import SwiftUI
import CoreModel
import CoreUI
import DesignSystem

public struct PlanScreen: View {
    private let viewModel: PlanViewModel
    private let onNavigateToAuth: () -> Void
    private let makePlanSubmitViewModel: (PlanType, String) -> PlanSubmitViewModel

    @State private var submitRoute: PlanSubmitRoute?
    @State private var selectedGroup: PlanGroup?

    public init(
        viewModel: PlanViewModel,
        onNavigateToAuth: @escaping () -> Void,
        makePlanSubmitViewModel: @escaping (PlanType, String) -> PlanSubmitViewModel
    ) {
        self.viewModel = viewModel
        self.onNavigateToAuth = onNavigateToAuth
        self.makePlanSubmitViewModel = makePlanSubmitViewModel
    }

    public var body: some View {
        content
            .navigationTitle("计划")
            .task { viewModel.load() }
            .navigationDestination(item: $submitRoute) { route in
                PlanSubmitScreen(
                    viewModel: makePlanSubmitViewModel(route.type, route.periodKey),
                    type: route.type,
                    periodKey: route.periodKey
                )
            }
            .sheet(item: $selectedGroup) { group in
                GroupDetailSheet(group: group)
            }
    }

    @ViewBuilder
    private var content: some View {
        switch viewModel.uiState {
        case .loading:
            LoadingView()
        case .loggedOut:
            LoggedOutView(onNavigateToAuth: onNavigateToAuth)
        case .error(let message):
            ErrorView(message: message) { viewModel.load() }
        case .success(let record):
            successContent(record)
        }
    }

    private func successContent(_ record: PlanRecord) -> some View {
        ScrollView {
            VStack(spacing: DS.Spacing.md) {
                Picker("类型", selection: Binding(get: { viewModel.selectedType }, set: { viewModel.selectType($0) })) {
                    ForEach(PlanType.allCases, id: \.self) { type in
                        Text(type.label).tag(type)
                    }
                }
                .pickerStyle(.segmented)
                .labelsHidden()

                PlanHead(record: record)
                MyPlanStatusCard(record: record) {
                    submitRoute = PlanSubmitRoute(type: record.type, periodKey: record.periodKey)
                }
                if record.myChecked, let myRecord = record.myRecord {
                    UploadedPlanCard(record: myRecord)
                }
                if let message = record.message {
                    WindowMessage(message: message)
                }
                if record.groups.isEmpty {
                    EmptyStateView(title: "暂无小组", systemImage: "person.2")
                } else {
                    Text("小组打卡")
                        .font(.subheadline.bold())
                        .foregroundStyle(DS.Color.brandDark)
                        .frame(maxWidth: .infinity, alignment: .leading)
                    ForEach(record.groups) { group in
                        GroupCard(group: group) { selectedGroup = group }
                    }
                }
                if record.unassignedCount > 0 {
                    Text("另有未分组 \(record.unassignedCount) 人")
                        .font(.caption)
                        .foregroundStyle(DS.Color.faintText)
                        .frame(maxWidth: .infinity, alignment: .leading)
                }
            }
            .padding(DS.Spacing.md)
        }
        .background(DS.Color.brandPaper)
    }
}

private struct PlanSubmitRoute: Hashable {
    let type: PlanType
    let periodKey: String
}

// MARK: - 头部 / 状态卡

private struct PlanHead: View {
    let record: PlanRecord

    var body: some View {
        HStack {
            VStack(alignment: .leading, spacing: 2) {
                Text(record.type.label)
                    .font(.title3.bold())
                    .foregroundStyle(DS.Color.brandDark)
                Text(record.periodKey)
                    .font(.caption)
                    .foregroundStyle(DS.Color.brandMuted)
            }
            Spacer()
            Text(record.myChecked ? "已提交" : "待提交")
                .font(.caption)
                .foregroundStyle(record.myChecked ? DS.Color.statusNormal : DS.Color.brandGold)
                .padding(.horizontal, DS.Spacing.sm)
                .padding(.vertical, 4)
                .background(record.myChecked ? DS.Color.fillDone : DS.Color.fillUndone)
                .clipShape(Capsule())
        }
    }
}

private struct MyPlanStatusCard: View {
    let record: PlanRecord
    let onSubmit: () -> Void

    var body: some View {
        HStack(spacing: DS.Spacing.md) {
            Text(record.myChecked ? "✓" : "●")
                .font(.headline)
                .foregroundStyle(.white)
                .frame(width: 44, height: 44)
                .background(
                    record.myChecked
                        ? AnyShapeStyle(LinearGradient(colors: [DS.Color.statusNormal, DS.Color.statusNormalBright], startPoint: .top, endPoint: .bottom))
                        : AnyShapeStyle(LinearGradient(colors: [DS.Color.danger, DS.Color.dangerBright], startPoint: .top, endPoint: .bottom))
                )
                .clipShape(Circle())
            VStack(alignment: .leading, spacing: 2) {
                Text(record.myChecked ? "已完成" : "未完成")
                    .font(.subheadline.bold())
                    .foregroundStyle(record.myChecked ? DS.Color.statusNormal : DS.Color.danger)
                Text("我的\(record.type.label)")
                    .font(.caption)
                    .foregroundStyle(DS.Color.brandMuted)
            }
            Spacer()
            Button(record.myChecked ? "修改" : "新增打卡", action: onSubmit)
                .buttonStyle(.bordered)
                .disabled(!record.canSubmit)
        }
        .padding(DS.Spacing.md)
        .background(Color.white)
        .clipShape(RoundedRectangle(cornerRadius: 16, style: .continuous))
    }
}

