cpp-httplib/example/accept_header.cc

#include "httplib.h"
#include <iostream>

int main() {
  using namespace httplib;

  // Example usage of parse_accept_header function
  std::cout << "=== Accept Header Parser Example ===" << std::endl;

  // Example 1: Simple Accept header
  std::string accept1 = "text/html,application/json,text/plain";
  std::vector<std::string> result1;
  if (detail::parse_accept_header(accept1, result1)) {
    std::cout << "\nExample 1: " << accept1 << std::endl;
    std::cout << "Parsed order:" << std::endl;
    for (size_t i = 0; i < result1.size(); ++i) {
      std::cout << "  " << (i + 1) << ". " << result1[i] << std::endl;
    }
  } else {
    std::cout << "\nExample 1: Failed to parse Accept header" << std::endl;
  }

  // Example 2: Accept header with quality values
  std::string accept2 =
      "text/html;q=0.9,application/json;q=1.0,text/plain;q=0.8";
  std::vector<std::string> result2;
  if (detail::parse_accept_header(accept2, result2)) {
    std::cout << "\nExample 2: " << accept2 << std::endl;
    std::cout << "Parsed order (sorted by priority):" << std::endl;
    for (size_t i = 0; i < result2.size(); ++i) {
      std::cout << "  " << (i + 1) << ". " << result2[i] << std::endl;
    }
  } else {
    std::cout << "\nExample 2: Failed to parse Accept header" << std::endl;
  }

  // Example 3: Browser-like Accept header
  std::string accept3 = "text/html,application/xhtml+xml,application/"
                        "xml;q=0.9,image/webp,*/*;q=0.8";
  std::vector<std::string> result3;
  if (detail::parse_accept_header(accept3, result3)) {
    std::cout << "\nExample 3: " << accept3 << std::endl;
    std::cout << "Parsed order:" << std::endl;
    for (size_t i = 0; i < result3.size(); ++i) {
      std::cout << "  " << (i + 1) << ". " << result3[i] << std::endl;
    }
  } else {
    std::cout << "\nExample 3: Failed to parse Accept header" << std::endl;
  }

  // Example 4: Invalid Accept header examples
  std::cout << "\n=== Invalid Accept Header Examples ===" << std::endl;

  std::vector<std::string> invalid_examples = {
      "text/html;q=1.5,application/json",     // q > 1.0
      "text/html;q=-0.1,application/json",    // q < 0.0
      "text/html;q=invalid,application/json", // invalid q value
      "invalidtype,application/json",         // invalid media type
      ",application/json"                     // empty entry
  };

  for (const auto &invalid_accept : invalid_examples) {
    std::vector<std::string> temp_result;
    std::cout << "\nTesting invalid: " << invalid_accept << std::endl;
    if (detail::parse_accept_header(invalid_accept, temp_result)) {
      std::cout << "  Unexpectedly succeeded!" << std::endl;
    } else {
      std::cout << "  Correctly rejected as invalid" << std::endl;
    }
  }

  // Example 4: Server usage example
  std::cout << "\n=== Server Usage Example ===" << std::endl;
  Server svr;

  svr.Get("/api/data", [](const Request &req, Response &res) {
    // Get Accept header
    auto accept_header = req.get_header_value("Accept");
    if (accept_header.empty()) {
      accept_header = "*/*"; // Default if no Accept header
    }

    // Parse accept header to get preferred content types
    std::vector<std::string> preferred_types;
    if (!detail::parse_accept_header(accept_header, preferred_types)) {
      // Invalid Accept header
      res.status = 400; // Bad Request
      res.set_content("Invalid Accept header", "text/plain");
      return;
    }

    std::cout << "Client Accept header: " << accept_header << std::endl;
    std::cout << "Preferred types in order:" << std::endl;
    for (size_t i = 0; i < preferred_types.size(); ++i) {
      std::cout << "  " << (i + 1) << ". " << preferred_types[i] << std::endl;
    }

    // Choose response format based on client preference
    std::string response_content;
    std::string content_type;

    for (const auto &type : preferred_types) {
      if (type == "application/json" || type == "application/*" ||
          type == "*/*") {
        response_content =
            "{\"message\": \"Hello, World!\", \"data\": [1, 2, 3]}";
        content_type = "application/json";
        break;
      } else if (type == "text/html" || type == "text/*") {
        response_content = "<html><body><h1>Hello, World!</h1><p>Data: 1, 2, "
                           "3</p></body></html>";
        content_type = "text/html";
        break;
      } else if (type == "text/plain") {
        response_content = "Hello, World!\nData: 1, 2, 3";
        content_type = "text/plain";
        break;
      }
    }

    if (response_content.empty()) {
      // No supported content type found
      res.status = 406; // Not Acceptable
      res.set_content("No acceptable content type found", "text/plain");
      return;
    }

    res.set_content(response_content, content_type);
    std::cout << "Responding with: " << content_type << std::endl;
  });

  std::cout << "Server configured. You can test it with:" << std::endl;
  std::cout
      << "  curl -H \"Accept: application/json\" http://localhost:8080/api/data"
      << std::endl;
  std::cout << "  curl -H \"Accept: text/html\" http://localhost:8080/api/data"
            << std::endl;
  std::cout << "  curl -H \"Accept: text/plain\" http://localhost:8080/api/data"
            << std::endl;
  std::cout << "  curl -H \"Accept: text/html;q=0.9,application/json;q=1.0\" "
               "http://localhost:8080/api/data"
            << std::endl;

  return 0;
}