//
//  DataResetView.swift
//  Haru_Danim
//
//  데이터 정리·초기화 (1.4, 설정 → 데이터). 무료 — 자기 데이터에 대한 접근권.
//  범위: 전체 / 처음부터 지정한 날짜까지(기록·일기만, 구조 보존 — DataReset 참고).
//  삭제 전 백업(CSV·일기 PDF·정리 리포트)을 같은 화면에서 만들어 공유하고,
//  2단계 확인(다이얼로그 → 얼럿)을 거쳐 삭제한다. 삭제 코어는 DataReset,
//  백업 부품은 CSVExport·DiaryExportRenderer·ArchiveReport 재사용.
//

import SwiftUI
import SwiftData

struct DataResetView: View {
    @Environment(\.modelContext) private var context
    @Environment(\.dismiss) private var dismiss
    @AppStorage(LocalPrefsKeys.actionOrder, store: AppGroup.defaults) private var actionOrderRaw = ""

    private enum RangeMode: String, CaseIterable, Identifiable {
        case all, upTo
        var id: String { rawValue }
        var label: String {
            switch self {
            case .all: return String(localized: "전체")
            case .upTo: return String(localized: "날짜 지정")
            }
        }
    }

    private enum ReportFormat: String, CaseIterable, Identifiable {
        case pdf, image
        var id: String { rawValue }
        var label: String {
            switch self {
            case .pdf: return "PDF"
            case .image: return String(localized: "이미지")
            }
        }
    }

    @State private var rangeMode: RangeMode = .all
    @State private var endDate: Date = Calendar.current.date(byAdding: .month, value: -3, to: .now) ?? .now
    @State private var includeCSV = true
    @State private var includeDiary = true
    @State private var includeReport = true
    @State private var reportFormat: ReportFormat = .pdf
    @State private var isGenerating = false
    @State private var backupURLs: [URL] = []
    @State private var confirmingDelete = false
    @State private var finalConfirm = false
    @State private var isDeleting = false
    @State private var deletedCounts: DataReset.Counts?

    private var math: DayMath { DayMath() }

    /// 선택한 달력일(포함)까지 — DatePicker의 달력일을 키로 직접 사용 (§4.1)
    private var endKey: Date { math.calendar.startOfDay(for: endDate) }
    private var upperBound: Date { math.dayRange(forKey: endKey).upperBound }

    /// 백업(CSV·리포트)용 범위 — 삭제와 달리 경계 걸침 세션까지 담는 게 안전해 겹침 포함
    private var backupRange: Range<Date>? {
        rangeMode == .all ? nil : Date.distantPast..<upperBound
    }

    /// 백업을 하나도 안 만들거나, 만들었을 때만 삭제로 진행 가능
    private var canDelete: Bool {
        let wantsBackup = includeCSV || includeDiary || includeReport
        return (!wantsBackup || !backupURLs.isEmpty) && !isGenerating && !isDeleting
            && deletedCounts == nil
    }

    // MARK: 삭제 대상 집계 (fetchCount — 전량 로드 없음)

    private var targetSessionCount: Int {
        let farFuture = Date.distantFuture
        let descriptor: FetchDescriptor<TimeSession>
        if rangeMode == .all {
            descriptor = FetchDescriptor<TimeSession>()
        } else {
            let upper = upperBound
            descriptor = FetchDescriptor<TimeSession>(
                predicate: #Predicate { ($0.endAt ?? farFuture) <= upper }
            )
        }
        return (try? context.fetchCount(descriptor)) ?? 0
    }

    private var targetEntryCount: Int {
        let descriptor: FetchDescriptor<CountEntry>
        if rangeMode == .all {
            descriptor = FetchDescriptor<CountEntry>()
        } else {
            let upper = upperBound
            descriptor = FetchDescriptor<CountEntry>(predicate: #Predicate { $0.timestamp < upper })
        }
        return (try? context.fetchCount(descriptor)) ?? 0
    }

    private var targetDiaryCount: Int {
        let descriptor: FetchDescriptor<DiaryEntry>
        if rangeMode == .all {
            descriptor = FetchDescriptor<DiaryEntry>()
        } else {
            let key = endKey
            descriptor = FetchDescriptor<DiaryEntry>(predicate: #Predicate { $0.dayKey <= key })
        }
        return (try? context.fetchCount(descriptor)) ?? 0
    }

