//  SPDX-License-Identifier: MIT
//
//  EmulationStation Desktop Edition
//  HttpReq.cpp
//
//  HTTP request functions.
//  Used by Scraper, GamesDBJSONScraper, GamesDBJSONScraperResources and
//  ScreenScraper to download game information and media files.
//

#include "HttpReq.h"

#include "resources/ResourceManager.h"
#include "utils/FileSystemUtil.h"
#include "Log.h"

#include <assert.h>

CURLM* HttpReq::s_multi_handle;
std::map<CURL*, HttpReq*> HttpReq::s_requests;

std::string HttpReq::urlEncode(const std::string &s)
{
    const std::string unreserved =
            "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.~";

    std::string escaped="";
    for (size_t i = 0; i < s.length(); i++) {
        if (unreserved.find_first_of(s[i]) != std::string::npos) {
            escaped.push_back(s[i]);
        }
        else {
            escaped.append("%");
            char buf[3];
            sprintf(buf, "%.2X", (unsigned char)s[i]);
            escaped.append(buf);
        }
    }
    return escaped;
}

bool HttpReq::isUrl(const std::string& str)
{
    // The worst guess.
    return (!str.empty() && !Utils::FileSystem::exists(str) &&
        (str.find("http://") != std::string::npos || str.find("https://") !=
                std::string::npos || str.find("www.") != std::string::npos));
}

HttpReq::HttpReq(const std::string& url) : mStatus(REQ_IN_PROGRESS), mHandle(nullptr)
{
    // The multi-handle is cleaned up via a call from GuiScraperSearch after the scraping
    // has been completed for a game, meaning the handle is valid for all cURL requests
    // performed for the current game.
    if (!s_multi_handle)
        s_multi_handle = curl_multi_init();

    mHandle = curl_easy_init();

    // On Windows, use the bundled cURL TLS/SSL certificates (which actually come from the
    // Mozilla project). There is a possibility to use the OS provided Schannel certificates
    // but I haven't been able to get this to work and it also seems to be problematic on
    // older Windows versions.
    #if defined(_WIN64)
    curl_easy_setopt(mHandle, CURLOPT_CAINFO, ResourceManager::getInstance()->
            getResourcePath(":/certificates/curl-ca-bundle.crt").c_str());
    #endif

    if (mHandle == nullptr) {
        mStatus = REQ_IO_ERROR;
        onError("curl_easy_init failed");
        return;
    }

    // Set the url.
    CURLcode err = curl_easy_setopt(mHandle, CURLOPT_URL, url.c_str());
    if (err != CURLE_OK) {
        mStatus = REQ_IO_ERROR;
        onError(curl_easy_strerror(err));
        return;
    }

    // Set curl to handle redirects.
    err = curl_easy_setopt(mHandle, CURLOPT_FOLLOWLOCATION, 1L);
    if (err != CURLE_OK) {
        mStatus = REQ_IO_ERROR;
        onError(curl_easy_strerror(err));
        return;
    }

    // Set curl max redirects.
    err = curl_easy_setopt(mHandle, CURLOPT_MAXREDIRS, 2L);
    if (err != CURLE_OK) {
        mStatus = REQ_IO_ERROR;
        onError(curl_easy_strerror(err));
        return;
    }

    // Set curl restrict redirect protocols.
    err = curl_easy_setopt(mHandle, CURLOPT_REDIR_PROTOCOLS, CURLPROTO_HTTP | CURLPROTO_HTTPS);
    if (err != CURLE_OK) {
        mStatus = REQ_IO_ERROR;
        onError(curl_easy_strerror(err));
        return;
    }

    // Tell curl how to write the data.
    err = curl_easy_setopt(mHandle, CURLOPT_WRITEFUNCTION, &HttpReq::write_content);
    if (err != CURLE_OK) {
        mStatus = REQ_IO_ERROR;
        onError(curl_easy_strerror(err));
        return;
    }

    // Give curl a pointer to this HttpReq so we know where to write the
    // data *to* in our write function.
    err = curl_easy_setopt(mHandle, CURLOPT_WRITEDATA, this);
    if (err != CURLE_OK) {
        mStatus = REQ_IO_ERROR;
        onError(curl_easy_strerror(err));
        return;
    }

    // Add the handle to our multi.
    CURLMcode merr = curl_multi_add_handle(s_multi_handle, mHandle);
    if (merr != CURLM_OK) {
        mStatus = REQ_IO_ERROR;
        onError(curl_multi_strerror(merr));
        return;
    }

    s_requests[mHandle] = this;
}

HttpReq::~HttpReq()
{
    if (mHandle) {
        s_requests.erase(mHandle);

        CURLMcode merr = curl_multi_remove_handle(s_multi_handle, mHandle);

        if (merr != CURLM_OK) {
            LOG(LogError) << "Error removing curl_easy handle from curl_multi: " <<
                    curl_multi_strerror(merr);
        }

        curl_easy_cleanup(mHandle);
    }
}

HttpReq::Status HttpReq::status()
{
    if (mStatus == REQ_IN_PROGRESS) {
        int handle_count;
        CURLMcode merr = curl_multi_perform(s_multi_handle, &handle_count);
        if (merr != CURLM_OK && merr != CURLM_CALL_MULTI_PERFORM) {
            mStatus = REQ_IO_ERROR;
            onError(curl_multi_strerror(merr));
            return mStatus;
        }

        int msgs_left;
        CURLMsg* msg;
        while ((msg = curl_multi_info_read(s_multi_handle, &msgs_left)) != nullptr) {
            if (msg->msg == CURLMSG_DONE) {
                HttpReq* req = s_requests[msg->easy_handle];

                if (req == nullptr) {
                    LOG(LogError) << "Cannot find easy handle!";
                    continue;
                }

                if (msg->data.result == CURLE_OK) {
                    req->mStatus = REQ_SUCCESS;
                }
                else {
                    req->mStatus = REQ_IO_ERROR;
                    req->onError(curl_easy_strerror(msg->data.result));
                }
            }
        }
    }

    return mStatus;
}

std::string HttpReq::getContent() const
{
    assert(mStatus == REQ_SUCCESS);
    return mContent.str();
}

void HttpReq::onError(const char* msg)
{
    mErrorMsg = msg;
}

std::string HttpReq::getErrorMsg()
{
    return mErrorMsg;
}

// Used as a curl callback.
// size = size of an element, nmemb = number of elements.
// Return value is number of elements successfully read.
size_t HttpReq::write_content(void* buff, size_t size, size_t nmemb, void* req_ptr)
{
    std::stringstream& ss = (static_cast<HttpReq*>(req_ptr))->mContent;
    ss.write(static_cast<char*>(buff), size * nmemb);

    return nmemb;
}