/**
 * TabataFit Collection Detail Screen
 * Shows collection info + list of workouts in that collection
 */

import { useMemo } from 'react'
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 { useTranslation } from 'react-i18next'

import { useHaptics } from '@/src/shared/hooks'
import { useCollection } from '@/src/shared/hooks/useSupabaseData'
import { getWorkoutById } from '@/src/shared/data'
import { useTranslatedWorkouts } from '@/src/shared/data/useTranslatedData'
import { StyledText } from '@/src/shared/components/StyledText'
import { track } from '@/src/shared/services/analytics'

import { useThemeColors, BRAND, GRADIENTS } 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'

export default function CollectionDetailScreen() {
  const insets = useSafeAreaInsets()
  const router = useRouter()
  const haptics = useHaptics()
  const { t } = useTranslation()
  const { id } = useLocalSearchParams<{ id: string }>()

  const colors = useThemeColors()
  const styles = useMemo(() => createStyles(colors), [colors])

  const { data: collection, isLoading } = useCollection(id)

  // Resolve workouts from collection's workoutIds
  const rawWorkouts = useMemo(() => {
    if (!collection) return []
    return collection.workoutIds
      .map((wId) => getWorkoutById(wId))
      .filter(Boolean) as NonNullable<ReturnType<typeof getWorkoutById>>[]
  }, [collection])

  const workouts = useTranslatedWorkouts(rawWorkouts)

  const handleBack = () => {
    haptics.selection()
    router.back()
  }

  const handleWorkoutPress = (workoutId: string) => {
    haptics.buttonTap()
    track('collection_workout_tapped', {
      collection_id: id,
      workout_id: workoutId,
    })
    router.push(`/workout/${workoutId}`)
  }

  if (isLoading) {
    return (
      <View style={[styles.container, styles.centered, { paddingTop: insets.top }]}>
        <StyledText size={17} color={colors.text.tertiary}>Loading...</StyledText>
      </View>
    )
  }

  if (!collection) {
    return (
      <View style={[styles.container, styles.centered, { paddingTop: insets.top }]}>
        <Icon name="folder" size={48} color={colors.text.tertiary} />
        <StyledText size={17} color={colors.text.tertiary} style={{ marginTop: SPACING[3] }}>
          Collection not found
        </StyledText>
      </View>
    )
  }

  return (
    <View testID="collection-detail-screen" style={[styles.container, { paddingTop: insets.top }]}>
      {/* Header */}
      <View style={styles.header}>
        <Pressable testID="collection-back-button" onPress={handleBack} style={styles.backButton}>
          <Icon name="chevron.left" size={24} color={colors.text.primary} />
        </Pressable>
        <StyledText size={22} weight="bold" color={colors.text.primary} numberOfLines={1} style={{ flex: 1, textAlign: 'center' }}>
          {collection.title}
        </StyledText>
        <View style={styles.backButton} />
      </View>

      <ScrollView
        style={styles.scrollView}
        contentContainerStyle={[styles.scrollContent, { paddingBottom: insets.bottom + 100 }]}
        showsVerticalScrollIndicator={false}
      >
        {/* Hero Card */}
        <View testID="collection-hero" style={styles.heroCard}>
          <LinearGradient
            colors={collection.gradient ?? [BRAND.PRIMARY, '#FF3B30']}
            start={{ x: 0, y: 0 }}
            end={{ x: 1, y: 1 }}
            style={StyleSheet.absoluteFill}
          />
          <View style={styles.heroContent}>
            <StyledText size={48} color="#FFFFFF" style={styles.heroIcon}>
              {collection.icon}
            </StyledText>
            <StyledText size={28} weight="bold" color="#FFFFFF">
              {collection.title}
            </StyledText>
            <StyledText size={15} color="rgba(255,255,255,0.8)" style={{ marginTop: SPACING[1] }}>
              {collection.description}
            </StyledText>
            <StyledText size={13} weight="semibold" color="rgba(255,255,255,0.6)" style={{ marginTop: SPACING[2] }}>
              {t('plurals.workout', { count: workouts.length })}
            </StyledText>
          </View>
        </View>

