const app = getApp()

const getReviewSettings = () => {
  const settings = app.globalData.userSettings || {}
  return {
    autoNextQuestion: Number(settings.auto_next_question || 0) === 1,
    showAnswerAfterSubmit: Number(settings.show_answer_after_submit || 0) === 1,
    blankCount: Number(settings.blank_count || 2),
    blankDifficulty: settings.blank_difficulty || 'normal',
  }
}

Page({
  data: {
    progress: 0,
    current: 1,
    total: 0,
    word: '',
    meaning: '',
    answer: '',
    answers: [],
    clozeAnswers: [],
    feedback: '',
    revealAnswer: '',
    feedbackType: '',
    showFeedback: false,
    completed: false,
    masterHint: false,
    questions: [],
    loading: false,
    error: '',
    settings: getReviewSettings(),
    questionBadge: '',
    entryTypeHint: '',
    isCloze: false,
    currentClozeQuestion: null,
    currentClozeResults: [],
    showClozeFeedback: false,
    clozeSegments: [],
    clozeFeedbackSummary: '',
    activeClozeBlankIndex: 0,
  },
  submitting: false,
  judged: false,
  onLoad() {
    this.loadSettingsAndQuestions()
  },
  loadSettingsAndQuestions() {
    if (!app.globalData.openid) {
      this.setData({ error: '请先登录' })
      return
    }
    wx.request({
      url: `${app.globalData.baseUrl}/api/v1/settings`,
      header: { 'X-OpenID': app.globalData.openid },
      success: (res) => {
        app.globalData.userSettings = res.data?.data || {}
        this.setData({ settings: getReviewSettings() })
        this.loadQuestions()
      },
      fail: () => {
        this.setData({ error: '设置加载失败' })
        this.loadQuestions()
      },
    })
  },
  buildClozeSegments(clozeQuestion) {
    if (!clozeQuestion || !Array.isArray(clozeQuestion.blanks)) return []
    const prompt = clozeQuestion.prompt_text || ''
    const blanks = clozeQuestion.blanks || []
    const segments = []
    const useUnderscorePrompt = prompt.includes('____')
    const workingPrompt = useUnderscorePrompt ? prompt : (clozeQuestion.original_text || prompt)

    const pushWordBlank = (blankIndex, blank) => {
      const answerText = String(blank?.answer || '')
      const answerLength = Math.max(1, answerText.length || Number(blank?.hint?.length || 1))
      const blankWidth = Math.max(88, Math.min(320, 32 + answerLength * 28))
      segments.push({
        type: 'word-blank',
        blankIndex,
        index: `blank-${blankIndex}`,
        width: `${blankWidth}rpx`,
        minWidth: `${blankWidth}rpx`,
        maxLength: Math.max(1, answerLength),
      })
    }

    if (useUnderscorePrompt) {
      let blankIndex = 0
      workingPrompt.split('____').forEach((text, index, parts) => {
        if (text) segments.push({ type: 'text', text, index: `text-${index}` })
        if (index < parts.length - 1) {
          pushWordBlank(blankIndex, blanks[blankIndex])
          blankIndex += 1
        }
      })
      return segments
    }

    if (blanks.length === 1 && workingPrompt === (clozeQuestion.original_text || prompt)) {
      // Keep the original word context visible for single-word cloze questions.
      // The general start/end slicing below will render visible letters around the blank.
    }

