import Foundation

// MARK: - Service Protocol

protocol ClubServiceProtocol: Sendable {
    func listClubs(filter: ClubFilter) async throws -> [Club]
    func getClub(id: String) async throws -> (club: Club, members: [ClubMember])
    func createClub(request: CreateClubRequest) async throws -> Club
    func updateClub(id: String, request: UpdateClubRequest) async throws -> Club
    func joinClub(id: String) async throws
    func leaveClub(id: String) async throws
    func inviteMember(clubId: String, email: String) async throws
    func removeMember(clubId: String, memberId: String) async throws
}

// MARK: - Default Service

class ClubService: ClubServiceProtocol {
    private let baseURL: URL
    private let session: URLSession
    private let authToken: String?

    init(
        baseURL: URL = URL(string: "http://localhost:3000")!,
        session: URLSession = .shared,
        authToken: String? = nil
    ) {
        self.baseURL = baseURL
        self.session = session
        self.authToken = authToken
    }

    func listClubs(filter: ClubFilter = ClubFilter()) async throws -> [Club] {
        var components = URLComponents(url: baseURL.appendingPathComponent("/api/clubs"), resolvingAgainstBaseURL: true)!
        var queryItems: [URLQueryItem] = [
            URLQueryItem(name: "limit", value: String(filter.limit)),
            URLQueryItem(name: "offset", value: String(filter.offset))
        ]
        if let type = filter.clubType { queryItems.append(URLQueryItem(name: "type", value: type.rawValue)) }
        if let privacy = filter.privacy { queryItems.append(URLQueryItem(name: "privacy", value: privacy.rawValue)) }
        if let status = filter.membershipStatus { queryItems.append(URLQueryItem(name: "status", value: status.rawValue)) }
        if let location = filter.location { queryItems.append(URLQueryItem(name: "location", value: location)) }
        if let radius = filter.radiusKm { queryItems.append(URLQueryItem(name: "radius", value: String(radius))) }
        components.queryItems = queryItems

        let request = try buildRequest(url: components.url!)
        let (data, response) = try await session.data(for: request)
        try validateResponse(response)

        let decoded = try JSONDecoder().decode(ClubListResponse.self, from: data)
        return decoded.clubs
    }

    func getClub(id: String) async throws -> (club: Club, members: [ClubMember]) {
        let url = baseURL.appendingPathComponent("/api/clubs/\(id)")
        let request = try buildRequest(url: url)
        let (data, response) = try await session.data(for: request)
        try validateResponse(response)

        let decoded = try JSONDecoder().decode(ClubDetailResponse.self, from: data)
        return (decoded.club, decoded.members)
    }

    func createClub(request: CreateClubRequest) async throws -> Club {
        let url = baseURL.appendingPathComponent("/api/clubs")
        var request = try buildRequest(url: url, method: .post)
        request.httpBody = try JSONEncoder().encode(request)

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

        let decoded = try JSONDecoder().decode(CreateClubResponse.self, from: data)
        return decoded.club
    }

    func updateClub(id: String, request: UpdateClubRequest) async throws -> Club {
        let url = baseURL.appendingPathComponent("/api/clubs/\(id)")
        var request = try buildRequest(url: url, method: .patch)
        request.httpBody = try JSONEncoder().encode(request)

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

        let decoded = try JSONDecoder().decode(UpdateClubResponse.self, from: data)
        return decoded.club
    }

    func joinClub(id: String) async throws {
        let url = baseURL.appendingPathComponent("/api/clubs/\(id)/join")
        let request = try buildRequest(url: url, method: .post)

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

    func leaveClub(id: String) async throws {
        let url = baseURL.appendingPathComponent("/api/clubs/\(id)/leave")
        let request = try buildRequest(url: url, method: .post)

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

    func inviteMember(clubId: String, email: String) async throws {
        let url = baseURL.appendingPathComponent("/api/clubs/\(clubId)/invite")
        var request = try buildRequest(url: url, method: .post)
        request.httpBody = try JSONEncoder().encode(["email": email])

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

    func removeMember(clubId: String, memberId: String) async throws {
        let url = baseURL.appendingPathComponent("/api/clubs/\(clubId)/members/\(memberId)")
        let request = try buildRequest(url: url, method: .delete)

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

    // MARK: - Helpers

    private func buildRequest(url: URL, method: HTTPMethod = .get, body: Data? = nil) throws -> URLRequest {
        var request = URLRequest(url: url)
        request.httpMethod = method.rawValue
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")

        if let token = authToken {
            request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
        }

        if let body = body {
            request.httpBody = body
        }

        return request
    }

    private func validateResponse(_ response: URLResponse) throws {
        guard let httpResponse = response as? HTTPURLResponse else {
            throw ClubError.invalidResponse
        }

        guard (200...299).contains(httpResponse.statusCode) else {
            switch httpResponse.statusCode {
            case 401: throw ClubError.unauthorized
            case 403: throw ClubError.forbidden
            case 404: throw ClubError.notFound
            case 429: throw ClubError.rateLimited
            case 500...599: throw ClubError.serverError(httpResponse.statusCode)
            default: throw ClubError.httpError(httpResponse.statusCode)
            }
        }
    }
}

// MARK: - Error Types

enum ClubError: LocalizedError {
    case invalidResponse
    case unauthorized
    case forbidden
    case notFound
    case rateLimited
    case serverError(Int)
    case httpError(Int)

    var errorDescription: String {
        switch self {
        case .invalidResponse: return "Invalid server response"
        case .unauthorized: return "Unauthorized — please log in again"
        case .forbidden: return "Forbidden — check permissions"
        case .notFound: return "Club not found"
        case .rateLimited: return "Too many requests — try again shortly"
        case .serverError(let code): return "Server error (\(code))"
        case .httpError(let code): return "HTTP error (\(code))"
        }
    }
}