# -*- encoding: utf-8 -*-
# -*- frozen_string_literal: true -*-
# -*- warn_indent: true -*-

require "unit_measurements/unit_groups/length"

module CompositeUnitMeasurements
  # A parser handling +length+ measurements, particularly for composite units
  # like +foot-inch+, +kilometre-metre+, +mile-yard+, etc.
  #
  # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
  # @since 0.2.0
  class Length
    class << self
      # Parses a given +string+ into a +UnitMeasurements::Length+ object.
      #
      # @example Parse 'metre-centimetre' measurement:
      #   CompositeUnitMeasurements::Length.parse("6 m 50 cm") #=> 6.5 m
      # @example Parse 'kilometre-metre' measurement:
      #   CompositeUnitMeasurements::Length.parse("5 km 500 m") #=> 5.5 km
      # @example Parse 'foot-inch' measurement:
      #   CompositeUnitMeasurements::Length.parse("5 ft 6 in") #=> 5.5 ft
      # @example Parse 'mile-yard' measurement:
      #   CompositeUnitMeasurements::Length.parse("20 mi 220 yd") #=> 20.125 mi
      #
      # @param [String] string The string to parse for length measurement.
      # @return [UnitMeasurements::Length]
      #   Returns a UnitMeasurements::Length object if parsing is successful.
      #
      # @raise [UnitMeasurements::ParseError]
      #   If the string does not match any known format.
      #
      # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
      # @since 0.2.0
      def parse(string)
        case string
        when FOOT_INCH        then parse_foot_inch(string)
        when KILOMETRE_METRE  then parse_kilometre_metre(string)
        when METRE_CENTIMETRE then parse_metre_centimetre(string)
        when MILE_YARD        then parse_mile_yard(string)
        else                       raise UnitMeasurements::ParseError, string
        end
      end

      private

      # @private
      # Parses a +string+ representing a length in the format of +foot-inch+
      # into a +UnitMeasurements::Length+ object.
      #
      # @param [String] string
      #   The string representing length measurement in the format of *foot-inch*.
      # @return [UnitMeasurements::Length]
      #   Returns a UnitMeasurements::Length object if parsing is successful.
      #
      # @see FOOT_INCH
      # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
      # @since 0.2.0
      def parse_foot_inch(string)
        foot, inch = string.match(FOOT_INCH)&.captures

        if foot && inch
          UnitMeasurements::Length.new(foot, "ft") + UnitMeasurements::Length.new(inch, "in")
        end
      end

      # @private
      # Parses a +string+ representing a length in the format of +metre-centimetre+
      # into a +UnitMeasurements::Length+ object.
      #
      # @param [String] string
      #   The string representing length measurement in the format of *metre-centimetre*.
      # @return [UnitMeasurements::Length]
      #   Returns a UnitMeasurements::Length object if parsing is successful.
      #
      # @see METRE_CENTIMETRE
      # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
      # @since 0.3.0
      def parse_metre_centimetre(string)
        metre, centimetre = string.match(METRE_CENTIMETRE)&.captures

        if metre && centimetre
          UnitMeasurements::Length.new(metre, "m") + UnitMeasurements::Length.new(centimetre, "cm")
        end
      end

      # @private
      # Parses a +string+ representing a length in the format of +kilometre-metre+
      # into a +UnitMeasurements::Length+ object.
      #
      # @param [String] string
      #   The string representing length measurement in the format of *kilometre-metre*.
      # @return [UnitMeasurements::Length]
      #   Returns a UnitMeasurements::Length object if parsing is successful.
      #
      # @see KILOMETRE_METRE
      # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
      # @since 0.3.0
      def parse_kilometre_metre(string)
        kilometre, metre = string.match(KILOMETRE_METRE)&.captures

        if kilometre && metre
          UnitMeasurements::Length.new(kilometre, "km") + UnitMeasurements::Length.new(metre, "m")
        end
      end

      # @private
      # Parses a +string+ representing a length in the format of +mile-yard+
      # into a +UnitMeasurements::Length+ object.
      #
      # @param [String] string
      #   The string representing length measurement in the format of *mile-yard*.
      # @return [UnitMeasurements::Length]
      #   Returns a UnitMeasurements::Length object if parsing is successful.
      #
      # @see MILE_YARD
      # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
      # @since 0.5.0
      def parse_mile_yard(string)
        mile, yard = string.match(MILE_YARD)&.captures

        if mile && yard
          UnitMeasurements::Length.new(mile, "mi") + UnitMeasurements::Length.new(yard, "yd")
        end
      end
    end

    # Regex pattern for aliases of +foot+ unit.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.2.0
    FOOT_ALIASES = /(?:'|ft|foot|feet)/.freeze

    # Regex pattern for aliases of +inch+ unit.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.2.0
    INCH_ALIASES = /(?:"|in|inch(?:es)?)/.freeze

    # Regex pattern for aliases of +metre+ unit.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.3.0
    METRE_ALIASES = /(?:m|meter(?:s)?|metre(?:s)?)/.freeze

    # Regex pattern for aliases of +centimetre+ unit.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.3.0
    CENTIMETRE_ALIASES = /(?:cm|centimeter(?:s)?|centimetre(?:s)?)/.freeze

    # Regex pattern for aliases of +kilometre+ unit.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.3.0
    KILOMETRE_ALIASES = /(?:km|kilometer(?:s)?|kilometre(?:s)?)/.freeze

    # Regex pattern for aliases of +mile+ unit.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.5.0
    MILE_ALIASES = /(?:mi|mile(?:s)?)/.freeze

    # Regex pattern for aliases of +yard+ unit.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.5.0
    YARD_ALIASES = /(?:yd|yard(?:s)?)/.freeze

    # Regex pattern for parsing a length measurement in the format of +foot-inch+.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.2.0
    FOOT_INCH = /\A#{ANY_NUMBER}\s*#{FOOT_ALIASES}\s*#{ANY_NUMBER}\s*#{INCH_ALIASES}\z/.freeze

    # Regex pattern for parsing a length measurement in the format of +metre-centimetre+.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.3.0
    METRE_CENTIMETRE = /\A#{ANY_NUMBER}\s*#{METRE_ALIASES}\s*#{ANY_NUMBER}\s*#{CENTIMETRE_ALIASES}\z/.freeze

    # Regex pattern for parsing a length measurement in the format of +kilometre-metre+.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.3.0
    KILOMETRE_METRE = /\A#{ANY_NUMBER}\s*#{KILOMETRE_ALIASES}\s*#{ANY_NUMBER}\s*#{METRE_ALIASES}\z/.freeze

    # Regex pattern for parsing a length measurement in the format of +mile-yard+.
    #
    # @author {Harshal V. Ladhe}[https://shivam091.github.io/]
    # @since 0.5.0
    MILE_YARD = /\A#{ANY_NUMBER}\s*#{MILE_ALIASES}\s*#{ANY_NUMBER}\s*#{YARD_ALIASES}\z/.freeze

    private_constant :FOOT_ALIASES, :INCH_ALIASES, :METRE_ALIASES, :CENTIMETRE_ALIASES,
                     :KILOMETRE_ALIASES, :MILE_ALIASES, :YARD_ALIASES, :MILE_YARD,
                     :FOOT_INCH, :KILOMETRE_METRE, :METRE_CENTIMETRE
  end
end