import { truncateToWidth, visibleWidth } from "@earendil-works/pi-tui";

/** Render a full-width row with a left item, right item, and a gap between them. */
export function buildFullWidthRow(
	left: string,
	right: string,
	width: number,
): string {
	if (width <= 0) return "";
	if (width <= 2) return " ".repeat(width);

	const contentWidth = width - 2;
	let l = left;
	let r = right;
	while (
		visibleWidth(l) + visibleWidth(r) + 1 > contentWidth &&
		visibleWidth(l) > 0
	) {
		l = truncateToWidth(l, Math.max(0, visibleWidth(l) - 1), "");
	}
	while (
		visibleWidth(l) + visibleWidth(r) + 1 > contentWidth &&
		visibleWidth(r) > 0
	) {
		r = truncateToWidth(r, Math.max(0, visibleWidth(r) - 1), "");
	}

	const gap = Math.max(1, contentWidth - visibleWidth(l) - visibleWidth(r));
	return " " + l + " ".repeat(gap) + r + " ";
}

/**
 * Pure text-layout helpers shared by the minimal-look extensions.
 *
 * These functions are ANSI-aware where it matters (width calculations use the
 * TUI's `visibleWidth`/`truncateToWidth`) and have no dependency on extension
 * state, making them trivial to unit test.
 */

/** Build a status line filling exactly `width`: prefix + left + gap + right. */
export function statusLine(
	prefix: string,
	left: string,
	right: string,
	width: number,
): string {
	const avail = Math.max(0, width - visibleWidth(prefix));
	let r = right;
	let l = left;
	const minGap = 1;
	while (
		visibleWidth(l) + visibleWidth(r) + minGap > avail &&
		visibleWidth(r) > 0
	) {
		r = truncateToWidth(r, Math.max(0, visibleWidth(r) - 1), "");
	}
	while (
		visibleWidth(l) + visibleWidth(r) + minGap > avail &&
		visibleWidth(l) > 0
	) {
		l = truncateToWidth(l, Math.max(0, visibleWidth(l) - 1), "");
	}
	const gap = Math.max(minGap, avail - visibleWidth(l) - visibleWidth(r));
	return `${prefix}${l}${" ".repeat(gap)}${r}`;
}

/** Shorten a cwd path: `$HOME` → `~`. */
export function formatCwd(cwd: string): string {
	const home = process.env.HOME;
	if (home && cwd.startsWith(home)) return `~${cwd.slice(home.length)}`;
	return cwd;
}

/** Strip ANSI/OSC/APC codes so we can classify a raw editor line. */
export function stripAnsi(s: string): string {
	return s.replace(/\x1b\][^\x07]*\x07/g, "").replace(/\x1b[[0-9;]*m/g, "");
}

/** A pi editor border line renders as a run of `─` (with optional indicator). */
export function isBorderLine(line: string): boolean {
	const stripped = stripAnsi(line);
	if (stripped.length === 0) return false;
	const trimmed = stripped.trim();
	if (trimmed.length === 0) return false;
	return [...trimmed].every((c) => c === "─" || c === "━" || c === "═");
}

/** Format a cost in USD: compact representation ($0, $0.0012, $1.23). */
export function formatCost(cost: number): string {
	if (cost === 0) return "$0";
	if (cost < 0.01) return `$${cost.toFixed(4)}`;
	return `$${cost.toFixed(2)}`;
}

/** Format tokens with up to three significant digits, using K or M units. */
export function formatTokenWindow(tokens: number): string {
	if (!Number.isFinite(tokens) || tokens <= 0) return "0K";

	const format = (value: number, unit: "K" | "M") => {
		const magnitude = Math.floor(Math.log10(Math.abs(value)));
		const decimals = Math.max(0, Math.min(2, 2 - magnitude));
		return `${Number(value.toFixed(decimals))}${unit}`;
	};

	if (tokens >= 1_000_000) {
		const formatted = format(tokens / 1_000_000, "M");
		return Number(formatted.slice(0, -1)) >= 1_000 ? "999M" : formatted;
	}

	const thousands = tokens / 1_000;
	const formatted = format(thousands, "K");
	return Number(formatted.slice(0, -1)) >= 1_000
		? format(tokens / 1_000_000, "M")
		: formatted;
}

/** Center `text` within `width` columns. */
export function center(text: string, width: number): string {
	const vis = visibleWidth(text);
	if (vis >= width) return text;
	const pad = Math.floor((width - vis) / 2);
	return " ".repeat(pad) + text;
}