import { json, error } from '@sveltejs/kit';
import { env } from '$env/dynamic/private';
import { db } from '$lib/server/db';
import type { RequestHandler } from './$types';

/**
 * Usage-gauge ingest. The agent PTY-drives `claude /usage` (see agent/usage.ts) and POSTs the
 * three subscription bars here. Separate from /api/ingest because the shape and cadence differ
 * (a slow, ~5-9s scrape done once per run, not per JSONL sweep).
 *
 * Auth: `Authorization: Bearer $API_TOKEN` (same token as /api/ingest).
 *
 * Accepted body — either a single gauge object or a batch:
 *   { host, ts_utc, session_pct?, week_all_pct?, week_sonnet_pct? }
 *   { host?, gauges: GaugeRow[] }            // host is a fallback for rows that omit their own
 *
 * Rows upsert by (host, ts_utc) — re-posting the same scrape is idempotent.
 */

interface IncomingGauge {
	host?: unknown;
	ts_utc?: unknown;
	session_pct?: unknown;
	week_all_pct?: unknown;
	week_sonnet_pct?: unknown;
}

interface UsageBody extends IncomingGauge {
	gauges?: unknown;
}

function str(v: unknown): string | null {
	return typeof v === 'string' && v.length > 0 ? v : null;
}

function num(v: unknown): number | null {
	return typeof v === 'number' && Number.isFinite(v) ? v : null;
}

// Lazily prepared on first request so importing this module (e.g. the build's
// analyse pass, which has no writable DB dir) never opens the database.
type Stmt = import('better-sqlite3').Statement<unknown[]>;

let prepared = false;
let upsertGaugeStmt!: Stmt;
let insertMany!: (rows: IncomingGauge[], fallbackHost: string | null) => number;

function ensurePrepared() {
	if (prepared) return;
	const conn = db();
	upsertGaugeStmt = conn.prepare(`
  INSERT INTO usage_gauges (host, ts_utc, session_pct, week_all_pct, week_sonnet_pct)
  VALUES (@host, @ts_utc, @session_pct, @week_all_pct, @week_sonnet_pct)
  ON CONFLICT(host, ts_utc) DO UPDATE SET
    session_pct     = COALESCE(excluded.session_pct, session_pct),
    week_all_pct    = COALESCE(excluded.week_all_pct, week_all_pct),
    week_sonnet_pct = COALESCE(excluded.week_sonnet_pct, week_sonnet_pct)
`);

	insertMany = conn.transaction((rows: IncomingGauge[], fallbackHost: string | null) => {
		let count = 0;
		for (const g of rows) {
			const host = str(g.host) ?? fallbackHost;
			const ts_utc = str(g.ts_utc);
			if (!host || !ts_utc) continue; // incomplete PK — skip
			upsertGaugeStmt.run({
				host,
				ts_utc,
				session_pct: num(g.session_pct),
				week_all_pct: num(g.week_all_pct),
				week_sonnet_pct: num(g.week_sonnet_pct)
			});
			count++;
		}
		return count;
	});
	prepared = true;
}

export const POST: RequestHandler = async ({ request }) => {
	const token = env.API_TOKEN;
	if (!token) throw error(500, 'server missing API_TOKEN');
	if (request.headers.get('authorization') !== `Bearer ${token}`) throw error(401, 'unauthorized');

	const body = (await request.json().catch(() => null)) as UsageBody | null;
	if (!body || typeof body !== 'object') throw error(400, 'invalid JSON body');

	ensurePrepared();
	const rows = Array.isArray(body.gauges) ? (body.gauges as IncomingGauge[]) : [body];
	const count = insertMany(rows, str(body.host));
	return json({ ok: true, gauges: count });
};

export const GET: RequestHandler = async () => json({ ok: true, service: 'toknmtr usage' });