/*
    * Copyright (C) 2008, 2010, Google Inc.
    * Copyright (C) 2017, 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.io.IOException;
  import java.net.URISyntaxException;
  import java.text.MessageFormat;
  import java.util.Arrays;
  import java.util.Collections;
  import java.util.List;
  import java.util.Set;
  import java.util.function.Supplier;
  
  import org.eclipse.jgit.annotations.NonNull;
  import org.eclipse.jgit.errors.ConfigInvalidException;
  import org.eclipse.jgit.internal.JGitText;
  import org.eclipse.jgit.lib.Config;
  import org.eclipse.jgit.lib.StoredConfig;
  import org.eclipse.jgit.util.StringUtils;
  import org.eclipse.jgit.util.SystemReader;
  import org.slf4j.Logger;
  import org.slf4j.LoggerFactory;
  
  /**
   * A representation of the "http.*" config values in a git
   * {@link org.eclipse.jgit.lib.Config}. git provides for setting values for
   * specific URLs through "http.&lt;url&gt;.*" subsections. git always considers
   * only the initial original URL for such settings, not any redirected URL.
   *
   * @since 4.9
   */
  public class HttpConfig {
  
  	private static final Logger LOG = LoggerFactory.getLogger(HttpConfig.class);
  
  	private static final String FTP = "ftp"; //$NON-NLS-1$
  
  	/** git config section key for http settings. */
  	public static final String HTTP = "http"; //$NON-NLS-1$
  
  	/** git config key for the "followRedirects" setting. */
  	public static final String FOLLOW_REDIRECTS_KEY = "followRedirects"; //$NON-NLS-1$
  
  	/** git config key for the "maxRedirects" setting. */
  	public static final String MAX_REDIRECTS_KEY = "maxRedirects"; //$NON-NLS-1$
  
  	/** git config key for the "postBuffer" setting. */
  	public static final String POST_BUFFER_KEY = "postBuffer"; //$NON-NLS-1$
  
  	/** git config key for the "sslVerify" setting. */
  	public static final String SSL_VERIFY_KEY = "sslVerify"; //$NON-NLS-1$
  
  	/**
  	 * git config key for the "userAgent" setting.
  	 *
  	 * @since 5.10
  	 */
  	public static final String USER_AGENT = "userAgent"; //$NON-NLS-1$
  
  	/**
  	 * git config key for the "extraHeader" setting.
  	 *
  	 * @since 5.10
  	 */
  	public static final String EXTRA_HEADER = "extraHeader"; //$NON-NLS-1$
  
  	/**
  	 * git config key for the "cookieFile" setting.
  	 *
  	 * @since 5.4
  	 */
  	public static final String COOKIE_FILE_KEY = "cookieFile"; //$NON-NLS-1$
  
  	/**
  	 * git config key for the "saveCookies" setting.
  	 *
  	 * @since 5.4
  	 */
  	public static final String SAVE_COOKIES_KEY = "saveCookies"; //$NON-NLS-1$
  
  	/**
  	 * Custom JGit config key which holds the maximum number of cookie files to
  	 * keep in the cache.
  	 *
  	 * @since 5.4
  	 */
  	public static final String COOKIE_FILE_CACHE_LIMIT_KEY = "cookieFileCacheLimit"; //$NON-NLS-1$
  
  	private static final int DEFAULT_COOKIE_FILE_CACHE_LIMIT = 10;
  
 	private static final String MAX_REDIRECT_SYSTEM_PROPERTY = "http.maxRedirects"; //$NON-NLS-1$
 
 	private static final int DEFAULT_MAX_REDIRECTS = 5;
 
 	private static final int MAX_REDIRECTS = (new Supplier<Integer>() {
 
 		@Override
 		public Integer get() {
 			String rawValue = SystemReader.getInstance()
 					.getProperty(MAX_REDIRECT_SYSTEM_PROPERTY);
 			Integer value = Integer.valueOf(DEFAULT_MAX_REDIRECTS);
 			if (rawValue != null) {
 				try {
 					value = Integer.valueOf(Integer.parseUnsignedInt(rawValue));
 				} catch (NumberFormatException e) {
 					LOG.warn(MessageFormat.format(
 							JGitText.get().invalidSystemProperty,
 							MAX_REDIRECT_SYSTEM_PROPERTY, rawValue, value));
 				}
 			}
 			return value;
 		}
 	}).get().intValue();
 
 	private static final String ENV_HTTP_USER_AGENT = "GIT_HTTP_USER_AGENT"; //$NON-NLS-1$
 
 	/**
 	 * Config values for http.followRedirect.
 	 */
 	public enum HttpRedirectMode implements Config.ConfigEnum {
 
