chalk/source/vendor/ansi-styles/index.js

const ANSI_BACKGROUND_OFFSET = 10;

const wrapAnsi16 = (offset = 0) => code => `\u001B[${code + offset}m`;

const wrapAnsi256 = (offset = 0) => code => `\u001B[${38 + offset};5;${code}m`;

const wrapAnsi16m = (offset = 0) => (red, green, blue) => `\u001B[${38 + offset};2;${Math.round(red)};${Math.round(green)};${Math.round(blue)}m`;

function assembleStyles() {
	const codes = new Map();
	const styles = {
		modifier: {
			reset: [0, 0],
			// 21 isn't widely supported and 22 does the same thing
			bold: [1, 22],
			dim: [2, 22],
			italic: [3, 23],
			underline: [4, 24],
			overline: [53, 55],
			inverse: [7, 27],
			hidden: [8, 28],
			strikethrough: [9, 29],
		},
		color: {
			black: [30, 39],
			red: [31, 39],
			green: [32, 39],
			yellow: [33, 39],
			blue: [34, 39],
			magenta: [35, 39],
			cyan: [36, 39],
			white: [37, 39],

			// Bright color
			blackBright: [90, 39],
			redBright: [91, 39],
			greenBright: [92, 39],
			yellowBright: [93, 39],
			blueBright: [94, 39],
			magentaBright: [95, 39],
			cyanBright: [96, 39],
			whiteBright: [97, 39],
		},
		bgColor: {
			bgBlack: [40, 49],
			bgRed: [41, 49],
			bgGreen: [42, 49],
			bgYellow: [43, 49],
			bgBlue: [44, 49],
			bgMagenta: [45, 49],
			bgCyan: [46, 49],
			bgWhite: [47, 49],

			// Bright color
			bgBlackBright: [100, 49],
			bgRedBright: [101, 49],
			bgGreenBright: [102, 49],
			bgYellowBright: [103, 49],
			bgBlueBright: [104, 49],
			bgMagentaBright: [105, 49],
			bgCyanBright: [106, 49],
			bgWhiteBright: [107, 49],
		},
	};

	// Alias bright black as gray (and grey)
	styles.color.gray = styles.color.blackBright;
	styles.bgColor.bgGray = styles.bgColor.bgBlackBright;
	styles.color.grey = styles.color.blackBright;
	styles.bgColor.bgGrey = styles.bgColor.bgBlackBright;

	for (const [groupName, group] of Object.entries(styles)) {
		for (const [styleName, style] of Object.entries(group)) {
			styles[styleName] = {
				open: `\u001B[${style[0]}m`,
				close: `\u001B[${style[1]}m`,
			};

			group[styleName] = styles[styleName];

			codes.set(style[0], style[1]);
		}

		Object.defineProperty(styles, groupName, {
			value: group,
			enumerable: false,
		});
	}

	Object.defineProperty(styles, 'codes', {
		value: codes,
		enumerable: false,
	});

	styles.color.close = '\u001B[39m';
	styles.bgColor.close = '\u001B[49m';

	styles.color.ansi = wrapAnsi16();
	styles.color.ansi256 = wrapAnsi256();
	styles.color.ansi16m = wrapAnsi16m();
	styles.bgColor.ansi = wrapAnsi16(ANSI_BACKGROUND_OFFSET);
	styles.bgColor.ansi256 = wrapAnsi256(ANSI_BACKGROUND_OFFSET);
	styles.bgColor.ansi16m = wrapAnsi16m(ANSI_BACKGROUND_OFFSET);

	// From https://github.com/Qix-/color-convert/blob/3f0e0d4e92e235796ccb17f6e85c72094a651f49/conversions.js
	Object.defineProperties(styles, {
		rgbToAnsi256: {
			value: (red, green, blue) => {
				// We use the extended greyscale palette here, with the exception of
				// black and white. normal palette only has 4 greyscale shades.
				if (red === green && green === blue) {
					if (red < 8) {
						return 16;
					}

					if (red > 248) {
						return 231;
					}

					return Math.round(((red - 8) / 247) * 24) + 232;
				}

				return 16
					+ (36 * Math.round(red / 255 * 5))
					+ (6 * Math.round(green / 255 * 5))
					+ Math.round(blue / 255 * 5);
			},
			enumerable: false,
		},
		hexToRgb: {
			value: hex => {
				const matches = /(?<colorString>[a-f\d]{6}|[a-f\d]{3})/i.exec(hex.toString(16));
				if (!matches) {
					return [0, 0, 0];
				}

				let {colorString} = matches.groups;

				if (colorString.length === 3) {
					colorString = [...colorString].map(character => character + character).join('');
				}

				const integer = Number.parseInt(colorString, 16);

				return [
					/* eslint-disable no-bitwise */
					(integer >> 16) & 0xFF,
					(integer >> 8) & 0xFF,
					integer & 0xFF,
					/* eslint-enable no-bitwise */
				];
			},
			enumerable: false,
		},
		hexToAnsi256: {
			value: hex => styles.rgbToAnsi256(...styles.hexToRgb(hex)),
			enumerable: false,
		},
		ansi256ToAnsi: {
			value: code => {
				if (code < 8) {
					return 30 + code;
				}

				if (code < 16) {
					return 90 + (code - 8);
				}

				let red;
				let green;
				let blue;

				if (code >= 232) {
					red = (((code - 232) * 10) + 8) / 255;
					green = red;
					blue = red;
				} else {
					code -= 16;

					const remainder = code % 36;

					red = Math.floor(code / 36) / 5;
					green = Math.floor(remainder / 6) / 5;
					blue = (remainder % 6) / 5;
				}

				const value = Math.max(red, green, blue) * 2;

				if (value === 0) {
					return 30;
				}

				// eslint-disable-next-line no-bitwise
				let result = 30 + ((Math.round(blue) << 2) | (Math.round(green) << 1) | Math.round(red));

				if (value === 2) {
					result += 60;
				}

				return result;
			},
			enumerable: false,
		},
		rgbToAnsi: {
			value: (red, green, blue) => styles.ansi256ToAnsi(styles.rgbToAnsi256(red, green, blue)),
			enumerable: false,
		},
		hexToAnsi: {
			value: hex => styles.ansi256ToAnsi(styles.hexToAnsi256(hex)),
			enumerable: false,
		},
	});

	return styles;
}

const ansiStyles = assembleStyles();

export default ansiStyles;