/*
  neon - Embeddable HTTP Server based on jdk.httpserver
  Copyright (C) 2024  Ulrich Hilger

  This program is free software: you can redistribute it and/or modify
  it under the terms of the GNU Affero General Public License as
  published by the Free Software Foundation, either version 3 of the
  License, or (at your option) any later version.

  This program is distributed in the hope that it will be useful,
  but WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  GNU Affero General Public License for more details.

  You should have received a copy of the GNU Affero General Public License
  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package de.uhilger.neon;

import com.sun.net.httpserver.Headers;
import com.sun.net.httpserver.HttpExchange;
import java.io.File;
import java.io.IOException;

/**
 * Objekte der Klasse FileServer liefern Dateien ueber HTTP aus
 * 
 * Im Attribut FileServer.ATTR_FILE_BASE in 
 * HttpExchange.getContext().getAttributes() wird das 
 * Verzeichnis erwartet, aus dem Dateien ausgeliefert 
 * werden sollen. 
 * 
 * Im Attribut FileServer.ATTR_WELCOME_FILES in 
 * HttpExchange.getContext().getAttributes() kann eine 
 * mit Komma getrennte Liste mit Dateinamen uebergeben 
 * werden, die ausgeliefert werden sollen, wenn ein 
 * Verzeichnis anstelle einer Datei angefragt ist. 
 * 
 * @author Ulrich Hilger
 */
public class FileServer {
  
  public static final String RANGE_HEADER = "Range";
  
  public static final String ATTR_FILE_BASE = "fileBase";
  public static final String ATTR_WELCOME_FILES = "welcomeFiles";

  public static final String DEFAULT_INDEX_FILE = "index.html";
  
  public static final String STR_SLASH = "/";
  public static final String STR_BLANK = " ";
  public static final String STR_DASH = "-";
  public static final String STR_COMMA = ",";
  public static final String STR_DOT = ".";
  public static final String STR_EMPTY = "";
  
  public void serveFile(HttpExchange exchange) throws IOException {
    String fName = new HttpHelper().getFileName(exchange);
    if (fName.startsWith(".")) {
      HttpResponder fs = new HttpResponder();
      fs.sendNotFound(exchange, fName);
    } else {
      File fileToDeliver = new File((String) exchange
              .getHttpContext().getAttributes()
              .getOrDefault(ATTR_FILE_BASE, STR_EMPTY), fName);
      Headers headers = exchange.getRequestHeaders();
      if (headers.containsKey(RANGE_HEADER)) {
        new PartialFileServer().serveFileParts(exchange, fileToDeliver);
      } else {
        if (fName.length() < 1 || fName.endsWith(STR_SLASH)) {
          //HttpHelper helper = new HttpHelper();
          File welcomeFile = tryWelcomeFiles(exchange, fName);
          if(welcomeFile != null) {
            fileToDeliver = welcomeFile;
          }
        }
        new HttpResponder().serveFile(exchange, fileToDeliver);
      }
    }    
  }

  public File tryWelcomeFiles(HttpExchange e, String fName) {
    boolean notFound = true;
    File file = null;
    String fileBase = (String) e.getHttpContext().getAttributes()
            .getOrDefault(ATTR_FILE_BASE, STR_EMPTY);
    Object welcomeFiles = e.getHttpContext().getAttributes().get(ATTR_WELCOME_FILES);
    if(welcomeFiles instanceof String) {
      String[] fileNames = welcomeFiles.toString().split(STR_COMMA);
      int i = -1;
      while(notFound && ++i < fileNames.length) {
        file = new File(fileBase, fName + fileNames[i]);
        if(file.exists()) {
          notFound = false;
        }
      }
    }
    if(notFound) {
      file = new File(fileBase, fName + DEFAULT_INDEX_FILE);
    }
    return file;
  }
}