[vcs]: create sha1 constructor with tests for future usages and reuse not_committed hash constant

platform/vcs-impl/src/com/intellij/openapi/vcs/changes/patch/BlobIndexUtil.java

@@ -0,0 +1,79 @@
+/*
+ * Copyright 2000-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.openapi.vcs.changes.patch;
+
+import com.google.common.base.Charsets;
+import com.google.common.hash.Hashing;
+import com.google.common.io.Files;
+import com.intellij.openapi.util.Couple;
+import com.intellij.openapi.util.text.StringUtil;
+import com.intellij.openapi.vcs.VcsException;
+import com.intellij.openapi.vcs.changes.BinaryContentRevision;
+import com.intellij.openapi.vcs.changes.Change;
+import com.intellij.openapi.vcs.changes.ContentRevision;
+import com.intellij.util.ObjectUtils;
+import org.jetbrains.annotations.NotNull;
+
+import java.io.File;
+import java.io.IOException;
+import java.nio.charset.Charset;
+
+import static com.intellij.util.ArrayUtil.EMPTY_BYTE_ARRAY;
+
+public class BlobIndexUtil {
+
+  public static final String NOT_COMMITTED_HASH = StringUtil.repeat("0", 40);
+
+
+  @NotNull
+  public static String getSha1(@NotNull File file) throws IOException {
+    return getSha1(Files.toByteArray(file));
+  }
+
+  /**
+   * Generate sha1 for file content using git-like algorithm
+   */
+  @NotNull
+  public static String getSha1(@NotNull byte[] bytes) {
+    String prefix = "blob " + bytes.length + '\u0000';
+    return Hashing.sha1().newHasher().putBytes(prefix.getBytes(Charsets.UTF_8)).putBytes(bytes).hash().toString();
+  }
+
+  @NotNull
+  public static Couple<String> getBeforeAfterSha1(@NotNull Change change) throws VcsException {
+    ContentRevision beforeRevision = change.getBeforeRevision();
+    ContentRevision afterRevision = change.getAfterRevision();
+
+    //noinspection ConstantConditions
+    Charset detectCharset = ObjectUtils.chooseNotNull(afterRevision, beforeRevision).getFile().getCharset();
+    String before = beforeRevision == null ? NOT_COMMITTED_HASH : getSha1(getContentBytes(beforeRevision, detectCharset));
+    String after = afterRevision == null ? NOT_COMMITTED_HASH : getSha1(getContentBytes(afterRevision, detectCharset));
+    return new Couple<>(before, after);
+  }
+
+  @NotNull
+  private static byte[] getContentBytes(@NotNull ContentRevision revision, @NotNull Charset charset) throws VcsException {
+    byte[] binaryContent;
+    if (revision instanceof BinaryContentRevision) {
+      binaryContent = ((BinaryContentRevision)revision).getBinaryContent();
+    }
+    else {
+      String stringContent = revision.getContent();
+      binaryContent = stringContent != null ? stringContent.getBytes(charset) : EMPTY_BYTE_ARRAY;
+    }
+    return binaryContent != null ? binaryContent : EMPTY_BYTE_ARRAY;
+  }
+}

plugins/git4idea/src/git4idea/GitRevisionNumber.java

@@ -18,8 +18,8 @@ package git4idea;
 import com.intellij.dvcs.DvcsUtil;
 import com.intellij.openapi.diagnostic.Logger;
 import com.intellij.openapi.project.Project;
-import com.intellij.openapi.util.text.StringUtil;
 import com.intellij.openapi.vcs.VcsException;
+import com.intellij.openapi.vcs.changes.patch.BlobIndexUtil;
 import com.intellij.openapi.vcs.history.ShortVcsRevisionNumber;
 import com.intellij.openapi.vcs.history.VcsRevisionNumber;
 import com.intellij.openapi.vfs.VirtualFile;
@@ -38,7 +38,7 @@ public class GitRevisionNumber implements ShortVcsRevisionNumber {
   /**
    * the hash from 40 zeros representing not yet created commit
    */
-  public static final String NOT_COMMITTED_HASH = StringUtil.repeat("0", 40);
+  public static final String NOT_COMMITTED_HASH = BlobIndexUtil.NOT_COMMITTED_HASH;
 
   public static final GitRevisionNumber HEAD = new GitRevisionNumber("HEAD");
 

plugins/git4idea/tests/git4idea/log/GitSha1Test.kt

@@ -0,0 +1,69 @@
+/*
+ * Copyright 2000-2016 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package git4idea.log
+
+import com.intellij.openapi.vcs.Executor.cd
+import com.intellij.openapi.vcs.Executor.touch
+import com.intellij.openapi.vcs.changes.patch.BlobIndexUtil
+import git4idea.test.GitExecutor.*
+import git4idea.test.GitSingleRepoTest
+import git4idea.test.GitTestUtil
+
+class GitSha1Test : GitSingleRepoTest() {
+  var A_FILE = "a.txt"
+
+  @Throws(Exception::class)
+  override fun setUp() {
+    super.setUp()
+    GitTestUtil.createFileStructure(myProjectRoot, A_FILE)
+    addCommit("initial")
+  }
+
+  fun `test sha for add`() {
+    cd(myProjectPath)
+    val newFile = "newFile.txt"
+    touch(newFile, "Hello World!")
+    add(newFile)
+    checkSha1ForSingleChange(BlobIndexUtil.NOT_COMMITTED_HASH, git("hash-object $newFile"))
+  }
+
+  fun `test sha for del`() {
+    cd(myProjectPath)
+    val path = myProjectRoot.findChild(A_FILE)!!.path
+    val expectedBefore = git("hash-object $path")
+    git("rm $path")
+    checkSha1ForSingleChange(expectedBefore, BlobIndexUtil.NOT_COMMITTED_HASH)
+  }
+
+  fun `test sha for modified`() {
+    cd(myProjectPath)
+    val virtualFile = myProjectRoot.findChild(A_FILE)
+    val path = virtualFile!!.path
+    val expectedBefore = git("hash-object $path")
+    setFileText(virtualFile, "echo content\n with line separator")
+    checkSha1ForSingleChange(expectedBefore, git("hash-object $path"))
+  }
+
+  private fun checkSha1ForSingleChange(expectedBefore: String?, expectedAfter: String?) {
+    updateChangeListManager()
+    val changes = changeListManager.allChanges
+    assertTrue(changes.size == 1)
+    val beforeAfterSha1 = BlobIndexUtil.getBeforeAfterSha1(changes.first())
+    assertEquals(expectedBefore, beforeAfterSha1.first)
+    assertEquals(expectedAfter, beforeAfterSha1.second)
+  }
+}
+