#!/usr/bin/env oil

# A quick script on moving a file with embedded data.
# It can only detect certain files and write the metadata with a certain program.
# For the argument, it needs the path of the files to be moved.

# Dependencies:
# * Oil shell v0.8.8
# * vorbis-tools v1.4.2
# * exiftool v12.16
# * file 5.38
# * coreutils 8.32

shopt --set strict:all

var help_section = "A script for embedding metadata and renaming them files.

edit-file-metadata [options...] FILE

Options:
    -h, --help              Show the help section.
    -a, --author [AUTHOR]   Set the author.
    -d, --date [DATE]       Set the date.
    -t, --title [TITLE]     Set the title.
    --skip                  Skip the prompt for missing metadata
                            and only change the needed metadata.
                            This only works if you've set any
                            of the metadata in the command line.
    --json                  Return a JSON object on stdout.
    --move                  Move the filename from the kebab-case
                            of the title.
"

var path = ''
var author = ''
var title = ''
var pub_date = ''
var skip = false
var json_data = false
var move = false

while test $# -gt 0 {
  case $1 {
    -h|--help)
      echo $help_section
      exit 0
      ;;
    -a|--author)
      set author = $2
      shift 2
      ;;
    -t|--title)
      set title = $2
      shift 2
      ;;
    -d|--date)
      set pub_date = $2
      shift 2
      ;;
    --skip)
      set skip = true
      shift
      ;;
    --json)
      set json_data = true
      shift
      ;;
    --move)
      set move = true
      shift
      ;;
    *)
      set path = $1
      shift
      ;;
  }
}

proc kebab-case(word) {
    # Convert into lower case.
    set word = $(echo $word | tr '[:upper:]' '[:lower:]')

    # What happens to this line:
    # * Convert all whitespace and dashes into a single dash.
    # * Remove all invalid characters (all that are not alphanumeric characters and dashes).
    # * Remove leading and trailing dashes.
    set word = $(echo $word | sed --regexp-extended --expression 's/\s+|-+/-/g' --expression 's/[^.a-z0-9-]//g' --expression 's/^-+|-+\$//g')

    echo $word
}

proc prompt(string, :out, prefix = ">> ") {
    >&2 printf "%s\\n%s" $string $prefix
    read --line
    setref out = $_line
}

proc file_parse(path, :out) {
    var extension_regex = / '.' ![ '.' ]+ %end /
    var file = {}
    set file['dir'] = $(dirname $path)
    set file['name'] = $(basename $path | sed --regexp-extended "s|(.+)${extension_regex}|\\1|")
    set file['ext'] = $(basename $path | sed --regexp-extended "s|.+(${extension_regex})|\\1|")
    set file['mime_type'] = $(file --mime-type --brief $path)

    setref out = file
}

test -f $path || {
    >&2 echo "${path} is not a regular file"
    exit 1
}

# Prompt for the missing metadata (if it's configured to not skip, anyways).
if (not skip) {
    test $title || prompt "What is the title?" :title
    test $author || prompt "Who are the authors?" :author
    test $pub_date || prompt "When this file published?" :pub_date
}

# Writing up the metadata time!
# Each file type has a different way of embedding metadata so it needs different tools.
# We'll use exiftool as a catch-all since it supports the most out of... 15 file types I considered.
case $(file --mime-type --brief $path) {
  "audio/ogg")
    vorbiscomment --write $path --tag "TITLE=${title}" --tag "ARTIST=${author}" --tag "DATE=${pub_date}" ||
    opustags $path --in-place --delete-all --add "TITLE=${title}" --add "ARTIST=${author}" --add "DATE=${pub_date}"
    ;;
  *)
    exiftool -title="${title}" -author="${author}" -date="${pub_date}" ${path}
    ;;
}

file_parse $path :file_info

if (json_data) {
    var metadata = {}
    set metadata['file'] = file_info
    set metadata['title'] = $title
    set metadata['author'] = $author
    set metadata['date'] = $pub_date
    json write :metadata
}

if (move) {
    mv $path "${file_info['dir']}/$(kebab-case $title)${file_info['ext']}"
}