/**
 * TabataFit Program Detail Screen
 * Shows week progression and workout list
 */

import { View, StyleSheet, ScrollView, Pressable } from 'react-native'
import { useRouter, useLocalSearchParams } from 'expo-router'
import { useSafeAreaInsets } from 'react-native-safe-area-context'
import { LinearGradient } from 'expo-linear-gradient'
import { Icon } from '@/src/shared/components/Icon'

import { useMemo } from 'react'
import { useTranslation } from 'react-i18next'
import { useHaptics } from '@/src/shared/hooks'
import { useProgramStore } from '@/src/shared/stores'
import { PROGRAMS } from '@/src/shared/data/programs'
import { StyledText } from '@/src/shared/components/StyledText'

import { useThemeColors, BRAND } from '@/src/shared/theme'
import type { ThemeColors } from '@/src/shared/theme/types'
import { SPACING, LAYOUT } from '@/src/shared/constants/spacing'
import { RADIUS } from '@/src/shared/constants/borderRadius'
import type { ProgramId } from '@/src/shared/types'

const FONTS = {
  LARGE_TITLE: 28,
  TITLE: 24,
  TITLE_2: 20,
  HEADLINE: 17,
  BODY: 16,
  CAPTION: 13,
  SMALL: 12,
}

export default function ProgramDetailScreen() {
  const { id } = useLocalSearchParams<{ id: string }>()
  const programId = id as ProgramId
  const { t } = useTranslation('screens')
  const insets = useSafeAreaInsets()
  const router = useRouter()
  const haptics = useHaptics()
  const colors = useThemeColors()
  const styles = useMemo(() => createStyles(colors), [colors])
  
  const program = PROGRAMS[programId]
  const selectProgram = useProgramStore((s) => s.selectProgram)
  const progress = useProgramStore((s) => s.programsProgress[programId])
  const isWeekUnlocked = useProgramStore((s) => s.isWeekUnlocked)
  const getCurrentWorkout = useProgramStore((s) => s.getCurrentWorkout)
  const completion = useProgramStore((s) => s.getProgramCompletion(programId))

  if (!program) {
    return (
      <View style={[styles.container, { paddingTop: insets.top }]}>
        <StyledText color={colors.text.primary}>Program not found</StyledText>
      </View>
    )
  }

  const handleStartProgram = () => {
    haptics.buttonTap()
    selectProgram(programId)
    const currentWorkout = getCurrentWorkout(programId)
    if (currentWorkout) {
      router.push(`/workout/${currentWorkout.id}`)
    }
  }

  const handleWorkoutPress = (workoutId: string, weekNumber: number) => {
    haptics.buttonTap()
    router.push(`/workout/${workoutId}`)
  }

  return (
    <View style={[styles.container, { paddingTop: insets.top }]}>
      {/* Header */}
      <View style={styles.header}>
        <Pressable style={styles.backButton} onPress={() => router.back()}>
          <Icon name="arrow.left" size={24} color={colors.text.primary} />
        </Pressable>
        <StyledText size={FONTS.TITLE} weight="bold" color={colors.text.primary}>
          {program.title}
        </StyledText>
        <View style={styles.placeholder} />
      </View>

      <ScrollView
        style={styles.scrollView}
        contentContainerStyle={[styles.scrollContent, { paddingBottom: insets.bottom + 120 }]}
        showsVerticalScrollIndicator={false}
      >
        {/* Program Overview */}
        <View style={styles.overviewSection}>
          <StyledText size={FONTS.BODY} color={colors.text.secondary} style={styles.description}>
            {program.description}
          </StyledText>

          {/* Stats Row */}
          <View style={styles.statsRow}>
            <View style={styles.statBox}>
              <StyledText size={FONTS.LARGE_TITLE} weight="bold" color={colors.text.primary}>
                {program.durationWeeks}
              </StyledText>
              <StyledText size={FONTS.SMALL} color={colors.text.tertiary}>
                {t('programs.weeks')}
              </StyledText>
            </View>
            <View style={styles.statBox}>
              <StyledText size={FONTS.LARGE_TITLE} weight="bold" color={colors.text.primary}>
                {program.totalWorkouts}
              </StyledText>
              <StyledText size={FONTS.SMALL} color={colors.text.tertiary}>
                {t('programs.workouts')}
              </StyledText>
            </View>
            <View style={styles.statBox}>
              <StyledText size={FONTS.LARGE_TITLE} weight="bold" color={colors.text.primary}>
                4
              </StyledText>
              <StyledText size={FONTS.SMALL} color={colors.text.tertiary}>
                {t('programs.minutes')}
              </StyledText>
            </View>
          </View>