    let cursor = 0
    blanks.forEach((blank, idx) => {
      const start = Math.max(0, Number(blank.start || 0))
      const end = Math.max(start, Number(blank.end || start + 1))
      if (start > cursor) {
        segments.push({ type: 'text', text: workingPrompt.slice(cursor, start), index: `text-${idx}` })
      }
      pushWordBlank(idx, blank)
      cursor = end
    })
    if (cursor < workingPrompt.length) {
      segments.push({ type: 'text', text: workingPrompt.slice(cursor), index: `text-tail` })
    }
    return segments
  },
  loadQuestions() {
    const session = app.globalData.reviewSessionMeta || wx.getStorageSync('reviewSessionMeta')
    if (!session?.id) {
      this.setData({ error: '暂无复习会话' })
      return
    }
    app.globalData.reviewSessionMeta = session
    this.setData({ loading: true, error: '' })
    wx.request({
      url: `${app.globalData.baseUrl}/api/v1/review/questions?session_id=${session.id}`,
      header: { 'X-OpenID': app.globalData.openid || '' },
      success: (res) => {
        if (res.statusCode < 200 || res.statusCode >= 300) {
          const message = res.data?.detail || res.data?.message || '题目加载失败'
          this.setData({ error: message, questions: [] })
          return
        }
        const questions = (res.data?.data || []).map((item) => {
          if (item.question_mode === 'C') {
            return {
              ...item,
              blank_prompt: item.blank_prompt || item.cloze_question?.prompt_text || item.prompt,
              cloze_question: item.cloze_question || null,
            }
          }
          return {
            ...item,
            entry_type: item.entry_type || 'word',
          }
        })
        if (!questions.length) {
          this.setData({ error: '当前复习会话没有题目，请返回重新选择范围', questions: [] })
          return
        }
        app.globalData.reviewSession = {
          deck: questions,
          currentIndex: 0,
          correctCount: 0,
          wrongCount: 0,
          completed: false,
          currentAnswer: '',
          currentAnswers: [],
          startedAt: Date.now(),
        }
        this.setData({ questions })
        this.syncSession()
      },
      fail: () => this.setData({ error: '题目加载失败' }),
      complete: () => this.setData({ loading: false }),
    })
  },
  syncSession() {
    const session = app.globalData.reviewSession
    const current = session.deck[session.currentIndex]
    const total = session.deck.length || 1
    const isCloze = current?.question_mode === 'C'
    const clozeQuestion = isCloze ? (current?.cloze_question || null) : null
    this.setData({
      progress: Math.round((session.currentIndex / total) * 100),
      current: session.currentIndex + 1,
      total,
      word: isCloze ? (current?.blank_prompt || clozeQuestion?.prompt_text || current?.prompt || '') : (current?.prompt || ''),
      meaning: isCloze ? (current?.answer_hint || '') : '',
      answer: session.currentAnswer || '',
      clozeAnswers: isCloze ? (Array.isArray(session.currentAnswers) ? session.currentAnswers : Array.from({ length: clozeQuestion?.blanks?.length || 0 }, () => '')) : [],
      activeClozeBlankIndex: 0,
      feedback: '',
      revealAnswer: '',
      feedbackType: '',
      showFeedback: false,
      completed: session.completed,
      masterHint: false,
      questionBadge: isCloze ? `填空 · ${current?.entry_type === 'sentence' ? '句子' : '单词'}` : `${current?.entry_type === 'sentence' ? '句子' : '单词'} · ${current?.question_mode || 'A'}`,
      entryTypeHint: isCloze ? '请逐空作答，提交后会显示每个空的结果。' : (current?.entry_type === 'sentence' ? '当前题目来自句子库，注意上下文表达。' : ''),
      isCloze,
      currentClozeQuestion: clozeQuestion,
      currentClozeResults: session.lastClozeResults || [],
      showClozeFeedback: false,
      clozeSegments: isCloze ? this.buildClozeSegments(clozeQuestion) : [],
      clozeFeedbackSummary: '',
    })
  },
  onAnswerInput(e) {
    const answer = e.detail.value
    app.globalData.reviewSession.currentAnswer = answer
    this.setData({ answer, showFeedback: false, revealAnswer: '', feedback: '', feedbackType: '', judged: false, showClozeFeedback: false })
  },
