#!/bin/bash

###############################################################################
# Script Name: resize-images.sh
#
# Description:
#   Resizes JPG/JPEG images and converts them to PNG format.
#
#   When no resize argument is supplied:
#     - Portrait images are resized to fit within 1080px height (x1080)
#     - Landscape images are resized to fit within 1920px width (1920)
#
#   When a resize argument is supplied:
#     - The supplied resize value is used for all images.
#
#   Additional features:
#     - Creates output directory NEW/ automatically.
#     - Optionally normalizes filenames by replacing spaces with underscores.
#     - Adds an optional date prefix to generated filenames.
#     - Converts JPG/JPEG images to PNG.
#
# Requirements:
#   - Bash
#   - ImageMagick (identify, convert)
#
# Usage:
#
#   Automatic portrait/landscape sizing:
#       ./resize-images.sh
#
#   Resize all images to width 2560:
#       ./resize-images.sh 2560
#
#   Resize all images to height 1440:
#       ./resize-images.sh x1440
#
# Output:
#   NEW/<date>filename.png
#
###############################################################################

DATE=$(date +"%d%m%y_")
DEFAULT_RESIZE="auto"

# Use supplied resize value or automatic mode
if [[ -n "${1:-}" ]]; then
    DEFAULT_RESIZE="$1"
fi

# Create output directory
mkdir -p NEW

for file in *.jpg *.jpeg *.JPG *.JPEG; do

    [[ -f "$file" ]] || continue

    # Replace spaces in filenames
    file_new="$(echo "$file" | tr ' ' '_')"

    if [[ "$file_new" != "$file" ]]; then
        echo "Rename: $file -> $file_new"
        mv "$file" "$file_new"
    fi

    resize_var="$DEFAULT_RESIZE"

    # Automatic resize mode
    if [[ "$resize_var" == "auto" ]]; then

        dimensions=$(identify -quiet -format "%wx%h" "$file_new" 2>/dev/null)

        width=${dimensions%x*}
        height=${dimensions#*x}

        if [[ -n "$width" && -n "$height" ]]; then
            if (( height > width )); then
                resize_var="x1080"
            else
                resize_var="1920"
            fi
        else
            echo "Skipping invalid image: $file_new"
            continue
        fi
    fi

    output="NEW/${DATE}$(basename "${file_new%.*}").png"

    echo "Transform: $file_new -> $output ($resize_var)"

    convert -quiet \
        "$file_new" \
        -resize "$resize_var" \
        "$output"

done

echo "Finished."