FileSizeFormatFilter.java

package com.hubspot.jinjava.lib.filter;

import java.util.Objects;

import org.apache.commons.lang3.BooleanUtils;
import org.apache.commons.lang3.math.NumberUtils;

import com.hubspot.jinjava.doc.annotations.JinjavaDoc;
import com.hubspot.jinjava.doc.annotations.JinjavaParam;
import com.hubspot.jinjava.doc.annotations.JinjavaSnippet;
import com.hubspot.jinjava.interpret.JinjavaInterpreter;

@JinjavaDoc(
    value = "Format the value like a ‘human-readable’ file size (i.e. 13 kB, 4.1 MB, 102 Bytes, etc).",
    params = {
        @JinjavaParam(value = "value", desc = "The value to convert to filesize format"),
        @JinjavaParam(value = "binary", type = "boolean", defaultValue = "False", desc = "Use binary prefixes (Mebi, Gibi)")
    },
    snippets = {
        @JinjavaSnippet(
            code = "{% set bytes = 100000 %}\n" +
                "{{ bytes|filesizeformat }}")
    })
public class FileSizeFormatFilter implements Filter {

  @Override
  public String getName() {
    return "filesizeformat";
  }

  @Override
  public Object filter(Object var, JinjavaInterpreter interpreter, String... args) {
    float bytes = NumberUtils.toFloat(Objects.toString(var), 0.0f);

    if (bytes == 1) {
      return "1 Byte";
    }

    boolean binary = false;
    if (args.length > 0) {
      binary = BooleanUtils.toBoolean(args[0]);
    }

    int base = binary ? 1024 : 1000;
    if (bytes < base) {
      return (int) bytes + " Bytes";
    }

    String[] sizes = binary ? BINARY_SIZES : DECIMAL_SIZES;
    int unit = 1;
    String prefix = "";

    for (int i = 0; i < sizes.length; i++) {
      unit = (int) Math.pow(base, i + 2);
      prefix = sizes[i];

      if (bytes < unit) {
        return String.format("%.1f %s", (base * bytes / unit), prefix);
      }
    }

    return String.format("%.1f %s", (base * bytes / unit), prefix);
  }

  private static final String[] BINARY_SIZES = { "KiB", "MiB", "GiB", "TiB", "PiB", "EiB", "ZiB", "YiB" };
  private static final String[] DECIMAL_SIZES = { "KB", "MB", "GB", "TB", "PB", "EB", "ZB", "YB" };
}