/**
 * pi-peak-hours — peak/off-peak billing-hours indicator for LLM APIs.
 *
 * Shows one widget line above the editor while any tracked provider is in
 * its peak billing window (hidden otherwise), plus a `/peak` command with
 * the full picture: current phase, windows in the local timezone, and the
 * next flip. Times come from the system clock; the display timezone is
 * auto-detected and can be overridden in settings (`peakHours.timezone`).
 *
 * The widget deliberately does NOT touch the footer: footer replacements
 * (e.g. pi-archimedes) would hide setStatus() items, while widgets stack
 * above the editor and coexist with anything.
 */
import type { ExtensionAPI, ExtensionContext } from "@earendil-works/pi-coding-agent";
import { loadConfig } from "./config.ts";
import { reportLines, resolveTimezone, summarize, widgetSegments, type ProviderStatus } from "./render.ts";
import { SCHEDULES } from "./schedules.ts";

const WIDGET_KEY = "peak-hours";
const TICK_MS = 30_000;

export default function peakHours(pi: ExtensionAPI): void {
	const cfg = loadConfig();
	if (!cfg.enabled) return;
	const schedules = SCHEDULES.filter((s) => cfg.providers.includes(s.id));
	if (schedules.length === 0) return;

	let timer: ReturnType<typeof setInterval> | null = null;
	let lastCtx: ExtensionContext | null = null;
	let statuses: ProviderStatus[] = [];
	let signature = "";

	const widgetSignature = (): string =>
		statuses.map((s) => `${s.schedule.id}:${s.peak ? 1 : 0}`).join(",") + `|${cfg.show}`;

	const refreshWidget = (): void => {
		const ctx = lastCtx;
		if (!ctx) return;
		statuses = summarize(schedules, new Date());
		const sig = widgetSignature();
		if (sig === signature) return;
		signature = sig;
		try {
			ctx.ui.setWidget(WIDGET_KEY, (_tui, theme) => ({
				render: () => {
					const tz = resolveTimezone(cfg.timezone);
					const segments = widgetSegments(statuses, new Date(), tz, cfg.show);
					return segments ? [segments.map((s) => theme.fg(s.tone, s.text)).join("")] : [];
				},
				invalidate() {},
			}));
		} catch {
			// setWidget is unavailable outside interactive UI modes — /peak still works.
		}
	};

	pi.on("session_start", (_event, ctx) => {
		if (timer) return;
		lastCtx = ctx;
		refreshWidget();
		timer = setInterval(refreshWidget, TICK_MS);
		timer.unref();
	});

	pi.on("model_select", (_event, ctx) => {
		lastCtx = ctx;
		refreshWidget();
	});

	pi.on("session_shutdown", () => {
		if (timer) {
			clearInterval(timer);
			timer = null;
		}
		try {
			lastCtx?.ui.setWidget(WIDGET_KEY, undefined);
		} catch {
			// UI already gone
		}
		lastCtx = null;
	});

	pi.registerCommand("peak", {
		description:
			"Peak/off-peak billing hours for tracked LLM providers (DeepSeek, GLM Coding Plan). Config: peakHours in settings.json",
		handler: async (_args, ctx) => {
			const now = new Date();
			const tz = resolveTimezone(cfg.timezone);
			const lines = reportLines(summarize(schedules, now), now, tz);
			if (ctx.hasUI) {
				ctx.ui.notify(lines.join("\n"), "info");
			} else {
				console.log(lines.join("\n"));
			}
		},
	});
}