import fs from 'node:fs';
import type {Page} from './browser/BrowserPage';
import type {StillImageFormat} from './image-format';
import {startPerfMeasure, stopPerfMeasure} from './perf';

export const screenshotTask = async ({
	format,
	height,
	omitBackground,
	page,
	width,
	path,
	jpegQuality,
	scale,
}: {
	page: Page;
	format: StillImageFormat;
	path?: string;
	jpegQuality?: number;
	omitBackground: boolean;
	width: number;
	height: number;
	scale: number;
}): Promise<Buffer> => {
	const client = page._client();
	const target = page.target();

	await client.send('Target.activateTarget', {
		targetId: target._targetId,
	});

	if (omitBackground) {
		await client.send('Emulation.setDefaultBackgroundColorOverride', {
			color: {r: 0, g: 0, b: 0, a: 0},
		});
	}

	const cap = startPerfMeasure('capture');
	try {
		let result;
		if (format === 'pdf') {
			const res = await client.send('Page.printToPDF', {
				paperWidth: width / 96, // Convert to Inch
				paperHeight: height / 96, // Convert to Inch
				marginTop: 0,
				marginBottom: 0,
				marginLeft: 0,
				marginRight: 0,
				scale: 1,
				printBackground: true,
			});
			result = res.value;
		} else {
			// We find that there is a 0.1% framedrop when rendering under memory pressure
			// which can be circumvented by disabling this option on Lambda.
			// To be determined: Is this a problem with Lambda, or the Chrome version
			// we are using on Lambda?
			// We already found out that the problem is not a general Linux problem.

			// However, if `fromSurface` is false, the screenshot is limited to 8192x8192 pixels.
			// If the image is larger, always use `fromSurface: true`.
			const fromSurface =
				!process.env.DISABLE_FROM_SURFACE || height > 8192 || width > 8192;
			const scaleFactor = fromSurface ? 1 : scale;

			const {value} = await client.send('Page.captureScreenshot', {
				format,
				quality: jpegQuality,
				clip: {
					x: 0,
					y: 0,
					height: height * scaleFactor,
					scale: 1,
					width: width * scaleFactor,
				},
				captureBeyondViewport: true,
				optimizeForSpeed: true,
				fromSurface,
			});
			result = value;
		}

		stopPerfMeasure(cap);
		if (omitBackground) {
			await client.send('Emulation.setDefaultBackgroundColorOverride');
		}

		const buffer = Buffer.from(result.data, 'base64');
		if (path) {
			await fs.promises.writeFile(path, buffer as never as Uint8Array);
		}

		return buffer;
	} catch (err) {
		if ((err as Error).message.includes('Unable to capture screenshot')) {
			const errMessage = [
				'Could not take a screenshot because Google Chrome ran out of memory or disk space.',
				process?.env?.__RESERVED_IS_INSIDE_REMOTION_LAMBDA
					? 'Deploy a new Lambda function with more memory or disk space.'
					: 'Decrease the concurrency to use less RAM.',
			].join(' ');
			throw new Error(errMessage);
		}

		throw err;
	}
};