const OBJECT_OBJECT = "[object Object]";

export function isObjectObject(value: string | undefined | null): boolean {
  return value?.trim() === OBJECT_OBJECT;
}

/** Extract human-readable text from AI fields that may be strings or nested objects. */
export function extractText(value: unknown): string {
  if (value == null) return "";
  if (typeof value === "string") {
    const trimmed = value.trim();
    return isObjectObject(trimmed) ? "" : trimmed;
  }
  if (typeof value === "number" || typeof value === "boolean") {
    return String(value);
  }
  if (Array.isArray(value)) {
    return value.map((item) => extractText(item)).filter(Boolean).join("; ");
  }
  if (typeof value === "object") {
    const o = value as Record<string, unknown>;
    const parts: string[] = [];
    for (const key of ["task", "text", "description", "content", "summary", "goal", "step"]) {
      const part = extractText(o[key]);
      if (part) parts.push(part);
    }
    if (Array.isArray(o.steps)) {
      const steps = o.steps.map((s) => extractText(s)).filter(Boolean);
      if (steps.length) parts.push(steps.join("; "));
    }
    if (Array.isArray(o.instructions)) {
      const instructions = o.instructions.map((s) => extractText(s)).filter(Boolean);
      if (instructions.length) parts.push(instructions.join("; "));
    }
    return parts.join(" — ").trim();
  }
  return "";
}

export function extractStringList(value: unknown): string[] {
  if (!Array.isArray(value)) return [];
  return value.map((item) => extractText(item)).filter(Boolean);
}

export function normalizeQuizAnswer(
  rawAnswer: unknown,
  options: string[]
): { answerIndex: number; answerText: string } {
  if (options.length === 0) {
    const text = extractText(rawAnswer);
    return { answerIndex: 0, answerText: text || "See explanation" };
  }

  if (typeof rawAnswer === "number" && Number.isFinite(rawAnswer)) {
    const idx = Math.min(Math.max(0, rawAnswer), options.length - 1);
    return { answerIndex: idx, answerText: options[idx] ?? "" };
  }

  const asString = extractText(rawAnswer).trim();
  if (!asString) return { answerIndex: 0, answerText: options[0] ?? "" };

  const asNum = Number(asString);
  if (Number.isFinite(asNum) && asNum >= 0 && asNum < options.length) {
    return { answerIndex: asNum, answerText: options[asNum] ?? "" };
  }

  const letterMatch = /^[A-Da-d]$/.exec(asString);
  if (letterMatch) {
    const idx = letterMatch[0].toUpperCase().charCodeAt(0) - 65;
    if (idx >= 0 && idx < options.length) {
      return { answerIndex: idx, answerText: options[idx] ?? "" };
    }
  }

  const optionIdx = options.findIndex(
    (opt) => opt.toLowerCase() === asString.toLowerCase()
  );
  if (optionIdx >= 0) {
    return { answerIndex: optionIdx, answerText: options[optionIdx] ?? "" };
  }

  return { answerIndex: 0, answerText: asString };
}