import type { Theme } from "@earendil-works/pi-coding-agent";
import { truncateToWidth, visibleWidth, wrapTextWithAnsi } from "@earendil-works/pi-tui";
import type { Quote } from "./quotes.js";

export interface TickerItem {
	symbol: string;
	quote?: Quote;
	error?: string;
	stale?: boolean;
}

export interface TickerView {
	items: TickerItem[];
	loading: boolean;
	updatedAt?: number;
}

export function renderTickerWidget(view: TickerView, theme: Theme, width: number): string[] {
	const renderWidth = Math.max(0, width);
	if (renderWidth === 0) return [""];
	const heading = renderHeading(view, theme);
	const separator = theme.fg("dim", "  │  ");
	const quotes = packItems(
		view.items.map((item) => renderItem(item, theme)),
		separator,
		renderWidth,
	);
	return [
		theme.fg("borderMuted", "─".repeat(renderWidth)),
		...fitLines(heading, renderWidth),
		...quotes,
	];
}

export function formatTickerPlain(view: TickerView): string[] {
	const status = view.loading
		? "Stocks · updating"
		: view.updatedAt
			? `Stocks · updated ${new Date(view.updatedAt).toLocaleTimeString()}`
			: "Stocks";
	return [status, ...view.items.map(formatItemPlain)];
}

export function mergeQuoteResults(
	current: readonly TickerItem[],
	results: ReadonlyArray<{ symbol: string; quote?: Quote; error?: string }>,
): TickerItem[] {
	const previous = new Map(current.map((item) => [item.symbol, item]));
	return results.map((result) => {
		if (result.quote) return { symbol: result.symbol, quote: result.quote };
		const existing = previous.get(result.symbol);
		return existing?.quote
			? { symbol: result.symbol, quote: existing.quote, error: result.error, stale: true }
			: { symbol: result.symbol, error: result.error };
	});
}

function renderHeading(view: TickerView, theme: Theme): string {
	if (view.loading) return theme.fg("muted", "Stocks · updating…");
	if (view.updatedAt) {
		return theme.fg("muted", `Stocks · updated ${new Date(view.updatedAt).toLocaleTimeString()}`);
	}
	return theme.fg("muted", "Stocks");
}

function renderItem(item: TickerItem, theme: Theme): string {
	const symbol = theme.fg("accent", theme.bold(item.symbol));
	if (!item.quote) return `${symbol} ${theme.fg("error", "unavailable")}`;
	const changeRole = item.quote.change >= 0 ? "success" : "error";
	const content = `${symbol} ${theme.fg("text", formatPrice(item.quote))} ${theme.fg(
		changeRole,
		formatChange(item.quote),
	)}`;
	return item.stale ? `${content} ${theme.fg("warning", "stale")}` : content;
}

function formatItemPlain(item: TickerItem): string {
	if (!item.quote) return `${item.symbol} unavailable`;
	const content = `${item.symbol} ${formatPrice(item.quote)} ${formatChange(item.quote)}`;
	return item.stale ? `${content} stale` : content;
}

function formatPrice(quote: Quote): string {
	const value = formatMarketNumber(quote.price);
	if (quote.currency === "GBp") return `${value}p`;
	return `${currencyPrefix(quote.currency)}${value}`;
}

function formatChange(quote: Quote): string {
	const sign = quote.change >= 0 ? "+" : "";
	return `${sign}${formatMarketNumber(quote.change)} (${sign}${quote.changePercent.toFixed(2)}%)`;
}

function formatMarketNumber(value: number): string {
	const absolute = Math.abs(value);
	if (absolute === 0) return "0.00";
	const magnitude = Math.floor(Math.log10(absolute));
	const significantDecimals = 6 - magnitude - 1;
	const formatted =
		significantDecimals > 8
			? value.toPrecision(6)
			: value.toFixed(Math.max(2, significantDecimals));
	return trimNumericZeros(formatted);
}

function trimNumericZeros(value: string): string {
	const [coefficient, exponent] = value.split("e");
	const [integer = value, fraction = ""] = coefficient?.split(".") ?? [value, ""];
	let trimmedFraction = fraction;
	const minimumFractionDigits = exponent === undefined ? 2 : 0;
	while (trimmedFraction.length > minimumFractionDigits && trimmedFraction.endsWith("0")) {
		trimmedFraction = trimmedFraction.slice(0, -1);
	}
	const trimmed = trimmedFraction ? `${integer}.${trimmedFraction}` : integer;
	return exponent === undefined ? trimmed : `${trimmed}e${exponent}`;
}

function currencyPrefix(currency: string | undefined): string {
	switch (currency) {
		case "USD":
			return "$";
		case "EUR":
			return "€";
		case "GBP":
			return "£";
		case "JPY":
			return "¥";
		case "CAD":
			return "C$";
		case "HKD":
			return "HK$";
		case "TWD":
			return "NT$";
		default:
			return currency ? `${currency} ` : "";
	}
}

function packItems(items: readonly string[], separator: string, width: number): string[] {
	const rows: string[] = [];
	let current = "";
	for (const item of items) {
		if (visibleWidth(item) > width) {
			if (current) rows.push(current);
			rows.push(...fitLines(item, width));
			current = "";
			continue;
		}
		const candidate = current ? `${current}${separator}${item}` : item;
		if (visibleWidth(candidate) <= width) {
			current = candidate;
			continue;
		}
		rows.push(current);
		current = item;
	}
	if (current) rows.push(current);
	return rows;
}

function fitLines(content: string, width: number): string[] {
	return wrapTextWithAnsi(content, width).map((line) => truncateToWidth(line, width, ""));
}