oh-my-pi/packages/tui/src/utils.ts

import type { Ellipsis, ExtractSegmentsResult, SliceResult } from "@oh-my-pi/pi-natives";
import {
	extractSegments as nativeExtractSegments,
	sliceWithWidth as nativeSliceWithWidth,
	truncateToWidth as nativeTruncateToWidth,
	wrapTextWithAnsi as nativeWrapTextWithAnsi,
} from "@oh-my-pi/pi-natives";
import { getDefaultTabWidth, getIndentation } from "@oh-my-pi/pi-utils";

export { Ellipsis } from "@oh-my-pi/pi-natives";

export { getDefaultTabWidth, getIndentation } from "@oh-my-pi/pi-utils";

export function sliceWithWidth(line: string, startCol: number, length: number, strict?: boolean | null): SliceResult {
	return nativeSliceWithWidth(line, startCol, length, strict, getDefaultTabWidth());
}

export function truncateToWidth(
	text: string,
	maxWidth: number,
	ellipsisKind?: Ellipsis | null,
	pad?: boolean | null,
): string {
	return nativeTruncateToWidth(text, maxWidth, ellipsisKind, pad, getDefaultTabWidth());
}

export function wrapTextWithAnsi(text: string, width: number): string[] {
	return nativeWrapTextWithAnsi(text, width, getDefaultTabWidth());
}

export function extractSegments(
	line: string,
	beforeEnd: number,
	afterStart: number,
	afterLen: number,
	strictAfter: boolean,
): ExtractSegmentsResult {
	return nativeExtractSegments(line, beforeEnd, afterStart, afterLen, strictAfter, getDefaultTabWidth());
}

// Pre-allocated space buffer for padding
const SPACE_BUFFER = " ".repeat(512);

/**
 * Tab width in columns for `file`, using `process.cwd()` as the project root for relative paths.
 */
export function getIndentationNoescape(file?: string): number {
	return getIndentation(file, process.cwd());
}

/*
 * Replace tabs with configured spacing for consistent rendering.
 */
export function replaceTabs(text: string, file?: string): string {
	return text.replaceAll("\t", " ".repeat(getIndentation(file)));
}

/**
 * Returns a string of n spaces. Uses a pre-allocated buffer for efficiency.
 */
export function padding(n: number): string {
	if (n <= 0) return "";
	if (n <= 512) return SPACE_BUFFER.slice(0, n);
	return " ".repeat(n);
}

// Grapheme segmenter (shared instance)
const segmenter = new Intl.Segmenter(undefined, { granularity: "grapheme" });

/**
 * Get the shared grapheme segmenter instance.
 */
export function getSegmenter(): Intl.Segmenter {
	return segmenter;
}

export function visibleWidthRaw(str: string): number {
	if (!str) {
		return 0;
	}

	// Fast path: pure ASCII printable
	let tabLength = 0;
	const tabWidth = getDefaultTabWidth();
	let isPureAscii = true;
	for (let i = 0; i < str.length; i++) {
		const code = str.charCodeAt(i);
		if (code === 9) {
			tabLength += tabWidth;
		} else if (code < 0x20 || code > 0x7e) {
			isPureAscii = false;
		}
	}
	if (isPureAscii) {
		return str.length + tabLength;
	}
	return Bun.stringWidth(str) + tabLength;
}

/**
 * Calculate the visible width of a string in terminal columns.
 */
export function visibleWidth(str: string): number {
	if (!str) return 0;
	return visibleWidthRaw(str);
}

const makeBoolArray = (chars: string): ReadonlyArray<boolean> => {
	const table = Array.from({ length: 128 }, () => false);
	for (let i = 0; i < chars.length; i++) {
		const code = chars.charCodeAt(i);
		if (code < table.length) {
			table[code] = true;
		}
	}
	return table;
};

const ASCII_WHITESPACE = makeBoolArray("\x09\x0a\x0b\x0c\x0d\x20");

/**
 * Check if a character is whitespace.
 */
export function isWhitespaceChar(char: string): boolean {
	const code = char.codePointAt(0) || 0;
	return ASCII_WHITESPACE[code] ?? false;
}

const ASCII_PUNCTUATION = makeBoolArray("(){}[]<>.,;:'\"!?+-=*/\\|&%^$#@~`");

/**
 * Check if a character is punctuation.
 */
export function isPunctuationChar(char: string): boolean {
	const code = char.codePointAt(0) || 0;
	return ASCII_PUNCTUATION[code] ?? false;
}

export type WordNavKind = "whitespace" | "delimiter" | "cjk" | "word" | "other";

const WORD_NAV_RE_WHITESPACE = /^\p{White_Space}$/u;
const WORD_NAV_RE_PUNCT = /^\p{P}$/u;
const WORD_NAV_RE_SYMBOL = /^\p{S}$/u;
const WORD_NAV_RE_LETTER = /^\p{L}$/u;
const WORD_NAV_RE_NUMBER = /^\p{N}$/u;
const WORD_NAV_RE_HAN = /^\p{Script=Han}$/u;
const WORD_NAV_RE_HIRAGANA = /^\p{Script=Hiragana}$/u;
const WORD_NAV_RE_KATAKANA = /^\p{Script=Katakana}$/u;
const WORD_NAV_RE_HANGUL = /^\p{Script=Hangul}$/u;

function firstCodePointChar(str: string): string {
	const cp = str.codePointAt(0);
	if (cp === undefined) return "";
	return String.fromCodePoint(cp);
}