          {/* Equipment */}
          <View style={styles.equipmentSection}>
            <StyledText size={FONTS.CAPTION} weight="semibold" color={colors.text.secondary}>
              {t('programs.equipment')}
            </StyledText>
            <View style={styles.equipmentList}>
              {program.equipment.required.map((item) => (
                <View key={item} style={styles.equipmentTag}>
                  <StyledText size={12} color={colors.text.primary}>
                    {item}
                  </StyledText>
                </View>
              ))}
              {program.equipment.optional.map((item) => (
                <View key={item} style={[styles.equipmentTag, styles.optionalTag]}>
                  <StyledText size={12} color={colors.text.tertiary}>
                    {item} {t('programs.optional')}
                  </StyledText>
                </View>
              ))}
            </View>
          </View>

          {/* Focus Areas */}
          <View style={styles.focusSection}>
            <StyledText size={FONTS.CAPTION} weight="semibold" color={colors.text.secondary}>
              {t('programs.focusAreas')}
            </StyledText>
            <View style={styles.focusList}>
              {program.focusAreas.map((area) => (
                <View key={area} style={styles.focusTag}>
                  <StyledText size={12} color={colors.text.primary}>
                    {area}
                  </StyledText>
                </View>
              ))}
            </View>
          </View>
        </View>

        {/* Progress Overview */}
        {progress.completedWorkoutIds.length > 0 && (
          <View style={styles.progressSection}>
            <View style={styles.progressHeader}>
              <StyledText size={FONTS.TITLE_2} weight="semibold" color={colors.text.primary}>
                {t('programs.yourProgress')}
              </StyledText>
              <StyledText size={FONTS.BODY} weight="semibold" color={BRAND.PRIMARY}>
                {completion}%
              </StyledText>
            </View>
            <View style={styles.progressBarContainer}>
              <View style={[styles.progressBar, { backgroundColor: colors.bg.surface }]}>
                <View 
                  style={[
                    styles.progressFill, 
                    { 
                      width: `${completion}%`,
                      backgroundColor: BRAND.PRIMARY,
                    }
                  ]} 
                />
              </View>
            </View>
            <StyledText size={FONTS.CAPTION} color={colors.text.tertiary}>
              {progress.completedWorkoutIds.length} {t('programs.of')} {program.totalWorkouts} {t('programs.workoutsComplete')}
            </StyledText>
          </View>
        )}

        {/* Weeks */}
        <View style={styles.weeksSection}>
          <StyledText size={FONTS.TITLE_2} weight="semibold" color={colors.text.primary} style={styles.weeksTitle}>
            {t('programs.trainingPlan')}
          </StyledText>

          {program.weeks.map((week) => {
            const isUnlocked = isWeekUnlocked(programId, week.weekNumber)
            const isCurrentWeek = progress.currentWeek === week.weekNumber
            const weekCompletion = week.workouts.filter(w => 
              progress.completedWorkoutIds.includes(w.id)
            ).length

            return (
              <View key={week.weekNumber} style={styles.weekCard}>
                {/* Week Header */}
                <View style={styles.weekHeader}>
                  <View style={styles.weekTitleRow}>
                    <StyledText size={FONTS.HEADLINE} weight="semibold" color={colors.text.primary}>
                      {week.title}
                    </StyledText>
                    {!isUnlocked && (
                      <Icon name="lock.fill" size={16} color={colors.text.tertiary} />
                    )}
                    {isCurrentWeek && isUnlocked && (
                      <View style={styles.currentBadge}>
                        <StyledText size={11} weight="semibold" color="#FFFFFF">
                          {t('programs.current')}
                        </StyledText>
                      </View>
                    )}
                  </View>
                  <StyledText size={FONTS.CAPTION} color={colors.text.secondary}>
                    {week.description}
                  </StyledText>
                  {weekCompletion > 0 && (
                    <StyledText size={FONTS.SMALL} color={colors.text.tertiary} style={styles.weekProgress}>
                      {weekCompletion}/{week.workouts.length} {t('programs.complete')}
                    </StyledText>
                  )}
                </View>

