remove commit hash logic from revision

revision might be a list of commits, it makes no sense to have those methods on revision.
on a reference, it does.

Author: alexandresalome

src/Gitonomy/Git/Commit.php

@@ -124,7 +124,8 @@ public function __construct(Repository $repository, $hash)
         }
 
         $this->hash = $hash;
-        parent::__construct($repository, $hash, $hash);
+
+        parent::__construct($repository, $hash);
     }
 
     /**
@@ -160,6 +161,9 @@ private function initialize()
         $this->initialized = true;
     }
 
+    /**
+     * @return Diff
+     */
     public function getDiff()
     {
         $args = array('-r', '-p', '-m', '-M', '--no-commit-id', '--full-index', $this->hash);

src/Gitonomy/Git/Log.php

@@ -12,6 +12,8 @@
 
 namespace Gitonomy\Git;
 
+use Gitonomy\Git\Exception\ProcessException;
+use Gitonomy\Git\Exception\ReferenceNotFoundException;
 use Gitonomy\Git\Util\StringHelper;
 
 /**
@@ -134,6 +136,20 @@ public function setLimit($limit)
         return $this;
     }
 
+    public function getSingleCommit()
+    {
+        $limit = $this->limit;
+        $this->limit = 1;
+        $commits = $this->getCommits();
+        $this->setLimit($limit);
+
+        if (count($commits) === 0) {
+            throw new ReferenceNotFoundException('The log is empty');
+        }
+
+        return array_pop($commits);
+    }
+
     /**
      * @return array
      */
@@ -160,7 +176,11 @@ public function getCommits()
 
         $args = array_merge($args, $this->paths);
 
-        $exp = explode("\n", $this->repository->run('log', $args));
+        try {
+            $exp = explode("\n", $this->repository->run('log', $args));
+        } catch (ProcessException $e) {
+            throw new ReferenceNotFoundException(sprintf('Can not find revision "%s"', implode(' ', $this->revisions->getAsTextArray())), null, $e);
+        }
 
         $result = array();
         foreach ($exp as $hash) {

src/Gitonomy/Git/Reference.php

@@ -20,6 +20,15 @@
  */
 abstract class Reference extends Revision
 {
+    protected $commitHash;
+
+    public function __construct(Repository $repository, $revision, $commitHash = null)
+    {
+        $this->repository = $repository;
+        $this->revision   = $revision;
+        $this->commitHash = $commitHash;
+    }
+
     public function getFullname()
     {
         return $this->revision;
@@ -29,4 +38,35 @@ public function delete()
     {
         $this->repository->getReferences()->delete($this->getFullname());
     }
+
+
+    public function getCommitHash()
+    {
+        if (null !== $this->commitHash) {
+            return $this->commitHash;
+        }
+
+        try {
+            $result = $this->repository->run('rev-parse', array('--verify', $this->revision));
+        } catch (ProcessException $e) {
+            throw new ReferenceNotFoundException(sprintf('Can not find revision "%s"', $this->revision));
+        }
+
+        return $this->commitHash = trim($result);
+    }
+
+    /**
+     * Returns the commit associated to the reference.
+     *
+     * @return Gitonomy\Git\Commit
+     */
+    public function getCommit()
+    {
+        return $this->repository->getCommit($this->getCommitHash());
+    }
+
+    public function getLastModification($path = null)
+    {
+        return $this->getCommit()->getLastModification($path);
+    }
 }

src/Gitonomy/Git/Revision.php

@@ -31,16 +31,10 @@ class Revision
      */
     protected $revision;
 
-    /**
-     * @var Commit
-     */
-    protected $commitHash;
-
-    public function __construct(Repository $repository, $revision, $commitHash = null)
+    public function __construct(Repository $repository, $revision)
     {
         $this->repository = $repository;
         $this->revision   = $revision;
-        $this->commitHash = $commitHash;
     }
 
     /**
@@ -51,39 +45,14 @@ public function getLog($paths = null, $offset = null, $limit = null)
         return $this->repository->getLog($this, $paths, $offset, $limit);
     }
 
-    /**
-     * Returns the commit associated to the reference.
-     *
-     * @return Gitonomy\Git\Commit
-     */
-    public function getCommit()
-    {
-        return $this->repository->getCommit($this->getCommitHash());
-    }
-
-    public function getCommitHash()
-    {
-        if (null !== $this->commitHash) {
-            return $this->commitHash;
-        }
-
-        try {
-            $result = $this->repository->run('rev-parse', array('--verify', $this->revision));
-        } catch (ProcessException $e) {
-            throw new ReferenceNotFoundException(sprintf('Can not find revision "%s"', $this->revision));
-        }
-
-        return $this->commitHash = trim($result);
-    }
-
     /**
      * Returns the last modification date of the reference.
      *
-     * @return DateTime
+     * @return Commit
      */
-    public function getLastModification($path = null)
+    public function getCommit()
     {
-        return $this->getCommit()->getLastModification($path);
+        return $this->getLog()->getSingleCommit();
     }
 
     /**