package com.guinetik.rr.http;
   
   import java.util.HashMap;
   import java.util.Map;
   
   /**
    * Fluent builder for HTTP request headers with convenience methods for common headers.
    *
    * <p>This class provides a type-safe way to build and manage HTTP headers for requests,
   * with predefined constants for common header names and content types.
   *
   * <h2>Building Headers</h2>
   * <pre class="language-java"><code>
   * // Create headers with fluent API
   * RocketHeaders headers = new RocketHeaders()
   *     .contentType(RocketHeaders.ContentTypes.APPLICATION_JSON)
   *     .accept(RocketHeaders.ContentTypes.APPLICATION_JSON)
   *     .set("X-Custom-Header", "custom-value");
   *
   * // Use in request
   * RequestSpec request = RequestBuilder.post("/users")
   *     .headers(headers)
   *     .body(user)
   *     .responseType(User.class)
   *     .build();
   * </code></pre>
   *
   * <h2>Authentication Headers</h2>
   * <pre class="language-java"><code>
   * // Bearer token authentication
   * RocketHeaders headers = new RocketHeaders()
   *     .bearerAuth("my-jwt-token");
   *
   * // Basic authentication
   * RocketHeaders basicAuth = new RocketHeaders()
   *     .basicAuth("username", "password");
   * </code></pre>
   *
   * <h2>Default JSON Headers</h2>
   * <pre class="language-java"><code>
   * // Get pre-configured JSON headers
   * RocketHeaders jsonHeaders = RocketHeaders.defaultJson();
   * // Equivalent to Content-Type: application/json + Accept: application/json
   * </code></pre>
   *
   * <h2>Merging Headers</h2>
   * <pre class="language-java"><code>
   * RocketHeaders base = RocketHeaders.defaultJson();
   * RocketHeaders auth = new RocketHeaders().bearerAuth("token");
   *
   * // Merge headers (auth values take precedence)
   * RocketHeaders merged = base.merge(auth);
   * </code></pre>
   *
   * @author guinetik &lt;guinetik@gmail.com&gt;
   * @see com.guinetik.rr.request.RequestBuilder
   * @since 1.0.0
   */
  public class RocketHeaders {
      
      private final Map<String, String> headers;
      
      /**
       * Standard HTTP header names as constants.
       */
      public static final class Names {
          public static final String CONTENT_TYPE = "Content-Type";
          public static final String ACCEPT = "Accept";
          public static final String AUTHORIZATION = "Authorization";
          public static final String USER_AGENT = "User-Agent";
          public static final String CONTENT_LENGTH = "Content-Length";
      }
      
      /**
       * Common content types as constants.
       */
      public static final class ContentTypes {
          public static final String APPLICATION_JSON = "application/json";
          public static final String APPLICATION_FORM = "application/x-www-form-urlencoded";
          public static final String TEXT_PLAIN = "text/plain";
          public static final String MULTIPART_FORM = "multipart/form-data";
      }
      
      /**
       * Creates a new empty header container.
       */
      public RocketHeaders() {
          this.headers = new HashMap<>();
      }
      
      /**
       * Creates a new header container with the specified headers.
       *
       * @param headers The initial headers
       */
      public RocketHeaders(Map<String, String> headers) {
          this.headers = new HashMap<>(headers);
      }
      
     /**
      * Sets a header value.
      *
      * @param name The header name
      * @param value The header value
      * @return This HttpHeader instance for chaining
      */
     public RocketHeaders set(String name, String value) {
         headers.put(name, value);
         return this;
     }
     
     /**
      * Gets a header value.
      *
      * @param name The header name
      * @return The header value or null if not present
      */
     public String get(String name) {
         return headers.get(name);
     }
     
     /**
      * Removes a header.
      *
      * @param name The header name
      * @return This HttpHeader instance for chaining
      */
     public RocketHeaders remove(String name) {
         headers.remove(name);
         return this;
     }
     
     /**
      * Checks if a header is present.
      *
      * @param name The header name
      * @return true if the header is present
      */
     public boolean contains(String name) {
         return headers.containsKey(name);
     }
     
     /**
      * Sets the Content-Type header.
      *
      * @param contentType The content type
      * @return This HttpHeader instance for chaining
      */
     public RocketHeaders contentType(String contentType) {
         return set(Names.CONTENT_TYPE, contentType);
     }
     
     /**
      * Sets the Accept header.
      *
      * @param accept The accept value
      * @return This HttpHeader instance for chaining
      */
     public RocketHeaders accept(String accept) {
         return set(Names.ACCEPT, accept);
     }
     
     /**
      * Sets the Authorization header with a Bearer token.
      *
      * @param token The token
      * @return This HttpHeader instance for chaining
      */
     public RocketHeaders bearerAuth(String token) {
         return set(Names.AUTHORIZATION, "Bearer " + token);
     }
     
     /**
      * Sets the Authorization header with Basic authentication.
      *
      * @param username The username
      * @param password The password
      * @return This HttpHeader instance for chaining
      */
     public RocketHeaders basicAuth(String username, String password) {
         String auth = java.util.Base64.getEncoder().encodeToString((username + ":" + password).getBytes());
         return set(Names.AUTHORIZATION, "Basic " + auth);
     }
     
     /**
      * Gets all headers as a Map.
      *
      * @return An unmodifiable view of the header map
      */
     public Map<String, String> asMap() {
         return java.util.Collections.unmodifiableMap(headers);
     }
     
     /**
      * Merges this header with another, with values from the other taking precedence.
      *
      * @param other The other HttpHeader instance
      * @return A new HttpHeader instance with merged values
      */
     public RocketHeaders merge(RocketHeaders other) {
         RocketHeaders result = new RocketHeaders(this.headers);
         result.headers.putAll(other.headers);
         return result;
     }
     
     /**
      * Creates a set of default headers with JSON content type.
      *
      * @return A new HttpHeader with JSON content type and accept headers
      */
     public static RocketHeaders defaultJson() {
         return new RocketHeaders()
             .contentType(ContentTypes.APPLICATION_JSON)
             .accept(ContentTypes.APPLICATION_JSON);
     }
 }