// Copyright 2012 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_TEST_EMBEDDED_TEST_SERVER_HTTP_REQUEST_H_
#define NET_TEST_EMBEDDED_TEST_SERVER_HTTP_REQUEST_H_

#include <stddef.h>

#include <map>
#include <memory>
#include <optional>
#include <string>
#include <string_view>

#include "base/strings/string_util.h"
#include "net/ssl/ssl_info.h"
#include "url/gurl.h"

namespace net {

class HttpChunkedDecoder;

namespace test_server {

// Methods of HTTP requests supported by the test HTTP server.
enum HttpMethod {
  METHOD_UNKNOWN,
  METHOD_GET,
  METHOD_HEAD,
  METHOD_POST,
  METHOD_PUT,
  METHOD_DELETE,
  METHOD_PATCH,
  METHOD_CONNECT,
  METHOD_OPTIONS,
};

// Represents a HTTP request. Since it can be big, `use std::unique_ptr` to pass
// it instead of copying. However, the struct is copyable so tests can save and
// examine a HTTP request.
struct HttpRequest {
  struct CaseInsensitiveStringComparator {
    // Allow using StringPiece instead of string for `find()`.
    using is_transparent = void;

    bool operator()(std::string_view left, std::string_view right) const {
      return base::CompareCaseInsensitiveASCII(left, right) < 0;
    }
  };

  using HeaderMap =
      std::map<std::string, std::string, CaseInsensitiveStringComparator>;

  HttpRequest();
  HttpRequest(const HttpRequest& other);
  ~HttpRequest();

  // Returns a GURL as a convenience to extract the path and query strings.
  GURL GetURL() const;

  // The request target. For most methods, this will start with '/', e.g.,
  // "/test?query=foo". If `method` is `METHOD_OPTIONS`, it may also be "*". If
  // `method` is `METHOD_CONNECT`, it will instead be a string like
  // "example.com:443".
  std::string relative_url;
  GURL base_url;
  // The HTTP method. If unknown, this will be `METHOD_UNKNOWN` and the actual
  // method will be in `method_string`.
  HttpMethod method = METHOD_UNKNOWN;
  std::string method_string;
  std::string all_headers;
  HeaderMap headers;
  std::string content;
  bool has_content = false;
  std::optional<SSLInfo> ssl_info;
};

// Parses the input data and produces a valid HttpRequest object. If there is
// more than one request in one chunk, then only the first one will be parsed.
// The common use is as below:
// HttpRequestParser parser;
// (...)
// void OnDataChunkReceived(Socket* socket, const char* data, int size) {
//   parser.ProcessChunk(std::string(data, size));
//   if (parser.ParseRequest() == HttpRequestParser::ACCEPTED) {
//     std::unique_ptr<HttpRequest> request = parser.GetRequest();
//     (... process the request ...)
//   }
class HttpRequestParser {
 public:
  // Parsing result.
  enum ParseResult {
    WAITING,  // A request is not completed yet, waiting for more data.
    ACCEPTED,  // A request has been parsed and it is ready to be processed.
  };

  // Parser state.
  enum State {
    STATE_HEADERS,  // Waiting for a request headers.
    STATE_CONTENT,  // Waiting for content data.
    STATE_ACCEPTED,  // Request has been parsed.
  };

  HttpRequestParser();

  HttpRequestParser(const HttpRequestParser&) = delete;
  HttpRequestParser& operator=(const HttpRequestParser&) = delete;

  ~HttpRequestParser();

  // Adds chunk of data into the internal buffer.
  void ProcessChunk(std::string_view data);

  // Parses the http request (including data - if provided).
  // If returns ACCEPTED, then it means that the whole request has been found
  // in the internal buffer (and parsed). After calling GetRequest(), it will be
  // ready to parse another request.
  ParseResult ParseRequest();

  // Retrieves parsed request. Can be only called, when the parser is in
  // STATE_ACCEPTED state. After calling it, the parser is ready to parse
  // another request.
  std::unique_ptr<HttpRequest> GetRequest();

  // Returns `METHOD_UNKNOWN` if `token` is not a recognized method. Methods are
  // case-sensitive.
  static HttpMethod GetMethodType(std::string_view token);

 private:
  // Parses headers and returns ACCEPTED if whole request was parsed. Otherwise
  // returns WAITING.
  ParseResult ParseHeaders();

  // Parses request's content data and returns ACCEPTED if all of it have been
  // processed. Chunked Transfer Encoding is supported.
  ParseResult ParseContent();

  // Fetches the next line from the buffer. Result does not contain \r\n.
  // Returns an empty string for an empty line. It will assert if there is
  // no line available.
  std::string ShiftLine();

  std::unique_ptr<HttpRequest> http_request_;
  std::string buffer_;
  size_t buffer_position_ = 0;  // Current position in the internal buffer.
  State state_ = STATE_HEADERS;
  // Content length of the request currently being parsed.
  size_t declared_content_length_ = 0;

  std::unique_ptr<HttpChunkedDecoder> chunked_decoder_;
};

}  // namespace test_server
}  // namespace net

#endif  // NET_TEST_EMBEDDED_TEST_SERVER_HTTP_REQUEST_H_