emdash-patch-imageupload/packages/core/tests/unit/media/placeholder.test.ts

import { describe, it, expect } from "vitest";

import { generatePlaceholder } from "../../../src/media/placeholder.js";

const CSS_RGB_PATTERN = /^rgb\(\d+,\s?\d+,\s?\d+\)$/;

/** Minimal 4x4 solid red JPEG */
const JPEG_4x4 = Buffer.from(
	"/9j/4AAQSkZJRgABAQAAAQABAAD/2wBDAAMCAgICAgMCAgIDAwMDBAYEBAQEBAgGBgUGCQgKCgkICQkKDA8MCgsOCwkJDRENDg8QEBEQCgwSExIQEw8QEBD/2wBDAQMDAwQDBAgEBAgQCwkLEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBAQEBD/wAARCAAEAAQDAREAAhEBAxEB/8QAFAABAAAAAAAAAAAAAAAAAAAACP/EABQQAQAAAAAAAAAAAAAAAAAAAAD/xAAVAQEBAAAAAAAAAAAAAAAAAAAHCf/EABQRAQAAAAAAAAAAAAAAAAAAAAD/2gAMAwEAAhEDEQA/ADoDFU3/2Q==",
	"base64",
);

/** Minimal 4x4 solid red PNG */
const PNG_4x4 = Buffer.from(
	"iVBORw0KGgoAAAANSUhEUgAAAAQAAAAEAQMAAACTPww9AAAAIGNIUk0AAHomAACAhAAA+gAAAIDoAAB1MAAA6mAAADqYAAAXcJy6UTwAAAAGUExURf8AAP///0EdNBEAAAABYktHRAH/Ai3eAAAAB3RJTUUH6gIcETMVn1ZhnwAAACV0RVh0ZGF0ZTpjcmVhdGUAMjAyNi0wMi0yOFQxNzo1MToyMCswMDowMJE6EiQAAAAldEVYdGRhdGU6bW9kaWZ5ADIwMjYtMDItMjhUMTc6NTE6MjArMDA6MDDgZ6qYAAAAKHRFWHRkYXRlOnRpbWVzdGFtcAAyMDI2LTAyLTI4VDE3OjUxOjIwKzAwOjAwt3KLRwAAAAtJREFUCNdjYIAAAAAIAAEvIN0xAAAAAElFTkSuQmCC",
	"base64",
);

/** 100x100 solid blue JPEG (for downsampling test) */
const JPEG_100x100 = Buffer.from(
	"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",
	"base64",
);

describe("generatePlaceholder", () => {
	it("generates blurhash and dominantColor from a JPEG", async () => {
		const result = await generatePlaceholder(new Uint8Array(JPEG_4x4), "image/jpeg");

		expect(result).not.toBeNull();
		expect(result!.blurhash).toBeTruthy();
		expect(typeof result!.blurhash).toBe("string");
		expect(result!.dominantColor).toBeTruthy();
		expect(typeof result!.dominantColor).toBe("string");
	});

	it("generates blurhash and dominantColor from a PNG", async () => {
		const result = await generatePlaceholder(new Uint8Array(PNG_4x4), "image/png");

		expect(result).not.toBeNull();
		expect(result!.blurhash).toBeTruthy();
		expect(result!.dominantColor).toBeTruthy();
	});

	it("returns a valid CSS color string for dominantColor", async () => {
		const result = await generatePlaceholder(new Uint8Array(JPEG_4x4), "image/jpeg");

		expect(result).not.toBeNull();
		// Should be rgb() format from rgbColorToCssString
		expect(result!.dominantColor).toMatch(CSS_RGB_PATTERN);
	});

	it("returns null for non-image MIME types", async () => {
		const buffer = new Uint8Array([0, 1, 2, 3]);
		const result = await generatePlaceholder(buffer, "application/pdf");

		expect(result).toBeNull();
	});

	it("returns null for unsupported image types", async () => {
		const buffer = new Uint8Array([0, 1, 2, 3]);
		const result = await generatePlaceholder(buffer, "image/svg+xml");

		expect(result).toBeNull();
	});

	it("returns null for corrupt image data", async () => {
		const buffer = new Uint8Array([0xff, 0xd8, 0xff, 0xe0, 0, 0, 0]);
		const result = await generatePlaceholder(buffer, "image/jpeg");

		expect(result).toBeNull();
	});

	it("handles larger images by downsampling", async () => {
		const result = await generatePlaceholder(new Uint8Array(JPEG_100x100), "image/jpeg");

		expect(result).not.toBeNull();
		expect(result!.blurhash).toBeTruthy();
		// Blurhash string length should be reasonable (not huge from 100x100)
		expect(result!.blurhash.length).toBeLessThan(50);
	});

	it("returns null when image dimensions from headers exceed memory budget", async () => {
		// Minimal valid JPEG with SOF0 declaring 5000x4000 dimensions.
		// SOF0 marker (FFC0) stores height (2 bytes) then width (2 bytes).
		// 5000×4000×4 = 80 MB > 32 MB threshold.
		const sof0 = new Uint8Array([
			0xff,
			0xd8, // SOI
			0xff,
			0xe0,
			0x00,
			0x10, // APP0 marker + length
			0x4a,
			0x46,
			0x49,
			0x46,
			0x00, // "JFIF\0"
			0x01,
			0x01,
			0x00,
			0x00,
			0x01,
			0x00,
			0x01,
			0x00,
			0x00, // JFIF fields
			0xff,
			0xc0,
			0x00,
			0x0b, // SOF0 marker + length
			0x08, // precision
			0x0f,
			0xa0, // height = 4000
			0x13,
			0x88, // width = 5000
			0x01, // number of components
			0x01,
			0x11,
			0x00, // component
		]);
		const result = await generatePlaceholder(sof0, "image/jpeg");
		expect(result).toBeNull();
	});

	it("returns null when fallback dimensions exceed memory budget", async () => {
		// Unrecognizable buffer — image-size can't parse it, so fallback dims are used
		const buffer = new Uint8Array([0x00, 0x01, 0x02, 0x03]);
		const result = await generatePlaceholder(buffer, "image/jpeg", {
			width: 5000,
			height: 4000,
		});
		expect(result).toBeNull();
	});

	it("still generates placeholder for small images with dimensions param", async () => {
		const result = await generatePlaceholder(new Uint8Array(JPEG_4x4), "image/jpeg", {
			width: 4,
			height: 4,
		});
		expect(result).not.toBeNull();
		expect(result!.blurhash).toBeTruthy();
	});
});