--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hg4j/src/main/java/org/tmatesoft/hg/internal/StoragePathHelper.java	Tue May 10 10:52:53 2011 +0200
@@ -0,0 +1,197 @@
+/*
+ * Copyright (c) 2011 TMate Software Ltd
+ *  
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * 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 General Public License for more details.
+ *
+ * For information on how to redistribute this software under
+ * the terms of a license other than GNU General Public License
+ * contact TMate Software at support@hg4j.com
+ */
+package org.tmatesoft.hg.internal;
+
+import java.util.Arrays;
+import java.util.TreeSet;
+
+import org.tmatesoft.hg.util.PathRewrite;
+
+/**
+ * @see http://mercurial.selenic.com/wiki/CaseFoldingPlan
+ * @see http://mercurial.selenic.com/wiki/fncacheRepoFormat
+ * 
+ * @author Artem Tikhomirov
+ * @author TMate Software Ltd.
+ */
+class StoragePathHelper implements PathRewrite {
+	
+	private final boolean store;
+	private final boolean fncache;
+	private final boolean dotencode;
+
+	public StoragePathHelper(boolean isStore, boolean isFncache, boolean isDotencode) {
+		store = isStore;
+		fncache = isFncache;
+		dotencode = isDotencode;
+	}
+
+	// FIXME document what path argument is, whether it includes .i or .d, and whether it's 'normalized' (slashes) or not.
+	// since .hg/store keeps both .i files and files without extension (e.g. fncache), guees, for data == false 
+	// we shall assume path has extension
+	public String rewrite(String path) {
+		final String STR_STORE = "store/";
+		final String STR_DATA = "data/";
+		final String STR_DH = "dh/";
+		final String reservedChars = "\\:*?\"<>|";
+		char[] hexByte = new char[2];
+		
+		path = path.replace(".hg/", ".hg.hg/").replace(".i/", ".i.hg/").replace(".d/", ".d.hg/");
+		StringBuilder sb = new StringBuilder(path.length() << 1);
+		if (store || fncache) {
+			// encodefilename
+			for (int i = 0; i < path.length(); i++) {
+				final char ch = path.charAt(i);
+				if (ch >= 'a' && ch <= 'z') {
+					sb.append(ch); // POIRAE
+				} else if (ch >= 'A' && ch <= 'Z') {
+					sb.append('_');
+					sb.append(Character.toLowerCase(ch)); // Perhaps, (char) (((int) ch) + 32)? Even better, |= 0x20? 
+				} else if (reservedChars.indexOf(ch) != -1) {
+					sb.append('~');
+					sb.append(toHexByte(ch, hexByte));
+				} else if ((ch >= '~' /*126*/ && ch <= 255) || ch < ' ' /*32*/) {
+					sb.append('~');
+					sb.append(toHexByte(ch, hexByte));
+				} else if (ch == '_') {
+					sb.append('_');
+					sb.append('_');
+				} else {
+					sb.append(ch);
+				}
+			}
+			// auxencode
+			if (fncache) {
+				encodeWindowsDeviceNames(sb);
+			}
+		}
+		final int MAX_PATH_LEN = 120;
+		if (fncache && (sb.length() + STR_DATA.length() + ".i".length() > MAX_PATH_LEN)) {
+			String digest = new DigestHelper().sha1(STR_DATA, path, ".i").asHexString();
+			final int DIR_PREFIX_LEN = 8;
+			 // not sure why (-4) is here. 120 - 40 = up to 80 for path with ext. dh/ + ext(.i) = 3+2
+			final int MAX_DIR_PREFIX = 8 * (DIR_PREFIX_LEN + 1) - 4;
+			sb = new StringBuilder(MAX_PATH_LEN);
+			for (int i = 0; i < path.length(); i++) {
+				final char ch = path.charAt(i);
+				if (ch >= 'a' && ch <= 'z') {
+					sb.append(ch);
+				} else if (ch >= 'A' && ch <= 'Z') {
+					sb.append((char) (ch | 0x20)); // lowercase 
+				} else if (reservedChars.indexOf(ch) != -1) {
+					sb.append('~');
+					sb.append(toHexByte(ch, hexByte));
+				} else if ((ch >= '~' /*126*/ && ch <= 255) || ch < ' ' /*32*/) {
+					sb.append('~');
