import Foundation

struct WordPressClient: PostingService {
    let account: Account
    private let token: String
    private let baseURL: String

    init(account: Account, token: String) {
        self.account = account
        self.token = token // format: "username:application_password"
        self.baseURL = account.instanceURL.trimmingCharacters(in: CharacterSet(charactersIn: "/"))
    }

    private var authHeader: String {
        "Basic \(Data(token.utf8).base64EncodedString())"
    }

    func uploadMedia(imageData: Data, filename: String, altText: String?) async throws -> String {
        let url = URL(string: "\(baseURL)/wp-json/wp/v2/media")!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue(authHeader, forHTTPHeaderField: "Authorization")
        request.setValue(mimeTypeFor(filename), forHTTPHeaderField: "Content-Type")
        request.setValue("attachment; filename=\"\(filename)\"", forHTTPHeaderField: "Content-Disposition")
        request.httpBody = imageData

        let (data, response) = try await URLSession.shared.data(for: request)
        let statusCode = (response as? HTTPURLResponse)?.statusCode ?? 0

        guard (200...201).contains(statusCode) else {
            let body = String(data: data, encoding: .utf8) ?? "Unknown error"
            throw PostingError(message: "WordPress media upload failed (\(statusCode)): \(body)")
        }

        guard let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              let mediaID = json["id"] as? Int
        else {
            throw PostingError(message: "Invalid response from WordPress media upload")
        }

        // Update alt text if provided
        if let altText, !altText.isEmpty {
            try await updateMediaAltText(mediaID: mediaID, altText: altText)
        }

        guard let sourceURL = json["source_url"] as? String else {
            throw PostingError(message: "No source_url in WordPress media response")
        }

        return sourceURL
    }

    private func updateMediaAltText(mediaID: Int, altText: String) async throws {
        let url = URL(string: "\(baseURL)/wp-json/wp/v2/media/\(mediaID)")!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue(authHeader, forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
        request.httpBody = try JSONSerialization.data(withJSONObject: ["alt_text": altText])

        let (_, response) = try await URLSession.shared.data(for: request)
        let statusCode = (response as? HTTPURLResponse)?.statusCode ?? 0
        guard statusCode == 200 else {
            throw PostingError(message: "Failed to update alt text (\(statusCode))")
        }
    }

    func createPost(text: String, mediaIDs: [String]) async throws -> URL {
        // mediaIDs are source_url strings for WordPress
        let url = URL(string: "\(baseURL)/wp-json/wp/v2/posts")!
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue(authHeader, forHTTPHeaderField: "Authorization")
        request.setValue("application/json", forHTTPHeaderField: "Content-Type")

        var content = text
        // Append images as HTML
        for imageURL in mediaIDs {
            content += "\n<img src=\"\(imageURL)\" />"
        }

        let body: [String: Any] = [
            "content": content,
            "status": "publish",
            "format": "status",
        ]

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

        let (data, response) = try await URLSession.shared.data(for: request)
        let statusCode = (response as? HTTPURLResponse)?.statusCode ?? 0

        guard (200...201).contains(statusCode) else {
            let errorBody = String(data: data, encoding: .utf8) ?? "Unknown error"
            throw PostingError(message: "WordPress post failed (\(statusCode)): \(errorBody)")
        }

        guard let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              let link = json["link"] as? String,
              let postURL = URL(string: link)
        else {
            throw PostingError(message: "Invalid response from WordPress")
        }

        return postURL
    }

    // MARK: - Auth Discovery

    static func discoverAuthEndpoint(siteURL: String) async throws -> String {
        let base = siteURL.trimmingCharacters(in: CharacterSet(charactersIn: "/"))
        let url = URL(string: "\(base)/wp-json/")!
        var request = URLRequest(url: url)
        request.httpMethod = "GET"

        let (data, response) = try await URLSession.shared.data(for: request)
        let statusCode = (response as? HTTPURLResponse)?.statusCode ?? 0

        guard statusCode == 200 else {
            throw PostingError(message: "Cannot reach WordPress API at \(siteURL)")
        }

        guard let json = try? JSONSerialization.jsonObject(with: data) as? [String: Any],
              let auth = json["authentication"] as? [String: Any],
              let appPasswords = auth["application-passwords"] as? [String: Any],
              let endpoints = appPasswords["endpoints"] as? [String: Any],
              let authURL = endpoints["authorization"] as? String
        else {
            throw PostingError(message: "Application Passwords not available on this site. Ensure WordPress 5.6+.")
        }

        return authURL
    }

    static func buildAuthURL(authEndpoint: String) -> URL {
        var components = URLComponents(string: authEndpoint)!
        components.queryItems = [
            URLQueryItem(name: "app_name", value: "qStatus"),
            URLQueryItem(name: "app_id", value: "a1b2c3d4-e5f6-7890-abcd-ef1234567890"),
            URLQueryItem(name: "success_url", value: "qstatus://wordpress-callback"),
            URLQueryItem(name: "reject_url", value: "qstatus://wordpress-rejected"),
        ]
        return components.url!
    }

    static func verifyCredentials(siteURL: String, username: String, password: String) async throws -> Bool {
        let base = siteURL.trimmingCharacters(in: CharacterSet(charactersIn: "/"))
        guard let url = URL(string: "\(base)/wp-json/wp/v2/users/me") else {
            throw PostingError(message: "Invalid site URL: \(siteURL)")
        }
        var request = URLRequest(url: url)
        let creds = "\(username):\(password)"
        request.setValue("Basic \(Data(creds.utf8).base64EncodedString())", forHTTPHeaderField: "Authorization")

        let (data, response): (Data, URLResponse)
        do {
            (data, response) = try await URLSession.shared.data(for: request)
        } catch {
            throw PostingError(message: "Cannot connect to \(siteURL). Check the URL and try again.")
        }

        let statusCode = (response as? HTTPURLResponse)?.statusCode ?? 0
        switch statusCode {
        case 200:
            return true
        case 401, 403:
            return false
        case 404:
            throw PostingError(message: "WordPress REST API not found at \(siteURL). Check the URL.")
        default:
            let body = String(data: data, encoding: .utf8) ?? ""
            throw PostingError(message: "Unexpected response (\(statusCode)): \(body)")
        }
    }

    private func mimeTypeFor(_ filename: String) -> String {
        let ext = (filename as NSString).pathExtension.lowercased()
        switch ext {
        case "png": return "image/png"
        case "gif": return "image/gif"
        case "webp": return "image/webp"
        default: return "image/jpeg"
        }
    }
}