1<?php
2
3namespace dokuwiki\ChangeLog;
4
5use dokuwiki\Utf8\PhpString;
6
7/**
8 * Provides methods for handling of changelog
9 */
10trait ChangeLogTrait
11{
12    /**
13     * Adds an entry to the changelog file
14     *
15     * @return array added log line as revision info
16     */
17    abstract public function addLogEntry(array $info, $timestamp = null);
18
19    /**
20     * Parses a changelog line into its components
21     *
22     * @param string $line changelog line
23     * @return array|bool parsed line or false
24     * @author Ben Coburn <btcoburn@silicodon.net>
25     *
26     */
27    public static function parseLogLine($line)
28    {
29        $info = sexplode("\t", rtrim($line, "\n"), 8);
30        if ($info[3]) { // we need at least the page id to consider it a valid line
31            return [
32                'date' => (int)$info[0], // unix timestamp
33                'ip' => $info[1], // IP address (127.0.0.1)
34                'type' => $info[2], // log line type
35                'id' => $info[3], // page id
36                'user' => $info[4], // user name
37                'sum' => $info[5], // edit summary (or action reason)
38                'extra' => $info[6], // extra data (varies by line type)
39                'sizechange' => ($info[7] != '') ? (int)$info[7] : null, // size difference in bytes
40            ];
41        } else {
42            return false;
43        }
44    }
45
46    /**
47     * Build a changelog line from its components
48     *
49     * @param array $info Revision info structure
50     * @param int $timestamp log line date (optional)
51     * @return string changelog line
52     */
53    public static function buildLogLine(array &$info, $timestamp = null)
54    {
55        $strip = ["\t", "\n"];
56        $entry = [
57            'date' => $timestamp ?? $info['date'],
58            'ip' => $info['ip'],
59            'type' => str_replace($strip, '', $info['type']),
60            'id' => $info['id'],
61            'user' => $info['user'],
62            'sum' => PhpString::substr(str_replace($strip, '', $info['sum'] ?? ''), 0, 255),
63            'extra' => str_replace($strip, '', $info['extra']),
64            'sizechange' => $info['sizechange']
65        ];
66        $info = $entry;
67        return implode("\t", $entry) . "\n";
68    }
69
70    /**
71     * Returns path to changelog
72     *
73     * @return string path to file
74     */
75    abstract protected function getChangelogFilename();
76
77    /**
78     * Checks if the ID has old revisions
79     * @return boolean
80     */
81    public function hasRevisions()
82    {
83        $logfile = $this->getChangelogFilename();
84        return file_exists($logfile);
85    }
86
87
88    /** @var int */
89    protected $chunk_size;
90
91    /**
92     * Set chunk size for file reading
93     * Chunk size zero let read whole file at once
94     *
95     * @param int $chunk_size maximum block size read from file
96     */
97    public function setChunkSize($chunk_size)
98    {
99        if (!is_numeric($chunk_size)) $chunk_size = 0;
100
101        $this->chunk_size = max($chunk_size, 0);
102    }
103
104    /**
105     * Returns lines from changelog.
106     * If file larger than $chunk_size, only chunk is read that could contain $rev.
107     *
108     * When reference timestamp $rev is outside time range of changelog, readloglines() will return
109     * lines in first or last chunk, but they obviously does not contain $rev.
110     *
111     * @param int $rev revision timestamp
112     * @return array|false
113     *     if success returns array(fp, array(changeloglines), $head, $tail, $eof)
114     *     where fp only defined for chuck reading, needs closing.
