pi/packages/tui/src/components/text.ts

import { stripVTControlCharacters } from "node:util";
import type { Component } from "../tui.js";

/**
 * Text component - displays multi-line text with word wrapping
 */
export class Text implements Component {
	private text: string;
	private paddingX: number; // Left/right padding
	private paddingY: number; // Top/bottom padding

	// Cache for rendered output
	private cachedText?: string;
	private cachedWidth?: number;
	private cachedLines?: string[];

	constructor(text: string = "", paddingX: number = 1, paddingY: number = 1) {
		this.text = text;
		this.paddingX = paddingX;
		this.paddingY = paddingY;
	}

	setText(text: string): void {
		this.text = text;
		// Invalidate cache when text changes
		this.cachedText = undefined;
		this.cachedWidth = undefined;
		this.cachedLines = undefined;
	}

	render(width: number): string[] {
		// Check cache
		if (this.cachedLines && this.cachedText === this.text && this.cachedWidth === width) {
			return this.cachedLines;
		}

		// Calculate available width for content (subtract horizontal padding)
		const contentWidth = Math.max(1, width - this.paddingX * 2);

		if (!this.text) {
			const result = [""];
			// Update cache
			this.cachedText = this.text;
			this.cachedWidth = width;
			this.cachedLines = result;
			return result;
		}

		const lines: string[] = [];
		const textLines = this.text.split("\n");

		for (const line of textLines) {
			if (line.length <= contentWidth) {
				lines.push(line);
			} else {
				// Word wrap
				const words = line.split(" ");
				let currentLine = "";

				for (const word of words) {
					if (currentLine.length === 0) {
						currentLine = word;
					} else if (currentLine.length + 1 + word.length <= contentWidth) {
						currentLine += " " + word;
					} else {
						lines.push(currentLine);
						currentLine = word;
					}
				}

				if (currentLine.length > 0) {
					lines.push(currentLine);
				}
			}
		}

		// Add padding to each line
		const leftPad = " ".repeat(this.paddingX);
		const paddedLines: string[] = [];

		for (const line of lines) {
			// Calculate visible length (strip ANSI codes)
			const visibleLength = stripVTControlCharacters(line).length;
			// Right padding to fill to width (accounting for left padding and content)
			const rightPadLength = Math.max(0, width - this.paddingX - visibleLength);
			const rightPad = " ".repeat(rightPadLength);
			paddedLines.push(leftPad + line + rightPad);
		}

		// Add top padding (empty lines)
		const emptyLine = " ".repeat(width);
		const topPadding: string[] = [];
		for (let i = 0; i < this.paddingY; i++) {
			topPadding.push(emptyLine);
		}

		// Add bottom padding (empty lines)
		const bottomPadding: string[] = [];
		for (let i = 0; i < this.paddingY; i++) {
			bottomPadding.push(emptyLine);
		}

		// Combine top padding, content, and bottom padding
		const result = [...topPadding, ...paddedLines, ...bottomPadding];

		// Update cache
		this.cachedText = this.text;
		this.cachedWidth = width;
		this.cachedLines = result;

		return result.length > 0 ? result : [""];
	}
}