import SwiftUI

enum TjTab: String, Hashable, CaseIterable {
    case home, records, trend, me
    var label: String {
        switch self {
        case .home:    return "主页"
        case .records: return "记录"
        case .trend:   return "趋势"
        case .me:      return "我的"
        }
    }
    var icon: String {
        switch self {
        case .home:    return "house"
        case .records: return "list.bullet.rectangle"
        case .trend:   return "chart.line.uptrend.xyaxis"
        case .me:      return "person.circle"
        }
    }
}

enum ActiveFlow: Identifiable {
    case quick, archive
    var id: String { String(describing: self) }
}

struct RootView: View {
    @State private var tab: TjTab = .home
    @State private var showRecordSheet = false
    @State private var activeFlow: ActiveFlow?
    @State private var showSymptomStart = false
    @State private var showDiary = false

    var body: some View {
        VStack(spacing: 0) {
            Group {
                switch tab {
                case .home:    HomeView(onTapArchive: { tab = .records })
                case .records: ArchiveListView()
                case .trend:   TrendsView()
                case .me:      MeView()
                }
            }
            .frame(maxWidth: .infinity, maxHeight: .infinity)

            TabBar(active: tab,
                   onTap: { tab = $0 },
                   onTapRecord: { showRecordSheet = true })
        }
        .background(Tj.Palette.sand.ignoresSafeArea())
        .sheet(isPresented: $showRecordSheet) {
            RecordSheet { kind in
                showRecordSheet = false
                DispatchQueue.main.asyncAfter(deadline: .now() + 0.3) {
                    switch kind {
                    case .quick:   activeFlow = .quick
                    case .archive: activeFlow = .archive
                    case .symptom: showSymptomStart = true
                    case .diary:   showDiary = true
                    }
                }
            }
        }
        .sheet(isPresented: $showSymptomStart) {
            SymptomStartSheet()
        }
        .sheet(isPresented: $showDiary) {
            DiaryQuickSheet()
        }
#if os(iOS)
        .fullScreenCover(item: $activeFlow) { flow in
            switch flow {
            case .quick:
                QuickCaptureFlow(onClose: { activeFlow = nil })
            case .archive:
                ArchiveFlow(onClose: { activeFlow = nil })
            }
        }
#else
        .sheet(item: $activeFlow) { flow in
            switch flow {
            case .quick:
                QuickCaptureFlow(onClose: { activeFlow = nil })
            case .archive:
                ArchiveFlow(onClose: { activeFlow = nil })
            }
        }
#endif
    }
}

private struct TabBar: View {
    let active: TjTab
    let onTap: (TjTab) -> Void
    let onTapRecord: () -> Void

    private let cornerRadius: CGFloat = 22
    private let slotHeight: CGFloat = 34

    var body: some View {
        HStack(alignment: .bottom, spacing: 0) {
            tabItem(.home)
            tabItem(.records)
            recordSlot
            tabItem(.trend)
            tabItem(.me)
        }
        .padding(.horizontal, 4)
        .padding(.top, 10)
        .padding(.bottom, 6)
        .background(barBackground)
    }

    private var barBackground: some View {
        UnevenRoundedRectangle(
            topLeadingRadius: cornerRadius,
            bottomLeadingRadius: 0,
            bottomTrailingRadius: 0,
            topTrailingRadius: cornerRadius,
            style: .continuous
        )
        .fill(Tj.Palette.paper)
        .overlay(alignment: .top) {
            Rectangle()
                .fill(Tj.Palette.lineSoft)
                .frame(height: 1)
        }
        .shadow(color: Tj.Palette.ink.opacity(0.05), radius: 10, x: 0, y: -2)
    }

    private func tabItem(_ t: TjTab) -> some View {
        let isActive = active == t
        return Button { onTap(t) } label: {
            VStack(spacing: 4) {
                ZStack {
                    if isActive {
                        Capsule()
                            .fill(Tj.Palette.sand2)
                            .frame(width: 44, height: slotHeight - 6)
                    }
                    Image(systemName: t.icon)
                        .font(.system(size: 18, weight: isActive ? .semibold : .regular))
                }
                .frame(width: 50, height: slotHeight)

                Text(t.label)
                    .font(.system(size: 11, weight: isActive ? .semibold : .regular))
            }
            .foregroundStyle(isActive ? Tj.Palette.ink : Tj.Palette.text3)
            .frame(maxWidth: .infinity)
            .contentShape(Rectangle())
        }
        .buttonStyle(TabPressStyle())
    }

    private var recordSlot: some View {
        Button(action: onTapRecord) {
            VStack(spacing: 4) {
                ZStack {
                    Circle()
                        .fill(Tj.Palette.ink)
                        .overlay(
                            Circle()
                                .strokeBorder(Tj.Palette.paper, lineWidth: 2)
                        )
                        .shadow(color: Tj.Palette.ink.opacity(0.18),
                                radius: 4, x: 0, y: 2)

                    Image(systemName: "plus")
                        .font(.system(size: 16, weight: .semibold))
                        .foregroundStyle(Tj.Palette.paper)
                }
                .frame(width: slotHeight, height: slotHeight)

                Text("新建")
                    .font(.system(size: 11, weight: .semibold))
                    .foregroundStyle(Tj.Palette.ink)
            }
            .frame(maxWidth: .infinity)
            .contentShape(Rectangle())
        }
        .buttonStyle(TabPressStyle())
    }
}

private struct TabPressStyle: ButtonStyle {
    func makeBody(configuration: Configuration) -> some View {
        configuration.label
            .scaleEffect(configuration.isPressed ? 0.92 : 1.0)
            .animation(.spring(response: 0.25, dampingFraction: 0.7),
                       value: configuration.isPressed)
    }
}

#Preview {
    RootView()
}