 		/** Always follow redirects (up to the http.maxRedirects limit). */
 		TRUE("true"), //$NON-NLS-1$
 		/**
 		 * Only follow redirects on the initial GET request. This is the
 		 * default.
 		 */
 		INITIAL("initial"), //$NON-NLS-1$
 		/** Never follow redirects. */
 		FALSE("false"); //$NON-NLS-1$
 
 		private final String configValue;
 
 		private HttpRedirectMode(String configValue) {
 			this.configValue = configValue;
 		}
 
 		@Override
 		public String toConfigValue() {
 			return configValue;
 		}
 
 		@Override
 		public boolean matchConfigValue(String s) {
 			return configValue.equals(s);
 		}
 	}
 
 	private int postBuffer;
 
 	private boolean sslVerify;
 
 	private HttpRedirectMode followRedirects;
 
 	private int maxRedirects;
 
 	private String userAgent;
 
 	private List<String> extraHeaders;
 
 	private String cookieFile;
 
 	private boolean saveCookies;
 
 	private int cookieFileCacheLimit;
 
 	/**
 	 * Get the "http.postBuffer" setting
 	 *
 	 * @return the value of the "http.postBuffer" setting
 	 */
 	public int getPostBuffer() {
 		return postBuffer;
 	}
 
 	/**
 	 * Get the "http.sslVerify" setting
 	 *
 	 * @return the value of the "http.sslVerify" setting
 	 */
 	public boolean isSslVerify() {
 		return sslVerify;
 	}
 
 	/**
 	 * Get the "http.followRedirects" setting
 	 *
 	 * @return the value of the "http.followRedirects" setting
 	 */
 	public HttpRedirectMode getFollowRedirects() {
 		return followRedirects;
 	}
 
 	/**
 	 * Get the "http.maxRedirects" setting
 	 *
 	 * @return the value of the "http.maxRedirects" setting
 	 */
 	public int getMaxRedirects() {
 		return maxRedirects;
 	}
 
 	/**
 	 * Get the "http.userAgent" setting
 	 *
 	 * @return the value of the "http.userAgent" setting
 	 * @since 5.10
 	 */
 	public String getUserAgent() {
 		return userAgent;
 	}
 
 	/**
 	 * Get the "http.extraHeader" setting
 	 *
 	 * @return the value of the "http.extraHeader" setting
 	 * @since 5.10
 	 */
 	@NonNull
 	public List<String> getExtraHeaders() {
 		return extraHeaders == null ? Collections.emptyList() : extraHeaders;
 	}
 
 	/**
 	 * Get the "http.cookieFile" setting
 	 *
 	 * @return the value of the "http.cookieFile" setting
 	 *
 	 * @since 5.4
 	 */
 	public String getCookieFile() {
 		return cookieFile;
 	}
 
 	/**
 	 * Get the "http.saveCookies" setting
 	 *
 	 * @return the value of the "http.saveCookies" setting
 	 *
 	 * @since 5.4
 	 */
 	public boolean getSaveCookies() {
 		return saveCookies;
 	}
 
 	/**
 	 * Get the "http.cookieFileCacheLimit" setting (gives the maximum number of
 	 * cookie files to keep in the LRU cache)
 	 *
 	 * @return the value of the "http.cookieFileCacheLimit" setting
 	 *
 	 * @since 5.4
 	 */
 	public int getCookieFileCacheLimit() {
 		return cookieFileCacheLimit;
 	}
 
 	/**
 	 * Creates a new {@link org.eclipse.jgit.transport.HttpConfig} tailored to
 	 * the given {@link org.eclipse.jgit.transport.URIish}.
 	 *
 	 * @param config
 	 *            to read the {@link org.eclipse.jgit.transport.HttpConfig} from
 	 * @param uri
 	 *            to get the configuration values for
 	 */
 	public HttpConfig(Config config, URIish uri) {
 		init(config, uri);
 	}
 
 	/**
 	 * Creates a {@link org.eclipse.jgit.transport.HttpConfig} that reads values
 	 * solely from the user config.
 	 *
 	 * @param uri
 	 *            to get the configuration values for
 	 */
 	public HttpConfig(URIish uri) {
 		StoredConfig userConfig = null;
 		try {
 			userConfig = SystemReader.getInstance().getUserConfig();
 		} catch (IOException | ConfigInvalidException e) {
 			// Log it and then work with default values.
 			LOG.error(e.getMessage(), e);
 			init(new Config(), uri);
 			return;
 		}
 		init(userConfig, uri);
 	}
 
