export const DEFAULT_VIEW_PLANE = Object.freeze({
  xMin: -0.6,
  xMax: 0.6,
  yMin: -0.45,
  yMax: 0.45,
});

export const SOURCE_COLORS = ["#65f2bf", "#58c7e8", "#ffc56e", "#ff8f87", "#be9bff", "#8ee36b"];

export const MAX_TRAJECTORY_KEYFRAMES = 4096;

function copyPosition(position) {
  return position.map((coordinate) => Number(coordinate));
}

function clamp(value, minimum, maximum) {
  return Math.max(minimum, Math.min(maximum, value));
}

export function synchronizeSourcePosition(source) {
  if (Array.isArray(source.trajectory) && source.trajectory.length > 0) {
    source.position = copyPosition(source.trajectory[0].position);
  }
  return source.position;
}

export function createDefaultTrajectory(source, sceneDuration, plane = DEFAULT_VIEW_PLANE) {
  const start = copyPosition(source.position);
  const width = Number.isFinite(plane?.xMax - plane?.xMin) && plane.xMax > plane.xMin
    ? plane.xMax - plane.xMin
    : DEFAULT_VIEW_PLANE.xMax - DEFAULT_VIEW_PLANE.xMin;
  const minimum = Number.isFinite(plane?.xMin) ? plane.xMin : DEFAULT_VIEW_PLANE.xMin;
  const maximum = Number.isFinite(plane?.xMax) ? plane.xMax : DEFAULT_VIEW_PLANE.xMax;
  const offset = Math.max(0.1, width * 0.25);
  const rightRoom = maximum - start[0];
  const leftRoom = start[0] - minimum;
  const direction = rightRoom >= offset || rightRoom >= leftRoom ? 1 : -1;
  const endX = clamp(start[0] + direction * offset, minimum, maximum);
  return [
    { time: 0, position: start },
    { time: sceneDuration, position: [endX, start[1], start[2]] },
  ];
}

export function enableSourceTrajectory(source, sceneDuration, plane = DEFAULT_VIEW_PLANE) {
  if (!Array.isArray(source.trajectory) || source.trajectory.length < 2) {
    source.trajectory = createDefaultTrajectory(source, sceneDuration, plane);
  }
  synchronizeSourcePosition(source);
  return source.trajectory;
}

export function disableSourceTrajectory(source) {
  synchronizeSourcePosition(source);
  delete source.trajectory;
}

export function insertTrajectoryKeyframe(source) {
  if (!Array.isArray(source.trajectory) || source.trajectory.length < 2 ||
      source.trajectory.length >= MAX_TRAJECTORY_KEYFRAMES) {
    return -1;
  }
  let leftIndex = 0;
  let largestGap = -Infinity;
  for (let index = 0; index < source.trajectory.length - 1; index += 1) {
    const gap = source.trajectory[index + 1].time - source.trajectory[index].time;
    if (gap > largestGap) {
      largestGap = gap;
      leftIndex = index;
    }
  }
  if (!(largestGap > 0)) return -1;
  const left = source.trajectory[leftIndex];
  const right = source.trajectory[leftIndex + 1];
  source.trajectory.splice(leftIndex + 1, 0, {
    time: left.time + largestGap / 2,
    position: left.position.map((coordinate, index) =>
      coordinate + (right.position[index] - coordinate) / 2,
    ),
  });
  synchronizeSourcePosition(source);
  return leftIndex + 1;
}

export function removeTrajectoryKeyframe(source, index) {
  if (!Array.isArray(source.trajectory) || source.trajectory.length <= 2 ||
      !Number.isInteger(index) || index < 0 || index >= source.trajectory.length) return false;
  source.trajectory.splice(index, 1);
  synchronizeSourcePosition(source);
  return true;
}

export function trajectoryTimeBounds(source, index, sceneDuration) {
  const trajectory = source.trajectory;
  const duration = Number.isFinite(sceneDuration) && sceneDuration > 0 ? sceneDuration : 0;
  const gap = Math.max(1e-9, duration * 1e-9);
  return {
    minimum: index === 0 ? 0 : trajectory[index - 1].time + gap,
    maximum: index === trajectory.length - 1 ? duration : trajectory[index + 1].time - gap,
  };
}

export function updateTrajectoryKeyframeTime(source, index, requestedTime, sceneDuration) {
  if (!Number.isFinite(requestedTime) || !source.trajectory?.[index]) return source.trajectory?.[index]?.time;
  const { minimum, maximum } = trajectoryTimeBounds(source, index, sceneDuration);
  source.trajectory[index].time = clamp(requestedTime, minimum, maximum);
  return source.trajectory[index].time;
}