/**
 * Coarse Unicode-aware character classification for word navigation (Option/Alt + Left/Right).
 * This intentionally avoids language-specific word segmentation for predictability across scripts.
 */
export function getWordNavKind(grapheme: string): WordNavKind {
	if (!grapheme) return "other";
	const ch = firstCodePointChar(grapheme);
	if (!ch) return "other";
	if (WORD_NAV_RE_WHITESPACE.test(ch)) return "whitespace";
	if (WORD_NAV_RE_PUNCT.test(ch) || WORD_NAV_RE_SYMBOL.test(ch)) return "delimiter";
	if (
		WORD_NAV_RE_HAN.test(ch) ||
		WORD_NAV_RE_HIRAGANA.test(ch) ||
		WORD_NAV_RE_KATAKANA.test(ch) ||
		WORD_NAV_RE_HANGUL.test(ch)
	) {
		return "cjk";
	}
	if (ch === "_" || WORD_NAV_RE_LETTER.test(ch) || WORD_NAV_RE_NUMBER.test(ch)) return "word";
	return "other";
}

const WORD_NAV_JOINERS = new Set(["'", "’", "-", "‐", "‑"]);

export function isWordNavJoiner(grapheme: string): boolean {
	const ch = firstCodePointChar(grapheme);
	return WORD_NAV_JOINERS.has(ch);
}

/**
 * Move the cursor one "word" to the left using Unicode-aware coarse navigation.
 *
 * Returns a new cursor index in the range [0, text.length].
 */
export function moveWordLeft(text: string, cursor: number): number {
	const len = text.length;
	if (len === 0) return 0;
	let i = Math.min(Math.max(cursor, 0), len);
	if (i === 0) return 0;

	const graphemes = [...segmenter.segment(text.slice(0, i))];
	if (graphemes.length === 0) return 0;

	// Skip trailing whitespace.
	while (graphemes.length > 0 && getWordNavKind(graphemes[graphemes.length - 1]?.segment || "") === "whitespace") {
		i -= graphemes.pop()?.segment.length || 0;
	}
	if (i === 0 || graphemes.length === 0) return i;

	const kind = getWordNavKind(graphemes[graphemes.length - 1]?.segment || "");
	if (kind === "delimiter" || kind === "cjk") {
		while (graphemes.length > 0 && getWordNavKind(graphemes[graphemes.length - 1]?.segment || "") === kind) {
			i -= graphemes.pop()?.segment.length || 0;
		}
		return i;
	}

	if (kind === "word") {
		// Skip word run (letters/numbers/underscore), keeping common joiners inside words.
		let hasRightWord = false;
		while (graphemes.length > 0) {
			const g = graphemes[graphemes.length - 1]?.segment || "";
			const k = getWordNavKind(g);
			if (k === "word") {
				hasRightWord = true;
				i -= graphemes.pop()?.segment.length || 0;
				continue;
			}
			if (hasRightWord && k === "delimiter" && isWordNavJoiner(g)) {
				const left = graphemes[graphemes.length - 2]?.segment || "";
				if (getWordNavKind(left) === "word") {
					i -= graphemes.pop()?.segment.length || 0;
					continue;
				}
			}
			break;
		}
		return i;
	}

	// Fallback: move by one grapheme.
	i -= graphemes.pop()?.segment.length || 0;
	return Math.max(0, i);
}

/**
 * Move the cursor one "word" to the right using Unicode-aware coarse navigation.
 *
 * Returns a new cursor index in the range [0, text.length].
 */
export function moveWordRight(text: string, cursor: number): number {
	const len = text.length;
	if (len === 0) return 0;
	let i = Math.min(Math.max(cursor, 0), len);
	if (i === len) return len;

	const iterator = segmenter.segment(text.slice(i))[Symbol.iterator]();
	let next = iterator.next();

	// Skip leading whitespace.
	while (!next.done && getWordNavKind(next.value.segment) === "whitespace") {
		i += next.value.segment.length;
		next = iterator.next();
	}
	if (next.done) return i;

	const firstKind = getWordNavKind(next.value.segment);
	if (firstKind === "delimiter" || firstKind === "cjk") {
		while (!next.done && getWordNavKind(next.value.segment) === firstKind) {
			i += next.value.segment.length;
			next = iterator.next();
		}
		return i;
	}

	if (firstKind === "word") {
		let hasLeftWord = false;
		while (!next.done) {
			const segment = next.value.segment;
			const k = getWordNavKind(segment);
			if (k === "word") {
				hasLeftWord = true;
				i += segment.length;
				next = iterator.next();
				continue;
			}
			if (hasLeftWord && k === "delimiter" && isWordNavJoiner(segment)) {
				const lookahead = iterator.next();
				if (!lookahead.done && getWordNavKind(lookahead.value.segment) === "word") {
					i += segment.length;
					next = lookahead;
					continue;
				}
			}
			break;
		}
		return i;
	}

	// Fallback: move by one grapheme.
	return i + next.value.segment.length;
}

/**
 * Apply background color to a line, padding to full width.
 *
 * @param line - Line of text (may contain ANSI codes)
 * @param width - Total width to pad to
 * @param bgFn - Background color function
 * @returns Line with background applied and padded to width
 */
export function applyBackgroundToLine(line: string, width: number, bgFn: (text: string) => string): string {
	// Calculate padding needed
	const visibleLen = visibleWidth(line);
	const paddingNeeded = Math.max(0, width - visibleLen);

	// Apply background to content + padding
	const withPadding = line + padding(paddingNeeded);
	return bgFn(withPadding);
}

/**
 * Extract a range of visible columns from a line. Handles ANSI codes and wide chars.
 *
 * @param strict - If true, exclude wide chars at boundary that would extend past the range
 */
export function sliceByColumn(line: string, startCol: number, length: number, strict = false): string {
	return sliceWithWidth(line, startCol, length, strict).text;
}