/*
 * Copyright 2008-2021 Max Kellermann <max.kellermann@gmail.com>
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * - Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 *
 * - Redistributions in binary form must reproduce the above copyright
 * notice, this list of conditions and the following disclaimer in the
 * documentation and/or other materials provided with the
 * distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE
 * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 */

#include "Adapter.hxx"
#include "Easy.hxx"
#include "Handler.hxx"
#include "util/CharUtil.hxx"
#include "util/RuntimeError.hxx"
#include "util/StringStrip.hxx"
#include "util/StringView.hxx"

#include <algorithm>
#include <cassert>

void
CurlResponseHandlerAdapter::Install(CurlEasy &easy)
{
	assert(state == State::UNINITIALISED);

	error_buffer[0] = 0;
	easy.SetErrorBuffer(error_buffer);

	easy.SetHeaderFunction(_HeaderFunction, this);
	easy.SetWriteFunction(WriteFunction, this);

	curl = easy.Get();

	state = State::HEADERS;
}

void
CurlResponseHandlerAdapter::FinishHeaders()
{
	assert(state >= State::HEADERS);

	if (state != State::HEADERS)
		return;

	state = State::BODY;

	long status = 0;
	curl_easy_getinfo(curl, CURLINFO_RESPONSE_CODE, &status);

	handler.OnHeaders(status, std::move(headers));
}

void
CurlResponseHandlerAdapter::FinishBody()
{
	FinishHeaders();

	if (state != State::BODY)
		return;

	state = State::CLOSED;
	handler.OnEnd();
}

void
CurlResponseHandlerAdapter::Done(CURLcode result) noexcept
{
	if (postponed_error) {
		state = State::CLOSED;
		handler.OnError(std::move(postponed_error));
		return;
	}

	try {
		if (result != CURLE_OK) {
			StripRight(error_buffer);
			const char *msg = error_buffer;
			if (*msg == 0)
				msg = curl_easy_strerror(result);
			throw FormatRuntimeError("CURL failed: %s", msg);
		}

		FinishBody();
	} catch (...) {
		state = State::CLOSED;
		handler.OnError(std::current_exception());
	}
}

[[gnu::pure]]
static bool
IsResponseBoundaryHeader(StringView s) noexcept
{
	return s.size > 5 && (s.StartsWith("HTTP/") ||
			      /* the proprietary "ICY 200 OK" is
				 emitted by Shoutcast */
			      s.StartsWith("ICY 2"));
}

inline void
CurlResponseHandlerAdapter::HeaderFunction(StringView s) noexcept
{
	if (state > State::HEADERS)
		return;

	if (IsResponseBoundaryHeader(s)) {
		/* this is the boundary to a new response, for example
		   after a redirect */
		headers.clear();
		return;
	}

	const char *header = s.data;
	const char *end = StripRight(header, header + s.size);

	const char *value = s.Find(':');
	if (value == nullptr)
		return;

	std::string name(header, value);
	std::transform(name.begin(), name.end(), name.begin(),
		       static_cast<char(*)(char)>(ToLowerASCII));

	/* skip the colon */

	++value;

	/* strip the value */

	value = StripLeft(value, end);
	end = StripRight(value, end);

	headers.emplace(std::move(name), std::string(value, end));
}

std::size_t
CurlResponseHandlerAdapter::_HeaderFunction(char *ptr, std::size_t size,
					    std::size_t nmemb,
					    void *stream) noexcept
{
	CurlResponseHandlerAdapter &c = *(CurlResponseHandlerAdapter *)stream;

	size *= nmemb;

	c.HeaderFunction({ptr, size});
	return size;
}

inline std::size_t
CurlResponseHandlerAdapter::DataReceived(const void *ptr,
					 std::size_t received_size) noexcept
{
	assert(received_size > 0);

	try {
		FinishHeaders();
		handler.OnData({ptr, received_size});
		return received_size;
	} catch (CurlResponseHandler::Pause) {
		return CURL_WRITEFUNC_PAUSE;
	} catch (...) {
		/* from inside this libCURL callback function, we
		   can't do much, so we remember the exception to be
		   handled later by Done(), and return 0, causing the
		   response to be aborted with CURLE_WRITE_ERROR */
		postponed_error = std::current_exception();
		return 0;
	}

}

std::size_t
CurlResponseHandlerAdapter::WriteFunction(char *ptr, std::size_t size,
					  std::size_t nmemb,
					  void *stream) noexcept
{
	CurlResponseHandlerAdapter &c = *(CurlResponseHandlerAdapter *)stream;

	size *= nmemb;
	if (size == 0)
		return 0;

	return c.DataReceived(ptr, size);
}