    private var targetActionCount: Int {
        (try? context.fetchCount(FetchDescriptor<Action>())) ?? 0
    }

    private var targetGoalCount: Int {
        (try? context.fetchCount(FetchDescriptor<Goal>())) ?? 0
    }

    var body: some View {
        List {
            if let counts = deletedCounts {
                doneSection(counts)
            } else {
                rangeSection
                targetSection
                backupSection
                deleteSection
            }
        }
        .tint(AppTheme.green)
        .scrollContentBackground(.hidden)
        .background(AppTheme.background)
        .navigationTitle("데이터 정리·초기화")
        .navigationBarTitleDisplayMode(.inline)
        .toolbar(.hidden, for: .tabBar)
        .onChange(of: rangeMode) { backupURLs = [] }
        .onChange(of: endDate) { backupURLs = [] }
        .onChange(of: includeCSV) { backupURLs = [] }
        .onChange(of: includeDiary) { backupURLs = [] }
        .onChange(of: includeReport) { backupURLs = [] }
        .onChange(of: reportFormat) { backupURLs = [] }
        .confirmationDialog(
            rangeMode == .all
                ? String(localized: "모든 데이터를 삭제할까요?")
                : String(localized: "\(Format.fullDate(endKey))까지의 기록·일기를 삭제할까요?"),
            isPresented: $confirmingDelete,
            titleVisibility: .visible
        ) {
            Button("삭제 진행", role: .destructive) { finalConfirm = true }
        } message: {
            Text(rangeMode == .all
                 ? "행동·꼬리표·목표·다짐·기록·일기·양식이 모두 삭제돼요. iCloud 동기화를 켰다면 다른 기기에서도 함께 삭제돼요."
                 : "지정한 날짜까지의 시간·횟수 기록과 일기가 삭제돼요. 과거 기록이 사라지면 다짐의 연속 달성 기록이 끊겨요. iCloud 동기화를 켰다면 다른 기기에서도 함께 삭제돼요.")
        }
        .alert("정말 삭제할까요?", isPresented: $finalConfirm) {
            Button("취소", role: .cancel) {}
            Button("삭제", role: .destructive) { performDelete() }
        } message: {
            Text("삭제는 되돌릴 수 없어요. 백업 파일을 저장했는지 다시 확인해 주세요.")
        }
        #if DEBUG
        .onAppear {
            // 검증용: -dataResetRangeDays <N> → '날짜 지정'(오늘-N일까지)로 시작
            let days = UserDefaults.standard.integer(forKey: "dataResetRangeDays")
            if days > 0 {
                rangeMode = .upTo
                endDate = math.calendar.date(byAdding: .day, value: -days, to: .now) ?? .now
            }
            // 검증용: -dataResetBackupRun pdf|image → 백업 3종 자동 생성 후 Documents 복사
            if let raw = UserDefaults.standard.string(forKey: "dataResetBackupRun") {
                includeCSV = true
                includeDiary = true
                includeReport = true
                reportFormat = raw == "image" ? .image : .pdf
                makeBackups(copyToDocuments: true)
            }
        }
        #endif
    }

    // MARK: 섹션들

    private var rangeSection: some View {
        Section {
            Picker("범위", selection: $rangeMode) {
                ForEach(RangeMode.allCases) { mode in
                    Text(mode.label).tag(mode)
                }
            }
            .pickerStyle(.segmented)
            if rangeMode == .upTo {
                DatePicker("까지", selection: $endDate, in: ...Date.now, displayedComponents: .date)
            }
        } header: {
            Text("정리할 범위")
        } footer: {
            Text(rangeMode == .all
                 ? "모든 행동·꼬리표·목표·다짐·기록·일기·양식을 삭제하고 처음 상태로 돌아가요. 앱 설정(테마·하루 시작 시간 등)과 프리미엄은 그대로예요."
                 : "처음부터 지정한 날짜(포함)까지의 시간·횟수 기록과 일기만 삭제해요. 행동·꼬리표·목표·다짐과 양식 라이브러리는 남아요. 지정한 날짜에 걸쳐 있는 측정과 진행 중인 측정은 남아요.")
        }
    }

    private var targetSection: some View {
        Section("삭제 대상") {
            countRow("timer", String(localized: "시간 기록"), String(localized: "\(targetSessionCount)건"))
            countRow("number", String(localized: "횟수 기록"), String(localized: "\(targetEntryCount)건"))
            countRow("book.closed.fill", String(localized: "일기"), String(localized: "\(targetDiaryCount)일"))
            if rangeMode == .all {
                countRow("figure.walk", String(localized: "행동"), String(localized: "\(targetActionCount)개"))
                countRow("flag.checkered", String(localized: "목표"), String(localized: "\(targetGoalCount)개"))
            }
        }
    }

