import Foundation
import SwiftUI

struct MainHomeFollowingScheduleSection: View {
    let monthlySchedules: [FollowingScheduleResponse]
    let onTapSchedule: (CreatorActivityType, Int) -> Void

    init(
        monthlySchedules: [FollowingScheduleResponse],
        onTapSchedule: @escaping (CreatorActivityType, Int) -> Void = { _, _ in }
    ) {
        self.monthlySchedules = monthlySchedules
        self.onTapSchedule = onTapSchedule
    }

    var body: some View {
        if !monthlySchedules.isEmpty {
            VStack(alignment: .leading, spacing: SodaSpacing.s14) {
                SectionTitle(title: I18n.HomeFollowing.monthlyScheduleTitle)

                VStack(alignment: .leading, spacing: SodaSpacing.s4) {
                    ForEach(monthlySchedules) { schedule in
                        MainHomeFollowingScheduleItemView(schedule: schedule) {
                            onTapSchedule(schedule.type, schedule.targetId)
                        }
                    }
                }
                .background(alignment: .leading) {
                    ScheduleTimelineLine()
                        .padding(.leading, 3)
                        .padding(.vertical, 52)
                        .opacity(monthlySchedules.count > 1 ? 1 : 0)
                }
                .padding(.horizontal, SodaSpacing.s14)
            }
        }
    }
}

private struct MainHomeFollowingScheduleItemView: View {
    let schedule: FollowingScheduleResponse
    let action: () -> Void

    var body: some View {
        HStack(alignment: .center, spacing: SodaSpacing.s14) {
            TimelineDotView(isHighlighted: schedule.isToday || schedule.isOnAir)

            Button(action: action) {
                HStack(alignment: .center, spacing: SodaSpacing.s12) {
                    DateBoxView(schedule: schedule)

                    VStack(alignment: .leading, spacing: SodaSpacing.s8) {
                        creatorInfo

                        HStack(alignment: .center, spacing: SodaSpacing.s8) {
                            Text(schedule.title)
                                .appFont(size: 16, weight: .medium)
                                .foregroundColor(.white)
                                .lineLimit(1)
                                .truncationMode(.tail)

                            Spacer(minLength: 0)
                        }

                        HStack(alignment: .center, spacing: SodaSpacing.s8) {
                            ActivityTypeTagView(type: schedule.type)

                            Spacer(minLength: 0)

                            Text(schedule.statusText)
                                .appFont(size: 16, weight: .regular)
                                .foregroundColor(schedule.isOnAir ? Color.soda400 : Color.gray500)
                                .lineLimit(1)
                                .multilineTextAlignment(.trailing)
                        }
                    }
                    .frame(maxWidth: .infinity, alignment: .leading)
                }
                .padding(SodaSpacing.s14)
                .padding(.leading, schedule.isOnAir ? SodaSpacing.s8 : 0)
                .background(Color.gray900)
                .clipShape(RoundedRectangle(cornerRadius: 14, style: .continuous))
                .overlay(alignment: .leading) {
                    if schedule.isOnAir {
                        Color.soda400
                            .frame(width: SodaSpacing.s4)
                    }
                }
            }
            .buttonStyle(.plain)
        }
    }

    private var creatorInfo: some View {
        HStack(alignment: .center, spacing: SodaSpacing.s6) {
            DownsampledKFImage(url: URL(string: schedule.creatorProfileImageUrl), size: CGSize(width: 20, height: 20))
                .clipShape(Circle())
                .frame(width: 20, height: 20)

            Text(schedule.creatorNickname)
                .appFont(size: 12, weight: .regular)
                .foregroundColor(.white)
                .lineLimit(1)
                .truncationMode(.tail)
        }
    }
}

private struct ScheduleTimelineLine: View {
    var body: some View {
        Rectangle()
            .fill(Color.gray700)
            .frame(width: 2)
            .frame(maxHeight: .infinity)
    }
}

private struct TimelineDotView: View {
    let isHighlighted: Bool

    var body: some View {
        Circle()
            .fill(isHighlighted ? Color.soda400 : Color.gray500)
            .frame(width: SodaSpacing.s8, height: SodaSpacing.s8)
            .frame(width: SodaSpacing.s8)
    }
}

private struct DateBoxView: View {
    let schedule: FollowingScheduleResponse

    var body: some View {
        VStack(alignment: .center, spacing: SodaSpacing.s4) {
            if schedule.isToday {
                Text(I18n.HomeFollowing.today)
                    .appFont(size: 22, weight: .bold)
                    .foregroundColor(.white)
                    .lineLimit(1)
            } else {
                Text(schedule.dayText)
                    .appFont(size: 22, weight: .bold)
                    .foregroundColor(.white)
                    .lineLimit(1)

