Check github URLs for existing pull request links

src/EntryCommand.php

@@ -134,16 +134,94 @@ private function prepareEntry(InputInterface $input) : string
 
     private function preparePullRequestLink(int $pr, ?string $package) : string
     {
-        $package = $package ?: (new ComposerPackage())->getName(realpath(getcwd()));
+        if (null !== $package) {
+            $link = $this->generatePullRequestLink($pr, $package);
 
+            if (null !== $link) {
+                return $link;
+            }
+
+            throw Exception\InvalidPullRequestLinkException::forPackage($package, $pr);
+        }
+
+        $link = $this->generatePullRequestLink($pr, (new ComposerPackage())->getName(realpath(getcwd())));
+
+        if (null !== $link) {
+            return $link;
+        }
+
+        foreach ($this->getGithubPackageNames() as $package) {
+            $link = $this->generatePullRequestLink($pr, $package);
+
+            if (null !== $link) {
+                return $link;
+            }
+        }
+
+        throw Exception\InvalidPullRequestLinkException::noValidLinks($pr);
+    }
+
+    private function getGithubPackageNames() : array
+    {
+        exec('git remote', $remotes, $return);
+
+        if (0 !== $return) {
+            return [];
+        }
+
+        $packages = [];
+
+        foreach ($remotes as $remote) {
+            $url = [];
+            exec(sprintf('git remote get-url %s', escapeshellarg($remote)), $url, $return);
+
+            if (0 !== $return) {
+                continue;
+            }
+
+            if (0 === preg_match('(github.com[:/](.*?)\.git)', $url[0], $matches)) {
+                continue;
+            }
+
+            $packages[] = $matches[1];
+        }
+
+        return $packages;
+    }
+
+    private function generatePullRequestLink(int $pr, string $package) : ?string
+    {
         if (! preg_match('#^[a-z0-9]+[a-z0-9_-]*/[a-z0-9]+[a-z0-9_-]*$#i', $package)) {
             throw Exception\InvalidPackageNameException::forPackage($package);
         }
 
-        return sprintf(
+        $link = sprintf(
             'https://github.com/%s/pull/%d',
             $package,
             $pr
         );
+
+        if (! $this->probeLink($link)) {
+            return null;
+        }
+
+        return $link;
+    }
+
+    private function probeLink(string $link) : bool
+    {
+        $headers = get_headers($link, 1, stream_context_create(['http' => ['method' => 'HEAD']]));
+        $statusLine = explode(' ', $headers[0]);
+        $statusCode = (int) $statusLine[1];
+
+        if ($statusCode < 300) {
+            return true;
+        }
+
+        if ($statusCode >= 300 && $statusCode <= 399 && array_key_exists('Location', $headers)) {
+            return $this->probeLink($headers['Location']);
+        }
+
+        return false;
     }
 }

src/Exception/InvalidPullRequestException.php

@@ -0,0 +1,23 @@
+<?php
+/**
+ * @see       https://github.com/phly/keep-a-changelog-tagger for the canonical source repository
+ * @copyright Copyright (c) 2018 Matthew Weier O'Phinney
+ * @license   https://github.com/phly/keep-a-changelog-tagger/blob/master/LICENSE.md New BSD License
+ */
+
+declare(strict_types=1);
+
+namespace Phly\KeepAChangelog\Exception;
+
+use RuntimeException;
+
+class InvalidPullRequestException extends RuntimeException
+{
+    public static function for(int $pr) : self
+    {
+        return new self(sprintf(
+            'PR %d is not valid',
+            $pr
+        ));
+    }
+}

src/Exception/InvalidPullRequestLinkException.php

@@ -0,0 +1,32 @@
+<?php
+/**
+ * @see       https://github.com/phly/keep-a-changelog-tagger for the canonical source repository
+ * @copyright Copyright (c) 2018 Matthew Weier O'Phinney
+ * @license   https://github.com/phly/keep-a-changelog-tagger/blob/master/LICENSE.md New BSD License
+ */
+
+declare(strict_types=1);
+
+namespace Phly\KeepAChangelog\Exception;
+
+use RuntimeException;
+
+class InvalidPullRequestLinkException extends RuntimeException
+{
+    public static function forPackage(string $package, int $pr) : self
+    {
+        return new self(sprintf(
+            'The pull request package %s has no PR %d',
+            $package,
+            $pr
+        ));
+    }
+
+    public static function noValidLinks(int $pr) : self
+    {
+        return new self(sprintf(
+            'No valid pull request link could be found for PR %d',
+            $pr
+        ));
+    }
+}

test/EntryCommandTest.php

@@ -86,7 +86,7 @@ public function testPrepareEntryReturnsEntryVerbatimIfNoPrOptionProvided()
     public function testPrepareEntryWithPrOptionRaisesExceptionIfPackageOptionIsInvalid()
     {
         $entry = 'This is the entry';
-        $pr = 42;
+        $pr = 1;
         $package = 'not-a-valid-package-name';
 
         $this->input->getArgument('entry')->willReturn($entry);
@@ -99,10 +99,26 @@ public function testPrepareEntryWithPrOptionRaisesExceptionIfPackageOptionIsInva
         $this->reflectMethod($command, 'prepareEntry')->invoke($command, $this->input->reveal());
     }
 
+    public function testPrepareEntryWithPrOptionRaisesExceptionIfLinkIsInvalid()
+    {
+        $entry = 'This is the entry';
+        $pr = 9999999999;
+        $package = 'phly/keep-a-changelog';
+
+        $this->input->getArgument('entry')->willReturn($entry);
+        $this->input->getOption('pr')->willReturn($pr);
+        $this->input->getOption('package')->willReturn($package);
+
+        $command = new EntryCommand('entry:added');
+
+        $this->expectException(Exception\InvalidPullRequestLinkException::class);
+        $this->reflectMethod($command, 'prepareEntry')->invoke($command, $this->input->reveal());
+    }
+
     public function testPrepareEntryReturnsEntryWithPrLinkPrefixedWhenPackageOptionPresentAndValid()
     {
         $entry = 'This is the entry';
-        $pr = 42;
+        $pr = 1;
         $package = 'phly/keep-a-changelog';
 
         $this->input->getArgument('entry')->willReturn($entry);
@@ -111,7 +127,7 @@ public function testPrepareEntryReturnsEntryWithPrLinkPrefixedWhenPackageOptionP
 
         $command = new EntryCommand('entry:added');
 
-        $expected = '[#42](https://github.com/phly/keep-a-changelog/pull/42) ' . $entry;
+        $expected = '[#1](https://github.com/phly/keep-a-changelog/pull/1) ' . $entry;
 
         $this->assertSame(
             $expected,