import "dotenv/config";
import { db } from "../src/shared/db";
import { 
  users, roles, usersToRoles, 
  questions, knowledgePoints, questionsToKnowledgePoints,
  exams, examQuestions,
  homeworkAssignments,
  homeworkAssignmentQuestions,
  homeworkAssignmentTargets,
  homeworkSubmissions,
  homeworkAnswers,
  textbooks, chapters,
  schools,
  grades,
  classes, classEnrollments, classSchedule
} from "../src/shared/db/schema";
import { createId } from "@paralleldrive/cuid2";
import { faker } from "@faker-js/faker";
import { sql } from "drizzle-orm";

/**
 * Enterprise-Grade Seed Script for Next_Edu
 * 
 * Scenarios Covered:
 * 1. IAM: RBAC with multiple roles (Teacher & Grade Head).
 * 2. Knowledge Graph: Nested Knowledge Points (Math -> Algebra -> Linear Equations).
 * 3. Question Bank: Rich Text Content & Nested Questions (Reading Comprehension).
 * 4. Exams: JSON Structure for Sectioning.
 */

async function seed() {
  console.log("🌱 Starting Database Seed...");
  const start = performance.now();

  // --- 0. Cleanup (Optional: Truncate tables for fresh start) ---
  // Note: Order matters due to foreign keys if checks are enabled.
  // Ideally, use: SET FOREIGN_KEY_CHECKS = 0;
  try {
    await db.execute(sql`SET FOREIGN_KEY_CHECKS = 0;`);
    const tables = [
      "class_schedule", "class_enrollments", "classes",
      "homework_answers", "homework_submissions", "homework_assignment_targets", "homework_assignment_questions", "homework_assignments",
      "submission_answers", "exam_submissions", "exam_questions", "exams",
      "questions_to_knowledge_points", "questions", "knowledge_points",
      "chapters", "textbooks",
      "grades", "schools",
      "users_to_roles", "roles", "users", "accounts", "sessions"
    ];
    for (const table of tables) {
      await db.execute(sql.raw(`TRUNCATE TABLE \`${table}\`;`));
    }
    await db.execute(sql`SET FOREIGN_KEY_CHECKS = 1;`);
    console.log("🧹 Cleaned up existing data.");
  } catch (e) {
    console.warn("⚠️ Cleanup warning (might be fresh DB):", e);
  }

  // --- 1. IAM & Roles ---
  console.log("👤 Seeding IAM...");
  
  // Roles
  const roleMap = {
    admin: "role_admin",
    teacher: "role_teacher",
    student: "role_student",
    grade_head: "role_grade_head",
    teaching_head: "role_teaching_head"
  };

  await db.insert(roles).values([
    { id: roleMap.admin, name: "admin", description: "System Administrator" },
    { id: roleMap.teacher, name: "teacher", description: "Academic Instructor" },
    { id: roleMap.student, name: "student", description: "Learner" },
    { id: roleMap.grade_head, name: "grade_head", description: "Head of Grade Year" },
    { id: roleMap.teaching_head, name: "teaching_head", description: "Teaching Research Lead" }
  ]);

  // Users
  const usersData = [
    {
      id: "user_admin",
      name: "Admin User",
      email: "admin@next-edu.com",
      role: "admin", // Legacy field
      image: "https://api.dicebear.com/7.x/avataaars/svg?seed=Admin"
    },
    {
      id: "user_teacher_math",
      name: "Mr. Math",
      email: "math@next-edu.com",
      role: "teacher",
      image: "https://api.dicebear.com/7.x/avataaars/svg?seed=Math"
    },
    {
      id: "user_student_1",
      name: "Alice Student",
      email: "alice@next-edu.com",
      role: "student",
      image: "https://api.dicebear.com/7.x/avataaars/svg?seed=Alice"
    }
  ];

  await db.insert(users).values(usersData);