 	private void init(Config config, URIish uri) {
 		// Set defaults from the section first
 		int postBufferSize = config.getInt(HTTP, POST_BUFFER_KEY,
 				1 * 1024 * 1024);
 		boolean sslVerifyFlag = config.getBoolean(HTTP, SSL_VERIFY_KEY, true);
 		HttpRedirectMode followRedirectsMode = config.getEnum(
 				HttpRedirectMode.values(), HTTP, null,
 				FOLLOW_REDIRECTS_KEY, HttpRedirectMode.INITIAL);
 		int redirectLimit = config.getInt(HTTP, MAX_REDIRECTS_KEY,
 				MAX_REDIRECTS);
 		if (redirectLimit < 0) {
 			redirectLimit = MAX_REDIRECTS;
 		}
 		String agent = config.getString(HTTP, null, USER_AGENT);
 		if (agent != null) {
 			agent = UserAgent.clean(agent);
 		}
 		userAgent = agent;
 		String[] headers = config.getStringList(HTTP, null, EXTRA_HEADER);
 		// https://git-scm.com/docs/git-config#Documentation/git-config.txt-httpextraHeader
 		// "an empty value will reset the extra headers to the empty list."
 		int start = findLastEmpty(headers) + 1;
 		if (start > 0) {
 			headers = Arrays.copyOfRange(headers, start, headers.length);
 		}
 		extraHeaders = Arrays.asList(headers);
 		cookieFile = config.getString(HTTP, null, COOKIE_FILE_KEY);
 		saveCookies = config.getBoolean(HTTP, SAVE_COOKIES_KEY, false);
 		cookieFileCacheLimit = config.getInt(HTTP, COOKIE_FILE_CACHE_LIMIT_KEY,
 				DEFAULT_COOKIE_FILE_CACHE_LIMIT);
 		String match = findMatch(config.getSubsections(HTTP), uri);
 
 		if (match != null) {
 			// Override with more specific items
 			postBufferSize = config.getInt(HTTP, match, POST_BUFFER_KEY,
 					postBufferSize);
 			sslVerifyFlag = config.getBoolean(HTTP, match, SSL_VERIFY_KEY,
 					sslVerifyFlag);
 			followRedirectsMode = config.getEnum(HttpRedirectMode.values(),
 					HTTP, match, FOLLOW_REDIRECTS_KEY, followRedirectsMode);
 			int newMaxRedirects = config.getInt(HTTP, match, MAX_REDIRECTS_KEY,
 					redirectLimit);
 			if (newMaxRedirects >= 0) {
 				redirectLimit = newMaxRedirects;
 			}
 			String uriSpecificUserAgent = config.getString(HTTP, match,
 					USER_AGENT);
 			if (uriSpecificUserAgent != null) {
 				userAgent = UserAgent.clean(uriSpecificUserAgent);
 			}
 			String[] uriSpecificExtraHeaders = config.getStringList(HTTP, match,
 					EXTRA_HEADER);
 			if (uriSpecificExtraHeaders.length > 0) {
 				start = findLastEmpty(uriSpecificExtraHeaders) + 1;
 				if (start > 0) {
 					uriSpecificExtraHeaders = Arrays.copyOfRange(
 							uriSpecificExtraHeaders, start,
 							uriSpecificExtraHeaders.length);
 				}
 				extraHeaders = Arrays.asList(uriSpecificExtraHeaders);
 			}
 			String urlSpecificCookieFile = config.getString(HTTP, match,
 					COOKIE_FILE_KEY);
 			if (urlSpecificCookieFile != null) {
 				cookieFile = urlSpecificCookieFile;
 			}
 			saveCookies = config.getBoolean(HTTP, match, SAVE_COOKIES_KEY,
 					saveCookies);
 		}
 		// Environment overrides config
 		agent = SystemReader.getInstance().getenv(ENV_HTTP_USER_AGENT);
 		if (!StringUtils.isEmptyOrNull(agent)) {
 			userAgent = UserAgent.clean(agent);
 		}
 		postBuffer = postBufferSize;
 		sslVerify = sslVerifyFlag;
 		followRedirects = followRedirectsMode;
 		maxRedirects = redirectLimit;
 	}
 
 	private int findLastEmpty(String[] values) {
 		for (int i = values.length - 1; i >= 0; i--) {
 			if (values[i] == null) {
 				return i;
 			}
 		}
 		return -1;
 	}
 
