export type ModelId = "maai" | "smart_turn";
export type ScorePoint = [timeMs: number, score: number];

export interface ScoreCall {
  call_id: string;
  audio_path: string;
  audio_sha256: string;
  duration_ms: number;
  points: ScorePoint[];
  checkpoints: ScorePoint[];
}

export interface ScoreExport {
  schema_version: 1;
  model: ModelId;
  name: string;
  score: string;
  sample_interval_ms: number;
  calls: ScoreCall[];
}

export interface ScoreSeries extends ScoreCall {
  model: ModelId;
  name: string;
  score: string;
  sample_interval_ms: number;
}

export interface ScoreResponse {
  callId: string;
  recordingPath: string;
  series: ScoreSeries[];
  messages: string[];
}

function validPoints(value: unknown, duration: number): value is ScorePoint[] {
  if (!Array.isArray(value)) return false;
  let previous = -1;
  return value.every(point => {
    if (!Array.isArray(point) || point.length !== 2) return false;
    const [time, score] = point;
    if (!Number.isFinite(time) || time < 0 || time > duration || time <= previous
      || !Number.isFinite(score) || score < 0 || score > 1) return false;
    previous = time;
    return true;
  });
}

/** Validate inference exports without accepting null as a zero score. */
export function parseScoreExport(value: unknown, model: ModelId): ScoreExport {
  const data = value as ScoreExport;
  if (!data || data.schema_version !== 1 || data.model !== model
    || typeof data.name !== "string" || typeof data.score !== "string"
    || !Number.isFinite(data.sample_interval_ms) || data.sample_interval_ms <= 0
    || !Array.isArray(data.calls)) throw new Error("模型评分文件格式不正确。");
  const calls = new Set<string>();
  for (const call of data.calls) {
    if (!call || typeof call.call_id !== "string" || !call.call_id || calls.has(call.call_id)
      || typeof call.audio_path !== "string" || !/^[a-f0-9]{64}$/.test(call.audio_sha256)
      || !Number.isFinite(call.duration_ms) || call.duration_ms <= 0
      || !validPoints(call.points, call.duration_ms) || !validPoints(call.checkpoints, call.duration_ms)) {
      throw new Error("模型评分包含重复时间、越界分数或缺失的录音信息。");
    }
    calls.add(call.call_id);
  }
  return data;
}

/** Only an already available sample may describe a playhead/hover position. */
export function scoreAt(points: readonly ScorePoint[], ms: number, maxAgeMs: number): ScorePoint | null {
  let low = 0, high = points.length - 1, found = -1;
  while (low <= high) {
    const mid = (low + high) >>> 1;
    if (points[mid][0] <= ms) { found = mid; low = mid + 1; } else high = mid - 1;
  }
  return found >= 0 && ms - points[found][0] <= maxAgeMs ? points[found] : null;
}

/** Step curves show measured updates; a missing interval starts a new segment. */
export function scorePath(points: readonly ScorePoint[], duration: number, width: number,
  height: number, interval: number): string {
  const x = (t: number) => (t / duration * width).toFixed(2);
  const y = (p: number) => (12 + (1 - p) * (height - 24)).toFixed(2);
  let previous: ScorePoint | null = null;
  return points.map(point => {
    const step = previous && point[0] - previous[0] <= interval * 2
      ? `H${x(point[0])}V${y(point[1])}` : `M${x(point[0])},${y(point[1])}`;
    previous = point;
    return step;
  }).join("");
}