import Foundation

import Combine

final class PushNotificationListViewModel: ObservableObject {
    private let repository = PushNotificationRepository()
    private var subscription = Set<AnyCancellable>()

    @Published var errorMessage = ""
    @Published var isShowPopup = false
    @Published var isLoading = false

    @Published var categories: [String] = []
    @Published var selectedCategory: String = "" {
        didSet {
            if oldValue != selectedCategory {
                let trimmed = selectedCategory.trimmingCharacters(in: .whitespacesAndNewlines)
                if !trimmed.isEmpty {
                    getPushNotificationList(reset: true)
                }
            }
        }
    }

    @Published var items: [PushNotificationListItem] = []
    @Published var totalCount: Int = 0

    private var page: Int = 1
    private let pageSize: Int = 20
    private var isLast: Bool = false

    func initialize() {
        getPushNotificationCategories { [weak self] in
            guard let self = self else { return }
            let trimmed = self.selectedCategory.trimmingCharacters(in: .whitespacesAndNewlines)
            if trimmed.isEmpty {
                self.getPushNotificationList(reset: true)
            }
        }
    }

    func getPushNotificationList(reset: Bool = false) {
        if reset {
            page = 1
            isLast = false
            totalCount = 0
            items.removeAll()
        }

        if isLoading || isLast {
            return
        }

        isLoading = true

        repository.getPushNotificationList(
            page: page,
            size: pageSize,
            category: requestCategory
        )
        .sink { [weak self] result in
            guard let self = self else { return }

            switch result {
            case .finished:
                DEBUG_LOG("finish")

            case .failure(let error):
                self.isLoading = false
                ERROR_LOG(error.localizedDescription)
                self.errorMessage = I18n.Common.commonError
                self.isShowPopup = true
            }
        } receiveValue: { [weak self] response in
            guard let self = self else { return }

            self.isLoading = false

            do {
                let decoded = try JSONDecoder().decode(
                    ApiResponse<GetPushNotificationListResponse>.self,
                    from: response.data
                )

                if let data = decoded.data, decoded.success {
                    self.totalCount = data.totalCount

                    if data.items.isEmpty {
                        self.isLast = true
                        return
                    }

                    self.items.append(contentsOf: data.items)

                    let totalPages = Int(ceil(Double(max(data.totalCount, 0)) / Double(self.pageSize)))
                    let isReachedByPage = totalPages > 0 ? self.page >= totalPages : true
                    let isReachedByCount = data.totalCount > 0 && self.items.count >= data.totalCount

                    if isReachedByPage || isReachedByCount {
                        self.isLast = true
                    } else {
                        self.page += 1
                    }
                } else {
                    self.errorMessage = decoded.message ?? I18n.Common.commonError
                    self.isShowPopup = true
                }
            } catch {
                self.errorMessage = I18n.Common.commonError
                self.isShowPopup = true
            }
        }
        .store(in: &subscription)
    }

    func onTapItem(_ item: PushNotificationListItem) {
        guard let deepLink = item.deepLink?.trimmingCharacters(in: .whitespacesAndNewlines), !deepLink.isEmpty else {
            return
        }

        _ = AppDeepLinkHandler.handle(urlString: deepLink, source: .notificationList)
    }

    private var requestCategory: String? {
        let trimmed = selectedCategory.trimmingCharacters(in: .whitespacesAndNewlines)
        return trimmed.isEmpty ? nil : trimmed
    }

    private func getPushNotificationCategories(completion: (() -> Void)? = nil) {
        repository.getPushNotificationCategories()
            .sink { result in
                switch result {
                case .finished:
                    DEBUG_LOG("finish")

                case .failure(let error):
                    ERROR_LOG(error.localizedDescription)
                }

                completion?()
            } receiveValue: { [weak self] response in
                guard let self = self else { return }

                do {
                    let decoded = try JSONDecoder().decode(
                        ApiResponse<GetPushNotificationCategoryResponse>.self,
                        from: response.data
                    )

                    if let data = decoded.data, decoded.success {
                        var filtered: [String] = []
                        for category in data.categories {
                            let trimmed = category.trimmingCharacters(in: .whitespacesAndNewlines)
                            if trimmed.isEmpty || filtered.contains(trimmed) {
                                continue
                            }
                            filtered.append(trimmed)
                        }

                        self.categories = filtered
                        self.selectedCategory = filtered.first ?? ""
                    } else {
                        self.errorMessage = decoded.message ?? I18n.Common.commonError
                        self.isShowPopup = true
                    }
                } catch {
                    self.errorMessage = I18n.Common.commonError
                    self.isShowPopup = true
                }
            }
            .store(in: &subscription)
    }
}