Script for converting VSCode theme to Kitty terminal theme

code-to-kitty-theme.ts

/**
 * Script for converting VSCode theme to Kitty terminal theme.
 * 
 * ```sh
 * deno code-to-kitty-theme.ts <url or file>
 * ```
 * and the output will be written to `current-theme.conf` file in the working directory.
 * 
 * Arugment can either be a remote URL to a theme JSON file or a local relative / absolute path.
 */

import { resolve, toFileUrl } from "jsr:@std/path";

if (Deno.args.length != 1) {
    throw new Error("Invalid arguments.");
}

const argument = Deno.args[0];
const url = URL.canParse(argument) ? argument : toFileUrl(resolve(argument));
const response = await fetch(url);
const { colors: themeColors } = await response.json();

const KEY_MAP: {
    [key: string]: [jsonKey: string, removeAlpha?: boolean];
} = {
    "background": ["terminal.background"],
    "foreground": ["terminal.foreground"],
    "cursor": ["terminalCursor.foreground"],
    "cursor_text_color": ["terminalCursor.background", true],
    "selection_foreground": ["terminal.background", true],
    "selection_background": ["terminal.selectionBackground", true],
    "color0": ["terminal.ansiBlack"],
    "color8": ["terminal.ansiBrightBlack"],
    "color1": ["terminal.ansiRed"],
    "color9": ["terminal.ansiBrightRed"],
    "color2": ["terminal.ansiGreen"],
    "color10": ["terminal.ansiBrightGreen"],
    "color3": ["terminal.ansiYellow"],
    "color11": ["terminal.ansiBrightYellow"],
    "color4": ["terminal.ansiBlue"],
    "color12": ["terminal.ansiBrightBlue"],
    "color5": ["terminal.ansiMagenta"],
    "color13": ["terminal.ansiBrightMagenta"],
    "color6": ["terminal.ansiCyan"],
    "color14": ["terminal.ansiBrightCyan"],
    "color7": ["terminal.ansiWhite"],
    "color15": ["terminal.ansiBrightWhite"],
};

function removeAlpha(hex: string): string {
    const hash = hex.indexOf("#");
    if (hash == -1) return "#" + hex.slice(0, 6);
    else if (hash == 0) return hex.slice(0, 7);
    throw new Error("invalid hex string input: " + hex);
}

const lines: string[] = [];

for (const key in KEY_MAP) {
    const [themeKey, alpha = false] = KEY_MAP[key];

    if (themeKey in themeColors) {
        const color = alpha
            ? removeAlpha(themeColors[themeKey])
            : themeColors[themeKey];
        lines.push(`${key.padEnd(24, " ")}${color}`);
    }
}

await Deno.writeTextFile("current-theme.conf", lines.join("\n") + "\n");