#!/bin/bash

# Change to your target directory
TARGET_DIR="./"  # or set it via "$1" to pass folder as argument

if [[ "$1" != "" ]]; then
	TARGET_DIR="$1"
	
fi

cd "$TARGET_DIR" || exit 1

for file in *.{jpg,jpeg,JPG,JPEG,png,PNG}; do
    [ -f "$file" ] || continue  # skip if not a file

    # Extract DateTimeOriginal using exiftool
    datetime=$(exiftool -DateTimeOriginal -s3 "$file")

    if [[ -n "$datetime" ]]; then
        # Format: "2023:08:21 14:32:10" -> "20230821_143210"
        formatted=$(echo "$datetime" | sed 's/://g' | sed 's/ /_/g' | cut -c1-15)
    	echo $formatted
	else
        # Fall back to file modification time if no EXIF data
        formatted=$(date -r "$file" +"%Y%m%d_%H%M%S")
    fi

    # Build new filename
    extension="${file##*.}"
    newname="IMG_${formatted}.${extension}"

    # Avoid overwriting
    if [[ -e "$newname" ]]; then
        i=1
        while [[ -e "IMG_${formatted}_$i.${extension}" ]]; do
            ((i++))
        done
        newname="IMG_${formatted}_$i.${extension}"
    fi

    echo "Renaming: '$file' -> '$newname'"
    mv "$file" "$newname"
done