// DragonX Wallet - ImGui Edition
// Copyright 2024-2026 The Hush Developers
// Released under the GPLv3

#include "http_download.h"

#include "logger.h"

#include <curl/curl.h>

#include <cstdint>
#include <cstdio>
#include <filesystem>
#include <fstream>
#include <system_error>
#include <utility>

namespace fs = std::filesystem;

namespace dragonx {
namespace util {

namespace {

// Cap for in-memory text/JSON responses (release metadata, price/candle data). Far above any
// legitimate body, but bounds memory if a hostile/MITM'd server streams an unbounded response.

struct StringSink {
    std::string* body;
    long long    cap;
};

size_t writeStringCb(void* contents, size_t size, size_t nmemb, void* userp)
{
    auto* sink = static_cast<StringSink*>(userp);
    const size_t n = size * nmemb;
    // Hard cap: a chunked response omits Content-Length, so CURLOPT_MAXFILESIZE cannot catch it —
    // aborting here (short count) makes curl fail the transfer instead of exhausting memory.
    if (httpSinkAccept(sink->body->size(), n, sink->cap) != n) return 0;
    sink->body->append(static_cast<char*>(contents), n);
    return n;
}

size_t writeFileCb(void* contents, size_t size, size_t nmemb, void* userp)
{
    return std::fwrite(contents, size, nmemb, static_cast<FILE*>(userp));
}

// Bridge libcurl's C progress callback to the caller's std::function: publish live byte counts
// and abort the transfer (return non-zero) when the callback returns false (cancellation).
int xferCb(void* clientp, curl_off_t dltotal, curl_off_t dlnow, curl_off_t, curl_off_t)
{
    auto* fn = static_cast<const std::function<bool(double, double)>*>(clientp);
    return (*fn)(static_cast<double>(dlnow), static_cast<double>(dltotal)) ? 0 : 1;
}

// httpGet's progress callback: abort the transfer (non-zero) once the caller's cancel flag is set.
int cancelXferCb(void* clientp, curl_off_t, curl_off_t, curl_off_t, curl_off_t)
{
    return static_cast<const std::atomic<bool>*>(clientp)->load(std::memory_order_relaxed) ? 1 : 0;
}

} // namespace

HttpGetResult httpGet(const std::string& url, const char* logTag, const HttpGetOptions& opt)
{
    HttpGetResult out;
    if (opt.cancel && opt.cancel->load(std::memory_order_relaxed)) {
        out.cancelled = true;
        out.error = "cancelled";
        return out;
    }
    CURL* curl = curl_easy_init();
    if (!curl) { out.error = "failed to initialize curl"; return out; }
    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeStringCb);
    StringSink sink{&out.body, opt.maxBytes};
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, &sink);
    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
    curl_easy_setopt(curl, CURLOPT_MAXREDIRS, opt.maxRedirects);
    curl_easy_setopt(curl, CURLOPT_USERAGENT, "ObsidianDragon/1.0");
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, opt.timeoutSec);
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, opt.connectTimeoutSec);
    curl_easy_setopt(curl, CURLOPT_NOSIGNAL, 1L);   // no SIGALRM for timeouts: these run on worker threads
    curl_easy_setopt(curl, CURLOPT_MAXFILESIZE_LARGE, static_cast<curl_off_t>(opt.maxBytes));  // reject oversized metadata
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 1L);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 2L);
    if (opt.cancel) {
        curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0L);
        curl_easy_setopt(curl, CURLOPT_XFERINFOFUNCTION, cancelXferCb);
        curl_easy_setopt(curl, CURLOPT_XFERINFODATA, const_cast<std::atomic<bool>*>(opt.cancel));
    }
    const CURLcode res = curl_easy_perform(curl);
    curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &out.httpStatus);
    curl_easy_cleanup(curl);
    out.transportOk = (res == CURLE_OK);
    out.cancelled   = (res == CURLE_ABORTED_BY_CALLBACK);
    if (!out.transportOk) out.error = out.cancelled ? "cancelled" : curl_easy_strerror(res);
    if (!out.cancelled && (!out.transportOk || out.httpStatus < 200 || out.httpStatus >= 300)) {
        DEBUG_LOGF("%s GET %s failed: %s (HTTP %ld)\n",
                   logTag, url.c_str(), curl_easy_strerror(res), out.httpStatus);
    }
    return out;
}

