import Foundation

enum URLNormalizer {
    static func normalizeBaseURL(_ input: String, fieldName: String = "URL") throws -> String {
        let trimmed = input.trimmingCharacters(in: .whitespacesAndNewlines)
        guard !trimmed.isEmpty else {
            throw PostingError(message: "\(fieldName) cannot be empty.")
        }

        let prefixed = if trimmed.hasPrefix("http://") || trimmed.hasPrefix("https://") {
            trimmed
        } else {
            "https://\(trimmed)"
        }

        guard var components = URLComponents(string: prefixed),
              let scheme = components.scheme?.lowercased(),
              (scheme == "https" || scheme == "http"),
              components.host != nil
        else {
            throw PostingError(message: "Invalid \(fieldName). Please provide a full domain, e.g. example.com.")
        }

        components.path = ""
        components.query = nil
        components.fragment = nil

        guard let normalized = components.url?.absoluteString else {
            throw PostingError(message: "Invalid \(fieldName).")
        }

        return normalized.trimmingCharacters(in: CharacterSet(charactersIn: "/"))
    }

    static func endpointURL(baseURL: String, path: String, fieldName: String = "URL") throws -> URL {
        let normalizedBase = try normalizeBaseURL(baseURL, fieldName: fieldName)
        guard let url = URL(string: normalizedBase + path) else {
            throw PostingError(message: "Failed to build API URL from \(fieldName).")
        }
        return url
    }

    static func endpointURL(base normalizedBase: String, path: String) throws -> URL {
        guard let url = URL(string: normalizedBase + path) else {
            throw PostingError(message: "Failed to build API URL.")
        }
        return url
    }
}