/*
    * Copyright (C) 2022 Thomas Wolf <thomas.wolf@paranor.ch> and others
    *
    * This program and the accompanying materials are made available under the
    * terms of the Eclipse Distribution License v. 1.0 which is available at
    * https://www.eclipse.org/org/documents/edl-v10.php.
    *
    * SPDX-License-Identifier: BSD-3-Clause
    */
  package org.eclipse.jgit.transport;
  
  import java.util.HashMap;
  import java.util.Map;
  import java.util.Map.Entry;
  
  import org.eclipse.jgit.lib.Config;
  
  /**
   * Support for URL translations via git configs {@code url.<base>.insteadOf} and
   * {@code url.<base>.pushInsteadOf}.
   *
   * @since 6.2
   */
  public class UrlConfig {
  
  	private static final String KEY_INSTEADOF = "insteadof"; //$NON-NLS-1$
  
  	private static final String KEY_PUSHINSTEADOF = "pushinsteadof"; //$NON-NLS-1$
  
  	private static final String SECTION_URL = "url"; //$NON-NLS-1$
  
  	private final Config config;
  
  	private Map<String, String> insteadOf;
  
  	private Map<String, String> pushInsteadOf;
  
  	/**
  	 * Creates a new {@link UrlConfig} instance.
  	 *
  	 * @param config
  	 *            {@link Config} to read values from
  	 */
  	public UrlConfig(Config config) {
  		this.config = config;
  	}
  
  	/**
  	 * Performs replacements as defined by git config
  	 * {@code url.<base>.insteadOf}. If there is no match, the input is returned
  	 * unchanged.
  	 *
  	 * @param url
  	 *            to substitute
  	 * @return the {@code url} with substitution applied
  	 */
  	public String replace(String url) {
  		if (insteadOf == null) {
  			insteadOf = load(KEY_INSTEADOF);
  		}
  		return replace(url, insteadOf);
  	}
  
  	/**
  	 * Tells whether there are push replacements.
  	 *
  	 * @return {@code true} if there are push replacements, {@code false}
  	 *         otherwise
  	 */
  	public boolean hasPushReplacements() {
  		if (pushInsteadOf == null) {
  			pushInsteadOf = load(KEY_PUSHINSTEADOF);
  		}
  		return !pushInsteadOf.isEmpty();
  	}
  
  	/**
  	 * Performs replacements as defined by git config
  	 * {@code url.<base>.pushInsteadOf}. If there is no match, the input is
  	 * returned unchanged.
  	 *
  	 * @param url
  	 *            to substitute
  	 * @return the {@code url} with substitution applied
  	 */
  	public String replacePush(String url) {
  		if (pushInsteadOf == null) {
  			pushInsteadOf = load(KEY_PUSHINSTEADOF);
  		}
  		return replace(url, pushInsteadOf);
  	}
  
  	private Map<String, String> load(String key) {
  		Map<String, String> replacements = new HashMap<>();
  		for (String url : config.getSubsections(SECTION_URL)) {
  			for (String prefix : config.getStringList(SECTION_URL, url, key)) {
  				replacements.put(prefix, url);
  			}
  		}
 		return replacements;
 	}
 
 	private String replace(String uri, Map<String, String> replacements) {
 		Entry<String, String> match = null;
 		for (Entry<String, String> replacement : replacements.entrySet()) {
 			// Ignore current entry if not longer than previous match
 			if (match != null && match.getKey().length() > replacement.getKey()
 					.length()) {
 				continue;
 			}
 			if (uri.startsWith(replacement.getKey())) {
 				match = replacement;
 			}
 		}
 		if (match != null) {
 			return match.getValue() + uri.substring(match.getKey().length());
 		}
 		return uri;
 	}
 }