ics.php

<?php

// ============================================================
//  CONFIG
//
//  Usage: ics_transform.php?cal=mycalendar&pw=secret
//
//  Reads: mycalendar.yaml  (password, source URL, and rules)
// ============================================================

require_once __DIR__ . '/yaml.php';

// ── ?cal parameter ──────────────────────────────────────────
$cal = $_GET['cal'] ?? '';
if ($cal === '' || !preg_match('/^[a-zA-Z0-9_-]+$/', $cal)) {
    http_response_code(400);
    header('Content-Type: text/plain');
    exit('Missing or invalid "cal" parameter.');
}

// ── Load calendar YAML ──────────────────────────────────────
$yamlFile = __DIR__ . '/' . $cal . '.yaml';
if (!is_readable($yamlFile)) {
    http_response_code(404);
    header('Content-Type: text/plain');
    exit('Calendar "' . htmlspecialchars($cal) . '" not found.');
}

$config = Spyc::YAMLLoad($yamlFile);

define('PASSWORD',   $config['password']   ?? '');
define('SOURCE_ICS', $config['source_ics'] ?? '');
$rules = $config['rules'] ?? [];

// ── AUTH ────────────────────────────────────────────────────
if (!isset($_GET['pw']) || $_GET['pw'] !== PASSWORD) {
    http_response_code(401);
    header('Content-Type: text/plain');
    exit('Unauthorized');
}

$debug = isset($_GET['debug']);
$text  = isset($_GET['text']);


// ============================================================
//  FETCH SOURCE
// ============================================================

$raw = @file_get_contents(SOURCE_ICS);
if ($raw === false) {
    http_response_code(502);
    header('Content-Type: text/plain');
    exit('Could not fetch source calendar.');
}


// ============================================================
//  HELPERS
// ============================================================

const DAY_MAP = [
    'mon' => 1,
    'tue' => 2,
    'wed' => 3,
    'thu' => 4,
    'fri' => 5,
    'sat' => 6,
    'sun' => 7,
];



/**
 * Parse DTSTART value.
 *
 * Returns:
 *   ['allday' => true,  'weekday' => 1–7]
 *   ['allday' => false, 'weekday' => 1–7, 'time' => 'HH:MM']
 *   null on failure
 */
function parseDtstart(string $value): ?array
{
    // Date-time: 20240313T110000[Z]  or  TZID=…:20240313T110000
    if (preg_match('/(\d{4})(\d{2})(\d{2})T(\d{2})(\d{2})/i', $value, $m)) {
        $ts = mktime(0, 0, 0, (int)$m[2], (int)$m[3], (int)$m[1]);
        return [
            'allday'  => false,
            'weekday' => (int)date('N', $ts),
            'time'    => $m[4] . ':' . $m[5],
            'date'    => $m[1] . '-' . $m[2] . '-' . $m[3], // YYYY-MM-DD
        ];
    }
    // Date-only (all-day): VALUE=DATE:20240313  or  bare 20240313
    if (preg_match('/(\d{4})(\d{2})(\d{2})\s*$/', trim($value), $m)) {
        $ts = mktime(0, 0, 0, (int)$m[2], (int)$m[3], (int)$m[1]);
        return [
            'allday'  => true,
            'weekday' => (int)date('N', $ts),
            'date'    => $m[1] . '-' . $m[2] . '-' . $m[3],
        ];
    }
    return null;
}

function timeToMinutes(string $hhmm): int
{
    [$h, $m] = explode(':', $hhmm);
    return (int)$h * 60 + (int)$m;
}

/** YYYY-MM-DD → integer YYYYMMDD for easy comparison */
function dateToInt(string $date): int
{
    return (int)str_replace('-', '', $date);
}

/**
 * Returns true when $event matches ALL non-null criteria in $filter.
 *
 * time/date/name filters are lists of condition objects:
 *   [{type: range, from: HH:MM, to: HH:MM}]
 *   [{type: exact, starts: HH:MM}]
 *   [{type: before, at: HH:MM}]
 *   [{type: allday}]
 *   [{type: startswith, text: Foo}]
 *   [{type: exact, at: YYYY-MM-DD}]
 * All conditions in the list must match (AND).
 */
function matchesFilter(array $filter, array $event): bool
{

    $dtstart = isset($event['DTSTART']) ? parseDtstart($event['DTSTART']) : null;

    // ── days ────────────────────────────────────────────────
    if (($filter['days'] ?? null) !== null) {
        if ($dtstart === null) return false;
        $days    = (array)$filter['days'];
        $allowed = array_map(fn($d) => DAY_MAP[strtolower($d)] ?? 0, $days);
        if (!in_array($dtstart['weekday'], $allowed, true)) return false;
    }

