//
//  ScannerView.swift
//  Expiranner
//
//  전체 화면 카메라 스캐너: 촬영 → OCR → 팝업 → 날짜 선택 → 저장

import SwiftUI
import SwiftData
import VisionKit
import Vision
import UIKit

struct ScannerView: View {
    /// 현재 보고 있는 연/월 (날짜 선택 범위 제한용)
    let year: Int
    let month: Int

    @Environment(\.dismiss) private var dismiss
    @Environment(\.modelContext) private var modelContext

    @State private var scannerHolder = ScannerHolder()
    @State private var isScanning = true
    @State private var capturedImage: UIImage?
    @State private var recognizedText = ""
    @State private var showPopup = false
    @State private var showDatePicker = false
    @State private var selectedDate = Date()

    /// 선택 가능한 날짜 범위: 현재 보고 있는 월로 제한
    private var monthRange: ClosedRange<Date> {
        let calendar = Calendar.current
        let start = calendar.date(from: DateComponents(year: year, month: month, day: 1)) ?? Date()
        let last = calendar.date(byAdding: DateComponents(month: 1, day: -1), to: start) ?? start
        return start...last
    }

    var body: some View {
        ZStack {
            if DataScannerViewController.isSupported && DataScannerViewController.isAvailable {
                DataScannerRepresentable(holder: scannerHolder, isScanning: $isScanning)
                    .ignoresSafeArea()
            } else {
                Color.black.ignoresSafeArea()
                Text("이 기기에서는 카메라 스캐너를 사용할 수 없습니다")
                    .foregroundStyle(.white)
            }

            VStack {
                HStack {
                    Spacer()
                    Button {
                        print("스캐너 종료")
                        dismiss()
                    } label: {
                        Image(systemName: "xmark")
                            .font(.title2)
                            .foregroundStyle(.white)
                            .padding(12)
                            .background(Circle().fill(.black.opacity(0.5)))
                    }
                    .padding()
                }
                Spacer()
                Button {
                    capturePhoto()
                } label: {
                    Circle()
                        .stroke(.white, lineWidth: 4)
                        .frame(width: 72, height: 72)
                        .overlay(Circle().fill(.white).frame(width: 58, height: 58))
                }
                .padding(.bottom, 32)
            }

            if showPopup {
                ocrPopup
            }
        }
        .sheet(isPresented: $showDatePicker) {
            datePickerSheet
        }
    }

    /// OCR 결과 팝업: 썸네일 + 편집 가능한 텍스트 + [재촬영]/[적용]
    private var ocrPopup: some View {
        VStack(spacing: 16) {
            if let capturedImage {
                Image(uiImage: capturedImage)
                    .resizable()
                    .scaledToFit()
                    .frame(maxHeight: 180)
                    .clipShape(RoundedRectangle(cornerRadius: 8))
            }
            TextField("인식된 텍스트", text: $recognizedText, axis: .vertical)
                .lineLimit(1...5)
                .textFieldStyle(.roundedBorder)
            HStack(spacing: 12) {
                Button("재촬영") {
                    print("재촬영 선택")
                    resumeScanning()
                }
                .frame(maxWidth: .infinity)
                .buttonStyle(.bordered)

                Button("적용") {
                    print("적용 선택: \(recognizedText)")
                    selectedDate = defaultDate()
                    showDatePicker = true
                }
                .frame(maxWidth: .infinity)
                .buttonStyle(.borderedProminent)
            }
        }
        .padding()
        .background(RoundedRectangle(cornerRadius: 14).fill(Color(.systemBackground)))
        .padding(24)
    }

    /// 날짜 선택 시트: 현재 보고 있는 월로 제한
    private var datePickerSheet: some View {
        NavigationStack {
            VStack {
                DatePicker("날짜", selection: $selectedDate, in: monthRange, displayedComponents: .date)
                    .datePickerStyle(.graphical)
                    .padding()
                Spacer()
            }
            .navigationTitle("\(String(year))년 \(month)월 날짜 선택")
            .navigationBarTitleDisplayMode(.inline)
            .toolbar {
                ToolbarItem(placement: .cancellationAction) {
                    Button("취소") { showDatePicker = false }
                }
                ToolbarItem(placement: .confirmationAction) {
                    Button("저장") { saveItem() }
                }
            }
        }
    }

    /// 기본 선택 날짜: 오늘이 해당 월에 포함되면 오늘, 아니면 월의 첫날
    private func defaultDate() -> Date {
        let today = Date()
        return monthRange.contains(today) ? today : monthRange.lowerBound
    }

    private func capturePhoto() {
        guard let scanner = scannerHolder.scanner else {
            print("스캐너를 사용할 수 없습니다")
            return
        }
        Task {
            do {
                let photo = try await scanner.capturePhoto()
                print("사진 촬영 완료")
                isScanning = false
                capturedImage = photo
                recognizedText = recognizeText(in: photo)
                showPopup = true
            } catch {
                print("사진 촬영 실패: \(error.localizedDescription)")
            }
        }
    }

    /// Vision 프레임워크로 한국어 텍스트 추출
    private func recognizeText(in image: UIImage) -> String {
        guard let cgImage = image.cgImage else { return "" }
        let request = VNRecognizeTextRequest()
        request.recognitionLanguages = ["ko-KR", "en-US"]
        request.recognitionLevel = .accurate
        request.usesLanguageCorrection = true
        let handler = VNImageRequestHandler(cgImage: cgImage)
        do {
            try handler.perform([request])
        } catch {
            print("텍스트 인식 실패: \(error.localizedDescription)")
            return ""
        }
        let text = request.results?
            .compactMap { $0.topCandidates(1).first?.string }
            .joined(separator: "\n") ?? ""
        print("인식된 텍스트: \(text)")
        return text
    }

    private func saveItem() {
        let imageData = capturedImage?.jpegData(compressionQuality: 0.5)
        let item = ProductItem(name: recognizedText, date: selectedDate, imageData: imageData)
        modelContext.insert(item)
        print("저장 완료: \(item.name) → \(selectedDate)")

        // 저장 시 햅틱 피드백
        UINotificationFeedbackGenerator().notificationOccurred(.success)

        showDatePicker = false
        resumeScanning()
    }

    /// 팝업을 닫고 카메라 스캐너로 복귀
    private func resumeScanning() {
        showPopup = false
        capturedImage = nil
        recognizedText = ""
        isScanning = true
    }
}

/// DataScannerViewController 참조 보관용
@Observable
final class ScannerHolder {
    var scanner: DataScannerViewController?
}

struct DataScannerRepresentable: UIViewControllerRepresentable {
    let holder: ScannerHolder
    @Binding var isScanning: Bool

    func makeUIViewController(context: Context) -> DataScannerViewController {
        let scanner = DataScannerViewController(
            recognizedDataTypes: [.text(languages: ["ko-KR"])],
            qualityLevel: .balanced,
            isHighlightingEnabled: false
        )
        holder.scanner = scanner
        return scanner
    }

    func updateUIViewController(_ scanner: DataScannerViewController, context: Context) {
        if isScanning, !scanner.isScanning {
            do {
                try scanner.startScanning()
                print("스캔 시작")
            } catch {
                print("스캔 시작 실패: \(error.localizedDescription)")
            }
        } else if !isScanning, scanner.isScanning {
            scanner.stopScanning()
            print("스캔 중지")
        }
    }
}