import { NextRequest } from 'next/server';
import { saveCapture, getLatestCapture, clearCaptures } from '@/lib/db';
import { corsJson, corsPreflight } from '../cors';

/** Guard against a runaway page dumping tens of megabytes into SQLite every poll. */
const MAX_HTML_BYTES = 8 * 1024 * 1024;

interface CapturePayload {
    url?: string;
    title?: string;
    html?: string;
    viewport?: unknown;
    elements?: unknown;
    capturedAt?: number;
}

/** Written by the Chromium extension each time it scrapes the target tab. */
export async function POST(req: NextRequest) {
    try {
        const body = await req.json() as CapturePayload;

        if (typeof body.html !== 'string' || typeof body.url !== 'string') {
            return corsJson({ error: '`url` and `html` are required' }, { status: 400 });
        }
        if (body.html.length > MAX_HTML_BYTES) {
            return corsJson({ error: `HTML exceeds ${MAX_HTML_BYTES} bytes` }, { status: 413 });
        }

        const capturedAt = typeof body.capturedAt === 'number' ? body.capturedAt : Date.now();

        saveCapture({
            url: body.url,
            title: typeof body.title === 'string' ? body.title : '',
            html: body.html,
            viewport: JSON.stringify(body.viewport ?? {}),
            elements: JSON.stringify(body.elements ?? []),
            captured_at: capturedAt,
        });

        return corsJson({ ok: true, capturedAt, bytes: body.html.length });
    } catch (err: any) {
        return corsJson({ error: err?.message ?? 'Failed to save capture' }, { status: 500 });
    }
}

/** Read by the AutoBuyer page. Pass `?since=<capturedAt>` to skip re-sending
 *  an unchanged capture — the HTML blob is megabytes and the page polls often. */
export async function GET(req: NextRequest) {
    const row = getLatestCapture();
    if (!row) return corsJson({ capture: null });

    const since = Number(req.nextUrl.searchParams.get('since'));
    if (Number.isFinite(since) && since > 0 && since >= row.captured_at) {
        return corsJson({ unchanged: true });
    }

    return corsJson({
        capture: {
            url: row.url,
            title: row.title,
            html: row.html,
            viewport: safeParse(row.viewport, {}),
            elements: safeParse(row.elements, []),
            capturedAt: row.captured_at,
        },
    });
}

export async function DELETE() {
    clearCaptures();
    return corsJson({ ok: true });
}

export async function OPTIONS() {
    return corsPreflight();
}

function safeParse<T>(json: string, fallback: T): T {
    try { return JSON.parse(json) as T; } catch { return fallback; }
}