## image_to_aa - from image file to ascii art text
##
## - module: image_to_aa
##   config:
##     file: convert file path
##     size_ratio: convert ascii art size ratio (1:normal size, 2:half size)
##
require 'aalib'

def image_to_aa(config, data)
  file = config["file"]
  size_ratio = config["size_ratio"]
  generate_aa(file, size_ratio)
end

# アスキーアートを生成
def generate_aa(file, size_ratio)
  cmd_name = get_cmd_name(file)
  ratio = get_ratio(size_ratio)
  cmd = "#{cmd_name} #{file} | ppmtopgm | pgmtopbm | pbmtoascii #{ratio}"
  `#{cmd}`
end

# 拡張子から変換コマンドを選択
def get_cmd_name(file)
  ext = File.extname(file)
  if /.*\.(jpg|jpeg|JPG|JPEG)\z/ =~ ext
    return "jpegtopnm"
  elsif /.*\.(png|PNG)\z/ =~ ext
    return "pngtopnm"
  elsif /.*\.(gif|GIF)\z/ =~ ext
    return "giftopnm"
  elsif /.*\.(bmp|BMP)\z/ =~ ext
    return "bmptopnm"
  else
    raise ArgumentError, "file format invalid!!"
  end
end

# AAサイズ比率選択
def get_ratio(size_ratio)
  if size_ratio == 1
    return ""
  elsif size_ratio == 2
    return "-2x4"
  else
    return ""
  end
end