    private var backupSection: some View {
        Section {
            Toggle(isOn: $includeCSV) {
                Label("CSV 내보내기", systemImage: "tablecells")
            }
            Toggle(isOn: $includeDiary) {
                Label("일기 PDF", systemImage: "book.closed")
            }
            Toggle(isOn: $includeReport) {
                Label("정리 리포트", systemImage: "doc.richtext")
            }
            if includeReport {
                Picker("리포트 형식", selection: $reportFormat) {
                    ForEach(ReportFormat.allCases) { format in
                        Text(format.label).tag(format)
                    }
                }
                .pickerStyle(.segmented)
            }
            if isGenerating {
                HStack {
                    ProgressView()
                    Text("백업 만드는 중…")
                        .foregroundStyle(.secondary)
                }
            } else if backupURLs.isEmpty {
                if includeCSV || includeDiary || includeReport {
                    Button {
                        makeBackups()
                    } label: {
                        Label("백업 파일 만들기", systemImage: "square.and.arrow.down.on.square")
                            .frame(maxWidth: .infinity)
                    }
                }
            } else {
                ShareLink(items: backupURLs) {
                    Label("백업 파일 \(backupURLs.count)개 공유", systemImage: "square.and.arrow.up")
                        .frame(maxWidth: .infinity)
                }
                Button("다시 만들기") {
                    backupURLs = []
                }
                .frame(maxWidth: .infinity)
            }
        } header: {
            Text("삭제 전 백업")
        } footer: {
            Text("CSV는 '데이터 가져오기'로 복원할 수 있는 원본 백업이에요. 정리 리포트는 삭제할 기록을 한눈에 정리한 문서예요(기간·행동별 누적·꼬리표·월별·목표 이력). 백업을 켰다면 파일을 만들어 저장한 뒤에 삭제할 수 있어요.")
        }
    }

    private var deleteSection: some View {
        Section {
            if isDeleting {
                HStack {
                    ProgressView()
                    Text("삭제하는 중…")
                        .foregroundStyle(.secondary)
                }
            } else {
                Button(role: .destructive) {
                    confirmingDelete = true
                } label: {
                    Label(rangeMode == .all ? "전체 데이터 삭제…" : "지정한 날짜까지 삭제…",
                          systemImage: "trash")
                        .frame(maxWidth: .infinity)
                }
                .disabled(!canDelete)
            }
        } footer: {
            if !canDelete && !isDeleting && deletedCounts == nil {
                Text("먼저 위에서 백업 파일을 만들어 주세요. 백업 없이 삭제하려면 백업 항목을 모두 꺼요.")
            }
        }
    }

    private func doneSection(_ counts: DataReset.Counts) -> some View {
        Section {
            Label {
                Text("삭제를 마쳤어요")
                    .font(.headline)
            } icon: {
                Image(systemName: "checkmark.circle.fill")
                    .foregroundStyle(AppTheme.green)
            }
            countRow("timer", String(localized: "시간 기록"), String(localized: "\(counts.sessions)건"))
            countRow("number", String(localized: "횟수 기록"), String(localized: "\(counts.entries)건"))
            countRow("book.closed.fill", String(localized: "일기"), String(localized: "\(counts.diaryEntries)일"))
            if counts.actions > 0 || counts.goals > 0 {
                countRow("figure.walk", String(localized: "행동"), String(localized: "\(counts.actions)개"))
                countRow("flag.checkered", String(localized: "목표"), String(localized: "\(counts.goals)개"))
            }
            Button("완료") { dismiss() }
                .frame(maxWidth: .infinity)
        } footer: {
            Text("iCloud 동기화를 켰다면 다른 기기에는 잠시 뒤에 반영돼요.")
        }
    }

    private func countRow(_ symbol: String, _ title: String, _ value: String) -> some View {
        HStack {
            Label {
                Text(title)
            } icon: {
                Image(systemName: symbol)
                    .foregroundStyle(AppTheme.green)
            }
            Spacer()
            Text(value).foregroundStyle(.secondary)
        }
    }

