(r.chords), () => leadInto(trackId, id, r.chords)));
    const adds = c && (toggleSeventh(c, key)?.tones.length ?? 0) > c.tones.length;
    const seventh = adds ? "+ 7th" : "− 7th";

    name.replaceChildren(
      <b>{v.label}</b>,
      <span>{v.analysis ? prettyRoman(v.analysis.roman) : ""}</span>,
    );
    panel.replaceChildren(
      group("voicing", [
        voicing("inversion ↓", notes => invertVoicing(notes, -1)),
        voicing("inversion ↑", notes => invertVoicing(notes, 1)),
        voicing("octave ↓", octave(-12)),
        voicing("octave ↑", octave(12)),
        button(
          "unpin",
          v.pinned ? "" : undefined,
          () => unpin(trackId, id),
          "back to voicing it from its neighbours",
        ),
      ]),
      ...(c
        ? [
            group("alterations", [
              change(seventh, c => toggleSeventh(c, key)),
              change("sus2", c => suspend(c, key, 2)),
              change("sus4", c => suspend(c, key, 5)),
              change("parallel", parallel, "the same chord with the other third"),
              change("relative", relative, "the chord a minor third away, sharing most notes"),
              change("tritone sub", tritoneSub, "a dominant a tritone away"),
            ]),
            ...(connect.length
              ? [group(before ? `from ${prev.label}` : "lead in", connect)]
              : []),
          ]
        : []),
    );
  });

  return (
    <section class="chord-panel" dataset={{ open: chordPanelOpen.derive(String) }}>
      {disclosure(chordPanelOpen, "chord")}
      {name}
      {panel}
    </section>
  );
}