import Foundation
import UniformTypeIdentifiers

public struct FileUploadResult: Codable, Sendable {
    public let url: String
    public let thumbnailUrl: String?
    public let hash: String
    public let size: Int64
    public let originalName: String?
    public let mimeType: String?
    public let ext: String?
}

public final class FileSDK: @unchecked Sendable {
    public static let shared = FileSDK()
    private init() {}

    public func upload(fileURL: URL, thumbnailData: Data? = nil) async throws -> FileUploadResult {
        let config = await XuqmSDK.shared.requireConfig()
        let tokenStore = await XuqmSDK.shared.tokenStore
        let boundary = "Boundary-\(UUID().uuidString)"

        let url = SDKEndpoints.apiBaseURL.appendingPathComponent("api/file/upload")
        var request = URLRequest(url: url)
        request.httpMethod = "POST"
        request.setValue("multipart/form-data; boundary=\(boundary)", forHTTPHeaderField: "Content-Type")
        if let token = tokenStore?.get() {
            request.setValue("Bearer \(token)", forHTTPHeaderField: "Authorization")
        }

        let body = try createMultipartBody(fileURL: fileURL, boundary: boundary, thumbnailData: thumbnailData)
        let (data, response) = try await URLSession.shared.upload(for: request, from: body)
        guard let http = response as? HTTPURLResponse, (200..<300).contains(http.statusCode) else {
            throw URLError(.badServerResponse)
        }
        let wrapper = try JSONDecoder().decode(ApiResponse<FileUploadResult>.self, from: data)
        guard let result = wrapper.data else {
            throw URLError(.cannotDecodeContentData)
        }
        return result
    }

    private func createMultipartBody(fileURL: URL, boundary: String, thumbnailData: Data?) throws -> Data {
        var body = Data()
        let filename = fileURL.lastPathComponent

        let mimeType: String
        if #available(iOS 14.0, macOS 11.0, *) {
            if let uti = UTType(filenameExtension: (fileURL.path as NSString).pathExtension),
               let preferred = uti.preferredMIMEType {
                mimeType = preferred
            } else {
                mimeType = "application/octet-stream"
            }
        } else {
            mimeType = "application/octet-stream"
        }

        body.append("--\(boundary)\r\n")
        body.append("Content-Disposition: form-data; name=\"file\"; filename=\"\(filename)\"\r\n")
        body.append("Content-Type: \(mimeType)\r\n\r\n")
        body.append(try Data(contentsOf: fileURL))
        body.append("\r\n")

        if let thumbnailData {
            let thumbFilename = "\((filename as NSString).deletingPathExtension)_thumb.jpg"
            body.append("--\(boundary)\r\n")
            body.append("Content-Disposition: form-data; name=\"thumbnail\"; filename=\"\(thumbFilename)\"\r\n")
            body.append("Content-Type: image/jpeg\r\n\r\n")
            body.append(thumbnailData)
            body.append("\r\n")
        }

        body.append("--\(boundary)--\r\n")
        return body
    }
}

private extension Data {
    mutating func append(_ string: String) {
        if let data = string.data(using: .utf8) {
            append(data)
        }
    }
}