  onClozeLetterInput(e) {
    const { index, letterIndex } = e.currentTarget.dataset
    const rawValue = e.detail.value || ''
    const cleaned = rawValue.slice(-1)
    const answers = [...(app.globalData.reviewSession.currentAnswers || [])]
    const current = answers[index] || ''
    const chars = current.split('')
    chars[letterIndex] = cleaned
    answers[index] = chars.join('').slice(0, Math.max(chars.length, letterIndex + 1))
    app.globalData.reviewSession.currentAnswers = answers
    this.setData({
      [`clozeAnswers[${index}]`]: answers[index],
      showFeedback: false,
      revealAnswer: '',
      feedback: '',
      feedbackType: '',
      judged: false,
      showClozeFeedback: false,
    }, () => {
      if (cleaned) this.focusNextLetterCell(Number(index), Number(letterIndex) + 1)
    })
  },
  focusNextLetterCell(blankIndex, letterIndex) {
    const selector = `#cloze-input-${blankIndex}-${letterIndex}`
    wx.nextTick(() => {
      const query = wx.createSelectorQuery().in(this)
      query.select(selector).fields({ node: true }).exec((res) => {
        if (!res || !res[0]) return
        const node = res[0].node
        if (node && typeof node.focus === 'function') node.focus()
      })
    })
  },
  handleLetterKeydown(e) {
    const key = e?.detail?.key || e?.detail?.value || ''
    const { index, letterIndex } = e.currentTarget.dataset
    if (key === 'Backspace' || key === 'Delete') {
      const answers = [...(app.globalData.reviewSession.currentAnswers || [])]
      const current = answers[index] || ''
      const chars = current.split('')
      const pos = Number(letterIndex)
      if (chars[pos]) {
        chars[pos] = ''
        answers[index] = chars.join('')
        app.globalData.reviewSession.currentAnswers = answers
        this.setData({ [`clozeAnswers[${index}]`]: answers[index] })
        return
      }
      const prevIndex = Number(letterIndex) - 1
      if (prevIndex >= 0) this.focusNextLetterCell(Number(index), prevIndex)
      return
    }
    if (key === 'ArrowLeft') {
      const prevIndex = Number(letterIndex) - 1
      if (prevIndex >= 0) this.focusNextLetterCell(Number(index), prevIndex)
      return
    }
    if (key === 'ArrowRight' || key === ' ' || key === 'Space') {
      this.focusNextLetterCell(Number(index), Number(letterIndex) + 1)
    }
  },
  onClozeAnswerInput(e) {
    const { index } = e.currentTarget.dataset
    const rawValue = e.detail.value || ''
    const clozeQuestion = this.data.currentClozeQuestion
    const blank = clozeQuestion?.blanks?.[index]
    const maxLength = Math.max(1, Number(blank?.answer?.length || 1))
    const normalizedValue = rawValue.slice(-maxLength).slice(0, maxLength)
    const answers = [...(app.globalData.reviewSession.currentAnswers || [])]
    answers[index] = normalizedValue
    app.globalData.reviewSession.currentAnswers = answers
    const nextIndex = Number(index) + (normalizedValue.length >= maxLength ? 1 : 0)
    const prevIndex = Number(index) - 1
    this.setData({
      [`clozeAnswers[${index}]`]: normalizedValue,
      activeClozeBlankIndex: nextIndex,
      showFeedback: false,
      revealAnswer: '',
      feedback: '',
      feedbackType: '',
      judged: false,
      showClozeFeedback: false,
    }, () => {
      if (!normalizedValue && this.data.isCloze && rawValue === '') {
        this.focusNextClozeInput(Math.max(0, prevIndex))
        return
      }
      if (normalizedValue.length >= maxLength && this.data.isCloze) this.focusNextClozeInput(nextIndex)
    })
  },
  focusNextClozeInput(nextIndex) {
    const selector = `#cloze-input-${nextIndex}`
    wx.nextTick(() => {
      const query = wx.createSelectorQuery().in(this)
      query.select(selector).fields({ node: true, size: true }).exec((res) => {
        if (!res || !res[0]) return
        const node = res[0].node
        if (node && typeof node.focus === 'function') node.focus()
      })
    })
  },
  submitAnswer(showExplanation = false, advanceAfterSubmit = false) {
    const session = app.globalData.reviewSession
    const current = session.deck[session.currentIndex]
    if (!current || this.submitting || this.judged) return