  // Assign Roles (RBAC)
  await db.insert(usersToRoles).values([
    { userId: "user_admin", roleId: roleMap.admin },
    { userId: "user_teacher_math", roleId: roleMap.teacher },
    // Math teacher is also a Grade Head
    { userId: "user_teacher_math", roleId: roleMap.grade_head },
    { userId: "user_student_1", roleId: roleMap.student },
  ]);

  const extraStudentIds: string[] = [];
  for (let i = 0; i < 12; i++) {
    const studentId = createId();
    extraStudentIds.push(studentId);
    await db.insert(users).values({
      id: studentId,
      name: faker.person.fullName(),
      email: faker.internet.email().toLowerCase(),
      role: "student",
      image: `https://api.dicebear.com/7.x/avataaars/svg?seed=${studentId}`,
    });
    await db.insert(usersToRoles).values({ userId: studentId, roleId: roleMap.student });
  }

  const schoolId = "school_nextedu"
  const grade10Id = "grade_10"

  await db.insert(schools).values([
    { id: schoolId, name: "Next_Edu School", code: "NEXTEDU" },
    { id: "school_demo_2", name: "Demo School No.2", code: "DEMO2" },
  ])

  await db.insert(grades).values([
    {
      id: grade10Id,
      schoolId,
      name: "Grade 10",
      order: 10,
      gradeHeadId: "user_teacher_math",
      teachingHeadId: "user_teacher_math",
    },
  ])

  await db.insert(classes).values([
    {
      id: "class_10_3",
      schoolName: "Next_Edu School",
      schoolId,
      name: "Grade 10 · Class 3",
      grade: "Grade 10",
      gradeId: grade10Id,
      homeroom: "10-3",
      room: "Room 304",
      invitationCode: "100003",
      teacherId: "user_teacher_math",
    },
    {
      id: "class_10_7",
      schoolName: "Next_Edu School",
      schoolId,
      name: "Grade 10 · Class 7",
      grade: "Grade 10",
      gradeId: grade10Id,
      homeroom: "10-7",
      room: "Room 201",
      invitationCode: "100007",
      teacherId: "user_teacher_math",
    },
  ]);

  await db.insert(classEnrollments).values([
    { classId: "class_10_3", studentId: "user_student_1", status: "active" },
    ...extraStudentIds.slice(0, 8).map((studentId) => ({ classId: "class_10_3", studentId, status: "active" as const })),
    ...extraStudentIds.slice(8, 12).map((studentId) => ({ classId: "class_10_7", studentId, status: "active" as const })),
  ]);

  await db.insert(classSchedule).values([
    { id: "cs_001", classId: "class_10_3", weekday: 1, startTime: "09:00", endTime: "09:45", course: "Mathematics", location: "Room 304" },
    { id: "cs_002", classId: "class_10_3", weekday: 3, startTime: "14:00", endTime: "14:45", course: "Physics", location: "Lab A" },
    { id: "cs_003", classId: "class_10_7", weekday: 2, startTime: "11:00", endTime: "11:45", course: "Mathematics", location: "Room 201" },
  ]);

  await db.insert(textbooks).values([
    {
      id: "tb_01",
      title: "Advanced Mathematics Grade 10",
      subject: "Mathematics",
      grade: "Grade 10",
      publisher: "Next Education Press",
    },
  ])

  await db.insert(chapters).values([
    {
      id: "ch_01",
      textbookId: "tb_01",
      title: "Chapter 1: Real Numbers",
      order: 1,
      parentId: null,
      content: "# Chapter 1: Real Numbers\n\nIn this chapter, we will explore the properties of real numbers...",
    },
    {
      id: "ch_01_01",
      textbookId: "tb_01",
      title: "1.1 Introduction to Real Numbers",
      order: 1,
      parentId: "ch_01",
      content: "## 1.1 Introduction\n\nReal numbers include rational and irrational numbers.",
    },
  ])

  // --- 2. Knowledge Graph (Tree) ---
  console.log("🧠 Seeding Knowledge Graph...");
  
  const kpMathId = createId();
  const kpAlgebraId = createId();
  const kpLinearId = createId();

  await db.insert(knowledgePoints).values([
    { id: kpMathId, name: "Mathematics", level: 0 },
    { id: kpAlgebraId, name: "Algebra", parentId: kpMathId, level: 1 },
    { id: kpLinearId, name: "Linear Equations", parentId: kpAlgebraId, level: 2 },
  ]);

  await db.insert(knowledgePoints).values([
    {
      id: "kp_01",
      name: "Real Numbers",
      description: "Definition and properties of real numbers",
      level: 1,
      order: 1,
      chapterId: "ch_01",
    },
    {
      id: "kp_02",
      name: "Rational Numbers",
      description: "Numbers that can be expressed as a fraction",
      level: 2,
      order: 1,
      chapterId: "ch_01_01",
    },
  ])

