wkdhkr/dedupper

// @flow
import { exec } from "child-process-promise";

export default class ImageMagickService {
  resize: (
    targetPath: string,
    outputPath: string,
    width: number,
    height: number
  ) => any = (
    targetPath: string,
    outputPath: string,
    width: number,
    height: number
  ) => {
    const cmd = [
      "magick",
      "convert",
      "-resize",
      `${width}x${height}`,
      JSON.stringify(targetPath),
      JSON.stringify(outputPath)
    ].join(" ");
    return exec(cmd).then(
      ({ stderr }: { stderr: ?string, stdout: ?string }) => {
        if (stderr) {
          throw new Error(
            `imageMagick convert error: path = ${targetPath} error = ${stderr}`
          );
        }
      }
    );
  };

  createIdentifyCommand: (targetPath: string, format: string) => string = (
    targetPath: string,
    format: string
  ): string =>
    ["magick", "identify", "-format", format, JSON.stringify(targetPath)].join(
      " "
    );

  statistic(
    targetPath: string
  ): Promise<{
    entropy: number,
    quality: number,
    mean: number
  }> {
    return exec(
      this.createIdentifyCommand(targetPath, "%[entropy],%Q,%[mean]")
    ).then(({ stderr, stdout }: { stderr: ?string, stdout: ?string }) => {
      if (stderr) {
        throw new Error(
          `imageMagick statistic error: path = ${targetPath} error = ${stderr}`
        );
      }
      const [rawEntropy, rawQuality, rawMean] = (stdout || "").split(",");
      const entropy = Number(rawEntropy);
      const quality = Number(rawQuality);
      const mean = Number(rawMean);

      return {
        entropy,
        quality,
        mean
      };
    });
  }

  identify(
    targetPath: string
  ): Promise<{
    ratio: number,
    width: number,
    height: number,
    hash: string,
    damaged: boolean
  }> {
    return exec(this.createIdentifyCommand(targetPath, "%w,%h,%#"))
      .then(({ stderr, stdout }: { stderr: ?string, stdout: ?string }) => {
        const [rawWidth, rawHeight, hash] = (stdout || "").split(",");
        const width = Number(rawWidth);
        const height = Number(rawHeight);
        const ratio = width / height || 0;

        return {
          width,
          height,
          hash,
          ratio,
          damaged: !!stderr
        };
      })
      .catch(() => ({
        width: 0,
        height: 0,
        hash: "",
        ratio: 0,
        damaged: true
      }));
  }
}