import { seekVideo } from "./video";

export function captureAnalysisFrame(
  video: HTMLVideoElement,
  canvas: HTMLCanvasElement,
  width: number,
  height: number,
): ImageData {
  canvas.width = width;
  canvas.height = height;

  const context = canvas.getContext("2d", { willReadFrequently: true });
  if (!context) throw new Error("Could not create the analysis canvas context.");

  context.drawImage(video, 0, 0, width, height);
  return context.getImageData(0, 0, width, height);
}

export async function createThumbnailUrl(video: HTMLVideoElement, maxWidth = 360): Promise<string> {
  const scale = Math.min(1, maxWidth / video.videoWidth);
  const width = Math.max(1, Math.round(video.videoWidth * scale));
  const height = Math.max(1, Math.round(video.videoHeight * scale));
  const canvas = document.createElement("canvas");
  canvas.width = width;
  canvas.height = height;

  const context = canvas.getContext("2d");
  if (!context) throw new Error("Could not create thumbnail canvas context.");

  context.drawImage(video, 0, 0, width, height);

  const blob = await canvasToBlob(canvas, "image/webp", 0.82);
  return URL.createObjectURL(blob);
}

export async function extractFullResolutionFrame(
  video: HTMLVideoElement,
  time: number,
  type: "image/png" | "image/jpeg" | "image/webp" = "image/png",
  quality?: number,
): Promise<Blob> {
  await seekVideo(video, time);

  const canvas = document.createElement("canvas");
  canvas.width = video.videoWidth;
  canvas.height = video.videoHeight;

  const context = canvas.getContext("2d");
  if (!context) throw new Error("Could not create full-resolution canvas context.");

  context.drawImage(video, 0, 0);
  return canvasToBlob(canvas, type, quality);
}

export async function canvasToBlob(
  canvas: HTMLCanvasElement,
  type: string,
  quality?: number,
): Promise<Blob> {
  return new Promise((resolve, reject) => {
    canvas.toBlob(
      (blob) => {
        if (!blob) reject(new Error("Canvas export failed."));
        else resolve(blob);
      },
      type,
      quality,
    );
  });
}