import sharp from "sharp";

/** Real encoded images, generated rather than checked in, so a fixture can never drift from what the
 * pipeline actually accepts. */
export async function makeImage(options: {
  readonly width: number;
  readonly height: number;
  readonly format: "png" | "jpeg" | "webp";
  readonly alpha?: boolean;
  readonly colour?: { r: number; g: number; b: number };
}): Promise<Uint8Array> {
  const colour = options.colour ?? { b: 40, g: 120, r: 200 };
  const pipeline = sharp({
    create: {
      background: { ...colour, alpha: options.alpha === true ? 0.5 : 1 },
      channels: options.alpha === true ? 4 : 3,
      height: options.height,
      width: options.width,
    },
  });
  const encoded =
    options.format === "png"
      ? await pipeline.png().toBuffer()
      : options.format === "jpeg"
        ? await pipeline.jpeg().toBuffer()
        : await pipeline.webp().toBuffer();
  return new Uint8Array(encoded);
}

/** A genuine two-frame animated WebP. Signage refuses animation: a signage slide is a still frame,
 * and an animated one would loop out of step with the authoritative slot deadline. */
export async function makeAnimatedWebp(): Promise<Uint8Array> {
  const frame = (red: number) =>
    sharp({
      create: { background: { alpha: 1, b: 0, g: 0, r: red }, channels: 4, height: 8, width: 8 },
    })
      .raw()
      .toBuffer();
  const frames = Buffer.concat([await frame(255), await frame(0)]);
  const encoded = await sharp(frames, {
    raw: { channels: 4, height: 16, pageHeight: 8, width: 8 },
  })
    .webp({ delay: [100, 100], loop: 0 })
    .toBuffer();
  return new Uint8Array(encoded);
}

/** A genuine two-frame animated GIF. GIF is refused outright, but animation is detected first, so
 * this proves the *animation* rule rather than the format rule. */
export async function makeAnimatedGif(): Promise<Uint8Array> {
  const frame = (red: number) =>
    sharp({
      create: { background: { alpha: 1, b: 0, g: 0, r: red }, channels: 4, height: 8, width: 8 },
    })
      .raw()
      .toBuffer();
  const frames = Buffer.concat([await frame(255), await frame(0)]);
  const encoded = await sharp(frames, {
    raw: { channels: 4, height: 16, pageHeight: 8, width: 8 },
  })
    .gif({ delay: [100, 100], loop: 0 })
    .toBuffer();
  return new Uint8Array(encoded);
}

export function bytesOf(value: string): Uint8Array {
  return new TextEncoder().encode(value);
}

/** A minimal, genuinely well-formed SVG. Signage refuses it: an SVG is a document with script and
 * external-reference capability, not a raster image. */
export const SVG_DOCUMENT =
  '<svg xmlns="http://www.w3.org/2000/svg" width="10" height="10"><rect width="10" height="10"/></svg>';

/** The first bytes of a PDF. Refused for the same reason as everything else that is not a still
 * raster image. */
export const PDF_DOCUMENT = "%PDF-1.7\n1 0 obj<</Type/Catalog>>endobj\ntrailer<</Root 1 0 R>>";

/** A GIF89a header with one tiny frame. */
export const GIF_DOCUMENT_BASE64 = "R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7";