require 'hanami/utils/inflector'

module Hanami
  module Utils
    # String on steroids
    #
    # @since 0.1.0
    class String
      # Empty string for #classify
      #
      # @since 0.6.0
      # @api private
      EMPTY_STRING        = ''.freeze

      # Separator between Ruby namespaces
      #
      # @since 0.1.0
      # @api private
      NAMESPACE_SEPARATOR = '::'.freeze

      # Separator for #classify
      #
      # @since 0.3.0
      # @api private
      CLASSIFY_SEPARATOR  = '_'.freeze

      # Regexp for #tokenize
      #
      # @since 0.3.0
      # @api private
      TOKENIZE_REGEXP     = /\((.*)\)/

      # Separator for #tokenize
      #
      # @since 0.3.0
      # @api private
      TOKENIZE_SEPARATOR  = '|'.freeze

      # Separator for #underscore
      #
      # @since 0.3.0
      # @api private
      UNDERSCORE_SEPARATOR = '/'.freeze

      # gsub second parameter used in #underscore
      #
      # @since 0.3.0
      # @api private
      UNDERSCORE_DIVISION_TARGET  = '\1_\2'.freeze

      # Separator for #titleize
      #
      # @since 0.4.0
      # @api private
      TITLEIZE_SEPARATOR = ' '.freeze

      # Separator for #capitalize
      #
      # @since 0.5.2
      # @api private
      CAPITALIZE_SEPARATOR = ' '.freeze

      # Separator for #dasherize
      #
      # @since 0.4.0
      # @api private
      DASHERIZE_SEPARATOR = '-'.freeze

      # Regexp for #classify
      #
      # @since 0.3.4
      # @api private
      CLASSIFY_WORD_SEPARATOR = /#{CLASSIFY_SEPARATOR}|#{NAMESPACE_SEPARATOR}|#{UNDERSCORE_SEPARATOR}|#{DASHERIZE_SEPARATOR}/

      # Initialize the string
      #
      # @param string [::String, Symbol] the value we want to initialize
      #
      # @return [String] self
      #
      # @since 0.1.0
      def initialize(string)
        @string = string.to_s
      end

      # Return a titleized version of the string
      #
      # @return [Hanami::Utils::String] the transformed string
      #
      # @since 0.4.0
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new 'hanami utils'
      #   string.titleize # => "Hanami Utils"
      def titleize
        self.class.new underscore.split(CLASSIFY_SEPARATOR).map(&:capitalize).join(TITLEIZE_SEPARATOR)
      end

      # Return a capitalized version of the string
      #
      # @return [Hanami::Utils::String] the transformed string
      #
      # @since 0.5.2
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new 'hanami'
      #   string.capitalize # => "Hanami"
      #
      #   string = Hanami::Utils::String.new 'hanami utils'
      #   string.capitalize # => "Hanami utils"
      #
      #   string = Hanami::Utils::String.new 'Hanami Utils'
      #   string.capitalize # => "Hanami utils"
      #
      #   string = Hanami::Utils::String.new 'hanami_utils'
      #   string.capitalize # => "Hanami utils"
      #
      #   string = Hanami::Utils::String.new 'hanami-utils'
      #   string.capitalize # => "Hanami utils"
      def capitalize
        head, *tail = underscore.split(CLASSIFY_SEPARATOR)

        self.class.new(
          tail.unshift(head.capitalize).join(CAPITALIZE_SEPARATOR)
        )
      end

      # Return a CamelCase version of the string
      #
      # @return [String] the transformed string
      #
      # @since 0.1.0
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new 'hanami_utils'
      #   string.classify # => 'HanamiUtils'
      def classify
        words = split(CLASSIFY_WORD_SEPARATOR).map!(&:capitalize)
        delimiters = scan(CLASSIFY_WORD_SEPARATOR)

        delimiters.map! do |delimiter|
          delimiter == CLASSIFY_SEPARATOR ? EMPTY_STRING : NAMESPACE_SEPARATOR
        end

