store side art as one ANSI file, render it with PHP (cached)

2026-10-03 15:22:16 +02:00
parent 8e3b3be401
commit 2e80e535b3
6 changed files with 195 additions and 189 deletions
@@ -0,0 +1,101 @@
+<?php
+/**
+ * ANSI art (a .ans file you can `cat` in a terminal) to HTML for the side
+ * panels. Understands foreground colors: truecolor (38;2;r;g;b), 256-color
+ * (38;5;n), the 16 basic ones, and resets; everything else is ignored.
+ * $mirror flips it left-right, swapping /\ () <> [] {} so shapes still read.
+ */
+
+function ansi_color(array $p, ?string $cur): ?string
+{
+    static $basic = ['000000', 'aa0000', '00aa00', 'aa5500', '0000aa', 'aa00aa', '00aaaa', 'aaaaaa',
+                     '555555', 'ff5555', '55ff55', 'ffff55', '5555ff', 'ff55ff', '55ffff', 'ffffff'];
+    for ($i = 0; $i < count($p); $i++) {
+        $n = (int) $p[$i];
+        if ($n === 0 || $n === 39) {
+            $cur = null;
+        } elseif ($n >= 30 && $n <= 37) {
+            $cur = $basic[$n - 30];
+        } elseif ($n >= 90 && $n <= 97) {
+            $cur = $basic[$n - 82];
+        } elseif ($n === 38 && ($p[$i + 1] ?? '') === '2') {
+            $cur = sprintf('%02x%02x%02x', $p[$i + 2] ?? 0, $p[$i + 3] ?? 0, $p[$i + 4] ?? 0);
+            $i += 4;
+        } elseif ($n === 38 && ($p[$i + 1] ?? '') === '5') {
+            $c = (int) ($p[$i + 2] ?? 0);
+            $i += 2;
+            if ($c < 16) {
+                $cur = $basic[$c];
+            } elseif ($c < 232) {
+                $c -= 16;
+                $lvl = static fn(int $v): int => $v ? 55 + 40 * $v : 0;
+                $cur = sprintf('%02x%02x%02x', $lvl(intdiv($c, 36)), $lvl(intdiv($c, 6) % 6), $lvl($c % 6));
+            } else {
+                $cur = str_repeat(sprintf('%02x', 8 + 10 * ($c - 232)), 3);
+            }
+        }
+    }
+    return $cur;
+}
+
+/** ansi_html(), cached on disk until the .ans file changes (parsing costs ~30 ms a side). */
+function ansi_html_cached(string $file, bool $mirror = false): string
+{
+    $dir = (defined('DATA_DIR') ? DATA_DIR : sys_get_temp_dir()) . '/art-cache';
+    $base = $dir . '/' . md5($file . '|' . (int) $mirror);
+    $key = $base . '-' . filemtime($file) . '.html';
+    if (is_file($key)) {
+        return (string) file_get_contents($key);
+    }
+    $html = ansi_html($file, $mirror);
+    @mkdir($dir, 0755, true);
+    array_map('unlink', glob($base . '-*.html') ?: []); // every deploy bumps the mtime
+    $tmp = $key . '.' . getmypid();
+    if (@file_put_contents($tmp, $html) !== false) {
+        rename($tmp, $key);
+    }
+    return $html;
+}
+
+function ansi_html(string $file, bool $mirror = false): string
+{
+    static $flip = ['/' => '\\', '\\' => '/', '(' => ')', ')' => '(', '<' => '>', '>' => '<',
+                    '[' => ']', ']' => '[', '{' => '}', '}' => '{'];
+    $lines = [];
+    foreach (explode("\n", rtrim((string) file_get_contents($file), "\n")) as $line) {
+        // split into [char, color] cells
+        $cells = [];
+        $cur = null;
+        foreach (preg_split('/(\e\[[0-9;]*m)/', $line, -1, PREG_SPLIT_DELIM_CAPTURE | PREG_SPLIT_NO_EMPTY) as $part) {
+            if ($part[0] === "\e") {
+                $cur = ansi_color(explode(';', substr($part, 2, -1)), $cur);
+                continue;
+            }
+            foreach (mb_str_split($part) as $ch) {
+                $cells[] = [$ch, $cur];
+            }
+        }
+        $lines[] = $cells;
+    }
+
+    $width = max(array_map('count', $lines) ?: [0]);
+    $out = [];
+    foreach ($lines as $cells) {
+        $cells = array_pad($cells, $width, [' ', null]);
+        if ($mirror) {
+            $cells = array_map(static fn($c) => [$flip[$c[0]] ?? $c[0], $c[1]], array_reverse($cells));
+        }
+        $html = '';
+        $open = null;
+        foreach ($cells as [$ch, $color]) {
+            // blanks have no color of their own; let them ride along in the open run
+            if ($ch !== ' ' && $color !== $open) {
+                $html .= ($open !== null ? '</i>' : '') . ($color !== null ? "<i style=\"color:#$color\">" : '');
+                $open = $color;
+            }
+            $html .= htmlspecialchars($ch);
+        }
+        $out[] = $html . ($open !== null ? '</i>' : '');
+    }
+    return implode("\n", $out);
+}