import Foundation

/// Errors from API calls
enum APIError: LocalizedError {
    case network(Error)
    case httpError(Int)
    case decodingError(Error)
    case serverError(String)
    case unauthorized
    case noData

    var errorDescription: String? {
        switch self {
        case .network(let e): return "Network error: \(e.localizedDescription)"
        case .httpError(let code): return "HTTP \(code)"
        case .decodingError(let e): return "Decode error: \(e.localizedDescription)"
        case .serverError(let msg): return msg
        case .unauthorized: return "Session expired. Please log in again."
        case .noData: return "No data received"
        }
    }
}

/// Lightweight API client — all Payfrit backend calls
actor APIClient {
    static let shared = APIClient()

    private let session: URLSession

    private init() {
        let config = URLSessionConfiguration.default
        config.timeoutIntervalForResource = APIConfig.readTimeout
        config.timeoutIntervalForRequest = APIConfig.connectTimeout
        self.session = URLSession(configuration: config)
    }

    // MARK: - Auth

    struct OTPResponse: Codable {
        let uuid: String?
        let UUID: String?
        var otpUUID: String { uuid ?? UUID ?? "" }
    }

    func sendOTP(phone: String) async throws -> String {
        let body: [String: Any] = ["ContactNumber": phone]
        let data = try await post(path: "/auth/loginOTP.php", body: body)
        let resp = try JSONDecoder().decode(APIResponse<OTPResponse>.self, from: data)
        guard resp.success, let payload = resp.data else {
            throw APIError.serverError(resp.message ?? "Failed to send OTP")
        }
        return payload.otpUUID
    }

    struct LoginResponse: Codable {
        let token: String?
        let Token: String?
        let userId: String?
        let UserID: String?
        var authToken: String { token ?? Token ?? "" }
        var authUserId: String { userId ?? UserID ?? "" }
    }

    func verifyOTP(uuid: String, code: String) async throws -> (token: String, userId: String) {
        let body: [String: Any] = ["UUID": uuid, "Code": code]
        let data = try await post(path: "/auth/verifyLoginOTP.php", body: body)
        let resp = try JSONDecoder().decode(APIResponse<LoginResponse>.self, from: data)
        guard resp.success, let payload = resp.data else {
            throw APIError.serverError(resp.message ?? "Invalid OTP")
        }
        return (payload.authToken, payload.authUserId)
    }

    // MARK: - Businesses

    func listBusinesses(token: String) async throws -> [Business] {
        let data = try await post(path: "/businesses/list.php", body: [:], token: token)
        let resp = try JSONDecoder().decode(APIResponse<[Business]>.self, from: data)
        guard resp.success else {
            throw APIError.serverError(resp.message ?? "Failed to load businesses")
        }
        return resp.data ?? []
    }

    // MARK: - Service Points

    func listServicePoints(businessId: String, token: String) async throws -> [ServicePoint] {
        let body: [String: Any] = ["BusinessID": businessId]
        let data = try await post(path: "/servicepoints/list.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<[ServicePoint]>.self, from: data)
        guard resp.success else {
            throw APIError.serverError(resp.message ?? "Failed to load service points")
        }
        return resp.data ?? []
    }

    func createServicePoint(name: String, businessId: String, token: String) async throws -> ServicePoint {
        let body: [String: Any] = ["Name": name, "BusinessID": businessId]
        let data = try await post(path: "/servicepoints/save.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<ServicePoint>.self, from: data)
        guard resp.success, let sp = resp.data else {
            throw APIError.serverError(resp.message ?? "Failed to create service point")
        }
        return sp
    }

    // MARK: - Beacon Sharding

    struct NamespaceResponse: Codable {
        let uuid: String?
        let UUID: String?
        let major: Int?
        let Major: Int?
        var shardUUID: String { uuid ?? UUID ?? "" }
        var shardMajor: Int { major ?? Major ?? 0 }
    }

    func allocateBusinessNamespace(businessId: String, token: String) async throws -> (uuid: String, major: Int) {
        let body: [String: Any] = ["BusinessID": businessId]
        let data = try await post(path: "/beacon-sharding/allocate_business_namespace.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<NamespaceResponse>.self, from: data)
        guard resp.success, let ns = resp.data else {
            throw APIError.serverError(resp.message ?? "Failed to allocate namespace")
        }
        return (ns.shardUUID, ns.shardMajor)
    }

    struct MinorResponse: Codable {
        let minor: Int?
        let Minor: Int?
        var allocated: Int { minor ?? Minor ?? 0 }
    }

