#!/bin/bash
#
# sync-newer-images — For each top-level image in SRC, find any matching
# filename recursively under DEST and copy over it if SRC is newer.
# Works on Linux and macOS (bash 3.2+ compatible).

usage() {
    cat <<'EOF'
Usage: sync-newer-images [options] <destination> <source>

For each top-level image in source, find any matching filename recursively
under destination and copy over it if the source file is newer.

Arguments:
  destination   Path to copy TO
  source        Path to copy FROM

Options:
  -h, --help    Show this help message and exit
EOF
    exit 0
}

for arg in "$@"; do
    case "$arg" in
        -h|--help) usage ;;
    esac
done

if [ $# -lt 2 ]; then
    echo "Error: destination and source are required" >&2
    echo "Usage: sync-newer-images <destination> <source>" >&2
    exit 1
fi

DEST="$1"
SRC="$2"

if [ ! -d "$DEST" ]; then
    echo "Error: destination '$DEST' is not a directory" >&2
    exit 1
fi

if [ ! -d "$SRC" ]; then
    echo "Error: source '$SRC' is not a directory" >&2
    exit 1
fi

copied=0

for srcfile in "$SRC"/*; do
    [ -f "$srcfile" ] || continue

    ext="${srcfile##*.}"
    case "$(echo "$ext" | tr '[:upper:]' '[:lower:]')" in
        jpg|jpeg|png|gif|heic|webp|bmp|tiff|tif) ;;
        *) continue ;;
    esac

    filename="${srcfile##*/}"
    while IFS= read -r destfile; do
        if [ -f "$destfile" ] && [ "$srcfile" -nt "$destfile" ]; then
            cp -v "$srcfile" "$destfile"
            copied=$((copied + 1))
        fi
    done < <(find "$DEST" -type f -name "$filename" 2>/dev/null)
done

echo "Copied ${copied} newer image(s) from ${SRC} into ${DEST}"