import Foundation

enum StickerClonerAPIError: LocalizedError {
	case invalidResponse(Int)
	case decodingFailed(Error)

	var errorDescription: String? {
		switch self {
		case .invalidResponse(let code):
			return "Server returned status \(code)"
		case .decodingFailed(let error):
			return "Failed to decode response: \(error.localizedDescription)"
		}
	}
}

enum StickerClonerAPI {
	private static let baseURL = URL(string: "https://serve.uber.space/sticker-cloner")!

	private static let decoder: JSONDecoder = {
		let d = JSONDecoder()
		d.keyDecodingStrategy = .convertFromSnakeCase
		return d
	}()

	static func fetchStickerSet(name: String) async throws -> StickerSetResponse {
		let url = baseURL.appendingPathComponent("api/stickersets/\(name)")
		let (data, response) = try await URLSession.shared.data(from: url)

		guard let http = response as? HTTPURLResponse, 200..<300 ~= http.statusCode else {
			let code = (response as? HTTPURLResponse)?.statusCode ?? -1
			throw StickerClonerAPIError.invalidResponse(code)
		}

		do {
			return try decoder.decode(StickerSetResponse.self, from: data)
		} catch {
			throw StickerClonerAPIError.decodingFailed(error)
		}
	}

	static func downloadSticker(from relativePath: String, to localURL: URL) async throws {
		let url = baseURL.appendingPathComponent(relativePath)
		let (tempURL, response) = try await URLSession.shared.download(from: url)

		guard let http = response as? HTTPURLResponse, 200..<300 ~= http.statusCode else {
			let code = (response as? HTTPURLResponse)?.statusCode ?? -1
			throw StickerClonerAPIError.invalidResponse(code)
		}

		let directory = localURL.deletingLastPathComponent()
		try FileManager.default.createDirectory(at: directory, withIntermediateDirectories: true)

		if FileManager.default.fileExists(atPath: localURL.path) {
			try FileManager.default.removeItem(at: localURL)
		}
		try FileManager.default.moveItem(at: tempURL, to: localURL)
	}
}