ppsspp/Common/Net/HTTPRequest.h

#pragma once

#include <string>
#include <functional>
#include <memory>

#include "Common/File/Path.h"
#include "Common/Net/NetBuffer.h"

namespace http {

enum class RequestMethod {
	GET,
	POST,
};

enum class RequestFlags {
	Default = 0,
	ProgressBar = 1,
	ProgressBarDelayed = 2,
	Cached24H = 4,
	KeepInMemory = 8,
};
ENUM_CLASS_BITOPS(RequestFlags);

class Request;

// Note that these are executed both on success and failure, so need to handle both by inspecting the Request.
using RequestCompletionCallback = std::function<void(Request &)>;

// Abstract request.
class Request {
public:
	Request(RequestMethod method, std::string_view url, std::string_view name, const Path &outFile, RequestFlags mode);
	virtual ~Request() {}

	void SetAccept(const char *mime) {
		acceptMime_ = mime;
	}

	void SetUserAgent(std::string_view userAgent) {
		userAgent_ = userAgent;
	}

	// NOTE: Completion callbacks (which these are) are deferred until RunCallback is called. This is so that
	// the call will end up on the thread that calls g_DownloadManager.Update().
	void SetCallback(RequestCompletionCallback callback) {
		callback_ = callback;
	}
	void RunCallback() {
		if (callback_) {
			callback_(*this);
		}
		hasRunCallback_ = true;
	}

	virtual void Start() = 0;
	virtual void Join() = 0;

	virtual bool Done() = 0;
	virtual bool Failed() const = 0;

	virtual bool HasRunCallback() { return Done() && hasRunCallback_; }

	std::string url() const { return url_; }

	const Path &OutFile() const { return outfile_; }
	void OverrideOutFile(const Path &path) {
		outfile_ = path;
	}
	void AddFlag(RequestFlags flag) {
		flags_ |= flag;
	}

	// Virtual so a backend can act on it. The HTTPS one has to tell naett, which is what actually
	// stops a transfer in progress - see HTTPSRequest::Cancel.
	virtual void Cancel() { cancel_.Cancel(); }
	bool IsCancelled() const { return cancel_.IsCancelled(); }

	// If not downloading to a file, access this to get the result.
	Buffer &buffer() { return buffer_; }
	const Buffer &buffer() const { return buffer_; }

	// NOTE! The value of ResultCode is INVALID until Done() returns true.
	int ResultCode() const { return resultCode_; }

protected:
	RequestMethod method_;
	std::string url_;
	std::string name_;
	const char *acceptMime_ = "*/*";
	std::string userAgent_;
	Path outfile_;
	Buffer buffer_;
	// Cancel() also wakes this request's socket waits.
	net::CancelToken cancel_;
	int resultCode_ = 0;
	bool hasRunCallback_ = false;
	std::vector<std::string> responseHeaders_;

	net::RequestProgress progress_;
	RequestFlags flags_;

private:
	RequestCompletionCallback callback_;
};

class RequestManager {
public:
	~RequestManager() {
		CancelAll();
	}

	// NOTE: This is the only version that supports the cache flag (for now).
	std::shared_ptr<Request> StartDownload(std::string_view url, const Path &outfile, RequestFlags flags, const char *acceptMime = nullptr, std::string_view name = "", RequestCompletionCallback completionCallback = {});

	std::shared_ptr<Request> AsyncPostWithCallback(
		std::string_view url,
		std::string_view postData,
		std::string_view postMime, // Use postMime = "application/x-www-form-urlencoded" for standard form-style posts, such as used by retroachievements. For encoding form data manually we have MultipartFormDataEncoder.
		RequestFlags flags,
		RequestCompletionCallback completionCallback,
		std::string_view name = "");

	// Drops finished downloads from the list.
	void Update();
	void CancelAll();

	void SetUserAgent(std::string_view userAgent) {
		userAgent_ = userAgent;
	}

	void SetCacheDir(const Path &path) {
		cacheDir_ = path;
	}

	// Just computes the path, doesn't check availability.
	Path UrlToCachePath(const std::string_view url) const;

	// Does the file read. Returns false if file missing or other error.
	bool ReadFileFromCache(std::string_view url, std::string *data);

private:
	std::vector<std::shared_ptr<Request>> downloads_;
	// These get copied to downloads_ in Update(). It's so that callbacks can add new downloads
	// while running.
	std::vector<std::shared_ptr<Request>> newDownloads_;

	std::string userAgent_;
	Path cacheDir_;
};

inline const char *RequestMethodToString(RequestMethod method) {
	switch (method) {
	case RequestMethod::GET: return "GET";
	case RequestMethod::POST: return "POST";
	default: return "N/A";
	}
}

}  // namespace net