import { register } from '@/services/mock/registry'
import { endpoints } from '@/services/api/endpoints'
import { adminExams } from '@/services/mock/fixtures/admin-exams'
import { adminCourses } from '@/services/mock/fixtures/admin-courses'
import { filterItems, isoNow, makeId, paginate } from '@/services/mock/helpers'

// In-memory attempt history for the mock student. Submissions append here and
// surface on the exam page via GET /student/exam-results.
const studentResults = [
  {
    id: 9001,
    examId: 201,
    score: 20,
    isPassed: true,
    correctCount: 2,
    totalQuestions: 2,
    startedAt: '2026-04-12T15:00:00+03:30',
    submittedAt: '2026-04-12T15:30:00+03:30',
    deadlineAt: '2026-04-12T15:30:00+03:30',
  },
]

// examId → un-submitted attempt, so POST /start is idempotent.
const openAttempts = new Map()

const termIdOfExam = (exam) => {
  const course = adminCourses.find((c) => c.id === Number(exam.course?.id))
  return course?.termId ?? course?.term?.id ?? null
}

register('GET', endpoints.getStudentExamsList, ({ query }) => {
  const list = filterItems(adminExams, query, {
    sessionId: (item, v) => String(item.sessionId) === String(v),
    courseId: (item, v) => String(item.course?.id) === String(v),
    termId: (item, v) => String(termIdOfExam(item)) === String(v),
  })
  const { data: items, meta } = paginate(list, query)
  return { success: true, message: 'OK', data: { items, meta } }
})

register('GET', endpoints.getStudentExamResults, ({ query }) => {
  const { data: items, meta } = paginate([...studentResults].reverse(), query)
  return { success: true, message: 'OK', data: { items, meta } }
})

register('POST', endpoints.startExam, ({ params }) => {
  const examId = Number(params.examId)
  const existing = openAttempts.get(examId)
  if (existing) return { success: true, message: 'Exam started.', data: existing }
  const exam = adminExams.find((e) => String(e.id) === String(examId))
  const duration = exam?.durationMinutes || 30
  const attempt = {
    id: makeId(),
    examId,
    score: 0,
    isPassed: false,
    correctCount: 0,
    totalQuestions: (exam?.questions || []).length,
    startedAt: isoNow(),
    submittedAt: null,
    deadlineAt: new Date(Date.now() + duration * 60_000).toISOString(),
  }
  openAttempts.set(examId, attempt)
  return { success: true, message: 'Exam started.', data: attempt }
})

register('POST', endpoints.submitExam, ({ params, data }) => {
  const examId = Number(params.examId)
  const exam = adminExams.find((e) => String(e.id) === String(examId))
  const questions = exam?.questions || []
  const answers = Array.isArray(data.answers) ? data.answers : []

  let score = 0
  let correctCount = 0
  for (const q of questions) {
    const correct = (q.options || []).find((o) => o.isCorrect)
    const ans = answers.find((a) => String(a.questionId) === String(q.id))
    if (ans && correct && String(ans.selectedOptionId) === String(correct.id)) {
      score += q.score || 0
      correctCount += 1
    }
  }

  const open = openAttempts.get(examId)
  const attempt = {
    id: open?.id ?? makeId(),
    examId,
    score,
    isPassed: score >= (exam?.minimumScore ?? 0),
    correctCount,
    totalQuestions: questions.length,
    startedAt: open?.startedAt ?? isoNow(),
    submittedAt: isoNow(),
    deadlineAt: open?.deadlineAt ?? isoNow(),
  }
  studentResults.push(attempt)
  openAttempts.delete(examId)
  return { success: true, message: 'Exam submitted.', data: attempt }
})