Converting Remote Relative Paths To Absolute Paths

I tried looking for a similar question, but was unable to. I'm looking for push in the right direction. What I'm currently doing is gathering a list of all href values of a remote

Solution 1:

I think you would need to use regular expressions on the href path to make sure that it is consistent. You can also get an accurate base url from parse_url():

<?php$href = '../images/sunflower.png';
$href = preg_replace('~^\.{0,2}\/~', '', $href);
?>

Here we strip the periods and the slashes from the beginning of the string. And then prepend the base url:

<?php$url = 'http://www.example.com/home/index.html';
$url = parse_url($url);

$abspath = $url['scheme'] . '://' . $url['host'] . '/' . $href;

echo$abspath;
?>

Should output what you want: http://www.example.com/images/sunflower.png

UPDATE

If you want the first directory from the base url, then use explode on the parsed url's path key:

$first_directory = '';
if (isset($url['path'])) {
    $patharray = explode('/', $url['path']);
    if (count($patharray)>2){
        $first_directory = explode('/', $url['path'])[1] . '/';
    }
}

And add that to the output variable:

$abspath = $url['scheme'] . '://' . $url['host'] . '/' . $first_directory . $href;

Another Update

To find how the href values relate to the base url, you can search for the occurence of ../ or / at the beginning of the href value, and then adjust your absolute url accordingly. This should help you figure out what the scenarios are:

<?php$href = '../../images/sunflower.png';
preg_match('~^(\.{0,2}\/)+~', $href, $matches); //preg_match to check if it existsif (substr_count($matches[0], '../')){ // substr_count to count number of '../'echo'Go up ' . substr_count($matches[0], '../') . ' directories';
}
elseif (substr_count($matches[0], '/')){
    echo'Root directory';
}
else {
    echo'Current directory';
}
?>

Check the demo on IDEONE.

Solution 2:

I ended up writing my own function, after a push in the right direction from @bozdoz.

The function takes two arguments, first one is $resource, which is the relative file path. And the second one is is the base url (which will be used to construct an absolute url).

This was design for my project purposes, I'm not sure it will fit anyone who is looking for a similar solution. Feel free to use it, and provide any efficiency improvements.

Updated version Thanks to Tim Cooper

functionrel2abs_v2($resource, $base_url) 
{
$base_url = parse_url($base_url);

if(substr($resource, 0, 4) !== "http" && substr($resource, 0, 5) !== "https") // if no http/https is present, then {$resource} is a relative path.
{
# There is a "../" in the stringif (strpos($resource, "../") !== false)
{
$dir_count = substr_count($resource, "../");

$path_array = explode("/", $base_url["path"]);
$path_count = count($path_array); // 4$path_index = ($path_count - $dir_count) - 2;

$resource = trim(str_replace("../", "", $resource));

if($path_index > 0) { $fs = "/"; }

if($dir_count > 0)
{
$base_url_path = implode("/", array_slice($path_array, $dir_count, $path_index - $dir_count + 1));
return$base_url['scheme'] . '://' . $base_url['host'] . $fs . $base_url_path ."/". $resource;
}
}

# Latest addition - remove if unexplained behaviour is in place.if(starts_with($resource, "//"))
{
return trim(str_replace("//", "", $resource));      
}

if (starts_with($resource, "/"))
{
return$base_url["scheme"] . "://" . $base_url["host"] . $resource;
}
else
{
$path_array = explode("/", $base_url["path"]);

end($path_array);
$last_id = key($path_array);

return$base_url["scheme"] . "://" . $base_url["host"] . "/" . $path_array[--$last_id] . "/" . $resource;
}

}
else
{
return$resource;
}
}