<?php

/**

* Handles loading data from raw git objects

*

* @author Christopher Han <xiphux@gmail.com>

* @copyright Copyright (c) 2012 Christopher Han

* @package GitPHP

* @subpackage Git

*/

class GitPHP_GitObjectLoader

{

/**

* The project

*

* @var GitPHP_Project

*/

protected $project;

/**

* The list of packs

*

* @var GitPHP_Pack[]

*/

protected $packs = array();

/**

* Whether packs have been read

*

* @var boolean

*/

protected $packsRead = false;

/**

* Constructor

*

* @param GitPHP_Project $project project

*/

public function __construct($project)

{

if (!$project)

throw new Exception('Project is required');

$this->project = $project;

}

/**

* Gets the project

*

* @return GitPHP_Project project

*/

public function GetProject()

{

return $this->project;

}

/**

* Gets the raw content of an object

*

* @param string $hash object hash

* @param int $type returns the object type

* @return string object data

*/

public function GetObject($hash, &$type = 0)

{

if (!preg_match('/^[0-9A-Fa-f]{40}$/', $hash)) {

return false;

}

// first check if it's unpacked

$path = $this->project->GetPath() . '/objects/' . substr($hash, 0, 2) . '/' . substr($hash, 2);

if (file_exists($path)) {

list($header, $data) = explode("\0", gzuncompress(file_get_contents($path)), 2);

sscanf($header, "%s %d", $typestr, $size);

switch ($typestr) {

case 'commit':

$type = GitPHP_Pack::OBJ_COMMIT;

break;

case 'tree':

$type = GitPHP_Pack::OBJ_TREE;

break;

case 'blob':

$type = GitPHP_Pack::OBJ_BLOB;

break;

case 'tag':

$type = GitPHP_Pack::OBJ_TAG;

break;

}

return $data;

}

if (!$this->packsRead) {

$this->ReadPacks();

}

// then try packs

foreach ($this->packs as $pack) {

$data = $pack->GetObject($hash, $type);

if ($data !== false) {

return $data;

}

}

return false;

}

/**

* Read the list of packs in the repository

*/

private function ReadPacks()

{

$dh = opendir($this->project->GetPath() . '/objects/pack');

if ($dh !== false) {

while (($file = readdir($dh)) !== false) {

if (preg_match('/^pack-([0-9A-Fa-f]{40})\.idx$/', $file, $regs)) {

$this->packs[] = new GitPHP_Pack($this->project, $regs[1], $this);

}

}

}

$this->packsRead = true;

}

/**

* Ensures a hash prefix is unique

*

* @param string $hash full hash

* @param string $prefix abbreviated hash prefix

*/

public function EnsureUniqueHash($hash, $prefix)

{

if (empty($hash) || empty($prefix))

return null;

if (!(preg_match('/[0-9A-Fa-f]{40}/', $hash)))

return $hash;

if (preg_match('/[0-9A-Fa-f]{40}/', $prefix))

return $prefix;

$hashMap = array();

$matches = $this->FindHashObjects($prefix);

foreach ($matches as $matchingHash) {

$hashMap[$matchingHash] = 1;

}

if (!$this->packsRead) {

$this->ReadPacks();

}

foreach ($this->packs as $pack) {

$matches = $pack->FindHashes($prefix);

foreach ($matches as $matchingHash) {

$hashMap[$matchingHash] = 1;

}

}

if (count($hashMap) == 0) {

return $hash;

}

if (count($hashMap) == 1) {

return $prefix;

}

for ($len = strlen($prefix)+1; $len < 40; $len++) {

$prefix = substr($hash, 0, $len);

foreach ($hashMap as $matchingHash => $val) {

if (substr_compare($matchingHash, $prefix, 0, $len) !== 0) {

unset($hashMap[$matchingHash]);

}

}

if (count($hashMap) == 1) {

return $prefix;

}

}

return $hash;

}

/**

* Expands an abbreviated hash to the full hash

*

* @param string $abbrevHash abbreviated hash

* @return string full hash

*/

public function ExpandHash($abbrevHash)

{

if (!(preg_match('/[0-9A-Fa-f]{4,39}/', $abbrevHash))) {

return $abbrevHash;

}

$matches = $this->FindHashObjects($abbrevHash);

if (!$this->packsRead) {

$this->ReadPacks();

}

foreach ($this->packs as $pack) {

$matches = array_merge($matches, $pack->FindHashes($abbrevHash));

}

$matches = array_unique($matches);

if (count($matches) < 1)

return $abbrevHash;

if (count($matches) > 1) {

throw new GitPHP_AmbiguousHashException($abbrevHash);

}

return $matches[0];

}

/**

* Finds loose hash files matching a given prefix

*

* @param string $prefix hash prefix

* @return string[] array of hashes

*/

private function FindHashObjects($prefix)

{

$matches = array();

if (empty($prefix)) {

return $matches;

}

$subdir = substr($prefix, 0, 2);

$fulldir = $this->project->GetPath() . '/objects/' . $subdir;

if (!is_dir($fulldir)) {

return $matches;

}

$prefixlen = strlen($prefix);

$dh = opendir($fulldir);

if ($dh !== false) {

while (($file = readdir($dh)) !== false) {

$fullhash = $subdir . $file;

if (substr_compare($fullhash, $prefix, 0, $prefixlen) === 0) {

$matches[] = $fullhash;

}

}

}

return $matches;

}

}