  // --- 3. Question Bank (Rich Content) ---
  console.log("📚 Seeding Question Bank...");

  const mathExamQuestions: Array<{
    id: string;
    type: "single_choice" | "text" | "judgment";
    difficulty: number;
    content: unknown;
    score: number;
  }> = [
    {
      id: createId(),
      type: "single_choice",
      difficulty: 1,
      score: 4,
      content: {
        text: "1) What is 2 + 2?",
        options: [
          { id: "A", text: "3", isCorrect: false },
          { id: "B", text: "4", isCorrect: true },
          { id: "C", text: "5", isCorrect: false },
          { id: "D", text: "6", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 2,
      score: 4,
      content: {
        text: "2) If f(x) = 2x + 1, then f(3) = ?",
        options: [
          { id: "A", text: "5", isCorrect: false },
          { id: "B", text: "7", isCorrect: true },
          { id: "C", text: "8", isCorrect: false },
          { id: "D", text: "10", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 2,
      score: 4,
      content: {
        text: "3) Solve 3x - 5 = 7. What is x?",
        options: [
          { id: "A", text: "3", isCorrect: false },
          { id: "B", text: "4", isCorrect: true },
          { id: "C", text: "5", isCorrect: false },
          { id: "D", text: "6", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 3,
      score: 4,
      content: {
        text: "4) Which is a factor of x^2 - 9?",
        options: [
          { id: "A", text: "(x - 3)", isCorrect: true },
          { id: "B", text: "(x + 9)", isCorrect: false },
          { id: "C", text: "(x - 9)", isCorrect: false },
          { id: "D", text: "(x^2 + 9)", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 2,
      score: 4,
      content: {
        text: "5) If a^2 = 49 and a > 0, then a = ?",
        options: [
          { id: "A", text: "-7", isCorrect: false },
          { id: "B", text: "0", isCorrect: false },
          { id: "C", text: "7", isCorrect: true },
          { id: "D", text: "49", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 3,
      score: 4,
      content: {
        text: "6) Simplify (x^2 y)(x y^3).",
        options: [
          { id: "A", text: "x^2 y^3", isCorrect: false },
          { id: "B", text: "x^3 y^4", isCorrect: true },
          { id: "C", text: "x^3 y^3", isCorrect: false },
          { id: "D", text: "x^4 y^4", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 2,
      score: 4,
      content: {
        text: "7) The slope of the line y = -3x + 2 is:",
        options: [
          { id: "A", text: "2", isCorrect: false },
          { id: "B", text: "-3", isCorrect: true },
          { id: "C", text: "3", isCorrect: false },
          { id: "D", text: "-2", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 1,
      score: 4,
      content: {
        text: "8) The probability of getting heads in one fair coin toss is:",
        options: [
          { id: "A", text: "0", isCorrect: false },
          { id: "B", text: "1/4", isCorrect: false },
          { id: "C", text: "1/2", isCorrect: true },
          { id: "D", text: "1", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 2,
      score: 4,
      content: {
        text: "9) In an arithmetic sequence with a1 = 2 and d = 3, a5 = ?",
        options: [
          { id: "A", text: "11", isCorrect: false },
          { id: "B", text: "12", isCorrect: false },
          { id: "C", text: "14", isCorrect: true },
          { id: "D", text: "17", isCorrect: false },
        ],
      },
    },
    {
      id: createId(),
      type: "single_choice",
      difficulty: 2,
      score: 4,
      content: {
        text: "10) The solution set of x^2 = 0 is:",
        options: [
          { id: "A", text: "{0}", isCorrect: true },
          { id: "B", text: "{1}", isCorrect: false },
          { id: "C", text: "{-1, 1}", isCorrect: false },
          { id: "D", text: "Empty set", isCorrect: false },
        ],
      },
    },

