import SwiftUI
import SwiftData

/// 첫 화면: 점검할 매장을 고르거나 새로 추가한다.
struct StoreListView: View {
    @Environment(\.modelContext) private var context
    @Query(sort: \Store.createdAt) private var stores: [Store]
    @Query private var allRecords: [ProductRecord]

    @State private var showingAdd = false
    @State private var newName = ""
    @State private var renameTarget: Store?
    @State private var renameText = ""
    @State private var deleteTarget: Store?

    var body: some View {
        NavigationStack {
            ZStack {
                Theme.bg.ignoresSafeArea()
                ScrollView {
                    VStack(alignment: .leading, spacing: 24) {
                        header
                        if stores.isEmpty {
                            emptyState
                        } else {
                            storeList
                        }
                    }
                    .padding(20)
                }
            }
            .navigationDestination(for: Store.self) { store in
                YearMonthView(store: store)
            }
            .toolbar(.hidden, for: .navigationBar)
        }
        .alert("새 매장 추가", isPresented: $showingAdd) {
            TextField("매장 이름", text: $newName)
            Button("추가") { addStore() }
            Button("취소", role: .cancel) { newName = "" }
        } message: {
            Text("점검할 매장의 이름을 입력하세요.")
        }
        .alert("이름 변경", isPresented: isRenaming) {
            TextField("매장 이름", text: $renameText)
            Button("변경") { renameStore() }
            Button("취소", role: .cancel) { renameTarget = nil }
        }
        .confirmationDialog(
            deleteMessage,
            isPresented: isDeleting,
            titleVisibility: .visible
        ) {
            Button("삭제", role: .destructive) { deleteStore() }
            Button("취소", role: .cancel) { deleteTarget = nil }
        }
    }

    // MARK: - 헤더

    private var header: some View {
        HStack(alignment: .top) {
            VStack(alignment: .leading, spacing: 6) {
                Text("유통기한 점검")
                    .font(.caption.weight(.bold))
                    .foregroundStyle(Theme.accent)
                    .kerning(1)
                Text("어느 매장을\n점검할까요?")
                    .font(.system(size: 30, weight: .bold, design: .rounded))
                    .foregroundStyle(Theme.textPrimary)
                    .lineSpacing(3)
            }
            Spacer()
            Button {
                newName = ""
                showingAdd = true
            } label: {
                Image(systemName: "plus")
                    .font(.title3.weight(.semibold))
                    .foregroundStyle(Theme.onAccent)
                    .frame(width: 44, height: 44)
                    .background(Circle().fill(Theme.accentGradient))
                    .shadow(color: Theme.accent.opacity(0.35), radius: 12, y: 4)
            }
        }
        .padding(.top, 12)
    }

    // MARK: - 매장 목록

    private var storeList: some View {
        VStack(spacing: 12) {
            ForEach(stores) { store in
                NavigationLink(value: store) {
                    storeCard(store)
                }
                .buttonStyle(.plain)
                .contextMenu {
                    Button {
                        renameText = store.name
                        renameTarget = store
                    } label: {
                        Label("이름 변경", systemImage: "pencil")
                    }
                    Button(role: .destructive) {
                        deleteTarget = store
                    } label: {
                        Label("매장 삭제", systemImage: "trash")
                    }
                }
            }
        }
    }

    private func storeCard(_ store: Store) -> some View {
        let counts = recordCounts(for: store)
        return HStack(spacing: 14) {
            ZStack {
                RoundedRectangle(cornerRadius: 14, style: .continuous)
                    .fill(Theme.accentSoft)
                    .frame(width: 50, height: 50)
                Image(systemName: "storefront.fill")
                    .font(.title3)
                    .foregroundStyle(Theme.accent)
            }
            VStack(alignment: .leading, spacing: 4) {
                Text(store.name)
                    .font(.system(.headline, design: .rounded))
                    .foregroundStyle(Theme.textPrimary)
                Text(countLine(counts))
                    .font(.caption)
                    .foregroundStyle(Theme.textSecondary)
            }
            Spacer()
            Image(systemName: "chevron.right")
                .font(.footnote.weight(.semibold))
                .foregroundStyle(Theme.textSecondary)
        }
        .padding(16)
        .cardStyle()
    }

    private func countLine(_ counts: (total: Int, thisMonth: Int)) -> String {
        counts.total == 0
            ? "아직 기록이 없어요"
            : "전체 \(counts.total)개 · 이번 달 \(counts.thisMonth)개"
    }

    // MARK: - 빈 상태

    private var emptyState: some View {
        VStack(spacing: 14) {
            Image(systemName: "storefront")
                .font(.system(size: 44))
                .foregroundStyle(Theme.accent.opacity(0.7))
            Text("등록된 매장이 없어요")
                .font(.system(.headline, design: .rounded))
                .foregroundStyle(Theme.textPrimary)
            Text("오른쪽 위 + 버튼으로\n첫 매장을 추가해 보세요.")
                .font(.subheadline)
                .foregroundStyle(Theme.textSecondary)
                .multilineTextAlignment(.center)
        }
        .frame(maxWidth: .infinity)
        .padding(.vertical, 70)
        .cardStyle()
    }

    // MARK: - 동작

    private func recordCounts(for store: Store) -> (total: Int, thisMonth: Int) {
        let records = allRecords.filter { $0.store === store }
        let now = KoreanCalendar.calendar.dateComponents([.year, .month], from: .now)
        let thisMonth = records.filter {
            let c = KoreanCalendar.calendar.dateComponents([.year, .month], from: $0.expiryDate)
            return c.year == now.year && c.month == now.month
        }
        return (records.count, thisMonth.count)
    }

    private func addStore() {
        let name = newName.trimmingCharacters(in: .whitespacesAndNewlines)
        newName = ""
        guard !name.isEmpty else { return }
        context.insert(Store(name: name))
        try? context.save()
        Haptics.success()
    }

    private func renameStore() {
        guard let store = renameTarget else { return }
        let name = renameText.trimmingCharacters(in: .whitespacesAndNewlines)
        renameTarget = nil
        guard !name.isEmpty else { return }
        store.name = name
        try? context.save()
        Haptics.tap()
    }

    private func deleteStore() {
        guard let store = deleteTarget else { return }
        deleteTarget = nil
        context.delete(store)
        try? context.save()
        Haptics.warning()
    }

    private var isRenaming: Binding<Bool> {
        Binding(
            get: { renameTarget != nil },
            set: { if !$0 { renameTarget = nil } }
        )
    }

    private var isDeleting: Binding<Bool> {
        Binding(
            get: { deleteTarget != nil },
            set: { if !$0 { deleteTarget = nil } }
        )
    }

    private var deleteMessage: String {
        guard let store = deleteTarget else { return "" }
        let count = allRecords.filter { $0.store === store }.count
        return count > 0
            ? "'\(store.name)'과 기록 \(count)개를 모두 삭제할까요?"
            : "'\(store.name)'을(를) 삭제할까요?"
    }
}