//
//  CharacterDetailGalleryViewModel.swift
//  SodaLive
//
//  Created by klaus on 9/2/25.
//

import Foundation
import Combine
import Moya

final class CharacterDetailGalleryViewModel: ObservableObject {
    // MARK: - Published State
    @Published var isLoading: Bool = false
    @Published var errorMessage: String = ""
    @Published var isShowPurchaseDialog = false
    @Published var isShowImageViewer = false
    @Published var isShowPopup = false
    
    // Gallery Data
    @Published var totalCount: Int = 0
    @Published var ownedCount: Int = 0
    @Published var galleryItems: [CharacterImageListItemResponse] = []
    @Published var selectedImageIndex: Int = 0
    
    // MARK: - Private
    private let repository = CharacterDetailGalleryRepository()
    private var subscription = Set<AnyCancellable>()
    private var currentPage = 0
    private var isLoadingMore = false
    private var hasMorePages = true
    private var selectedItem: CharacterImageListItemResponse?
    
    var characterId: Int = 0
    
    // MARK: - Computed Properties
    var ownershipPercentage: Int {
        guard totalCount > 0 else { return 0 }
        return Int(round(Double(ownedCount) / Double(totalCount) * 100))
    }
    
    var ownedImages: [CharacterImageListItemResponse] {
        return galleryItems.filter { $0.isOwned }
    }
    
    var selectedItemPrice: String {
        return "\(selectedItem?.imagePriceCan ?? 0)캔으로 구매"
    }
    
    // MARK: - Public Methods
    func loadInitialData() {
        currentPage = 0
        hasMorePages = true
        galleryItems.removeAll()
        loadImageList()
    }
    
    func loadMoreIfNeeded(currentItem: CharacterImageListItemResponse) {
        guard !isLoadingMore,
              hasMorePages,
              let lastItem = galleryItems.last,
              lastItem.id == currentItem.id else { return }
        
        loadMoreImages()
    }
    
    func onImageTapped(_ item: CharacterImageListItemResponse, index: Int) {
        selectedItem = item
        
        if item.isOwned {
            // 소유한 이미지 - 전체화면 뷰어 표시
            selectedImageIndex = ownedImages.firstIndex { $0.id == item.id } ?? 0
            isShowImageViewer = true
        } else {
            // 미소유 이미지 - 구매 다이얼로그 표시
            isShowPurchaseDialog = true
        }
    }
    
    func onPurchaseConfirm() {
        // TODO: 구매 API 연동 구현 예정
        print("구매 확인: \(selectedItem?.id ?? 0)")
        isShowPurchaseDialog = false
    }
    
    func onPurchaseCancel() {
        isShowPurchaseDialog = false
        selectedItem = nil
    }
    
    // MARK: - Private Methods
    private func loadImageList() {
        guard !isLoading else { return }
        
        isLoading = true
        
        repository.getCharacterImageList(
            characterId: characterId,
            page: currentPage,
            size: 20
        )
        .receive(on: DispatchQueue.main)
        .sink { result in
            switch result {
            case .finished:
                DEBUG_LOG("finish")
            case .failure(let error):
                ERROR_LOG(error.localizedDescription)
            }
        } receiveValue: { [weak self] response in
            let responseData = response.data
            self?.isLoading = false
            
            do {
                let jsonDecoder = JSONDecoder()
                let decoded = try jsonDecoder.decode(ApiResponse<CharacterImageListResponse>.self, from: responseData)
                
                if let data = decoded.data, decoded.success {
                    self?.handleImageListResponse(data)
                } else {
                    if let message = decoded.message {
                        self?.errorMessage = message
                    } else {
                        self?.errorMessage = "다시 시도해 주세요.\n계속 같은 문제가 발생할 경우 고객센터로 문의 주시기 바랍니다."
                    }
                    
                    self?.isShowPopup = true
                }
            } catch {
                ERROR_LOG(String(describing: error))
                self?.errorMessage = "다시 시도해 주세요.\n계속 같은 문제가 발생할 경우 고객센터로 문의 주시기 바랍니다."
                self?.isShowPopup = true
            }
        }
        .store(in: &subscription)
    }
    
    private func loadMoreImages() {
        guard !isLoadingMore, hasMorePages else { return }
        
        isLoadingMore = true
        currentPage += 1
        
        repository.getCharacterImageList(
            characterId: characterId,
            page: currentPage,
            size: 20
        )
        .receive(on: DispatchQueue.main)
        .sink { result in
            switch result {
            case .finished:
                DEBUG_LOG("finish")
            case .failure(let error):
                ERROR_LOG(error.localizedDescription)
            }
        } receiveValue: { [weak self] response in
            let responseData = response.data
            self?.isLoading = false
            
            do {
                let jsonDecoder = JSONDecoder()
                let decoded = try jsonDecoder.decode(ApiResponse<CharacterImageListResponse>.self, from: responseData)
                
                if let data = decoded.data, decoded.success {
                    self?.handleImageListResponse(data)
                } else {
                    if let message = decoded.message {
                        self?.errorMessage = message
                    } else {
                        self?.errorMessage = "다시 시도해 주세요.\n계속 같은 문제가 발생할 경우 고객센터로 문의 주시기 바랍니다."
                    }
                    
                    self?.isShowPopup = true
                }
            } catch {
                ERROR_LOG(String(describing: error))
                self?.errorMessage = "다시 시도해 주세요.\n계속 같은 문제가 발생할 경우 고객센터로 문의 주시기 바랍니다."
                self?.isShowPopup = true
            }
        }
        .store(in: &subscription)
    }
    
    private func handleImageListResponse(_ response: CharacterImageListResponse) {
        totalCount = response.totalCount
        ownedCount = response.ownedCount
        galleryItems = response.items
        hasMorePages = response.items.count >= 20
    }
    
    private func handleMoreImagesResponse(_ response: CharacterImageListResponse) {
        galleryItems.append(contentsOf: response.items)
        hasMorePages = response.items.count >= 20
    }
}