export function scaleSceneTrajectories(scene, previousDuration, nextDuration) {
  if (!Number.isFinite(previousDuration) || previousDuration <= 0 ||
      !Number.isFinite(nextDuration) || nextDuration <= 0) return;
  const scale = nextDuration / previousDuration;
  for (const source of scene.sources) {
    if (!Array.isArray(source.trajectory)) continue;
    source.trajectory.forEach((keyframe) => { keyframe.time *= scale; });
    synchronizeSourcePosition(source);
  }
}

export function prepareSceneForEditing(scene) {
  const prepared = structuredClone(scene);
  prepared.assets ??= [];
  prepared.ambient ??= [];
  prepared.mix ??= { normalization: "none", targetPeak: 0.95 };
  prepared.sources.forEach(synchronizeSourcePosition);
  return prepared;
}

export function createSceneId(now = Date.now(), randomValue = crypto.getRandomValues(new Uint32Array(1))[0]) {
  return `scene-${now.toString(36)}-${randomValue.toString(36)}`;
}

export function uniqueId(base, existingIds) {
  const normalized = String(base)
    .toLowerCase()
    .normalize("NFKD")
    .replace(/[^a-z0-9._-]+/g, "-")
    .replace(/^[^a-z0-9]+|[^a-z0-9]+$/g, "") || "asset";
  let candidate = normalized;
  let suffix = 2;
  while (existingIds.has(candidate)) {
    candidate = `${normalized}-${suffix}`;
    suffix += 1;
  }
  return candidate;
}

export function assetDescriptorForFile(file, kind, existingIds) {
  const baseName = file.name.replace(/\.[^.]+$/, "") || kind;
  return {
    id: uniqueId(`${kind}-${baseName}`, existingIds),
    kind,
    fileName: file.name,
    mimeType: file.type || (kind === "image" ? "image/*" : "audio/*"),
  };
}

export function matchAssetDescriptor(assets, boundAssetIds, fileName, kind, hash) {
  const candidates = assets.filter((asset) => asset.kind === kind);
  const hashMatches = candidates.filter((asset) => asset.sha256 === hash);
  const hashMatch = hashMatches.find((asset) => !boundAssetIds.has(asset.id)) ?? hashMatches[0];
  if (hashMatch) return { descriptor: hashMatch, conflict: false };
  const baseName = (path) => path.split(/[\\/]/).pop();
  const nameCandidates = candidates.filter((asset) => baseName(asset.fileName) === fileName);
  const compatible = nameCandidates.find((asset) => !asset.sha256 && !boundAssetIds.has(asset.id));
  if (compatible) return { descriptor: compatible, conflict: false };
  return { descriptor: null, conflict: nameCandidates.some((asset) => asset.sha256 !== hash) };
}

export function createSource(scene) {
  const existingIds = new Set(scene.sources.map((source) => source.id));
  const ordinal = scene.sources.length + 1;
  return {
    id: uniqueId(`source-${ordinal}`, existingIds),
    name: `음원 ${ordinal}`,
    position: [0, 0, scene.image?.plane?.z ?? scene.sources[0]?.position?.[2] ?? 2],
    gainDb: -6,
    startTime: 0,
    duration: scene.duration,
    signal: { type: "tone", frequency: Math.min(1000, scene.sampleRate / 4), phaseDeg: 0 },
  };
}

export function changeSignalType(source, type, firstAudioAssetId = "") {
  if (type === "tone") {
    source.signal = { type: "tone", frequency: 1000, phaseDeg: 0 };
  } else if (type === "noise") {
    source.signal = { type: "noise", color: "white", seedOffset: 0 };
  } else if (type === "asset") {
    source.signal = { type: "asset", assetId: firstAudioAssetId, channel: 0, loop: false };
  }
}

export function describeSignal(signal) {
  if (signal.type === "tone") return `${signal.frequency} Hz tone`;
  if (signal.type === "noise") return `${signal.color} noise`;
  if (signal.type === "asset") return `asset · ${signal.assetId || "미선택"}`;
  return "알 수 없는 신호";
}

export function referencedAssetIds(scene) {
  const ids = new Set();
  if (scene.image?.assetId) ids.add(scene.image.assetId);
  for (const entry of [...scene.sources, ...(scene.ambient ?? [])]) {
    if (entry.signal?.type === "asset" && entry.signal.assetId) ids.add(entry.signal.assetId);
  }
  return ids;
}

export function isAssetReferenced(scene, assetId) {
  return referencedAssetIds(scene).has(assetId);
}

export function safeDownloadStem(scene) {
  return uniqueId(scene.id || scene.name || "scene", new Set());
}