#!/bin/bash

###############################################################################
# Script Name: get_element_spectra.sh
#
# Description:
#   Downloads visible-light emission spectrum images for chemical elements
#   from Wikimedia Commons and converts them into panorama wallpapers.
#
#   For each entry in get_images.txt, the script:
#     1. Reads element information from the input file.
#     2. Builds a standardized output filename.
#     3. Locates the corresponding spectrum image on Wikimedia Commons.
#     4. Downloads the original PNG file.
#     5. Renames the image using element metadata.
#     6. Resizes the image to 3840 pixels wide.
#     7. Crops the image to 3840x540 pixels.
#     8. Moves the finished panorama wallpaper to the destination folder.
#
# Input Format (get_images.txt):
#   element_name atomic_number symbol
#
# Example:
#   hydrogen 001 H
#   helium   002 He
#   lithium  003 Li
#
# Output Example:
#   Elements_Panorama_001_H_Hydrogen.png
#
# Requirements:
#   - Bash
#   - wget
#   - ImageMagick (convert)
#   - Internet connection
#
# Usage:
#   chmod +x get_element_spectra.sh
#   ./get_element_spectra.sh
#
# Notes:
#   - The script expects get_images.txt in the current directory.
#   - Images are downloaded from Wikimedia Commons.
#   - Missing images are reported and skipped.
#
###############################################################################

while IFS= read -r line; do

    # Build output filename:
    # <atomic_number>_<symbol>_<Element>.png
    element_name="$(
        printf "%s_%s_%s%s\n" \
            "$(echo "$line" | cut -f2 -d' ')" \
            "$(echo "$line" | cut -f3 -d' ')" \
            "$(echo "$line" | cut -f1 -d' ' | head -c 1 | tr 'a-z' 'A-Z')" \
            "$(echo "$line" | cut -f1 -d' ' | tail -c +2)"
    )"

    # Build capitalized element name used by Wikimedia
    element="$(
        printf "%s%s\n" \
            "$(echo "$line" | cut -f1 -d' ' | head -c 1 | tr 'a-z' 'A-Z')" \
            "$(echo "$line" | cut -f1 -d' ' | tail -c +2)"
    )"

    # Retrieve original image URL from Wikimedia Commons
    LINK="$(
        wget -qO- "https://commons.wikimedia.org/wiki/File:${element}_spectrum_visible.png" \
        | grep "Original file" \
        | grep -o 'href="[^"]*' \
        | tail -c +7
    )"

    if [ -z "$LINK" ]; then
        echo "No spectrum image found for ${element}"
        continue
    else
        echo "Downloading ${element}: ${LINK}"
    fi

    # Download original image
    wget "$LINK"

    # Rename downloaded image
    mv "${element}_spectrum_visible.png" "${element_name}.png"

    # Resize image to 3840 pixels wide
    convert "${element_name}.png" \
        -resize 3840x \
        "${element_name}.png"

    # Crop to panorama format
    convert "${element_name}.png" \
        -crop 3840x540+0+0 \
        "${element_name}.png"

    # Move final image to wallpaper directory
    mv "${element_name}.png" \
        "/home/lucas/Documents/Dokumente/Zeug/Wallpaper/Desktop1920x1080/Elements/Elements_Panorama_${element_name}.png"

done < "get_images.txt"