        {/* Workout List */}
        <StyledText
          size={20}
          weight="bold"
          color={colors.text.primary}
          style={{ marginTop: SPACING[6], marginBottom: SPACING[3] }}
        >
          {t('screens:explore.workouts')}
        </StyledText>

        {workouts.map((workout) => (
          <Pressable
            key={workout.id}
            testID={`collection-workout-${workout.id}`}
            style={styles.workoutCard}
            onPress={() => handleWorkoutPress(workout.id)}
          >
            <View style={[styles.workoutAvatar, { backgroundColor: BRAND.PRIMARY }]}>
               <Icon name="flame.fill" size={20} color="#FFFFFF" />
            </View>
            <View style={styles.workoutInfo}>
              <StyledText size={17} weight="semibold" color={colors.text.primary}>
                {workout.title}
              </StyledText>
              <StyledText size={13} color={colors.text.tertiary}>
                {t('durationLevel', {
                  duration: workout.duration,
                  level: t(`levels.${(workout.level ?? 'Beginner').toLowerCase()}`),
                })}
              </StyledText>
            </View>
            <View style={styles.workoutMeta}>
              <StyledText size={13} color={BRAND.PRIMARY}>
                {t('units.calUnit', { count: workout.calories })}
              </StyledText>
              <Icon name="chevron.right" size={16} color={colors.text.tertiary} />
            </View>
          </Pressable>
        ))}

        {workouts.length === 0 && (
          <View style={styles.emptyState}>
            <Icon name="dumbbell" size={48} color={colors.text.tertiary} />
            <StyledText size={17} color={colors.text.tertiary} style={{ marginTop: SPACING[3] }}>
              No workouts in this collection
            </StyledText>
          </View>
        )}
      </ScrollView>
    </View>
  )
}

function createStyles(colors: ThemeColors) {
  return StyleSheet.create({
    container: {
      flex: 1,
      backgroundColor: colors.bg.base,
    },
    centered: {
      alignItems: 'center',
      justifyContent: 'center',
    },
    header: {
      flexDirection: 'row',
      alignItems: 'center',
      justifyContent: 'space-between',
      paddingHorizontal: LAYOUT.SCREEN_PADDING,
      paddingVertical: SPACING[3],
    },
    backButton: {
      width: 44,
      height: 44,
      alignItems: 'center',
      justifyContent: 'center',
    },
    heroCard: {
      height: 200,
      borderRadius: RADIUS.XL,
      overflow: 'hidden',
      ...colors.shadow.lg,
    },
    heroContent: {
      flex: 1,
      padding: SPACING[5],
      justifyContent: 'flex-end',
    },
    heroIcon: {
      marginBottom: SPACING[2],
    },
    scrollView: {
      flex: 1,
    },
    scrollContent: {
      paddingHorizontal: LAYOUT.SCREEN_PADDING,
    },
    workoutCard: {
      flexDirection: 'row',
      alignItems: 'center',
      paddingVertical: SPACING[3],
      paddingHorizontal: SPACING[4],
      backgroundColor: colors.bg.surface,
      borderRadius: RADIUS.LG,
      marginBottom: SPACING[2],
      gap: SPACING[3],
    },
    workoutAvatar: {
      width: 44,
      height: 44,
      borderRadius: 22,
      alignItems: 'center',
      justifyContent: 'center',
    },
    workoutInfo: {
      flex: 1,
      gap: 2,
    },
    workoutMeta: {
      alignItems: 'flex-end',
      gap: 4,
    },
    emptyState: {
      alignItems: 'center',
      justifyContent: 'center',
      paddingVertical: SPACING[12],
    },
  })
}