import Foundation

@MainActor
final class MessagesViewModel: ObservableObject {
    enum DirectionFilter: String, CaseIterable, Identifiable {
        case all = "全部"
        case incoming = "收件"
        case outgoing = "发件"

        var id: String { rawValue }
    }

    @Published var rows: [SMSMessage] = []
    @Published var instances: [Instance] = []
    @Published var selectedInstanceID: UUID?
    @Published var searchText = ""
    @Published var direction: DirectionFilter = .all
    @Published var isLoading = false
    @Published var errorMessage: String?
    @Published var showingSendForm = false

    private let repository: any InstanceRepository
    private let service: MessageService

    init(repository: any InstanceRepository, service: MessageService) {
        self.repository = repository
        self.service = service
    }

    var filteredRows: [SMSMessage] {
        rows.filter { message in
            selectedInstanceID == nil || message.instanceID == selectedInstanceID
        }.filter { message in
            switch direction {
            case .all: return true
            case .incoming: return message.direction == .incoming
            case .outgoing: return message.direction == .outgoing
            }
        }.filter { message in
            let query = searchText.trimmingCharacters(in: .whitespacesAndNewlines)
            guard !query.isEmpty else { return true }
            return message.phoneNumber.localizedCaseInsensitiveContains(query)
                || message.content.localizedCaseInsensitiveContains(query)
                || message.instanceName.localizedCaseInsensitiveContains(query)
        }
    }

    var selectedInstance: Instance? {
        instances.first { $0.id == selectedInstanceID }
    }

    func refresh() async {
        isLoading = true
        errorMessage = nil
        do {
            let loaded = try await repository.list(InstanceQuery())
            instances = loaded
            if selectedInstanceID == nil || !loaded.contains(where: { $0.id == selectedInstanceID }) {
                selectedInstanceID = nil
            }
            let page = try await service.messages(loaded, limit: 100)
            rows = page.messages
        } catch MessageServiceError.unauthorized {
            errorMessage = "有实例需要登录，未获取受保护消息。"
        } catch {
            errorMessage = "无法加载消息。"
        }
        isLoading = false
    }

    func send(phoneNumber: String, content: String) async throws {
        guard let instance = selectedInstance ?? instances.first else {
            throw MessageServiceError.invalidInput
        }
        try await service.send(instance, phoneNumber: phoneNumber, content: content)
        await refresh()
    }

    func delete(_ message: SMSMessage) async {
        guard let instance = instances.first(where: { $0.id == message.instanceID }) else { return }
        do {
            try await service.delete([message.id], from: instance)
            rows.removeAll { $0.id == message.id && $0.instanceID == message.instanceID }
        } catch {
            errorMessage = "删除消息失败。"
        }
    }
}