    { id: createId(), type: "text", difficulty: 1, score: 4, content: { text: "11) Fill in the blank: √81 = ____.", correctAnswer: "9" } },
    { id: createId(), type: "text", difficulty: 2, score: 4, content: { text: "12) Fill in the blank: (a - b)^2 = ____.", correctAnswer: ["a^2 - 2ab + b^2", "a² - 2ab + b²"] } },
    { id: createId(), type: "text", difficulty: 1, score: 4, content: { text: "13) Fill in the blank: 2^5 = ____.", correctAnswer: "32" } },
    { id: createId(), type: "text", difficulty: 2, score: 4, content: { text: "14) Fill in the blank: The area of a circle with radius r is ____.", correctAnswer: ["πr^2", "pi r^2", "πr²"] } },
    { id: createId(), type: "text", difficulty: 1, score: 4, content: { text: "15) Fill in the blank: If x = -2, then x^3 = ____.", correctAnswer: "-8" } },

    { id: createId(), type: "judgment", difficulty: 1, score: 2, content: { text: "16) If x > y, then x + 1 > y + 1.", correctAnswer: true } },
    { id: createId(), type: "judgment", difficulty: 1, score: 2, content: { text: "17) The graph of y = 2x is a parabola.", correctAnswer: false } },
    { id: createId(), type: "judgment", difficulty: 1, score: 2, content: { text: "18) The sum of interior angles of a triangle is 180°.", correctAnswer: true } },
    { id: createId(), type: "judgment", difficulty: 2, score: 2, content: { text: "19) (x + y)^2 = x^2 + y^2.", correctAnswer: false } },
    { id: createId(), type: "judgment", difficulty: 1, score: 2, content: { text: "20) 0 is a positive number.", correctAnswer: false } },

    { id: createId(), type: "text", difficulty: 3, score: 10, content: { text: "21) Solve the system: x + y = 5, x - y = 1." } },
    { id: createId(), type: "text", difficulty: 3, score: 10, content: { text: "22) Expand and simplify: (2x - 3)(x + 4)." } },
    { id: createId(), type: "text", difficulty: 3, score: 10, content: { text: "23) In a right triangle with legs 6 and 8, find the hypotenuse and the area." } },
  ];

  await db.insert(questions).values(
    mathExamQuestions.map((q) => ({
      id: q.id,
      type: q.type,
      difficulty: q.difficulty,
      content: q.content,
      authorId: "user_teacher_math",
    }))
  );

  await db.insert(questionsToKnowledgePoints).values({
    questionId: mathExamQuestions[0].id,
    knowledgePointId: kpLinearId
  });

  // --- 4. Exams (New Structure) ---
  console.log("📝 Seeding Exams...");

  const examId = createId();

  const makeGroup = (title: string, children: unknown[]) => ({
    id: createId(),
    type: "group",
    title,
    children,
  });

  const makeQuestionNode = (questionId: string, score: number) => ({
    id: createId(),
    type: "question",
    questionId,
    score,
  });

  const choiceIds = mathExamQuestions.slice(0, 10).map((q) => q.id);
  const fillIds = mathExamQuestions.slice(10, 15).map((q) => q.id);
  const judgmentIds = mathExamQuestions.slice(15, 20).map((q) => q.id);
  const shortAnswerIds = mathExamQuestions.slice(20, 23).map((q) => q.id);

  const examStructure = [
    makeGroup(
      "第一部分：单项选择题（共10题，每题4分，共40分）",
      choiceIds.map((id) => makeQuestionNode(id, 4))
    ),
    makeGroup(
      "第二部分：填空题（共5题，每题4分，共20分）",
      fillIds.map((id) => makeQuestionNode(id, 4))
    ),
    makeGroup(
      "第三部分：判断题（共5题，每题2分，共10分）",
      judgmentIds.map((id) => makeQuestionNode(id, 2))
    ),
    makeGroup(
      "第四部分：解答题（共3题，每题10分，共30分）",
      shortAnswerIds.map((id) => makeQuestionNode(id, 10))
    ),
  ];

  await db.insert(exams).values({
    id: examId,
    title: "Grade 10 Mathematics Final Exam (Seed)",
    description: JSON.stringify({
      subject: "Mathematics",
      grade: "Grade 10",
      difficulty: 3,
      totalScore: 100,
      durationMin: 120,
      questionCount: 23,
      tags: ["seed", "math", "grade10", "final"],
    }),
    creatorId: "user_teacher_math",
    status: "published",
    startTime: new Date(),
    structure: examStructure as unknown
  });