private struct UploadedPlanCard: View {
    let record: MyPlanRecord

    var body: some View {
        VStack(alignment: .leading, spacing: DS.Spacing.sm) {
            HStack {
                Text("我上传的计划")
                    .font(.subheadline.bold())
                    .foregroundStyle(DS.Color.brandDark)
                Spacer()
                Text(record.status)
                    .font(.caption)
                    .foregroundStyle(DS.Color.brandGold)
                    .padding(.horizontal, DS.Spacing.sm)
                    .padding(.vertical, 2)
                    .background(DS.Color.fillUndone)
                    .clipShape(Capsule())
            }
            Text("\(record.submittedTime) 提交")
                .font(.caption)
                .foregroundStyle(DS.Color.brandMuted)
            Text(record.content)
                .font(.subheadline)
                .foregroundStyle(DS.Color.brandBrown)
            if !record.attachments.isEmpty {
                HStack(spacing: DS.Spacing.sm) {
                    ForEach(record.attachments, id: \.self) { _ in
                        Text("🖼️")
                            .frame(width: 64, height: 64)
                            .background(DS.Color.brandChip)
                            .clipShape(RoundedRectangle(cornerRadius: 8, style: .continuous))
                    }
                }
            }
        }
        .padding(DS.Spacing.md)
        .frame(maxWidth: .infinity, alignment: .leading)
        .background(Color.white)
        .clipShape(RoundedRectangle(cornerRadius: 16, style: .continuous))
    }
}

private struct WindowMessage: View {
    let message: String

    var body: some View {
        HStack(spacing: DS.Spacing.sm) {
            Text("⏰")
            Text(message)
                .font(.caption)
                .foregroundStyle(DS.Color.danger)
        }
        .padding(DS.Spacing.sm)
        .frame(maxWidth: .infinity, alignment: .leading)
        .background(DS.Color.fillUndone)
        .clipShape(RoundedRectangle(cornerRadius: 10, style: .continuous))
    }
}

// MARK: - 小组卡片 / 明细

private struct GroupCard: View {
    let group: PlanGroup
    let onTap: () -> Void

    var body: some View {
        Button(action: onTap) {
            HStack(spacing: DS.Spacing.sm) {
                Text(String(group.name.prefix(1)))
                    .font(.subheadline.bold())
                    .foregroundStyle(DS.Color.brandGold)
                    .frame(width: 40, height: 40)
                    .background(DS.Gradient.groupTile)
                    .clipShape(RoundedRectangle(cornerRadius: 10, style: .continuous))
                VStack(alignment: .leading, spacing: DS.Spacing.xs) {
                    Text(group.name)
                        .font(.subheadline.bold())
                        .foregroundStyle(DS.Color.brandDark)
                    ProgressView(value: Double(group.checkedCount), total: Double(max(group.memberCount, 1)))
                        .tint(DS.Color.brandGold)
                }
                Spacer()
                Text("已打卡 \(group.checkedCount)")
                    .font(.caption2)
                    .foregroundStyle(DS.Color.statusNormal)
                Text("\(group.memberCount)人")
                    .font(.caption2)
                    .foregroundStyle(DS.Color.brandGold)
                Text("›")
                    .font(.headline)
                    .foregroundStyle(DS.Color.faintText)
            }
            .padding(DS.Spacing.md)
            .background(Color.white)
            .clipShape(RoundedRectangle(cornerRadius: 14, style: .continuous))
        }
        .buttonStyle(.plain)
    }
}

private struct GroupDetailSheet: View {
    let group: PlanGroup
    @Environment(\.dismiss) private var dismiss

    var body: some View {
        NavigationStack {
            List(group.members) { member in
                HStack(spacing: DS.Spacing.sm) {
                    Text(String(member.name.prefix(1)))
                        .font(.subheadline.bold())
                        .foregroundStyle(member.filled ? DS.Color.statusNormal : DS.Color.brandGold)
                        .frame(width: 30, height: 30)
                        .background(member.filled ? DS.Color.fillDone : DS.Color.brandChip)
                        .clipShape(Circle())
                    Text(member.name)
                        .font(.subheadline)
                        .foregroundStyle(DS.Color.brandDark)
                    Spacer()
                    Text(member.filled ? "已完成" : "未完成")
                        .font(.caption)
                        .foregroundStyle(member.filled ? DS.Color.statusNormal : DS.Color.danger)
                }
            }
            .navigationTitle(group.name)
            .toolbar {
                ToolbarItem(placement: .primaryAction) {
                    Button("关闭") { dismiss() }
                }
            }
        }
        .presentationDetents([.medium])
    }
}