    // ── time ────────────────────────────────────────────────
    if (($filter['time'] ?? null) !== null) {
        if ($dtstart === null) return false;
        foreach ((array)$filter['time'] as $cond) {
            $type = $cond['type'] ?? '';
            if ($type === 'allday') {
                if (!$dtstart['allday']) return false;
                continue;
            }
            // For timed comparisons, all-day events are treated as 00:00
            $eventMin = $dtstart['allday'] ? 0 : timeToMinutes($dtstart['time']);
            switch ($type) {
                case 'exact':
                    if (isset($cond['starts']) && $eventMin !== timeToMinutes($cond['starts'])) return false;
                    break;
                case 'range':
                    if ($eventMin < timeToMinutes($cond['from']) || $eventMin > timeToMinutes($cond['to'])) return false;
                    break;
                case 'before':
                    if ($eventMin >= timeToMinutes($cond['at'])) return false;
                    break;
                case 'after':
                    if ($eventMin <= timeToMinutes($cond['at'])) return false;
                    break;
            }
        }
    }

    // ── date ────────────────────────────────────────────────
    if (($filter['date'] ?? null) !== null) {
        if ($dtstart === null) return false;
        $eventDate = dateToInt($dtstart['date']);
        foreach ((array)$filter['date'] as $cond) {
            switch ($cond['type'] ?? '') {
                case 'exact':
                    if ($eventDate !== dateToInt($cond['at'])) return false;
                    break;
                case 'range':
                    if ($eventDate < dateToInt($cond['from']) || $eventDate > dateToInt($cond['to'])) return false;
                    break;
                case 'before':
                    if ($eventDate >= dateToInt($cond['at'])) return false;
                    break;
                case 'after':
                    if ($eventDate <= dateToInt($cond['at'])) return false;
                    break;
            }
        }
    }

    // ── busy_status ─────────────────────────────────────────
    if (($filter['busy_status'] ?? null) !== null) {
        $actual = strtoupper($event['X-MICROSOFT-CDO-BUSYSTATUS'] ?? '');
        if ($actual !== strtoupper($filter['busy_status'])) return false;
    }

    // ── name ────────────────────────────────────────────────
    if (($filter['name'] ?? null) !== null) {
        $summary = $event['SUMMARY'] ?? '';
        foreach ((array)$filter['name'] as $cond) {
            $needle = $cond['text'] ?? '';
            switch ($cond['type'] ?? '') {
                case 'exact':
                    if ($summary !== $needle) return false;
                    break;
                case 'contains':
                    if (stripos($summary, $needle) === false) return false;
                    break;
                case 'startswith':
                    if (stripos($summary, $needle) !== 0) return false;
                    break;
                case 'endswith':
                    $len = strlen($needle);
                    if ($len > 0 && substr_compare($summary, $needle, -$len, $len, true) !== 0) return false;
                    break;
            }
        }
    }

    // ── recurrent ───────────────────────────────────────────
    if (($filter['recurrent'] ?? null) !== null) {
        $isRecurrent = isset($event['RRULE']) || isset($event['RECURRENCE-ID']);
        if ($filter['recurrent'] !== $isRecurrent) return false;
    }

    return true;
}

/**
 * Replace or insert a property inside a VEVENT block string.
 * Correctly handles folded (multi-line) property values.
 */
function setProperty(string $block, string $prop, string $value): string
{
    // Match property including any folded continuation lines
    $pattern = '/^' . preg_quote($prop, '/') . '(?:;[^:]*)?:.*?(?=\r?\n[^ \t\r\n])/ms';
    $line    = $prop . ':' . $value;
    if (preg_match($pattern, $block)) {
        return preg_replace($pattern, $line, $block);
    }
    // Property not present → insert before END:VEVENT
    return str_replace("\r\nEND:VEVENT", "\r\n" . $line . "\r\nEND:VEVENT", $block);
}

/**
 * Parse a VEVENT block into a key→value map.
 * Unfolds RFC 5545 folded lines; uses base property keys (strips parameters).
 */
function parseVEvent(string $block): array
{
    $unfolded = preg_replace('/\r?\n[ \t]/', '', $block);
    $props    = [];
    foreach (explode("\n", $unfolded) as $line) {
        $line = rtrim($line, "\r");
        if ($line === '' || $line === 'BEGIN:VEVENT' || $line === 'END:VEVENT') continue;
        $colon = strpos($line, ':');
        if ($colon === false) continue;
        $baseKey         = strtok(substr($line, 0, $colon), ';');
        $props[$baseKey] = substr($line, $colon + 1);
    }
    return $props;
}


// ============================================================
//  TRANSFORM
// ============================================================

$timeStart   = hrtime(true);
$linesBefore = substr_count($raw, "\n");
$countTotal   = 0;
$countChanged = 0;
$countRemoved = 0;
$eventLog     = []; // [{summary, date, status}]

$output = preg_replace_callback(
    '/BEGIN:VEVENT\r?\n.*?END:VEVENT/s',
    function (array $matches) use ($rules, &$countTotal, &$countChanged, &$countRemoved, &$eventLog): string {
        $block = $matches[0];
        $event = parseVEvent($block);
        $countTotal++;