  // Link questions physically (Source of Truth)
  const orderedQuestionIds = [...choiceIds, ...fillIds, ...judgmentIds, ...shortAnswerIds];
  const scoreById = new Map(mathExamQuestions.map((q) => [q.id, q.score] as const));

  await db.insert(examQuestions).values(
    orderedQuestionIds.map((questionId, order) => ({
      examId,
      questionId,
      score: scoreById.get(questionId) ?? 0,
      order,
    }))
  );

  console.log("📌 Seeding Homework Assignments...");

  const assignmentId = createId();
  const now = new Date();
  const dueAt = new Date(now.getTime() + 7 * 24 * 60 * 60 * 1000);
  const lateDueAt = new Date(now.getTime() + 9 * 24 * 60 * 60 * 1000);

  await db.insert(homeworkAssignments).values({
    id: assignmentId,
    sourceExamId: examId,
    title: "Grade 10 Mathematics Final - Homework (Seed)",
    description: "Auto-generated homework assignment from seeded math exam.",
    structure: examStructure as unknown,
    status: "published",
    creatorId: "user_teacher_math",
    availableAt: now,
    dueAt,
    allowLate: true,
    lateDueAt,
    maxAttempts: 2,
  });

  await db.insert(homeworkAssignmentQuestions).values(
    orderedQuestionIds.map((questionId, order) => ({
      assignmentId,
      questionId,
      score: scoreById.get(questionId) ?? 0,
      order,
    }))
  );

  const targetStudentIds = ["user_student_1", ...extraStudentIds.slice(0, 4)];
  await db.insert(homeworkAssignmentTargets).values(
    targetStudentIds.map((studentId) => ({
      assignmentId,
      studentId,
    }))
  );

  const scoreForQuestion = (questionId: string) => scoreById.get(questionId) ?? 0;
  const buildAnswer = (questionId: string, type: string) => {
    if (type === "single_choice") return { answer: "B" };
    if (type === "judgment") return { answer: true };
    return { answer: "Seed answer" };
  };

  const questionTypeById = new Map(mathExamQuestions.map((q) => [q.id, q.type] as const));

  const submissionIds: string[] = [];
  for (let i = 0; i < 3; i++) {
    const studentId = targetStudentIds[i];
    const submissionId = createId();
    submissionIds.push(submissionId);
    const submittedAt = new Date(now.getTime() - (i + 1) * 24 * 60 * 60 * 1000);
    const status = i === 0 ? "graded" : i === 1 ? "graded" : "submitted";

    const perQuestionScores = orderedQuestionIds.map((qid, idx) => {
      const max = scoreForQuestion(qid);
      if (status !== "graded") return null;
      if (max <= 0) return 0;
      if (idx % 7 === 0) return Math.max(0, max - 1);
      return max;
    });

    const totalScore =
      status === "graded"
        ? perQuestionScores.reduce<number>((sum, s) => sum + Number(s ?? 0), 0)
        : null;

    await db.insert(homeworkSubmissions).values({
      id: submissionId,
      assignmentId,
      studentId,
      attemptNo: 1,
      score: totalScore,
      status,
      startedAt: submittedAt,
      submittedAt,
      isLate: false,
      createdAt: submittedAt,
      updatedAt: submittedAt,
    });

    await db.insert(homeworkAnswers).values(
      orderedQuestionIds.map((questionId, idx) => {
        const questionType = questionTypeById.get(questionId) ?? "text";
        const score = status === "graded" ? (perQuestionScores[idx] ?? 0) : null;
        return {
          id: createId(),
          submissionId,
          questionId,
          answerContent: buildAnswer(questionId, questionType),
          score,
          feedback: status === "graded" ? (score === scoreForQuestion(questionId) ? "Good" : "Check calculation") : null,
          createdAt: submittedAt,
          updatedAt: submittedAt,
        };
      })
    );
  }

  const end = performance.now();
  console.log(`✅ Seed completed in ${(end - start).toFixed(2)}ms`);
  process.exit(0);
}

seed().catch((err) => {
  console.error("❌ Seed failed:", err);
  process.exit(1);
});