duplicate-exif-from-webp

#!/bin/bash

# Given a file, list of files, or directory, including images,
# Process them all by:
# Checking if a webp file of the same name exists nearby
# Migrating metadata from the webp into the gif

# Utility to synchronise information from one version of an image to another.
# Used to propogate information that was attached to a webp to its derivative gif
#  Because I downloaded a bunch, then converted them,
# but actually should have saved some of their info from the original.
# Specifically original GUID and provenance. the webp UUID is the canonic.


function processFile {

    local pid=$$
    local identifier="[PID $pid]"
    local exif_option="-quiet -overwrite_original"

    local source_file="$1"
    # Generate the target file name
    local source_file="$1"
    local target_file="${source_file%.*}.webp"

    if [[ ! -f "${source_file}" ]]; then
        echo "$identifier Error: $source_file is not a file" >&2
        return 1
    fi

    local mime_type=$(exiftool -s -S -MimeType "${source_file}")
    if [[ "$mime_type" != "image/gif" ]] ; then
      echo "$source_file is not a gif, it's a $mime_type" >&2
      return 1
    fi

    echo "Looking for a '$target_file' to match the '$source_file'" >&2
    if [[ ! -f "${target_file}" ]]; then
        echo "No '$target_file' to scrape metadata from." >&2
        return 1
    fi

    echo "Duplicating metadata from '$target_file' to '$source_file'."  >&2
    # Not all, just the UUID.
    exiftool $exif_option -tagsFromFile "$target_file" "-UUID>UUID" -overwrite_original "$source_file"
    exiftool $exif_option -tagsFromFile "$target_file" "-Source>Source" "$source_file"
    exiftool $exif_option -tagsFromFile "$target_file" "-Identifier>Identifier" "$source_file"
    exiftool $exif_option -tagsFromFile "$target_file" "-Description>Description" "$source_file"
    echo "Updated EXIF metadata on $source_file" >&2

    return 0
}

function parallalProcessFiles {
    # Find all files recursively in the input arguments.
    # This uses parallal processing - note that feedback from the sub-processes may get jumpbled.
    export -f processFile;
    # Additional options `-print0` & `-0` are here to manage spaces in filenames.
    # -P 4 is parallalization.
    find "$@" -type f -print0 | xargs -0 -P 4 -n 1 -I{} bash -c 'processFile "$1"' _ "{}"
}

# Call the processFiles function with the provided arguments
parallalProcessFiles "$@"