115     *     otherwise false
116     */
117    protected function readloglines($rev)
118    {
119        $file = $this->getChangelogFilename();
120
121        if (!file_exists($file)) {
122            return false;
123        }
124
125        $fp = null;
126        $head = 0;
127        $tail = 0;
128        $eof = 0;
129
130        if (filesize($file) < $this->chunk_size || $this->chunk_size == 0) {
131            // read whole file
132            $lines = file($file);
133            if ($lines === false) {
134                return false;
135            }
136        } else {
137            // read by chunk
138            $fp = fopen($file, 'rb'); // "file pointer"
139            if ($fp === false) {
140                return false;
141            }
142            fseek($fp, 0, SEEK_END);
143            $eof = ftell($fp);
144            $tail = $eof;
145
146            // find chunk
147            while ($tail - $head > $this->chunk_size) {
148                $finger = $head + (int)(($tail - $head) / 2);
149                $finger = $this->getNewlinepointer($fp, $finger);
150                $tmp = fgets($fp);
151                if ($finger == $head || $finger == $tail) {
152                    break;
153                }
154                $info = $this->parseLogLine($tmp);
155                $finger_rev = $info['date'];
156
157                if ($finger_rev > $rev) {
158                    $tail = $finger;
159                } else {
160                    $head = $finger;
161                }
162            }
163
164            if ($tail - $head < 1) {
165                // could not find chunk, assume requested rev is missing
166                fclose($fp);
167                return false;
168            }
169
170            $lines = $this->readChunk($fp, $head, $tail);
171        }
172        return [$fp, $lines, $head, $tail, $eof];
173    }
174
175    /**
176     * Read chunk and return array with lines of given chunk.
177     * Has no check if $head and $tail are really at a new line
178     *
179     * @param resource $fp resource file pointer
180     * @param int $head start point chunk
181     * @param int $tail end point chunk
182     * @return array lines read from chunk
183     */
184    protected function readChunk($fp, $head, $tail)
185    {
186        $chunk = '';
187        $chunk_size = max($tail - $head, 0); // found chunk size
188        $got = 0;
189        fseek($fp, $head);
190        while ($got < $chunk_size && !feof($fp)) {
191            $tmp = @fread($fp, max(min($this->chunk_size, $chunk_size - $got), 0));
192            if ($tmp === false) { //error state
193                break;
194            }
195            $got += strlen($tmp);
196            $chunk .= $tmp;
197        }
198        $lines = explode("\n", $chunk);
199        array_pop($lines); // remove trailing newline
200        return $lines;
201    }
202
203    /**
204     * Set pointer to first new line after $finger and return its position
205     *
206     * @param resource $fp file pointer
207     * @param int $finger a pointer
208     * @return int pointer
209     */
210    protected function getNewlinepointer($fp, $finger)
211    {
212        fseek($fp, $finger);
213        $nl = $finger;
214        if ($finger > 0) {
215            fgets($fp); // slip the finger forward to a new line
216            $nl = ftell($fp);
217        }
218        return $nl;
219    }
220
221    /**
222     * Returns the next lines of the changelog  of the chunk before head or after tail
223     *
224     * @param resource $fp file pointer
225     * @param int $head position head of last chunk
226     * @param int $tail position tail of last chunk
227     * @param int $direction positive forward, negative backward
228     * @return array with entries:
229     *    - $lines: changelog lines of read chunk
230     *    - $head: head of chunk
231     *    - $tail: tail of chunk
232     */
233    protected function readAdjacentChunk($fp, $head, $tail, $direction)
234    {
235        if (!$fp) return [[], $head, $tail];
236
237        if ($direction > 0) {
238            //read forward
239            $head = $tail;
240            $tail = $head + (int)($this->chunk_size * (2 / 3));
241            $tail = $this->getNewlinepointer($fp, $tail);
242        } else {
243            //read backward
244            $tail = $head;
245            $head = max($tail - $this->chunk_size, 0);
246            while (true) {
247                $nl = $this->getNewlinepointer($fp, $head);
248                // was the chunk big enough? if not, take another bite
249                if ($nl > 0 && $tail <= $nl) {
250                    $head = max($head - $this->chunk_size, 0);
251                } else {
252                    $head = $nl;
253                    break;
254                }
255            }
256        }
257
258        //load next chunk
259        $lines = $this->readChunk($fp, $head, $tail);
260        return [$lines, $head, $tail];
261    }
262}
263