Compress Media Folder Bash Script

compress-media-folder.sh

#!/bin/bash  
# OVERVIEW 
# This bash script handles the organization and compression for blog media items winthin the app
# when a directory is suppied to the script, the script loops through the directory's items and handles the
# renaming and compression accordingly. Currently, there is only one type of media item that is handled by the script
# -- image items - .JPG, .jpg

targetedFolder=$1

# Ensure argument is a valid directory
if [ -z "$targetedFolder" ]; then
    echo "ERROR: the compress-media-folder requires a valid directory as the first argument"
    exit 1
elif [ ! -d "$targetedFolder" ]; then
    echo "ERROR: the supplied argument is not a valid directory"
    exit 1
fi

# Move into supplied directory
echo "moving into supplied directory"
cd $targetedFolder

# ensure items are present inside supplied directory
imageCount=0;
shopt -s nullglob
for image in ./*.{jpg,JPG}; do 
    $((imageCount++))
done;

if [ $imageCount == 0 ]; then
    echo "ERROR: no images found in the supplied directory with the extensions: .jpg, .JPG"
    exit 1;
fi

echo "Found $imageCount .jpg images to compress"

# function to calculate the index of the last renamed image
function calculate_last_renamed_image_index {
    lastRenamedImageIndex=0
    
    shopt -s nullglob
    for image in ./*.{jpg,JPG}; do 
        if is_image_renamed $image; then
            $((lastRenamedImageIndex++))
        fi  
    done;

    return $lastRenamedImageIndex
}

# function to check if image is specified as a cover image
# will return truthy value if image has -cover extension attached
# will return falsey value if image does not have -cover extension attached
function is_image_cover {
    image=$1
    
    #check if image has already been renamed(if it fits regex "<parent folder name>_<media type>_<last index of all renamed pics>") 
    COVER_IMAGE_REGEX='(-cover)'
    
    if [[ "$image" =~ $COVER_IMAGE_REGEX ]]; then
        return
    fi

    false
}

# function to check if image has been renamed
# will return truthy value if image has already been re-named
# will return falsey value if image has not been re-named
function is_image_renamed {
    image=$1

    parentFolder=$(echo "$PWD" | sed -E 's/\/[A-Za-z0-9/]+\/([A-Za-z0-9\-]+)$/\1/')
    
    #check if image has already been renamed(if it fits regex "<parent folder name>_<media type>_<last index of all renamed pics>") 
    RENAMED_REGEX="(" + parentFolder + ")_(image)_[0-9]+"
    
    if [[ "$image" =~ $RENAMED_REGEX ]]; then
        return
    fi 

    false
}

# function to handle renaming of an image
# will return truthy value if image is re-named by function 
# will return falsey value if the image has already previously been re-named
function rename_image {
    image=$1

    # if image has already been renamed, return with falsey value
    if is_image_renamed $image; then 
        echo "$image has been renamed already"
        false
        return
    fi

    echo "$image has not been renamed, renaming..."

    lastRenamedImageIndex=$2
    parentFolder=$(echo "$PWD" | sed -E 's/\/[A-Za-z0-9/]+\/([A-Za-z0-9\-]+)$/\1/')
    mediaType='image'
    renamedImage="$parentFolder"_"$mediaType"_"$lastRenamedImageIndex"

    echo $parentFolder

    # if image is specified as a cover image, add cover extension 
    if is_image_cover $image; then
        renamedImage+="-cover"
    fi

    # if image has been compressed, add compression extension 
    if is_image_compressed $image; then
        renamedImage+="-compressed"
    fi

    renamedImage+=".jpg"

    echo "$image" has been renamed to "$renamedImage"
    
    mv $image $renamedImage
    
    return
}

# function to check if image has been compressed
# will return truthy value if image has already been compressed 
# will return falsey value if image has not already been compressed
function is_image_compressed {
    image=$1
    
    COMPRESSED_REGEX='(-compressed)'
    
    if [[ "$image" =~ $COMPRESSED_REGEX ]]; then
        return
    fi

    false

}

# function to handle conversion, resize, and compression of an image
# will return truthy value if image is compressed by function
# will return falsey value if image has not already previously been compressed
function compress_image {
    image=$1
    fileName=${image%.*}
    fileExtension=${image##*.}
    
    # if image has been compressed, return
    if is_image_compressed $image; then
        echo "$image has been compressed already"
        false
        return   
    fi
    
    echo "$image has not been compressed already, compressing..."
    
    
    # re-size image (re-size dimensions are based on whether the file is a cover image or not)
    if is_image_cover $image; then
        magick $image -resize 2200x1800 $image
    else
        magick $image -resize 1500x1200 $image
    fi
    

    
    
    # compress image - this outputs a new image with the -compressed extension
    
    # NOTE: commenting jpegtran out as it doesnt let you specify image quality. Using cjpeg instead
    # jpegtran -outfile "$fileName"-compressed."$fileExtension" -quality 85 -optimise -copy none $image

    cjpeg -outfile "$fileName"-compressed."$fileExtension" -quality 85 -optimise $image
    
    # remove un-compressed image
    rm $image
    
}


calculate_last_renamed_image_index
lastRenamedImageIndex=$?

# Loop through image items in folder and rename/compress
shopt -s nullglob
for image in ./*.{jpg,JPG,jpeg}; do

    echo $image
    # call re-name image func., and if the func .returns 1 (false), this means the image has already been re-named
    # if the func. returns 0 (true), this means the image has not been re-named and we need to increment the lastRenamedImageIndex
    rename_image $image $lastRenamedImageIndex
    
    if [[ ! "$renamedImage" == "" ]]; then
        $((lastRenamedImageIndex++))
        compress_image $renamedImage
    else 
        compress_image $image
    fi
    
    

done;