std::string httpGetString(const std::string& url, const char* logTag, const HttpGetOptions& opt)
{
    HttpGetResult r = httpGet(url, logTag, opt);
    if (!r.transportOk || r.httpStatus < 200 || r.httpStatus >= 300) return {};
    return std::move(r.body);
}

std::string httpGetString(const std::string& url, const char* logTag,
                          long connectTimeoutSec, long timeoutSec)
{
    HttpGetOptions opt;
    opt.connectTimeoutSec = connectTimeoutSec;
    opt.timeoutSec        = timeoutSec;
    return httpGetString(url, logTag, opt);
}

bool httpDownloadToFile(const std::string& url, const std::string& destPath,
                        const char* logTag, long long maxBytes,
                        const std::function<bool(double, double)>& onProgress)
{
    FILE* fp = std::fopen(destPath.c_str(), "wb");
    if (!fp) return false;
    CURL* curl = curl_easy_init();
    if (!curl) { std::fclose(fp); return false; }
    curl_easy_setopt(curl, CURLOPT_URL, url.c_str());
    curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, writeFileCb);
    curl_easy_setopt(curl, CURLOPT_WRITEDATA, fp);
    curl_easy_setopt(curl, CURLOPT_FOLLOWLOCATION, 1L);
    curl_easy_setopt(curl, CURLOPT_USERAGENT, "ObsidianDragon/1.0");
    curl_easy_setopt(curl, CURLOPT_TIMEOUT, 0L);
    curl_easy_setopt(curl, CURLOPT_CONNECTTIMEOUT, 30L);
    curl_easy_setopt(curl, CURLOPT_LOW_SPEED_LIMIT, 1024L);
    curl_easy_setopt(curl, CURLOPT_LOW_SPEED_TIME, 60L);
    curl_easy_setopt(curl, CURLOPT_MAXFILESIZE_LARGE, static_cast<curl_off_t>(maxBytes));  // refuse oversized bodies
    // Live progress + cancellation: the callback publishes byte counts and aborts on cancel().
    curl_easy_setopt(curl, CURLOPT_NOPROGRESS, 0L);
    curl_easy_setopt(curl, CURLOPT_XFERINFOFUNCTION, xferCb);
    curl_easy_setopt(curl, CURLOPT_XFERINFODATA, &onProgress);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYPEER, 1L);
    curl_easy_setopt(curl, CURLOPT_SSL_VERIFYHOST, 2L);
    const CURLcode res = curl_easy_perform(curl);
    long httpCode = 0;
    curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &httpCode);
    curl_easy_cleanup(curl);
    std::fclose(fp);
    if (res != CURLE_OK || httpCode < 200 || httpCode >= 300) {
        DEBUG_LOGF("%s download %s failed: %s (HTTP %ld)\n",
                   logTag, url.c_str(), curl_easy_strerror(res), httpCode);
        std::error_code ec; fs::remove(destPath, ec);
        return false;
    }
    return true;
}

bool readFileExact(const std::string& path, std::string& out, std::uintmax_t maxBytes)
{
    out.clear();
    std::ifstream f(path, std::ios::binary | std::ios::ate);
    if (!f) return false;
    const std::streamoff size = f.tellg();
    if (size <= 0 || static_cast<std::uintmax_t>(size) > maxBytes) return false;
    f.seekg(0, std::ios::beg);
    out.resize(static_cast<std::size_t>(size));
    if (!f.read(out.data(), size) || f.gcount() != size) { out.clear(); return false; }
    return true;
}

} // namespace util
} // namespace dragonx