#!/usr/bin/env bash
# requires magick from ImageMagick >= 6.5 (7+ is okay too)
# Suppors output to non-pcx formats too:
#   --ext .bmp
# Can be sourced by zsh or bash, but only use filetopcx__convert_file or filetopcx__main
filetopcx__tmpdir=
filetopcx__ext='.pcx'
filetopcx__files=()
filetopcx__args=(
  -compress RLE
  -alpha off
  -dither FloydSteinberg
  -density 300
  -colors 256
  -verbose
)
filetopcx__one_arg_flags=(
  -adaptive-blur
  -adaptive-resize
  -adaptive-sharpen
  -alpha
  -attenuate
  -authenticate
  -auto-threshold
  -background
  -bench
  -bias
  -bilateral-blur
  -black-threshold
  -blend
  -blue-primary
  -blue-shift
  -blur
  -border
  -bordercolor
  -borderwidth
  -brightness-contrast
  -cache
  -canny
  -caption
  -cdl
  -channel
  +channel
  -channel-fx
  -charcoal
  -chop
  -clahe
  -clip-path
  -clone
  -color-matrix
  -color-threshold
  -colorize
  -colormap
  -colors
  -colorspace
  -comment
  -complex
  -compose
  -compress
  -connected-components
  -contrast-stretch
  -convolve
  -crop
  -cycle
  -debug
  -decipher
  -define
  -delay
  -delete
  -density
  -depth
  -deskew
  -direction
  -displace
  -display
  -dispose
  -dissimilarity-threshold
  -dissolve
  -distribute-cache
  -dither
  -draw
  -duplicate
  -edge
  -emboss
  -encipher
  -encoding
  -endian
  -evaluate-sequence
  -extent
  -extract
  -family
  -features
  -fill
  -filter
  -font
  -foreground
  -format
  -frame
  -fuzz
  -fx
  -gamma
  -gaussian-blur
  -geometry
  -gravity
  -grayscale
  -green-primary
  -highlight-color
  -hough-lines
  -iconGeometry
  -illuminant
  -implode
  -insert
  -intensity
  -intent
  -interlace
  -interline-spacing
  -interpolate
  -interpolative-resize
  -interword-spacing
  -kerning
  -kmeans
  -kuwahara
  -kuwahara
  -label
  -lat
  -layers
  -level
  +level
  -level-colors
  +level-colors
  -linear-stretch
  -liquid-rescale
  -list
  -log
  -loop
  -lowlight-color
  -map
  -mattecolor
  -mean-shift
  -median
  -metric
  -mode
  -modulate
  -morph
  -motion-blur
  -noise
  +noise
  -opaque
  -ordered-dither
  -page
  -paint
  -path
  -pause
  -perceptible
  -pointsize
  -polaroid
  -poly
  -posterize
  -precision
  -preview
  -print
  -process
  -profile
  +profile
  -quality
  -quantize
  -raise
  -random-threshold
  -range-threshold
  -read
  -read-mask
  -red-primary
  -region
  -remap
  -repage
  -resample
  -reshape
  -resize
  -roll
  -rotate
  -rotational-blur
  -sample
  -sampling-factor
  -scale
  -scene
  -script
  -segment
  +set
  -selective-blur
  -sepia-tone
  -shade
  -shadow
  -sharpen
  -shave
  -shear
  -sigmoidal-contrast
  +sigmoidal-contrast
  -similarity-threshold
  -size
  -sketch
  -smush
  -snaps
  -solarize
  -splice
  -spread
  -stegano
  -stereo
  -storage-type
  -stretch
  -stroke
  -strokewidth
  -style
  -swap
  -swirl
  -text-font
  -texture
  -threshold
  -thumbnail
  -tile
  -tile-offset
  -tint
  -title
  -transparent
  -transparent-color
  -treedepth
  -type
  -undercolor
  -units
  -unsharp
  -update
  -view
  -vignette
  -virtual-pixel
  -visual
  -watermark
  -wave
  -wavelet-denoise
  -weight
  -white-point
  -white-threshold
  -window
  -word-break
  -write
  +write
  -write-mask
)
filetopcx__two_arg_flags=(
  -copy
  -distort
  -evaluate
  -floodfill
  -function
  -limit
  -orient
  -set
  -sparse-color
  -statistic
)

filetopcx__count_args_for_flag() {
  local a
  for a in "${filetopcx__one_arg_flags[@]}"; do
    if [[ "$1" == "$a" ]]; then
      echo 2
      return
    fi
  done
  for a in "${filetopcx__two_arg_flags[@]}"; do
    if [[ "$1" == "$a" ]]; then
      echo 3
      return
    fi
  done
  echo 1
}

filetopcx__die() {
  echo >&2 "$@"
  exit 1
}

filetopcx__parse_options() {
  (("$#" > 0)) || filetopcx__die "Usage: $0 [magick options] file..."

  while (($# > 0)); do
    case "$1" in
    -) filetopcx__files+=("$1") ;;
    --)
      shift
      break
      ;;
    --ext)
      (($# >= 2)) || filetopcx__die "Missing argument(s) for option: $1"
      filetopcx__ext=".${2#.}"
      shift
      ;;
    -* | +*)
      n=$(filetopcx__count_args_for_flag "$1")
      (($# >= n)) || filetopcx__die "Missing argument(s) for option: $1"
      filetopcx__args+=("${@:1:n}")
      shift $((n - 1))
      ;;
    *) filetopcx__files+=("$1") ;;
    esac
    shift
  done

  filetopcx__files+=("$@")
}

filetopcx__ensure_tmpdir() {
  if [[ -z "$filetopcx__tmpdir" ]]; then
    # shellcheck disable=SC2154
    trap 'e=$?; trap - EXIT; [[ -n "$filetopcx__tmpdir" ]] && rm -rf "$filetopcx__tmpdir"; exit $e' EXIT
    filetopcx__tmpdir=$(mktemp -d)
  fi
}

filetopcx__convert_file() {
  (
    set -euEo pipefail
    [[ -z "${FILETOPCX__DEBUG-}" ]] || set -x

    filetopcx__ensure_tmpdir

    file="$1"
    orig_base=$(basename "$file")
    new_base="${orig_base%.*}${filetopcx__ext}"
    tmp="$filetopcx__tmpdir/$new_base"
    out="$(dirname "$(realpath "$(file)")")/$new_base"

    "${MAGICK:-magick}" \
      "$file" \
      "${filetopcx__args[@]}" \
      "$tmp"

    mv "$tmp" "$out"
  )
}

filetopcx__main() {
  (
    set -euEo pipefail
    [[ -z "${FILETOPCX__DEBUG-}" ]] || set -x

    filetopcx__parse_options "$@"

    for file in "${filetopcx__files[@]}"; do
      filetopcx__convert_file "$file"
    done
  )
}

filetopcx__is_sourced() {
  if [ -n "${ZSH_VERSION-}" ]; then
    [[ "$ZSH_EVAL_CONTEXT" = *:file:* ]]
  elif [ -n "${BASH_VERSION-}" ]; then
    (return 0 2>/dev/null)
  else
    filetopcx__die 'only bash and zsh are supported'
  fi
}

#### main

filetopcx__is_sourced || filetopcx__main "$@"