    func allocateMinor(businessId: String, servicePointId: String, token: String) async throws -> Int {
        let body: [String: Any] = ["BusinessID": businessId, "ServicePointID": servicePointId]
        let data = try await post(path: "/beacon-sharding/allocate_servicepoint_minor.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<MinorResponse>.self, from: data)
        guard resp.success, let m = resp.data else {
            throw APIError.serverError(resp.message ?? "Failed to allocate minor")
        }
        return m.allocated
    }

    func registerBeaconHardware(
        businessId: String,
        servicePointId: String,
        uuid: String,
        major: Int,
        minor: Int,
        macAddress: String?,
        beaconType: String,
        token: String
    ) async throws {
        var body: [String: Any] = [
            "BusinessID": businessId,
            "ServicePointID": servicePointId,
            "UUID": uuid,
            "Major": major,
            "Minor": minor,
            "BeaconType": beaconType
        ]
        if let mac = macAddress { body["MacAddress"] = mac }
        let data = try await post(path: "/beacon-sharding/register_beacon_hardware.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<EmptyData>.self, from: data)
        guard resp.success else {
            throw APIError.serverError(resp.message ?? "Failed to register beacon")
        }
    }

    func verifyBeaconBroadcast(
        uuid: String,
        major: Int,
        minor: Int,
        token: String
    ) async throws {
        let body: [String: Any] = ["UUID": uuid, "Major": major, "Minor": minor]
        let data = try await post(path: "/beacon-sharding/verify_beacon_broadcast.php", body: body, token: token)
        let resp = try JSONDecoder().decode(APIResponse<EmptyData>.self, from: data)
        guard resp.success else {
            throw APIError.serverError(resp.message ?? "Failed to verify broadcast")
        }
    }

    struct ResolveResponse: Codable {
        let businessName: String?
        let BusinessName: String?
        var name: String { businessName ?? BusinessName ?? "Unknown" }
    }

    func resolveBusiness(uuid: String, major: Int, token: String) async throws -> String {
        let body: [String: Any] = ["UUID": uuid, "Major": major]
        let data = try await post(path: "/beacon-sharding/resolve_business.php", body: body, token: token)
        let resp = try JSONDecoder().decode(APIResponse<ResolveResponse>.self, from: data)
        return resp.data?.name ?? "Unknown"
    }

    // MARK: - Service Point Management

    func deleteServicePoint(servicePointId: String, businessId: String, token: String) async throws {
        let body: [String: Any] = ["ID": servicePointId, "BusinessID": businessId]
        let data = try await post(path: "/servicepoints/delete.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<EmptyData>.self, from: data)
        guard resp.success else {
            throw APIError.serverError(resp.message ?? "Failed to delete service point")
        }
    }

    func updateServicePoint(servicePointId: String, name: String, businessId: String, token: String) async throws {
        let body: [String: Any] = ["ID": servicePointId, "Name": name, "BusinessID": businessId]
        let data = try await post(path: "/servicepoints/save.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<EmptyData>.self, from: data)
        guard resp.success else {
            throw APIError.serverError(resp.message ?? "Failed to update service point")
        }
    }

    // MARK: - Beacon Management

    struct BeaconListResponse: Codable {
        let id: String?
        let ID: String?
        let uuid: String?
        let UUID: String?
        let major: Int?
        let Major: Int?
        let minor: Int?
        let Minor: Int?
        let macAddress: String?
        let MacAddress: String?
        let beaconType: String?
        let BeaconType: String?
        let servicePointId: String?
        let ServicePointID: String?
        let isVerified: Bool?
        let IsVerified: Bool?
    }

    func listBeacons(businessId: String, token: String) async throws -> [BeaconListResponse] {
        let body: [String: Any] = ["BusinessID": businessId]
        let data = try await post(path: "/beacon-sharding/list_beacons.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<[BeaconListResponse]>.self, from: data)
        guard resp.success else {
            throw APIError.serverError(resp.message ?? "Failed to list beacons")
        }
        return resp.data ?? []
    }

    func decommissionBeacon(beaconId: String, businessId: String, token: String) async throws {
        let body: [String: Any] = ["ID": beaconId, "BusinessID": businessId]
        let data = try await post(path: "/beacon-sharding/decommission_beacon.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<EmptyData>.self, from: data)
        guard resp.success else {
            throw APIError.serverError(resp.message ?? "Failed to decommission beacon")
        }
    }

