import type { ExtensionCommandContext } from "@earendil-works/pi-coding-agent";
import { matchesKey } from "@earendil-works/pi-tui";
import { fmt } from "../format";
import type { ListRow } from "../types";
import { showPanel } from "./panel";

/** Scrollable list panel (↑↓/PgUp/PgDn/Home/End), closed with Esc/Enter. No-op outside TUI mode. */
export const showListUi = async (
	ctx: ExtensionCommandContext,
	title: string,
	rows: ListRow[],
): Promise<void> => {
	if (ctx.mode !== "tui") return;

	const sorted = [...rows].sort((a, b) => b.tokens - a.tokens);

	if (sorted.length === 0) {
		await showPanel(ctx, ctx.ui.theme.fg("dim", `No ${title.toLowerCase()} loaded.`));
		return;
	}

	await ctx.ui.custom((tui, theme, _kb, done) => {
		let offset = 0;

		const pageHeight = () => Math.max(8, tui.terminal.rows - 6);

		const render = (width: number): string[] => {
			const nameCol = 26;
			const tokCol = 8;
			const descCol = Math.max(8, width - nameCol - tokCol - 6);
			const page = pageHeight();

			const out: string[] = [];
			out.push(theme.fg("accent", theme.bold(title)));
			out.push(
				theme.fg(
					"dim",
					`${sorted.length} items, largest first — ↑↓/PgUp/PgDn scroll · Esc/Enter close`,
				),
			);
			out.push("");
			for (let i = offset; i < Math.min(offset + page, sorted.length); i++) {
				const r = sorted[i];
				const name =
					r.name.length > nameCol - 1 ? r.name.slice(0, nameCol - 2) + "…" : r.name;
				const desc =
					r.desc.length > descCol ? r.desc.slice(0, descCol - 1) + "…" : r.desc;
				const highlight = i === offset ? "accent" : "text";
				out.push(
					theme.fg(
						highlight,
						name.padEnd(nameCol) + desc.padEnd(descCol) + " " + fmt(r.tokens),
					),
				);
			}
			out.push("");
			out.push(
				theme.fg(
					"dim",
					`Showing ${offset + 1}–${Math.min(offset + page, sorted.length)} of ${sorted.length}`,
				),
			);
			return out;
		};

		return {
			render,
			invalidate: () => {},
			handleInput: (data: string) => {
				const page = pageHeight();
				if (matchesKey(data, "up")) offset = Math.max(0, offset - 1);
				else if (matchesKey(data, "down")) offset = Math.min(sorted.length - 1, offset + 1);
				else if (matchesKey(data, "pageUp")) offset = Math.max(0, offset - page);
				else if (matchesKey(data, "pageDown"))
					offset = Math.min(sorted.length - 1, offset + page);
				else if (matchesKey(data, "home")) offset = 0;
				else if (matchesKey(data, "end")) offset = Math.max(0, sorted.length - 1);
				else if (matchesKey(data, "enter") || matchesKey(data, "escape")) done(undefined);
			},
		};
	});
};