package com.atlassian.httpclient.apache.httpcomponents;
   
   import com.atlassian.httpclient.api.Buildable;
   import com.google.common.base.Preconditions;
   import org.apache.http.protocol.HTTP;
   
   import java.nio.charset.Charset;
   import java.util.Collections;
   import java.util.Map;
  
  import static com.google.common.collect.Maps.newHashMap;
  
  public class Headers {
      private final Map<String, String> headers;
      private final String contentCharset;
      private final String contentType;
  
      private Headers(Map<String, String> headers, String contentCharset, String contentType) {
          this.headers = headers;
          this.contentCharset = contentCharset;
          this.contentType = contentType;
      }
  
      public String getContentCharset() {
          return contentCharset;
      }
  
      public String getContentType() {
          return contentType;
      }
  
      public Map<String, String> getHeaders() {
          Map<String, String> headers = newHashMap(this.headers);
          if (contentType != null) {
              headers.put(Names.CONTENT_TYPE, buildContentType());
          }
          return Collections.unmodifiableMap(headers);
      }
  
      public String getHeader(final String name) {
          String value;
          if (name.equalsIgnoreCase(Names.CONTENT_TYPE)) {
              value = buildContentType();
          } else {
              value = headers.get(name);
          }
          return value;
      }
  
      private String buildContentType() {
          String value = contentType != null ? contentType : "text/plain";
          if (contentCharset != null) {
              value += "; charset=" + contentCharset;
          }
          return value;
      }
  
      public static class Builder implements Buildable<Headers> {
          private final Map<String, String> headers = newHashMap();
          private String contentType;
          private String contentCharset;
  
          public Builder setHeaders(Map<String, String> headers) {
              this.headers.clear();
              for (Map.Entry<String, String> entry : headers.entrySet()) {
                  setHeader(entry.getKey(), entry.getValue());
              }
              return this;
          }
  
          public Builder setHeader(String name, String value) {
              if (name.equalsIgnoreCase("Content-Type")) {
                  parseContentType(value);
              } else {
                  headers.put(name, value);
              }
              return this;
          }
  
          public Builder setContentLength(long contentLength) {
              Preconditions.checkArgument(contentLength >= 0, "Content-Length must be greater than or equal to 0");
              setHeader(Names.CONTENT_LENGTH, Long.toString(contentLength));
              return this;
          }
  
          public Builder setContentCharset(String contentCharset) {
              this.contentCharset = contentCharset != null ? Charset.forName(contentCharset).name() : null;
              return this;
          }
  
          public Builder setContentType(String contentType) {
              parseContentType(contentType);
              return this;
          }
  
          private void parseContentType(String value) {
              if (value != null) {
                  String[] parts = value.split(";");
                  if (parts.length >= 1) {
                     contentType = parts[0].trim();
                 }
                 if (parts.length >= 2) {
                     String subtype = parts[1].trim();
                     if (subtype.startsWith("charset=")) {
                         setContentCharset(subtype.substring(8));
                     } else if (subtype.startsWith("boundary=")) {
                         contentType = contentType.concat(';' + subtype);
                     }
                 }
             } else {
                 contentType = null;
             }
         }
 
         @Override
         public Headers build() {
             return new Headers(headers, contentCharset, contentType);
         }
     }
 
     public static class Names {
         public static final String CONTENT_LENGTH = HTTP.CONTENT_LEN;
         public static final String CONTENT_TYPE = HTTP.CONTENT_TYPE;
 
         private Names() {
         }
     }
 }