From 35add63ec4dce39710095f17abd86777de9e5b49 Mon Sep 17 00:00:00 2001
From: Elizabeth Hunt <me@liz.coffee>
Date: Sat, 4 Oct 2025 18:36:10 -0700
Subject: Working history state

---
 src/utils/ansi.ts | 68 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 src/utils/grid.ts | 50 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 118 insertions(+)
 create mode 100644 src/utils/ansi.ts
 create mode 100644 src/utils/grid.ts

(limited to 'src/utils')

diff --git a/src/utils/ansi.ts b/src/utils/ansi.ts
new file mode 100644
index 0000000..551a365
--- /dev/null
+++ b/src/utils/ansi.ts
@@ -0,0 +1,68 @@
+import type { AnsiTermColor, AnsiColorVal, AnsiRgb } from '@/types/grid';
+import type { NumericRange } from '@/types/num';
+import type { CSSProperties } from 'react';
+
+const byteToAnsiValRatio = 255 / 5;
+
+export const ansiRgbToHex = ({ r, g, b }: AnsiRgb): string => {
+    // Scale ANSI colors (0-5) to RGB range (0-255)
+    const scaleToRgb = (val: number) => Math.round(val * byteToAnsiValRatio);
+    const rHex = scaleToRgb(r).toString(16).padStart(2, '0');
+    const gHex = scaleToRgb(g).toString(16).padStart(2, '0');
+    const bHex = scaleToRgb(b).toString(16).padStart(2, '0');
+    return `#${rHex}${gHex}${bHex}`;
+};
+
+export const hexToAnsi = (_hex: string): AnsiRgb => {
+    const hex = _hex.split('#').at(-1)!;
+    const rgb = [hex.slice(0, 2), hex.slice(2, 4), hex.slice(4, 6)].map(
+        (val) => parseInt(val, 16) || 0,
+    );
+
+    const [r, g, b] = rgb.map(
+        (value) =>
+            Math.floor(
+                Math.min(value, 255) * (1 / byteToAnsiValRatio),
+            ) as AnsiColorVal,
+    );
+    return { r, g, b };
+};
+
+export const getAnsiColorEscape = (ansi: AnsiTermColor) => {
+    const [fg, bg] = [ansi.foreground, ansi.background].map((color, i) => {
+        if (color === null) return `\x1b[39;49m`;
+        const { r, g, b } = color;
+        const id = (16 + 36 * r + 6 * g + b) as NumericRange<16, 231>;
+        return `\x1b[${3 + i}8;5;${id}m`;
+    });
+    return { fg, bg };
+};
+
+export const getAnsiEscapeCodeFromDiff = (
+    currentColor: AnsiTermColor,
+    newColor: AnsiTermColor,
+): string => {
+    const { fg: currentFg, bg: currentBg } = getAnsiColorEscape(currentColor);
+    const { fg: newFg, bg: newBg } = getAnsiColorEscape(newColor);
+
+    const fg = currentFg === newFg ? '' : newFg;
+    const bg = currentBg === newBg ? '' : newBg;
+
+    return `${fg}${bg}`;
+};
+
+export const ansiColorsEqual = (
+    color1: AnsiTermColor,
+    color2: AnsiTermColor,
+): boolean => {
+    // eh.
+    return JSON.stringify(color1) === JSON.stringify(color2);
+};
+
+export const getStyleForAnsiColor = (color: AnsiTermColor): CSSProperties => {
+    const { background, foreground } = color;
+    return {
+        backgroundColor: background ? ansiRgbToHex(background) : undefined,
+        color: foreground ? ansiRgbToHex(foreground) : undefined,
+    };
+};
diff --git a/src/utils/grid.ts b/src/utils/grid.ts
new file mode 100644
index 0000000..71370da
--- /dev/null
+++ b/src/utils/grid.ts
@@ -0,0 +1,50 @@
+import type { AnsiTermColor, Grid } from '@/types/grid';
+import { getAnsiColorEscape, getAnsiEscapeCodeFromDiff } from './ansi';
+
+const defaultColor: AnsiTermColor = { foreground: null, background: null };
+export const gridFromAscii = (
+    ascii: string,
+    color: AnsiTermColor = defaultColor,
+): Grid => {
+    const lineWidth = Math.max(...ascii.split('\n').map((line) => line.length));
+    return ascii.split('\n').map((line, y) =>
+        line
+            .split('')
+            .map((char, x) => ({
+                char,
+                color,
+                x,
+                y,
+            }))
+            .concat(
+                Array(lineWidth - line.length)
+                    .fill(0)
+                    .map((_, x) => ({
+                        char: ' ',
+                        color,
+                        x: x + line.length,
+                        y,
+                    })),
+            ),
+    );
+};
+
+export const gridToAnsi = (grid: Grid) => {
+    const reset: AnsiTermColor = { foreground: null, background: null };
+    const { fg, bg } = getAnsiColorEscape(reset);
+    const resetCode = `${fg}${bg}`;
+
+    const rows = [];
+    for (let y = 0; y < grid.length; y++) {
+        let row = '';
+        for (let x = 0; x < grid[y].length; x++) {
+            const cell = grid[y][x];
+            const previousColor = x > 0 ? grid[y][x - 1].color : reset;
+            row +=
+                getAnsiEscapeCodeFromDiff(previousColor, cell.color) +
+                cell.char;
+        }
+        rows.push(row);
+    }
+    return resetCode + rows.join(resetCode + '\n');
+};
-- 
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