import type {
  ApiDocument,
  DocumentStatus,
  ExamModeOutput,
  FlashcardResponseItem,
  FlashcardsPayload,
  NotesOutput,
  PreviousPaperAnalysisResponse,
  QuizQuestionResponse,
  QuizQuestionsPayload,
  StudyPathResponse,
  VideoPlanV2Response,
  VideoRenderJob,
  VideoRenderJobStatus,
  VideoScenePlanResponse,
} from "@/lib/api/types";

type UnknownRecord = Record<string, unknown>;

function isRecord(value: unknown): value is UnknownRecord {
  return Boolean(value && typeof value === "object" && !Array.isArray(value));
}

function readString(value: unknown, fallback = "") {
  return typeof value === "string" && value.trim() ? value : fallback;
}

function readStringArray(value: unknown): string[] {
  if (!Array.isArray(value)) return [];
  return value.map((item) => String(item)).filter((item) => item.trim().length > 0);
}

export function normalizeDocument(value: unknown): ApiDocument {
  const record = isRecord(value) ? value : {};
  const now = new Date().toISOString();
  return {
    id: readString(record.id, `doc-local-${Date.now()}`),
    user_id: readString(record.user_id, "demo-user-student"),
    title: readString(record.title, "Study source"),
    file_name: readString(record.file_name, "source.pdf"),
    file_type: readString(record.file_type, "PDF"),
    subject: typeof record.subject === "string" ? record.subject : null,
    chapter: typeof record.chapter === "string" ? record.chapter : null,
    syllabus: typeof record.syllabus === "string" ? record.syllabus : null,
    status: normalizeDocumentStatus(record.status),
    // extracted_text removed — raw OCR text is not returned by the API
    extracted_text_length: typeof record.extracted_text_length === "number" ? record.extracted_text_length : null,
    chunk_count: typeof record.chunk_count === "number" ? record.chunk_count : 0,
    created_at: readString(record.created_at, now),
  };
}

export function normalizeDocumentStatus(value: unknown): DocumentStatus {
  if (value === "ready" || value === "processing" || value === "failed" || value === "uploaded") {
    return value;
  }
  return "ready";
}

export function normalizeNotes(value: unknown): NotesOutput {
  const record = isRecord(value) ? value : {};
  // Backend returns exam_keywords; exam_focus is a frontend-side alias
  const examKeywords = readStringArray(record.exam_keywords);
  return {
    title: readString(record.title, "Smart Notes"),
    summary: typeof record.summary === "string" ? record.summary : undefined,
    student_level_summary: typeof record.student_level_summary === "string" ? record.student_level_summary : undefined,
    key_points: readStringArray(record.key_points).length ? readStringArray(record.key_points) : ["Review the main ideas first."],
    important_keywords: readStringArray(record.important_keywords),
    important_definitions: readStringArray(record.important_definitions),
    formulas: readStringArray(record.formulas),
    diagrams_to_practice: readStringArray(record.diagrams_to_practice),
    memory_tricks: readStringArray(record.memory_tricks),
    exam_keywords: examKeywords,
    exam_focus: readStringArray(record.exam_focus).length ? readStringArray(record.exam_focus) : examKeywords,
    possible_exam_questions: readStringArray(record.possible_exam_questions),
    last_minute_revision: readStringArray(record.last_minute_revision),
    quick_check: readStringArray(record.quick_check),
    source_summary: typeof record.source_summary === "string" ? record.source_summary : undefined,
    scoring_keywords: readStringArray(record.scoring_keywords),
    common_mistakes: readStringArray(record.common_mistakes),
    ten_minute_revision: readStringArray(record.ten_minute_revision),
    next_study_action: typeof record.next_study_action === "string" ? record.next_study_action : undefined,
    caution_note: typeof record.caution_note === "string" ? record.caution_note : undefined,
  };
}

export function normalizeQuiz(value: unknown): QuizQuestionResponse[] {
  const payload: QuizQuestionsPayload | unknown = value;
  if (Array.isArray(payload)) return payload.filter(isRecord).map(normalizeQuizQuestion);
  if (isRecord(payload) && Array.isArray(payload.questions)) {
    return payload.questions.filter(isRecord).map(normalizeQuizQuestion);
  }
  return [];
}

function normalizeQuizQuestion(value: UnknownRecord): QuizQuestionResponse {
  return {
    question: readString(value.question, "Practice question"),
    type: readString(value.type, "MCQ"),
    options: readStringArray(value.options),
    answer: readString(value.answer, "Review the explanation."),
    explanation: typeof value.explanation === "string" ? value.explanation : undefined,
    difficulty: readString(value.difficulty, "Practice"),
    topic: typeof value.topic === "string" ? value.topic : undefined,
    why_this_matters: typeof value.why_this_matters === "string" ? value.why_this_matters : undefined,
    common_trap: typeof value.common_trap === "string" ? value.common_trap : undefined,
  };
}

export function normalizeFlashcards(value: unknown): FlashcardResponseItem[] {
  const payload: FlashcardsPayload | unknown = value;
  if (Array.isArray(payload)) return payload.filter(isRecord).map(normalizeFlashcard);
  if (isRecord(payload) && Array.isArray(payload.cards)) {
    return payload.cards.filter(isRecord).map(normalizeFlashcard);
  }
  return [];
}

function normalizeFlashcard(value: UnknownRecord): FlashcardResponseItem {
  return {
    front: readString(value.front, "Key idea"),
    back: readString(value.back, "Short explanation"),
    hint: typeof value.hint === "string" ? value.hint : undefined,
    tag: typeof value.tag === "string" ? value.tag : undefined,
    topic: typeof value.topic === "string" ? value.topic : undefined,
    memory_hook: typeof value.memory_hook === "string" ? value.memory_hook : undefined,
    exam_use: typeof value.exam_use === "string" ? value.exam_use : undefined,
  };
}

export function normalizePYQAnalysis(value: unknown): PreviousPaperAnalysisResponse | null {
  return isRecord(value) && Array.isArray(value.repeated_topics)
    ? (value as PreviousPaperAnalysisResponse)
    : null;
}

export function normalizeStudyPlan(value: unknown): StudyPathResponse | null {
  return isRecord(value) && Array.isArray(value.blocks) ? (value as StudyPathResponse) : null;
}

export function normalizeExamAnswer(value: unknown): ExamModeOutput | null {
  return isRecord(value) ? (value as ExamModeOutput) : null;
}

export function normalizeVideoPlan(value: unknown): VideoScenePlanResponse | VideoPlanV2Response | null {
  if (!isRecord(value)) return null;
  if (Array.isArray(value.scenes) || Array.isArray(value.sections)) {
    return value as VideoScenePlanResponse | VideoPlanV2Response;
  }
  return null;
}

export function normalizeRenderJob(value: unknown): VideoRenderJob | null {
  return isRecord(value) && typeof value.id === "string" ? (value as VideoRenderJob) : null;
}

export function normalizeRenderStatus(value: unknown): VideoRenderJobStatus {
  if (
    value === "ready" ||
    value === "failed" ||
    value === "queued" ||
    value === "running" ||
    value === "planning" ||
    value === "script_ready" ||
    value === "audio_generating" ||
    value === "visuals_generating" ||
    value === "rendering" ||
    value === "uploading" ||
    value === "complete"
  ) {
    return value;
  }
  if (value === "completed") return "complete";
  if (value === "processing") return "running";
  return "queued";
}