import { api } from '$lib/convex/_generated/api';
import { error } from '@sveltejs/kit';
import type { RequestHandler } from './$types';

function detectImageType(bytes: Uint8Array): string | null {
	if (bytes[0] === 0xff && bytes[1] === 0xd8 && bytes[2] === 0xff) {
		return 'image/jpeg';
	}
	if (bytes[0] === 0x89 && bytes[1] === 0x50 && bytes[2] === 0x4e && bytes[3] === 0x47) {
		return 'image/png';
	}
	if (bytes[0] === 0x47 && bytes[1] === 0x49 && bytes[2] === 0x46) {
		return 'image/gif';
	}
	if (bytes[0] === 0x52 && bytes[1] === 0x49 && bytes[2] === 0x46 && bytes[3] === 0x46) {
		return 'image/webp';
	}
	return null;
}

export const POST: RequestHandler = async ({ params, request, locals }) => {
	const mnemonic = params.mnemonic;

	const chatData = await locals.convex.query(api.chats.getByMnemonic, { mnemonic });
	if (!chatData) {
		throw error(404, 'Chat not found');
	}

	const rawContentType = request.headers.get('content-type') || '';
	const caption = request.headers.get('x-caption') || '';

	console.log('[POST /{mnemonic}] headers:', Object.fromEntries(request.headers.entries()));
	console.log('[POST /{mnemonic}] content-type:', rawContentType);

	let base64: string;
	let mediaType: string;

	if (rawContentType.includes('multipart/form-data')) {
		const formData = await request.formData();
		const keys = [...formData.keys()];
		console.log('[POST /{mnemonic}] formData keys:', keys);

		let file: File | null = null;
		for (const key of ['file', 'image', 'photo', 'upload', 'attachment', ...keys]) {
			const value = formData.get(key);
			if (value instanceof File) {
				file = value;
				console.log('[POST /{mnemonic}] found file in field:', key);
				break;
			}
		}

		if (!file) {
			throw error(400, `No file found in form data. Keys: ${keys.join(', ')}`);
		}

		const buffer = await file.arrayBuffer();
		const bytes = new Uint8Array(buffer);
		base64 = Buffer.from(buffer).toString('base64');
		mediaType = detectImageType(bytes) || file.type || 'image/jpeg';

		console.log('[POST /{mnemonic}] file:', file.name, file.type, 'size:', buffer.byteLength);
	} else if (rawContentType.includes('application/x-www-form-urlencoded')) {
		throw error(400, 'Use Form with File field, not URL-encoded form');
	} else {
		const buffer = await request.arrayBuffer();
		const bytes = new Uint8Array(buffer);
		base64 = Buffer.from(buffer).toString('base64');
		mediaType = detectImageType(bytes) || rawContentType || 'image/jpeg';

		console.log('[POST /{mnemonic}] raw bytes size:', buffer.byteLength);
		console.log('[POST /{mnemonic}] detected type:', mediaType);
	}

	if (!base64 || base64.length === 0) {
		throw error(400, 'Empty image data');
	}

	await locals.convex.mutation(api.messages.create, {
		chatId: chatData._id,
		role: 'user',
		content: caption,
		source: 'web',
		imageBase64: base64,
		imageMediaType: mediaType
	});

	return new Response(JSON.stringify({ ok: true, mediaType, size: base64.length }), {
		headers: { 'Content-Type': 'application/json' }
	});
};