import type { ChapterIntent } from '@/audio/types';

export const SOUNDTRACK_SAMPLE_RATE = 48_000;
export const MUSIC_BPM = 86;
export const MUSIC_BEAT_SECONDS = 60 / MUSIC_BPM;
export const MUSIC_BEAT_SAMPLES = Math.round(
  SOUNDTRACK_SAMPLE_RATE * MUSIC_BEAT_SECONDS,
);
export const MUSIC_BAR_SECONDS = 4 * 60 / MUSIC_BPM;
export const MUSIC_BAR_SAMPLES = 133_953;
export const MAIN_PHRASE_BARS = 8;

export const MAIN_DURATION_SAMPLES = 8_573_023;
export const MAIN_DURATION_SECONDS = MAIN_DURATION_SAMPLES / SOUNDTRACK_SAMPLE_RATE;
export const AFTERGLOW_TRANSITION_SAMPLES = MUSIC_BAR_SAMPLES;
export const AFTERGLOW_TRANSITION_SECONDS = AFTERGLOW_TRANSITION_SAMPLES /
  SOUNDTRACK_SAMPLE_RATE;
export const AFTERGLOW_LOOP_START_SAMPLE = AFTERGLOW_TRANSITION_SAMPLES;
export const AFTERGLOW_LOOP_SAMPLES = 1_071_628;
export const AFTERGLOW_LOOP_END_SAMPLE = 1_205_581;
export const AFTERGLOW_LOOP_START_SECONDS = AFTERGLOW_LOOP_START_SAMPLE /
  SOUNDTRACK_SAMPLE_RATE;
export const AFTERGLOW_LOOP_END_SECONDS = AFTERGLOW_LOOP_END_SAMPLE /
  SOUNDTRACK_SAMPLE_RATE;
export const DRIVE_LIFT_LOOP_SAMPLES = 535_814;
export const DRIVE_LIFT_LOOP_SECONDS = DRIVE_LIFT_LOOP_SAMPLES /
  SOUNDTRACK_SAMPLE_RATE;

export const INTRO_IN_END_SAMPLE = 267_907;
export const INTRO_FIRST_PASS_END_SAMPLE = 1_339_535;
export const INTRO_LOOP_START_SAMPLE = INTRO_FIRST_PASS_END_SAMPLE;
export const INTRO_LOOP_END_SAMPLE = 2_411_163;
export const INTRO_OUT_START_SAMPLE = INTRO_LOOP_END_SAMPLE;
export const INTRO_OUT_END_SAMPLE = 2_679_070;
export const INTRO_RUNTIME_END_SAMPLE = 2_691_070;

export const INTRO_IN_END_SECONDS = INTRO_IN_END_SAMPLE / SOUNDTRACK_SAMPLE_RATE;
export const INTRO_FIRST_PASS_END_SECONDS = INTRO_FIRST_PASS_END_SAMPLE / SOUNDTRACK_SAMPLE_RATE;
export const INTRO_LOOP_START_SECONDS = INTRO_LOOP_START_SAMPLE / SOUNDTRACK_SAMPLE_RATE;
export const INTRO_LOOP_END_SECONDS = INTRO_LOOP_END_SAMPLE / SOUNDTRACK_SAMPLE_RATE;
export const INTRO_OUT_START_SECONDS = INTRO_OUT_START_SAMPLE / SOUNDTRACK_SAMPLE_RATE;
export const INTRO_OUT_END_SECONDS = INTRO_OUT_END_SAMPLE / SOUNDTRACK_SAMPLE_RATE;
export const INTRO_RUNTIME_END_SECONDS = INTRO_RUNTIME_END_SAMPLE / SOUNDTRACK_SAMPLE_RATE;

export type InitialPlayback =
  | { readonly kind: 'intro' }
  | { readonly kind: 'main'; readonly offsetSeconds: number };

export function resolveInitialPlayback(state: ChapterIntent): InitialPlayback {
  return state.atStart
    ? { kind: 'intro' }
    : { kind: 'main', offsetSeconds: mainPhraseOffsetSeconds(state.entryPhrase) };
}

export function mainPhraseOffsetSeconds(entryPhrase: number): number {
  const finitePhrase = Number.isFinite(entryPhrase) ? Math.trunc(entryPhrase) : 0;
  const phrase = Math.min(7, Math.max(0, finitePhrase));
  const targetSamples = Math.round(
    phrase * MAIN_PHRASE_BARS * MUSIC_BAR_SECONDS * SOUNDTRACK_SAMPLE_RATE,
  );
  return targetSamples / SOUNDTRACK_SAMPLE_RATE;
}

export function nextSafeBarTime(
  now: number,
  anchorTime: number,
  minimumLeadSeconds: number,
): number {
  const earliest = Math.max(anchorTime, now + Math.max(0, minimumLeadSeconds));
  const elapsedBars = (earliest - anchorTime) / MUSIC_BAR_SECONDS;
  const oneSampleInBars = 1 / SOUNDTRACK_SAMPLE_RATE / MUSIC_BAR_SECONDS;
  const nextBar = Math.ceil(elapsedBars - oneSampleInBars);
  return anchorTime + nextBar * MUSIC_BAR_SECONDS;
}

export function nextBeatTime(earliest: number, anchorTime: number): number {
  const elapsedBeats = (Math.max(anchorTime, earliest) - anchorTime) /
    MUSIC_BEAT_SECONDS;
  const oneSampleInBeats = 1 / SOUNDTRACK_SAMPLE_RATE / MUSIC_BEAT_SECONDS;
  return anchorTime + Math.ceil(elapsedBeats - oneSampleInBeats) *
    MUSIC_BEAT_SECONDS;
}

export function phaseAlignedLoopOffset(
  when: number,
  anchorTime: number,
  loopDuration: number,
): number {
  if (!Number.isFinite(loopDuration) || loopDuration <= 0) return 0;
  const elapsed = when - anchorTime;
  return ((elapsed % loopDuration) + loopDuration) % loopDuration;
}

export interface MainScheduleInput {
  readonly startTime: number;
  readonly offsetSeconds: number;
  readonly bufferDuration: number;
}

export interface MainSchedule {
  readonly sourceStartTime: number;
  readonly sourceOffsetSeconds: number;
  readonly musicalAnchorTime: number;
  readonly sourceEndTime: number;
  readonly afterglowStartTime: number;
}

export function resolveMainSchedule(input: MainScheduleInput): MainSchedule {
  const sourceOffsetSeconds = Math.min(
    Math.max(0, input.offsetSeconds),
    Math.max(0, input.bufferDuration - 0.05),
  );
  const sourceEndTime = input.startTime + input.bufferDuration -
    sourceOffsetSeconds;
  return {
    sourceStartTime: input.startTime,
    sourceOffsetSeconds,
    musicalAnchorTime: input.startTime - sourceOffsetSeconds,
    sourceEndTime,
    afterglowStartTime: sourceEndTime - AFTERGLOW_TRANSITION_SECONDS,
  };
}