                Text(schedule.weekdayText)
                    .appFont(size: 12, weight: .medium)
                    .foregroundColor(Color.gray500)
                    .lineLimit(1)
            }
        }
        .frame(width: 53, height: 53)
    }
}

private struct ActivityTypeTagView: View {
    let type: CreatorActivityType

    var body: some View {
        Text(type.scheduleTagTitle)
            .appFont(size: 14, weight: .regular)
            .foregroundColor(Color.gray100)
            .padding(.horizontal, SodaSpacing.s4)
            .padding(.vertical, 2)
            .background(Color.gray700)
            .clipShape(RoundedRectangle(cornerRadius: SodaSpacing.s4, style: .continuous))
            .lineLimit(1)
    }
}

private extension FollowingScheduleResponse {
    var scheduledDate: Date? {
        DateParser.parse(scheduledAtUtc)
    }

    var isToday: Bool {
        guard let scheduledDate else { return false }
        return Calendar.current.isDateInToday(scheduledDate)
    }

    var dayText: String {
        guard let scheduledDate else { return scheduledAtUtc }
        return ScheduleDateFormatter.day.string(from: scheduledDate)
    }

    var weekdayText: String {
        guard let scheduledDate else { return "" }
        return ScheduleDateFormatter.weekday.string(from: scheduledDate)
    }

    var statusText: String {
        if isOnAir {
            return I18n.HomeFollowing.onAirStatus
        }

        guard let scheduledDate else { return scheduledAtUtc }
        return ScheduleDateFormatter.time.string(from: scheduledDate)
    }
}

private extension CreatorActivityType {
    var scheduleTagTitle: String {
        switch self {
        case .live:
            return I18n.HomeFollowing.liveScheduleTag
        case .liveReplay:
            return I18n.HomeFollowing.liveReplayScheduleTag
        case .audio:
            return I18n.HomeFollowing.audioScheduleTag
        case .community:
            return I18n.HomeFollowing.communityScheduleTag
        case .unknown(let rawValue):
            return rawValue
        }
    }
}

private enum ScheduleDateFormatter {
    static let day: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "ko_KR")
        formatter.dateFormat = "d"
        return formatter
    }()

    static let weekday: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "ko_KR")
        formatter.dateFormat = "E"
        return formatter
    }()

    static let time: DateFormatter = {
        let formatter = DateFormatter()
        formatter.locale = Locale(identifier: "ko_KR")
        formatter.dateFormat = "a hh:mm"
        return formatter
    }()
}

struct MainHomeFollowingScheduleSection_Previews: PreviewProvider {
    private static let previewImageUrl = "https://picsum.photos/500/500"

    static var previews: some View {
        MainHomeFollowingScheduleSection(
            monthlySchedules: [
                FollowingScheduleResponse(
                    scheduleId: "today-on-air",
                    creatorId: 1,
                    creatorProfileImageUrl: previewImageUrl,
                    creatorNickname: "크리에이터",
                    title: "오늘 밤 같이 이야기해요",
                    type: .live,
                    targetId: 100,
                    scheduledAtUtc: ISO8601DateFormatter().string(from: Date()),
                    isOnAir: false
                ),
                FollowingScheduleResponse(
                    scheduleId: "normal-schedule",
                    creatorId: 2,
                    creatorProfileImageUrl: previewImageUrl,
                    creatorNickname: "소다",
                    title: "신규 오디오 콘텐츠 공개",
                    type: .audio,
                    targetId: 200,
                    scheduledAtUtc: "2026-07-12T12:30:00Z",
                    isOnAir: false
                )
            ]
        )
        .padding(.vertical, SodaSpacing.s20)
        .background(Color.black)
        .previewLayout(.sizeThatFits)
    }
}