NextEdu/src/shared/db/relations.ts

import { relations } from "drizzle-orm";
import { 
  users, 
  accounts,
  sessions,
  roles, 
  usersToRoles, 
  questions, 
  knowledgePoints, 
  questionsToKnowledgePoints, 
  textbooks, 
  chapters, 
  exams, 
  examQuestions, 
  examSubmissions, 
  submissionAnswers,
  homeworkAssignments,
  homeworkAssignmentQuestions,
  homeworkAssignmentTargets,
  homeworkSubmissions,
  homeworkAnswers
} from "./schema";

// --- Users & Roles Relations ---

export const usersRelations = relations(users, ({ many }) => ({
  accounts: many(accounts),
  sessions: many(sessions),
  usersToRoles: many(usersToRoles),
  createdExams: many(exams),
  createdHomeworkAssignments: many(homeworkAssignments),
  submissions: many(examSubmissions),
  homeworkSubmissions: many(homeworkSubmissions),
  authoredQuestions: many(questions),
}));

export const accountsRelations = relations(accounts, ({ one }) => ({
  user: one(users, {
    fields: [accounts.userId],
    references: [users.id],
  }),
}));

export const sessionsRelations = relations(sessions, ({ one }) => ({
  user: one(users, {
    fields: [sessions.userId],
    references: [users.id],
  }),
}));

export const rolesRelations = relations(roles, ({ many }) => ({
  usersToRoles: many(usersToRoles),
}));

export const usersToRolesRelations = relations(usersToRoles, ({ one }) => ({
  user: one(users, {
    fields: [usersToRoles.userId],
    references: [users.id],
  }),
  role: one(roles, {
    fields: [usersToRoles.roleId],
    references: [roles.id],
  }),
}));

// --- Questions Relations (Self-Reference & KP) ---

export const questionsRelations = relations(questions, ({ one, many }) => ({
  author: one(users, {
    fields: [questions.authorId],
    references: [users.id],
  }),
  // Self-Reference: Parent Question
  parent: one(questions, {
    fields: [questions.parentId],
    references: [questions.id],
    relationName: "question_hierarchy",
  }),
  // Self-Reference: Child Questions
  children: many(questions, {
    relationName: "question_hierarchy",
  }),
  
  // Many-to-Many with Knowledge Points
  questionsToKnowledgePoints: many(questionsToKnowledgePoints),
  
  // Usage in Exams
  examQuestions: many(examQuestions),
}));

export const knowledgePointsRelations = relations(knowledgePoints, ({ one, many }) => ({
  // Tree Structure
  parent: one(knowledgePoints, {
    fields: [knowledgePoints.parentId],
    references: [knowledgePoints.id],
    relationName: "kp_hierarchy",
  }),
  children: many(knowledgePoints, {
    relationName: "kp_hierarchy",
  }),
  
  questionsToKnowledgePoints: many(questionsToKnowledgePoints),
}));

export const questionsToKnowledgePointsRelations = relations(questionsToKnowledgePoints, ({ one }) => ({
  question: one(questions, {
    fields: [questionsToKnowledgePoints.questionId],
    references: [questions.id],
  }),
  knowledgePoint: one(knowledgePoints, {
    fields: [questionsToKnowledgePoints.knowledgePointId],
    references: [knowledgePoints.id],
  }),
}));

// --- Academic Relations ---

export const textbooksRelations = relations(textbooks, ({ many }) => ({
  chapters: many(chapters),
}));

export const chaptersRelations = relations(chapters, ({ one, many }) => ({
  textbook: one(textbooks, {
    fields: [chapters.textbookId],
    references: [textbooks.id],
  }),
  parent: one(chapters, {
    fields: [chapters.parentId],
    references: [chapters.id],
    relationName: "chapter_hierarchy",
  }),
  children: many(chapters, {
    relationName: "chapter_hierarchy",
  }),
}));

export const examsRelations = relations(exams, ({ one, many }) => ({
  creator: one(users, {
    fields: [exams.creatorId],
    references: [users.id],
  }),
  questions: many(examQuestions),
  submissions: many(examSubmissions),
}));

export const examQuestionsRelations = relations(examQuestions, ({ one }) => ({
  exam: one(exams, {
    fields: [examQuestions.examId],
    references: [exams.id],
  }),
  question: one(questions, {
    fields: [examQuestions.questionId],
    references: [questions.id],
  }),
}));

export const examSubmissionsRelations = relations(examSubmissions, ({ one, many }) => ({
  exam: one(exams, {
    fields: [examSubmissions.examId],
    references: [exams.id],
  }),
  student: one(users, {
    fields: [examSubmissions.studentId],
    references: [users.id],
  }),
  answers: many(submissionAnswers),
}));

export const submissionAnswersRelations = relations(submissionAnswers, ({ one }) => ({
  submission: one(examSubmissions, {
    fields: [submissionAnswers.submissionId],
    references: [examSubmissions.id],
  }),
  question: one(questions, {
    fields: [submissionAnswers.questionId],
    references: [questions.id],
  }),
}));

export const homeworkAssignmentsRelations = relations(homeworkAssignments, ({ one, many }) => ({
  creator: one(users, {
    fields: [homeworkAssignments.creatorId],
    references: [users.id],
  }),
  sourceExam: one(exams, {
    fields: [homeworkAssignments.sourceExamId],
    references: [exams.id],
  }),
  questions: many(homeworkAssignmentQuestions),
  targets: many(homeworkAssignmentTargets),
  submissions: many(homeworkSubmissions),
}));

export const homeworkAssignmentQuestionsRelations = relations(homeworkAssignmentQuestions, ({ one }) => ({
  assignment: one(homeworkAssignments, {
    fields: [homeworkAssignmentQuestions.assignmentId],
    references: [homeworkAssignments.id],
  }),
  question: one(questions, {
    fields: [homeworkAssignmentQuestions.questionId],
    references: [questions.id],
  }),
}));

export const homeworkAssignmentTargetsRelations = relations(homeworkAssignmentTargets, ({ one }) => ({
  assignment: one(homeworkAssignments, {
    fields: [homeworkAssignmentTargets.assignmentId],
    references: [homeworkAssignments.id],
  }),
  student: one(users, {
    fields: [homeworkAssignmentTargets.studentId],
    references: [users.id],
  }),
}));

export const homeworkSubmissionsRelations = relations(homeworkSubmissions, ({ one, many }) => ({
  assignment: one(homeworkAssignments, {
    fields: [homeworkSubmissions.assignmentId],
    references: [homeworkAssignments.id],
  }),
  student: one(users, {
    fields: [homeworkSubmissions.studentId],
    references: [users.id],
  }),
  answers: many(homeworkAnswers),
}));

export const homeworkAnswersRelations = relations(homeworkAnswers, ({ one }) => ({
  submission: one(homeworkSubmissions, {
    fields: [homeworkAnswers.submissionId],
    references: [homeworkSubmissions.id],
  }),
  question: one(questions, {
    fields: [homeworkAnswers.questionId],
    references: [questions.id],
  }),
}));