import Foundation

struct ServerAddress: Equatable {
    let url: URL

    init(_ input: String) throws {
        let value = input.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !value.contains("\\"), !value.contains(where: { $0.isWhitespace }),
            var parts = URLComponents(string: value),
            parts.scheme?.lowercased() == "https",
            let host = parts.host, !host.isEmpty,
            parts.user == nil, parts.password == nil,
            parts.query == nil, parts.fragment == nil,
            parts.percentEncodedPath.isEmpty || parts.percentEncodedPath == "/",
            parts.port == nil || (1...65535).contains(parts.port!)
        else {
            throw ConnectionError.invalidAddress
        }
        parts.scheme = "https"
        parts.host = host.lowercased()
        parts.path = ""
        if parts.port == 443 { parts.port = nil }
        guard let url = parts.url else { throw ConnectionError.invalidAddress }
        self.url = url
    }

    func owns(_ candidate: URL) -> Bool {
        guard let parts = URLComponents(url: candidate, resolvingAgainstBaseURL: false),
            let own = URLComponents(url: url, resolvingAgainstBaseURL: false)
        else { return false }
        return parts.scheme?.lowercased() == "https" && parts.user == nil && parts.password == nil
            && parts.host?.lowercased() == own.host?.lowercased()
            && (parts.port ?? 443) == (own.port ?? 443)
    }

    func ownsDownload(_ candidate: URL) -> Bool {
        if owns(candidate) { return true }
        guard candidate.scheme == "blob",
            let inner = URL(string: String(candidate.absoluteString.dropFirst(5)))
        else { return false }
        return owns(inner)
    }
}

enum ConnectionError: LocalizedError {
    case invalidAddress, incompatible, unavailable
    var errorDescription: String? {
        switch self {
        case .invalidAddress:
            return "Use a root HTTPS URL with a valid host and port. Remove credentials, subpaths, query and fragment."
        case .incompatible:
            return "This server does not expose compatible Yuvomi metadata."
        case .unavailable:
            return "Cannot verify the server. Check its certificate, VPN, network and reverse proxy."
        }
    }
}