/**
 * pi-usage-stats — 扩展包工具使用次数统计
 *
 * agent_end 时从 session jsonl 增量扫描 toolCall/toolResult，
 * 用 cursor（byte offset）记录处理进度，避免重复累加。
 * 零运行时事件监听，只在 turn 结束时处理。
 *
 * 数据文件：~/.pi/agent/data/usage-stats.json
 */

import type { ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { homedir } from "node:os";
import { join } from "node:path";
import { existsSync } from "node:fs";
import { UsageTracker } from "./lib/tracker";
import { setTracker } from "./lib/wrap-command";
import type { UsageQuery } from "./lib/types";
import { buildReport } from "./lib/query";

/** 格式化统计报告为可读文本 */
function formatReport(report: ReturnType<typeof buildReport>): string {
	const lines: string[] = [];
	const colW = [24, 8, 8, 8, 8];

	// 计算字符串的终端显示宽度（CJK 字符占 2 列）
	const displayWidth = (s: string) => {
		let w = 0;
		for (const ch of s) {
			const cp = ch.codePointAt(0)!;
			// CJK Unified Ideographs + CJK Extension + Fullwidth + Katakana/Hangul etc.
			w += (cp >= 0x4e00 && cp <= 0x9fff) || (cp >= 0x3000 && cp <= 0x30ff) || (cp >= 0xff00 && cp <= 0xffef) || (cp >= 0x2e80 && cp <= 0x2eff) || (cp >= 0x3400 && cp <= 0x4dbf) || (cp >= 0xf900 && cp <= 0xfaff) ? 2 : 1;
		}
		return w;
	};

	const pad = (s: string | number, w: number) => {
		const str = String(s);
		return str + " ".repeat(Math.max(0, w - displayWidth(str)));
	};
	const rpad = (s: string | number, w: number) => {
		const str = String(s);
		return " ".repeat(Math.max(0, w - displayWidth(str))) + str;
	};

	lines.push(`📊 工具使用统计 (${report.period})`);
	lines.push("─".repeat(58));
	lines.push(
		`${pad("工具名", colW[0])} ${rpad("AI调用", colW[1])} ${rpad("用户", colW[2])} ${rpad("错误", colW[3])} ${rpad("总计", colW[4])}`,
	);
	lines.push("─".repeat(58));

	for (const row of report.rows) {
		lines.push(
			`${pad(row.toolName, colW[0])} ${rpad(row.ai, colW[1])} ${rpad(row.user, colW[2])} ${rpad(row.errors, colW[3])} ${rpad(row.total, colW[4])}`,
		);
	}

	lines.push("─".repeat(58));
	lines.push(
		`${pad("合计", colW[0])} ${rpad(report.totals.ai, colW[1])} ${rpad(report.totals.user, colW[2])} ${rpad(report.totals.errors, colW[3])} ${rpad(report.totals.total, colW[4])}`,
	);
	lines.push(`\n共 ${report.uniqueTools} 个工具`);

	return lines.join("\n");
}

/** 获取当前 session 的 jsonl 文件路径 */
function getSessionJsonlPath(sessionId: string): string | null {
	// 项目级 session
	const projectPath = join(process.cwd(), ".pi/sessions", `${sessionId}.jsonl`);
	if (existsSync(projectPath)) return projectPath;
	// 全局 session
	const globalPath = join(homedir(), ".pi/sessions", `${sessionId}.jsonl`);
	if (existsSync(globalPath)) return globalPath;
	return null;
}

export default function (pi: ExtensionAPI): void {
	const statsPath = join(homedir(), ".pi/agent/data/usage-stats.json");
	const tracker = new UsageTracker(statsPath);
	setTracker(tracker);

	// ── 1. agent_end — 增量扫描 session jsonl ────────────────
	pi.on("agent_end", async () => {
		const sessionId = process.env.PI_SESSION_ID;
		if (!sessionId) return;

		const jsonlPath = getSessionJsonlPath(sessionId);
		if (!jsonlPath) return;

		tracker.processSessionFile(sessionId, jsonlPath);
		tracker.cleanup(180);
		tracker.flush();
	});

	// ── 2. /usage 命令（自身记录用户调用）────────────────────
	pi.registerCommand("usage", {
		description: "查看扩展包工具使用统计。用法: /usage [today|week|all] [--tool <名称>]",
		handler: async (args: unknown, ctx: any) => {
			tracker.recordUserCall("usage");
			const options = parseUsageArgs(typeof args === "string" ? args : "");
			const report = buildReport(tracker.getStats(), options);
			ctx.ui.notify(formatReport(report), "info");
		},
	});

	// ── 3. usage_stats 工具（供 AI 调用）──────────────────────
	pi.registerTool({
		name: "usage_stats",
		label: "Usage Stats",
		description:
			"查询扩展包工具使用统计。返回 AI 调用次数、用户命令调用次数、错误次数等。",
		parameters: {
			type: "object",
			properties: {
				period: {
					type: "string",
					enum: ["today", "week", "all"],
					description: "时间范围：today=今天，week=近7天，all=全部",
				},
				toolName: {
					type: "string",
					description: "按工具名过滤（前缀匹配）",
				},
			},
		},
		async execute(
			_id: string,
			params: Record<string, unknown>,
			_signal: AbortSignal | undefined,
			_onUpdate: undefined,
			_ctx: undefined,
		): Promise<{ content: Array<{ type: "text"; text: string }> }> {
			const options: UsageQuery = {};
			if (params.period) options.period = params.period as UsageQuery["period"];
			if (params.toolName) options.toolName = params.toolName as string;

			const report = buildReport(tracker.getStats(), options);
			return { content: [{ type: "text", text: formatReport(report) }] };
		},
	});
}

/** 解析 /usage 命令参数 */
function parseUsageArgs(args: string): UsageQuery {
	const options: UsageQuery = {};
	const parts = args.split(/\s+/);
	for (let i = 0; i < parts.length; i++) {
		if (["today", "week", "all"].includes(parts[i])) {
			options.period = parts[i] as UsageQuery["period"];
		} else if (parts[i] === "--tool" && parts[i + 1]) {
			options.toolName = parts[++i];
		}
	}
	return options;
}