+					sb.append(toHexByte(ch, hexByte));
+				} else {
+					sb.append(ch);
+				}
+			}
+			encodeWindowsDeviceNames(sb);
+			int fnameStart = sb.lastIndexOf("/"); // since we rewrite file names, it never ends with slash (for dirs, I'd pass length-2);
+			StringBuilder completeHashName = new StringBuilder(MAX_PATH_LEN);
+			completeHashName.append(STR_STORE);
+			completeHashName.append(STR_DH);
+			if (fnameStart == -1) {
+				// no dirs, just long filename
+				sb.setLength(MAX_PATH_LEN - 40 /*digest.length()*/ - STR_DH.length() - ".i".length());
+				completeHashName.append(sb);
+			} else {
+				StringBuilder sb2 = new StringBuilder(MAX_PATH_LEN);
+				int x = 0;
+				do {
+					int i = sb.indexOf("/", x);
+					final int sb2Len = sb2.length(); 
+					if (i-x <= DIR_PREFIX_LEN) { // a b c d e f g h /
+						sb2.append(sb, x, i + 1); // with slash
+					} else {
+						sb2.append(sb, x, x + DIR_PREFIX_LEN);
+						// may unexpectedly end with bad character
+						final int last = sb2.length()-1;
+						char lastChar = sb2.charAt(last); 
+						assert lastChar == sb.charAt(x + DIR_PREFIX_LEN - 1);
+						if (lastChar == '.' || lastChar == ' ') {
+							sb2.setCharAt(last, '_');
+						}
+						sb2.append('/');
+					}
+					if (sb2.length()-1 > MAX_DIR_PREFIX) {
+						sb2.setLength(sb2Len); // strip off last segment, it's too much
+						break;
+					}
+					x = i+1; 
+				} while (x < fnameStart);
+				assert sb2.charAt(sb2.length() - 1) == '/';
+				int left = MAX_PATH_LEN - sb2.length() - 40 /*digest.length()*/ - STR_DH.length() - ".i".length();
+				assert left >= 0;
+				fnameStart++; // move from / to actual name
+				sb2.append(sb, fnameStart, fnameStart + left > sb.length() ? sb.length() : fnameStart+left);
+				completeHashName.append(sb2);
+			}
+			completeHashName.append(digest);
+			sb = completeHashName;
+		} else if (store) {
+			sb.insert(0, STR_STORE + STR_DATA);
+		}
+		sb.append(".i");
+		return sb.toString();
+	}
+	
+	private void encodeWindowsDeviceNames(StringBuilder sb) {
+		char[] hexByte = new char[2];
+		int x = 0; // last segment start
+		final TreeSet<String> windowsReservedFilenames = new TreeSet<String>();
+		windowsReservedFilenames.addAll(Arrays.asList("con prn aux nul com1 com2 com3 com4 com5 com6 com7 com8 com9 lpt1 lpt2 lpt3 lpt4 lpt5 lpt6 lpt7 lpt8 lpt9".split(" "))); 
+		do {
+			int i = sb.indexOf("/", x);
+			if (i == -1) {
+				i = sb.length();
+			}
+			// windows reserved filenames are at least of length 3 
+			if (i - x >= 3) {
+				boolean found = false;
+				if (i-x == 3 || i-x == 4) {
+					found = windowsReservedFilenames.contains(sb.subSequence(x, i));
+				} else if (sb.charAt(x+3) == '.') { // implicit i-x > 3
+					found = windowsReservedFilenames.contains(sb.subSequence(x, x+3));
+				} else if (i-x > 4 && sb.charAt(x+4) == '.') {
+					found = windowsReservedFilenames.contains(sb.subSequence(x, x+4));
+				}
+				if (found) {
+					sb.insert(x+3, toHexByte(sb.charAt(x+2), hexByte));
+					sb.setCharAt(x+2, '~');
+					i += 2;
+				}
+			}
+			if (dotencode && (sb.charAt(x) == '.' || sb.charAt(x) == ' ')) {
+				sb.insert(x+1, toHexByte(sb.charAt(x), hexByte));
+				sb.setCharAt(x, '~'); // setChar *after* charAt/insert to get ~2e, not ~7e for '.'
+				i += 2;
+			}
+			x = i+1;
+		} while (x < sb.length());
+	}
+
+	private static char[] toHexByte(int ch, char[] buf) {
+		assert buf.length > 1;
+		final String hexDigits = "0123456789abcdef";
+		buf[0] = hexDigits.charAt((ch & 0x00F0) >>> 4);
+		buf[1] = hexDigits.charAt(ch & 0x0F);
+		return buf;
+	}
+}