/**
 * 查询与报告生成
 *
 * 从 UsageStatsData 的 daily 数据聚合查询结果。
 */

import type { UsageStatsData, UsageQuery, UsageReport, ToolUsageRow } from "./types";

/** 获取今天的 YYYY-MM-DD */
export function today(): string {
	return new Date().toISOString().slice(0, 10);
}

/** 获取 N 天前的 YYYY-MM-DD */
export function daysAgo(n: number): string {
	return new Date(Date.now() - n * 86400000).toISOString().slice(0, 10);
}

/** 获取日期范围 */
function getDaysForPeriod(
	period: "today" | "week" | "all",
	daily: UsageStatsData["daily"],
): string[] {
	if (period === "today") return [today()];
	if (period === "week") {
		return Array.from({ length: 7 }, (_, i) => daysAgo(i));
	}
	return Object.keys(daily).sort();
}

/** 格式化日期范围为可读文本 */
function formatPeriod(period: "today" | "week" | "all", days: string[]): string {
	if (period === "today") return today();
	if (period === "week") return `${days[days.length - 1]} ~ ${days[0]}`;
	if (days.length === 0) return "无数据";
	return `${days[0]} ~ ${days[days.length - 1]}`;
}

/** 从 daily 数据生成查询报告 */
export function buildReport(
	data: UsageStatsData,
	options: UsageQuery = {},
): UsageReport {
	const period = options.period ?? "today";
	const toolFilter = options.toolName?.toLowerCase();
	const days = getDaysForPeriod(period, data.daily);

	// 聚合
	const aggregated = new Map<string, { ai: number; user: number; errors: number }>();
	for (const day of days) {
		const dayData = data.daily[day];
		if (!dayData) continue;
		for (const [toolName, stats] of Object.entries(dayData)) {
			const existing = aggregated.get(toolName) ?? { ai: 0, user: 0, errors: 0 };
			existing.ai += stats.ai;
			existing.user += stats.user;
			existing.errors += stats.errors;
			aggregated.set(toolName, existing);
		}
	}

	// 过滤 + 组装 rows
	const rows: ToolUsageRow[] = [];
	for (const [toolName, stats] of aggregated) {
		if (toolFilter && !toolName.toLowerCase().startsWith(toolFilter)) continue;
		rows.push({
			toolName,
			ai: stats.ai,
			user: stats.user,
			errors: stats.errors,
			total: stats.ai + stats.user,
		});
	}

	rows.sort((a, b) => b.total - a.total);

	const totals = rows.reduce(
		(acc, r) => ({
			ai: acc.ai + r.ai,
			user: acc.user + r.user,
			errors: acc.errors + r.errors,
			total: acc.total + r.total,
		}),
		{ ai: 0, user: 0, errors: 0, total: 0 },
	);

	return {
		period: formatPeriod(period, days),
		rows,
		totals,
		uniqueTools: rows.length,
	};
}