# frozen_string_literal: true

require "fastimage"

module Notare
  class ImageDimensions
    EMUS_PER_INCH = 914_400
    DEFAULT_DPI = 96

    def self.read(path)
      FastImage.size(path) || raise(ArgumentError, "Could not read image dimensions: #{path}")
    end

    def self.calculate_emus(path, width: nil, height: nil)
      native_width, native_height = read(path)
      calculate_dimensions_emu(native_width, native_height, width, height)
    end

    def self.calculate_dimensions_emu(native_width, native_height, width, height)
      if width && height
        [parse_dimension(width), parse_dimension(height)]
      elsif width
        w = parse_dimension(width)
        ratio = native_height.to_f / native_width
        [w, (w * ratio).to_i]
      elsif height
        h = parse_dimension(height)
        ratio = native_width.to_f / native_height
        [(h * ratio).to_i, h]
      else
        pixels_to_emus(native_width, native_height)
      end
    end

    def self.parse_dimension(value)
      case value
      when Integer
        pixels_to_emus(value, 0).first
      when /\A(\d+(?:\.\d+)?)\s*in\z/i
        (::Regexp.last_match(1).to_f * EMUS_PER_INCH).to_i
      when /\A(\d+(?:\.\d+)?)\s*cm\z/i
        (::Regexp.last_match(1).to_f * 360_000).to_i
      when /\A(\d+(?:\.\d+)?)\s*px\z/i, /\A(\d+)\z/
        pixels_to_emus(::Regexp.last_match(1).to_i, 0).first
      else
        raise ArgumentError, "Invalid dimension format: #{value}. Use '2in', '5cm', '100px', or integer pixels."
      end
    end

    def self.pixels_to_emus(width_px, height_px)
      emu_per_pixel = EMUS_PER_INCH / DEFAULT_DPI
      [(width_px * emu_per_pixel).to_i, (height_px * emu_per_pixel).to_i]
    end
  end
end