    const answer = (this.data.answer || '').trim()
    const clozeQuestion = current.cloze_question
    const payload = {
      session_id: app.globalData.reviewSessionMeta.id,
      record_id: current.record_id,
      user_answer: answer,
    }
    if (current.question_mode === 'C' && clozeQuestion?.blanks?.length) {
      const answers = (this.data.clozeAnswers || []).map((item) => (item || '').trim())
      while (answers.length < clozeQuestion.blanks.length) answers.push('')
      const isLetterCellMode = Array.isArray(this.data.clozeSegments) && this.data.clozeSegments.some((segment) => segment.type === 'letter-cell')
      const normalizedAnswers = isLetterCellMode
        ? answers
        : answers
      if (!normalizedAnswers.some((item) => item)) {
        wx.showToast({ title: '请先输入答案', icon: 'none' })
        return
      }
      payload.user_answers = normalizedAnswers
    } else if (!answer) {
      wx.showToast({ title: '请先输入答案', icon: 'none' })
      return
    }

    this.submitting = true
    wx.request({
      url: `${app.globalData.baseUrl}/api/v1/review/submit`,
      method: 'POST',
      header: { 'Content-Type': 'application/json', 'X-OpenID': app.globalData.openid || '' },
      data: payload,
      success: (res) => {
        const result = res.data?.data || {}
        session.correctCount += result.is_correct ? 1 : 0
        session.wrongCount += result.is_correct ? 0 : 1
        this.judged = true
        const shouldShowAnswer = showExplanation || this.data.settings.showAnswerAfterSubmit
        const correctAnswerText = result.correct_answer_text || ''
        const clozeResults = Array.isArray(result.cloze_results) ? result.cloze_results : []
        const fallbackClozeResults = clozeResults.length
          ? clozeResults
          : (this.data.currentClozeQuestion?.blanks || []).map((blank, idx) => ({
              index: typeof blank?.index === 'number' ? blank.index : idx,
              user_answer: '',
              correct_answers: [blank?.answer, ...(Array.isArray(blank?.accepted_answers) ? blank.accepted_answers : [])].filter(Boolean),
              correct_answer_text: blank?.answer || '',
              is_correct: false,
            }))
        const normalizedClozeResults = fallbackClozeResults.map((item, idx) => {
          const correctAnswers = Array.isArray(item.correct_answers)
            ? item.correct_answers.filter(Boolean)
            : [item.correct_answer_text, ...(Array.isArray(item.accepted_answers) ? item.accepted_answers : [])].filter(Boolean)
          const standardAnswerText = correctAnswers.join(' / ') || item.correct_answer_text || ''
          return {
            index: item.index ?? idx,
            user_answer: item.user_answer ?? '',
            correct_answers: correctAnswers,
            correct_answer_text: item.correct_answer_text || standardAnswerText,
            standard_answer_text: standardAnswerText,
            is_correct: Boolean(item.is_correct),
          }
        })
        const derivedClozeResults = normalizedClozeResults.length
          ? normalizedClozeResults
          : (correctAnswerText
              ? [{ index: 0, user_answer: '', correct_answers: [correctAnswerText], correct_answer_text: correctAnswerText, standard_answer_text: correctAnswerText, is_correct: false }]
              : [])
        if (derivedClozeResults.length) {
          session.lastClozeResults = derivedClozeResults
          app.globalData.reviewSession.lastClozeResults = derivedClozeResults
        }
        const clozeFeedbackSummary = result.is_correct ? '回答正确' : '回答错误'
        this.setData({
          feedback: clozeFeedbackSummary,
          feedbackType: result.is_correct ? 'correct' : 'wrong',
          revealAnswer: '',
          showFeedback: true,
          showClozeFeedback: derivedClozeResults.length > 0,
          currentClozeResults: derivedClozeResults,
          clozeFeedbackSummary,
        })
        if (this.data.isCloze) {
          app.globalData.reviewSession.currentAnswers = []
          this.setData({ clozeAnswers: [] })
        }
        if (this.data.settings.autoNextQuestion || advanceAfterSubmit) {
          const delay = shouldShowAnswer ? 2500 : 0
          setTimeout(() => this.nextQuestion(), delay)
        }
      },
      complete: () => {
        this.submitting = false
      },
    })
  },
  checkAnswer() {
    this.submitAnswer(true)
  },
  nextQuestion() {
    const session = app.globalData.reviewSession
    if (!session.deck.length) return
    if (!this.judged) {
      this.submitAnswer(true, true)
      return
    }
    this.judged = false
    if (session.currentIndex >= session.deck.length - 1) {
      session.completed = true
      session.endedAt = Date.now()
      wx.request({
        url: `${app.globalData.baseUrl}/api/v1/review/finish?session_id=${app.globalData.reviewSessionMeta.id}`,
        method: 'POST',
        header: { 'X-OpenID': app.globalData.openid || '' },
        success: () => wx.navigateTo({ url: '/pages/review-result/review-result' }),
        fail: () => {
          wx.showToast({ title: '提交结果失败，已本地完成', icon: 'none' })
          wx.navigateTo({ url: '/pages/review-result/review-result' })
        },
      })
      return
    }
    session.currentIndex += 1
    session.currentAnswer = ''
    session.currentAnswers = []
    this.syncSession()
  },
  markMastered() {
    this.setData({ masterHint: true })
    wx.showToast({ title: '已标记', icon: 'success' })
  },
})