    // MARK: 백업 생성 (부품 재사용 — CSVExport·DiaryExportRenderer·ArchiveReport)

    private func makeBackups(copyToDocuments: Bool = false) {
        isGenerating = true
        Task { @MainActor in
            try? await Task.sleep(for: .milliseconds(60))
            var urls: [URL] = []
            do {
                let actions = try context.fetch(
                    FetchDescriptor<Action>(sortBy: [SortDescriptor(\.createdAt)])
                )
                let sessions = try context.fetch(
                    FetchDescriptor<TimeSession>(sortBy: [SortDescriptor(\.startAt)])
                )
                let entries = try context.fetch(
                    FetchDescriptor<CountEntry>(sortBy: [SortDescriptor(\.timestamp)])
                )
                let goals = try context.fetch(FetchDescriptor<Goal>(
                    sortBy: [SortDescriptor(\.sortOrder), SortDescriptor(\.createdAt)]
                ))
                let diaryDescriptor: FetchDescriptor<DiaryEntry> = {
                    if rangeMode == .all {
                        return FetchDescriptor<DiaryEntry>(sortBy: [SortDescriptor(\.dayKey)])
                    }
                    let key = endKey
                    return FetchDescriptor<DiaryEntry>(
                        predicate: #Predicate { $0.dayKey <= key },
                        sortBy: [SortDescriptor(\.dayKey)]
                    )
                }()
                let diaryEntries = try context.fetch(diaryDescriptor).filter(\.hasContent)

                if includeCSV {
                    // ⚠️ CSVExport.fileSuffix(for:)는 dayKeys 순회라 distantPast 범위 금지 —
                    // '처음~까지'는 끝 날짜만 접미로 표기한다
                    var suffix = ""
                    if rangeMode == .upTo {
                        let formatter = DateFormatter()
                        formatter.locale = Locale(identifier: "en_US_POSIX")
                        formatter.dateFormat = "yyyyMMdd"
                        suffix = "-upto-\(formatter.string(from: endKey))"
                    }
                    urls += CSVExport.makeFiles(
                        actions: actions, sessions: sessions, entries: entries, goals: goals,
                        range: backupRange, fileSuffix: suffix
                    )
                }
                if includeDiary, !diaryEntries.isEmpty {
                    let orderedActions = LocalPrefs.orderedActions(actions, raw: actionOrderRaw)
                    let templates = try context.fetch(FetchDescriptor<DiaryTemplate>())
                    let renderer = DiaryExportRenderer(
                        context: context, orderedActions: orderedActions,
                        templates: templates, math: math
                    )
                    let slug = String(localized: "일기-정리-\(DiaryExportRenderer.slugDate(diaryEntries.first!.dayKey))~\(DiaryExportRenderer.slugDate(diaryEntries.last!.dayKey))")
                    if let url = renderer.pdfURL(entries: diaryEntries, fileSlug: slug) {
                        urls.append(url)
                    }
                }
                if includeReport {
                    if let url = ArchiveReport.makeURL(
                        format: reportFormat == .pdf ? .pdf : .image,
                        actions: actions, sessions: sessions, entries: entries, goals: goals,
                        diaryDayKeys: diaryEntries.map(\.dayKey),
                        range: backupRange, math: math
                    ) {
                        urls.append(url)
                    }
                }
            } catch {
                urls = []
            }
            backupURLs = urls
            isGenerating = false
            #if DEBUG
            if copyToDocuments,
               let docs = FileManager.default.urls(for: .documentDirectory, in: .userDomainMask).first {
                for url in urls {
                    let dest = docs.appendingPathComponent(url.lastPathComponent)
                    try? FileManager.default.removeItem(at: dest)
                    try? FileManager.default.copyItem(at: url, to: dest)
                }
            }
            #endif
        }
    }

    // MARK: 삭제 실행

    private func performDelete() {
        isDeleting = true
        Task { @MainActor in
            try? await Task.sleep(for: .milliseconds(60))
            do {
                let counts: DataReset.Counts
                if rangeMode == .all {
                    counts = try DataReset.deleteAll(context: context)
                } else {
                    counts = try DataReset.deleteRecords(upToDayKey: endKey, context: context, math: math)
                }
                // 저장 + 위젯·워치·LiveActivity 동기화 (진행 중 측정도 전체 삭제면 함께 정리됨)
                DataChange.commit(context: context)
                deletedCounts = counts
            } catch {
                deletedCounts = nil
            }
            isDeleting = false
        }
    }
}