 	/**
 	 * Determines the best match from a set of subsection names (representing
 	 * prefix URLs) for the given {@link URIish}.
 	 *
 	 * @param names
 	 *            to match against the {@code uri}
 	 * @param uri
 	 *            to find a match for
 	 * @return the best matching subsection name, or {@code null} if no
 	 *         subsection matches
 	 */
 	private String findMatch(Set<String> names, URIish uri) {
 		String bestMatch = null;
 		int bestMatchLength = -1;
 		boolean withUser = false;
 		String uPath = uri.getPath();
 		boolean hasPath = !StringUtils.isEmptyOrNull(uPath);
 		if (hasPath) {
 			uPath = normalize(uPath);
 			if (uPath == null) {
 				// Normalization failed; warning was logged.
 				return null;
 			}
 		}
 		for (String s : names) {
 			try {
 				URIish candidate = new URIish(s);
 				// Scheme and host must match case-insensitively
 				if (!compare(uri.getScheme(), candidate.getScheme())
 						|| !compare(uri.getHost(), candidate.getHost())) {
 					continue;
 				}
 				// Ports must match after default ports have been substituted
 				if (defaultedPort(uri.getPort(),
 						uri.getScheme()) != defaultedPort(candidate.getPort(),
 								candidate.getScheme())) {
 					continue;
 				}
 				// User: if present in candidate, must match
 				boolean hasUser = false;
 				if (candidate.getUser() != null) {
 					if (!candidate.getUser().equals(uri.getUser())) {
 						continue;
 					}
 					hasUser = true;
 				}
 				// Path: prefix match, longer is better
 				String cPath = candidate.getPath();
 				int matchLength = -1;
 				if (StringUtils.isEmptyOrNull(cPath)) {
 					matchLength = 0;
 				} else {
 					if (!hasPath) {
 						continue;
 					}
 					// Paths can match only on segments
 					matchLength = segmentCompare(uPath, cPath);
 					if (matchLength < 0) {
 						continue;
 					}
 				}
 				// A longer path match is always preferred even over a user
 				// match. If the path matches are equal, a match with user wins
 				// over a match without user.
 				if (matchLength > bestMatchLength
 						|| (!withUser && hasUser && matchLength >= 0
 								&& matchLength == bestMatchLength)) {
 					bestMatch = s;
 					bestMatchLength = matchLength;
 					withUser = hasUser;
 				}
 			} catch (URISyntaxException e) {
 				LOG.warn(MessageFormat
 						.format(JGitText.get().httpConfigInvalidURL, s));
 			}
 		}
 		return bestMatch;
 	}
 
 	private boolean compare(String a, String b) {
 		if (a == null) {
 			return b == null;
 		}
 		return a.equalsIgnoreCase(b);
 	}
 
 	private int defaultedPort(int port, String scheme) {
 		if (port >= 0) {
 			return port;
 		}
 		if (FTP.equalsIgnoreCase(scheme)) {
 			return 21;
 		} else if (HTTP.equalsIgnoreCase(scheme)) {
 			return 80;
 		} else {
 			return 443; // https
 		}
 	}
 
 	static int segmentCompare(String uriPath, String m) {
 		// Precondition: !uriPath.isEmpty() && !m.isEmpty(),and u must already
 		// be normalized
 		String matchPath = normalize(m);
 		if (matchPath == null || !uriPath.startsWith(matchPath)) {
 			return -1;
 		}
 		// We can match only on a segment boundary: either both paths are equal,
 		// or if matchPath does not end in '/', there is a '/' in uriPath right
 		// after the match.
 		int uLength = uriPath.length();
 		int mLength = matchPath.length();
 		if (mLength == uLength || matchPath.charAt(mLength - 1) == '/'
 				|| (mLength < uLength && uriPath.charAt(mLength) == '/')) {
 			return mLength;
 		}
 		return -1;
 	}
 
 	static String normalize(String path) {
 		// C-git resolves . and .. segments
 		int i = 0;
 		int length = path.length();
 		StringBuilder builder = new StringBuilder(length);
 		builder.append('/');
 		if (length > 0 && path.charAt(0) == '/') {
 			i = 1;
 		}
 		while (i < length) {
 			int slash = path.indexOf('/', i);
 			if (slash < 0) {
 				slash = length;
 			}
 			if (slash == i || (slash == i + 1 && path.charAt(i) == '.')) {
 				// Skip /. or also double slashes
 			} else if (slash == i + 2 && path.charAt(i) == '.'
 					&& path.charAt(i + 1) == '.') {
 				// Remove previous segment if we have "/.."
 				int l = builder.length() - 2; // Skip terminating slash.
 				while (l >= 0 && builder.charAt(l) != '/') {
 					l--;
 				}
 				if (l < 0) {
 					LOG.warn(MessageFormat.format(
 							JGitText.get().httpConfigCannotNormalizeURL, path));
 					return null;
 				}
 				builder.setLength(l + 1);
 			} else {
 				// Include the slash, if any
 				builder.append(path, i, Math.min(length, slash + 1));
 			}
 			i = slash + 1;
 		}
 		if (builder.length() > 1 && builder.charAt(builder.length() - 1) == '/'
 				&& length > 0 && path.charAt(length - 1) != '/') {
 			// . or .. normalization left a trailing slash when the original
 			// path had none at the end
 			builder.setLength(builder.length() - 1);
 		}
 		return builder.toString();
 	}
 }