                {/* Week Workouts */}
                {isUnlocked && (
                  <View style={styles.workoutsList}>
                    {week.workouts.map((workout, index) => {
                      const isCompleted = progress.completedWorkoutIds.includes(workout.id)
                      const isLocked = !isCompleted && index > 0 && 
                        !progress.completedWorkoutIds.includes(week.workouts[index - 1].id) &&
                        week.weekNumber === progress.currentWeek

                      return (
                        <Pressable
                          key={workout.id}
                          style={[
                            styles.workoutItem,
                            isCompleted && styles.workoutCompleted,
                            isLocked && styles.workoutLocked,
                          ]}
                          onPress={() => !isLocked && handleWorkoutPress(workout.id, week.weekNumber)}
                          disabled={isLocked}
                        >
                          <View style={styles.workoutNumber}>
                            {isCompleted ? (
                              <Icon name="checkmark.circle.fill" size={24} color={BRAND.SUCCESS} />
                            ) : isLocked ? (
                              <Icon name="lock.fill" size={20} color={colors.text.tertiary} />
                            ) : (
                              <StyledText size={14} weight="semibold" color={colors.text.primary}>
                                {index + 1}
                              </StyledText>
                            )}
                          </View>
                          <View style={styles.workoutInfo}>
                            <StyledText 
                              size={14} 
                              weight={isCompleted ? "medium" : "semibold"}
                              color={isLocked ? colors.text.tertiary : colors.text.primary}
                              style={isCompleted && styles.completedText}
                            >
                              {workout.title}
                            </StyledText>
                            <StyledText size={12} color={colors.text.tertiary}>
                              {workout.exercises.length} {t('programs.exercises')} • {workout.duration} {t('programs.min')}
                            </StyledText>
                          </View>
                          {!isLocked && !isCompleted && (
                            <Icon name="chevron.right" size={20} color={colors.text.tertiary} />
                          )}
                        </Pressable>
                      )
                    })}
                  </View>
                )}
              </View>
            )
          })}
        </View>
      </ScrollView>

      {/* Bottom CTA */}
      <View style={[styles.bottomBar, { paddingBottom: insets.bottom + SPACING[4] }]}>
        <Pressable style={styles.ctaButton} onPress={handleStartProgram}>
          <LinearGradient
            colors={['#FF6B35', '#FF3B30']}
            style={styles.ctaGradient}
          >
            <StyledText size={16} weight="bold" color="#FFFFFF">
              {progress.completedWorkoutIds.length === 0 
                ? t('programs.startProgram')
                : progress.isProgramCompleted
                  ? t('programs.restartProgram')
                  : t('programs.continueTraining')
              }
            </StyledText>
            <Icon name="arrow.right" size={20} color="#FFFFFF" style={styles.ctaIcon} />
          </LinearGradient>
        </Pressable>
      </View>
    </View>
  )
}

function createStyles(colors: ThemeColors) {
  return StyleSheet.create({
    container: {
      flex: 1,
      backgroundColor: colors.bg.base,
    },
    scrollView: {
      flex: 1,
    },
    scrollContent: {
      paddingHorizontal: LAYOUT.SCREEN_PADDING,
    },

    // Header
    header: {
      flexDirection: 'row',
      alignItems: 'center',
      justifyContent: 'space-between',
      paddingHorizontal: LAYOUT.SCREEN_PADDING,
      paddingVertical: SPACING[3],
    },
    backButton: {
      width: 40,
      height: 40,
      alignItems: 'center',
      justifyContent: 'center',
    },
    placeholder: {
      width: 40,
    },

