//
//  ContentView.swift
//  Expiranner
//
//  메인 뷰: 연도 선택 + 월(1~12) 그리드

import SwiftUI
import SwiftData

struct ContentView: View {
    @State private var selectedYear = Calendar.current.component(.year, from: Date())
    @State private var showScanner = false

    private let years = Array(2020...2040)
    private let columns = Array(repeating: GridItem(.flexible()), count: 3)

    var body: some View {
        NavigationStack {
            ZStack(alignment: .bottomTrailing) {
                VStack {
                    Picker("연도", selection: $selectedYear) {
                        ForEach(years, id: \.self) { year in
                            Text(String(format: "%d년", year)).tag(year)
                        }
                    }
                    .pickerStyle(.menu)
                    .font(.title2)

                    LazyVGrid(columns: columns, spacing: 16) {
                        ForEach(1...12, id: \.self) { month in
                            NavigationLink {
                                MonthCalendarView(year: selectedYear, month: month)
                            } label: {
                                MonthCell(year: selectedYear, month: month)
                            }
                            .buttonStyle(.plain)
                        }
                    }
                    .padding()

                    Spacer()
                }

                FloatingScanButton {
                    showScanner = true
                }
            }
            .navigationTitle("Expiranner")
            .fullScreenCover(isPresented: $showScanner) {
                ScannerView(
                    year: Calendar.current.component(.year, from: Date()),
                    month: Calendar.current.component(.month, from: Date())
                )
            }
        }
    }
}

/// 월 셀: 해당 월에 저장된 아이템 개수 표시
struct MonthCell: View {
    let year: Int
    let month: Int

    @Query private var items: [ProductItem]

    init(year: Int, month: Int) {
        self.year = year
        self.month = month
        let (start, end) = Self.monthBounds(year: year, month: month)
        _items = Query(filter: #Predicate<ProductItem> { $0.date >= start && $0.date < end })
    }

    static func monthBounds(year: Int, month: Int) -> (Date, Date) {
        let calendar = Calendar.current
        let start = calendar.date(from: DateComponents(year: year, month: month, day: 1)) ?? Date()
        let end = calendar.date(byAdding: .month, value: 1, to: start) ?? start
        return (start, end)
    }

    var body: some View {
        VStack(spacing: 4) {
            Text("\(month)월")
                .font(.title3)
            Text(items.isEmpty ? " " : "\(items.count)개")
                .font(.caption)
                .foregroundStyle(.red)
        }
        .frame(maxWidth: .infinity)
        .padding(.vertical, 16)
        .background(Color(.secondarySystemBackground))
        .clipShape(RoundedRectangle(cornerRadius: 10))
    }
}

/// 플로팅 액션 버튼 (카메라 스캐너 실행)
struct FloatingScanButton: View {
    let action: () -> Void

    var body: some View {
        Button(action: action) {
            Image(systemName: "camera.fill")
                .font(.title2)
                .foregroundStyle(.white)
                .padding(18)
                .background(Circle().fill(.blue))
                .shadow(radius: 4)
        }
        .padding(24)
    }
}

#Preview {
    ContentView()
        .modelContainer(for: ProductItem.self, inMemory: true)
}