        $summary    = $event['SUMMARY'] ?? '(no title)';
        $dtRaw      = $event['DTSTART'] ?? '';
        $dt         = parseDtstart($dtRaw);
        $timeCol    = $dt ? ($dt['allday'] ? '(allday)' : $dt['time']) : '?';
        $dateStr    = $dt ? ($dt['date'] . "\t\t" . str_pad($timeCol, 10)) : "?\t\t?\t\t";
        $isRecurring = isset($event['RRULE']) || isset($event['RECURRENCE-ID']);

        foreach ($rules as $ruleIndex => $rule) {
            if (!matchesFilter($rule['filter'], $event)) {
                continue;
            }

            $apply = $rule['apply'] ?? [];

            if (!empty($apply['remove'])) {
                $countRemoved++;
                $eventLog[] = ['summary' => $summary, 'date' => $dateStr, 'status' => 'removed', 'rule' => $ruleIndex, 'recurring' => $isRecurring];
                return '';
            }

            $modified = $block;
            if (!empty($apply['name'])) {
                $modified = setProperty($modified, 'SUMMARY', $apply['name']);
            }
            if (!empty($apply['busy_status'])) {
                $modified = setProperty($modified, 'X-MICROSOFT-CDO-BUSYSTATUS', $apply['busy_status']);
            }
            if (!empty($apply['location'])) {
                $modified = setProperty($modified, 'LOCATION', $apply['location']);
            }
            if (isset($apply['reminder'])) {
                $minutes  = (int)$apply['reminder'];
                $valarm   = "\r\nBEGIN:VALARM"
                    . "\r\nTRIGGER:-PT{$minutes}M"
                    . "\r\nACTION:DISPLAY"
                    . "\r\nDESCRIPTION:Reminder"
                    . "\r\nEND:VALARM";
                // Remove any existing VALARM first, then insert before END:VEVENT
                $modified = preg_replace('/\r?\nBEGIN:VALARM.*?END:VALARM/s', '', $modified);
                $modified = str_replace("\r\nEND:VEVENT", $valarm . "\r\nEND:VEVENT", $modified);
            }

            if ($modified !== $block) {
                $countChanged++;
                $newSummary = parseVEvent($modified)['SUMMARY'] ?? $summary;
                $displaySummary = $newSummary !== $summary ? $summary . ' --> ' . $newSummary : $summary;
                $eventLog[] = ['summary' => $displaySummary, 'date' => $dateStr, 'status' => 'changed', 'rule' => $ruleIndex, 'recurring' => $isRecurring];
            } else {
                $eventLog[] = ['summary' => $summary, 'date' => $dateStr, 'status' => 'matched/unchanged', 'rule' => $ruleIndex, 'recurring' => $isRecurring];
            }
            return $modified;

            break; // first matching rule wins
        }

        $eventLog[] = ['summary' => $summary, 'date' => $dateStr, 'status' => 'unchanged', 'rule' => null, 'recurring' => $isRecurring];
        return $block;
    },
    $raw
);

// Tidy up blank lines left by removed events
$output = preg_replace('/(\r?\n){3,}/', "\r\n", $output) ?? $output;

$linesAfter = substr_count($output, "\n");
$timeMs     = round((hrtime(true) - $timeStart) / 1e6, 2);


// ============================================================
//  OUTPUT
// ============================================================

header('Cache-Control: no-store');

if ($debug) {
    header('Content-Type: text/plain; charset=utf-8');
    $total   = $countTotal ?: 1; // avoid division by zero
    $pct     = fn(int $n) => $n . ' (' . round($n / $total * 100) . '%)';
    $linesIn = $linesBefore ?: 1;
    $sep     = str_repeat('─', 80);
    $lines   = [
        'calendar : ' . $cal,
        'events   : ' . $countTotal,
        'changed  : ' . $pct($countChanged),
        'removed  : ' . $pct($countRemoved),
        'unchanged: ' . $pct($countTotal - $countChanged - $countRemoved),
        '',
        'lines in : ' . $linesBefore,
        'lines out: ' . $linesAfter . ' (' . round($linesAfter / $linesIn * 100) . '%)',
        '',
        'duration : ' . $timeMs . ' ms',
        '',
    ];
    $groups = ['removed' => [], 'changed' => [], 'matched/unchanged' => [], 'unchanged' => []];
    foreach ($eventLog as $e) $groups[$e['status']][] = $e;
    foreach ($groups as $status => $entries) {
        if (empty($entries)) continue;
        $lines[] = strtoupper($status) . ' (' . count($entries) . ')';
        $lines[] = $sep;
        foreach ($entries as $e) {
            $ruleLabel = $e['rule'] !== null ? '[rule ' . $e['rule'] . ']' : '';
            $recLabel  = $e['recurring'] ? ' ↻' : '';
            $lines[] = '  ' . $e['date'] . "\t\t" . str_pad($ruleLabel, 10) . "\t\t" . $e['summary'] . $recLabel;
        }
        $lines[] = '';
    }
    echo implode("\n", $lines);
} elseif ($text) {
    header('Content-Type: text/plain; charset=utf-8');
    echo $output;
} else {
    header('Content-Type: text/calendar; charset=utf-8');
    header('Content-Disposition: inline');
    echo $output;
}