    // Overview
    overviewSection: {
      marginTop: SPACING[2],
      marginBottom: SPACING[6],
    },
    description: {
      marginBottom: SPACING[5],
      lineHeight: 24,
    },
    statsRow: {
      flexDirection: 'row',
      justifyContent: 'space-around',
      marginBottom: SPACING[5],
      paddingVertical: SPACING[4],
      backgroundColor: colors.bg.surface,
      borderRadius: RADIUS.LG,
    },
    statBox: {
      alignItems: 'center',
    },

    // Equipment
    equipmentSection: {
      marginBottom: SPACING[4],
    },
    equipmentList: {
      flexDirection: 'row',
      flexWrap: 'wrap',
      gap: SPACING[2],
      marginTop: SPACING[2],
    },
    equipmentTag: {
      backgroundColor: colors.bg.surface,
      paddingHorizontal: SPACING[3],
      paddingVertical: SPACING[1],
      borderRadius: RADIUS.FULL,
    },
    optionalTag: {
      opacity: 0.7,
    },

    // Focus
    focusSection: {
      marginBottom: SPACING[4],
    },
    focusList: {
      flexDirection: 'row',
      flexWrap: 'wrap',
      gap: SPACING[2],
      marginTop: SPACING[2],
    },
    focusTag: {
      backgroundColor: `${BRAND.PRIMARY}15`,
      paddingHorizontal: SPACING[3],
      paddingVertical: SPACING[1],
      borderRadius: RADIUS.FULL,
    },

    // Progress
    progressSection: {
      backgroundColor: colors.bg.surface,
      borderRadius: RADIUS.LG,
      padding: SPACING[4],
      marginBottom: SPACING[6],
    },
    progressHeader: {
      flexDirection: 'row',
      justifyContent: 'space-between',
      alignItems: 'center',
      marginBottom: SPACING[3],
    },
    progressBarContainer: {
      marginBottom: SPACING[2],
    },
    progressBar: {
      height: 8,
      borderRadius: 4,
      overflow: 'hidden',
    },
    progressFill: {
      height: '100%',
      borderRadius: 4,
    },

    // Weeks
    weeksSection: {
      marginBottom: SPACING[6],
    },
    weeksTitle: {
      marginBottom: SPACING[4],
    },
    weekCard: {
      backgroundColor: colors.bg.surface,
      borderRadius: RADIUS.LG,
      marginBottom: SPACING[4],
      overflow: 'hidden',
    },
    weekHeader: {
      padding: SPACING[4],
      borderBottomWidth: 1,
      borderBottomColor: colors.border.glass,
    },
    weekTitleRow: {
      flexDirection: 'row',
      alignItems: 'center',
      justifyContent: 'space-between',
      marginBottom: SPACING[1],
    },
    currentBadge: {
      backgroundColor: BRAND.PRIMARY,
      paddingHorizontal: SPACING[2],
      paddingVertical: 2,
      borderRadius: RADIUS.SM,
    },
    weekProgress: {
      marginTop: SPACING[2],
    },

    // Workouts List
    workoutsList: {
      padding: SPACING[2],
    },
    workoutItem: {
      flexDirection: 'row',
      alignItems: 'center',
      paddingVertical: SPACING[3],
      paddingHorizontal: SPACING[3],
      borderRadius: RADIUS.MD,
    },
    workoutCompleted: {
      opacity: 0.7,
    },
    workoutLocked: {
      opacity: 0.5,
    },
    workoutNumber: {
      width: 32,
      height: 32,
      alignItems: 'center',
      justifyContent: 'center',
      marginRight: SPACING[3],
    },
    workoutInfo: {
      flex: 1,
    },
    completedText: {
      textDecorationLine: 'line-through',
    },

    // Bottom Bar
    bottomBar: {
      position: 'absolute',
      bottom: 0,
      left: 0,
      right: 0,
      backgroundColor: colors.bg.base,
      paddingHorizontal: LAYOUT.SCREEN_PADDING,
      paddingTop: SPACING[3],
      borderTopWidth: 1,
      borderTopColor: colors.border.glass,
    },
    ctaButton: {
      borderRadius: RADIUS.LG,
      overflow: 'hidden',
    },
    ctaGradient: {
      flexDirection: 'row',
      alignItems: 'center',
      justifyContent: 'center',
      paddingVertical: SPACING[4],
    },
    ctaIcon: {
      marginLeft: SPACING[2],
    },
  })
}