    func lookupByMac(macAddress: String, token: String) async throws -> BeaconListResponse? {
        let body: [String: Any] = ["MacAddress": macAddress]
        let data = try await post(path: "/beacon-sharding/lookup_by_mac.php", body: body, token: token)
        let resp = try JSONDecoder().decode(APIResponse<BeaconListResponse>.self, from: data)
        return resp.data
    }

    func getBeaconStatus(uuid: String, major: Int, minor: Int, token: String) async throws -> BeaconListResponse? {
        let body: [String: Any] = ["UUID": uuid, "Major": major, "Minor": minor]
        let data = try await post(path: "/beacon-sharding/beacon_status.php", body: body, token: token)
        let resp = try JSONDecoder().decode(APIResponse<BeaconListResponse>.self, from: data)
        return resp.data
    }

    // MARK: - Beacon Config (server-configured values)

    struct BeaconConfigResponse: Codable {
        let uuid: String?
        let UUID: String?
        let major: Int?
        let Major: Int?
        let minor: Int?
        let Minor: Int?
        let txPower: Int?
        let TxPower: Int?
        let measuredPower: Int?
        let MeasuredPower: Int?
        let advInterval: Int?
        let AdvInterval: Int?

        var configUUID: String { uuid ?? UUID ?? "" }
        var configMajor: Int { major ?? Major ?? 0 }
        var configMinor: Int { minor ?? Minor ?? 0 }
        var configTxPower: Int { txPower ?? TxPower ?? 1 }
        var configMeasuredPower: Int { measuredPower ?? MeasuredPower ?? -100 }
        var configAdvInterval: Int { advInterval ?? AdvInterval ?? 2 }
    }

    func getBeaconConfig(businessId: String, servicePointId: String, token: String) async throws -> BeaconConfigResponse {
        let body: [String: Any] = ["BusinessID": businessId, "ServicePointID": servicePointId]
        let data = try await post(path: "/beacon-sharding/get_beacon_config.php", body: body, token: token, businessId: businessId)
        let resp = try JSONDecoder().decode(APIResponse<BeaconConfigResponse>.self, from: data)
        guard resp.success, let config = resp.data else {
            throw APIError.serverError(resp.message ?? "Failed to get beacon config")
        }
        return config
    }

    // MARK: - User Profile

    struct UserProfile: Codable {
        let id: String?
        let ID: String?
        let firstName: String?
        let FirstName: String?
        let lastName: String?
        let LastName: String?
        let contactNumber: String?
        let ContactNumber: String?
    }

    func getProfile(token: String) async throws -> UserProfile {
        let data = try await post(path: "/users/profile.php", body: [:], token: token)
        let resp = try JSONDecoder().decode(APIResponse<UserProfile>.self, from: data)
        guard resp.success, let profile = resp.data else {
            throw APIError.serverError(resp.message ?? "Failed to load profile")
        }
        return profile
    }

    // MARK: - Internal

    private struct EmptyData: Codable {}

    private struct APIResponse<T: Codable>: Codable {
        let success: Bool
        let message: String?
        let data: T?

        enum CodingKeys: String, CodingKey {
            case success = "Success"
            case message = "Message"
            case data = "Data"
        }

        init(from decoder: Decoder) throws {
            let container = try decoder.container(keyedBy: CodingKeys.self)
            // Handle both bool and int/string for Success
            if let b = try? container.decode(Bool.self, forKey: .success) {
                success = b
            } else if let i = try? container.decode(Int.self, forKey: .success) {
                success = i != 0
            } else {
                success = false
            }
            message = try? container.decode(String.self, forKey: .message)
            data = try? container.decode(T.self, forKey: .data)
        }
    }

    private func post(
        path: String,
        body: [String: Any],
        token: String? = nil,
        businessId: String? = nil
    ) async throws -> Data {
        guard let url = URL(string: APIConfig.baseURL + path) else {
            throw APIError.serverError("Invalid URL: \(path)")
        }

        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")

        if let token = token {
            request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
            request.setValue(token, forHTTPHeaderField: "X-User-Token")
        }
        if let bizId = businessId {
            request.setValue(bizId, forHTTPHeaderField: "X-Business-Id")
        }

        request.httpBody = try JSONSerialization.data(withJSONObject: body)

        let (data, response) = try await session.data(for: request)

        if let http = response as? HTTPURLResponse {
            if http.statusCode == 401 { throw APIError.unauthorized }
            guard (200...299).contains(http.statusCode) else {
                throw APIError.httpError(http.statusCode)
            }
        }

        return data
    }
}