//
//  GoalTabView.swift
//  HaruDanim
//
//  Lists all `Goal`s and hosts a sheet for creating new ones.
//

import SwiftUI
import SwiftData

struct GoalTabView: View {
    @Environment(\.modelContext) private var modelContext
    @Query(sort: \Goal.createdAt, order: .reverse) private var goals: [Goal]

    @State private var isAddSheetPresented = false

    private var dateRangeFormatter: Date.FormatStyle {
        .dateTime.year().month().day()
    }

    var body: some View {
        NavigationStack {
            List {
                ForEach(goals) { goal in
                    NavigationLink {
                        GoalDetailView(goal: goal)
                    } label: {
                        HStack(spacing: 12) {
                            Circle()
                                .fill(Color(hex: goal.colorHex))
                                .frame(width: 20, height: 20)

                            VStack(alignment: .leading, spacing: 4) {
                                Text(goal.title)
                                Text("\(goal.startDate.formatted(dateRangeFormatter)) ~ \(goal.endDate.formatted(dateRangeFormatter))")
                                    .font(.caption)
                                    .foregroundStyle(.secondary)
                            }

                            Spacer()

                            Text("다짐 \(goal.quests.count)")
                                .font(.caption)
                                .foregroundStyle(.secondary)
                        }
                    }
                }
                .onDelete(perform: deleteGoals)
            }
            .navigationTitle("목표")
            .overlay {
                if goals.isEmpty {
                    ContentUnavailableView(
                        "목표가 없어요",
                        systemImage: "flag",
                        description: Text("오른쪽 위 + 버튼으로 목표를 추가하세요.")
                    )
                }
            }
            .toolbar {
                ToolbarItem(placement: .topBarTrailing) {
                    Button {
                        isAddSheetPresented = true
                    } label: {
                        Label("목표 추가", systemImage: "plus")
                    }
                }
            }
            .sheet(isPresented: $isAddSheetPresented) {
                AddGoalSheet()
            }
        }
    }

    private func deleteGoals(at offsets: IndexSet) {
        for index in offsets {
            modelContext.delete(goals[index])
        }
    }
}

// MARK: - Add Goal Sheet

private struct AddGoalSheet: View {
    @Environment(\.modelContext) private var modelContext
    @Environment(\.dismiss) private var dismiss

    @State private var title = ""
    @State private var color = Color(hex: "#2F6B4F")
    @State private var startDate = Date.now
    @State private var endDate = Date.now

    private var trimmedTitle: String {
        title.trimmingCharacters(in: .whitespacesAndNewlines)
    }

    private var isValid: Bool {
        !trimmedTitle.isEmpty && endDate >= startDate
    }

    var body: some View {
        NavigationStack {
            Form {
                Section("이름") {
                    TextField("목표 이름", text: $title)
                }

                Section("색상") {
                    ColorPicker("색상 선택", selection: $color, supportsOpacity: false)
                }

                Section("기간") {
                    DatePicker("시작일", selection: $startDate, displayedComponents: .date)
                    DatePicker("종료일", selection: $endDate, in: startDate..., displayedComponents: .date)
                }
            }
            .navigationTitle("새 목표")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("취소") { dismiss() }
                }
                ToolbarItem(placement: .confirmationAction) {
                    Button("저장") { save() }
                        .disabled(!isValid)
                }
            }
        }
    }

    private func save() {
        let goal = Goal(
            title: trimmedTitle,
            colorHex: color.toHex(),
            startDate: startDate,
            endDate: endDate
        )
        modelContext.insert(goal)
        dismiss()
    }
}

#Preview {
    GoalTabView()
        .modelContainer(for: [Goal.self, Quest.self, Action.self, Tag.self], inMemory: true)
}