import Foundation

struct AniConverterError: LocalizedError {
    let message: String
    var errorDescription: String? { message }
}

/// 将源视频/图片转换为设备可用的 ANI 文件。
final class AniConverter {
    private let config: DuooomiBleConfig

    private var endpoint: URL {
        config.apiHost.appendingPathComponent("api/auth/loomart/file/convert-to-ani")
    }

    private let session: URLSession = {
        let cfg = URLSessionConfiguration.default
        cfg.timeoutIntervalForRequest = 120
        cfg.timeoutIntervalForResource = 180
        cfg.waitsForConnectivity = true
        return URLSession(configuration: cfg)
    }()

    init(config: DuooomiBleConfig) {
        self.config = config
    }

    /// 调用 ANI 转换接口，返回 ani 文件的 CDN URL。
    func convert(fileUrl: String) async throws -> String {
        do {
            return try await performConvert(fileUrl: fileUrl)
        } catch let error as NSError where error.code == NSURLErrorNetworkConnectionLost {
            return try await performConvert(fileUrl: fileUrl)
        }
    }

    private func performConvert(fileUrl: String) async throws -> String {
        var request = URLRequest(url: endpoint)
        request.httpMethod = "POST"
        request.setValue("application/json", forHTTPHeaderField: "content-type")
        request.setValue(config.apiKey, forHTTPHeaderField: "x-api-key")
        request.timeoutInterval = 120

        let body: [String: Any] = [
            "videoUrl": fileUrl,
            "width": 360,
            "height": 360,
            "fps": "24",
        ]
        request.httpBody = try JSONSerialization.data(withJSONObject: body)

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

        if let http = response as? HTTPURLResponse, !(200..<300).contains(http.statusCode) {
            throw AniConverterError(message: "HTTP \(http.statusCode)")
        }

        guard let json = try JSONSerialization.jsonObject(with: data) as? [String: Any] else {
            throw AniConverterError(message: "Invalid JSON response")
        }

        guard (json["success"] as? Bool) == true,
              let outer = json["data"] as? [String: Any] else {
            throw AniConverterError(message: "ANI API reported failure")
        }

        if (outer["status"] as? Bool) != true {
            let msg = (outer["msg"] as? String) ?? "ANI conversion failed"
            throw AniConverterError(message: msg)
        }

        guard let aniUrl = outer["data"] as? String, !aniUrl.isEmpty else {
            throw AniConverterError(message: "Missing ani url in response")
        }

        return aniUrl
    }
}