        self.class.new words.zip(delimiters).join
      end

      # Return a downcased and underscore separated version of the string
      #
      # Revised version of `ActiveSupport::Inflector.underscore` implementation
      # @see https://github.com/rails/rails/blob/feaa6e2048fe86bcf07e967d6e47b865e42e055b/activesupport/lib/active_support/inflector/methods.rb#L90
      #
      # @return [String] the transformed string
      #
      # @since 0.1.0
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new 'HanamiUtils'
      #   string.underscore # => 'hanami_utils'
      def underscore
        new_string = gsub(NAMESPACE_SEPARATOR, UNDERSCORE_SEPARATOR)
        new_string.gsub!(/([A-Z\d]+)([A-Z][a-z])/, UNDERSCORE_DIVISION_TARGET)
        new_string.gsub!(/([a-z\d])([A-Z])/, UNDERSCORE_DIVISION_TARGET)
        new_string.gsub!(/[[:space:]]|\-/, UNDERSCORE_DIVISION_TARGET)
        new_string.downcase!
        self.class.new new_string
      end

      # Return a downcased and dash separated version of the string
      #
      # @return [Hanami::Utils::String] the transformed string
      #
      # @since 0.4.0
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new 'Hanami Utils'
      #   string.dasherize # => 'hanami-utils'
      #
      #   string = Hanami::Utils::String.new 'hanami_utils'
      #   string.dasherize # => 'hanami-utils'
      #
      #   string = Hanami::Utils::String.new 'HanamiUtils'
      #   string.dasherize # => "hanami-utils"
      def dasherize
        self.class.new underscore.split(CLASSIFY_SEPARATOR).join(DASHERIZE_SEPARATOR)
      end

      # Return the string without the Ruby namespace of the class
      #
      # @return [String] the transformed string
      #
      # @since 0.1.0
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new 'Hanami::Utils::String'
      #   string.demodulize # => 'String'
      #
      #   string = Hanami::Utils::String.new 'String'
      #   string.demodulize # => 'String'
      def demodulize
        self.class.new split(NAMESPACE_SEPARATOR).last
      end

      # Return the top level namespace name
      #
      # @return [String] the transformed string
      #
      # @since 0.1.2
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new 'Hanami::Utils::String'
      #   string.namespace # => 'Hanami'
      #
      #   string = Hanami::Utils::String.new 'String'
      #   string.namespace # => 'String'
      def namespace
        self.class.new split(NAMESPACE_SEPARATOR).first
      end

      # It iterates through the tokens and calls the given block.
      # A token is a substring wrapped by `()` and separated by `|`.
      #
      # @yield the block that is called for each token.
      #
      # @return [void]
      #
      # @since 0.1.0
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new 'Hanami::(Utils|App)'
      #   string.tokenize do |token|
      #     puts token
      #   end
      #
      #   # =>
      #     'Hanami::Utils'
      #     'Hanami::App'
      def tokenize
        if match = TOKENIZE_REGEXP.match(@string)
          pre, post = match.pre_match, match.post_match
          tokens = match[1].split(TOKENIZE_SEPARATOR)
          tokens.each do |token|
            yield(self.class.new("#{pre}#{token}#{post}"))
          end
        else
          yield(self.class.new(@string))
        end

        nil
      end

      # Return a pluralized version of self.
      #
      # @return [Hanami::Utils::String] the pluralized string.
      #
      # @api private
      # @since 0.4.1
      #
      # @see Hanami::Utils::Inflector
      def pluralize
        self.class.new Inflector.pluralize(self)
      end

      # Return a singularized version of self.
      #
      # @return [Hanami::Utils::String] the singularized string.
      #
      # @api private
      # @since 0.4.1
      #
      # @see Hanami::Utils::Inflector
      def singularize
        self.class.new Inflector.singularize(self)
      end

      # Returns the hash of the internal string
      #
      # @return [Fixnum]
      #
      # @since 0.3.0
      def hash
        @string.hash
      end

      # Returns a string representation
      #
      # @return [String]
      #
      # @since 0.3.0
      def to_s
        @string
      end

      alias_method :to_str,  :to_s

      # Equality
      #
      # @return [TrueClass,FalseClass]
      #
      # @since 0.3.0
      def ==(other)
        to_s == other
      end

      alias_method :eql?, :==

      # Split the string with the given pattern
      #
      # @return [Array<String>]
      #
      # @see http://www.ruby-doc.org/core/String.html#method-i-split
      #
      # @since 0.3.0
      def split(pattern, limit = 0)
        @string.split(pattern, limit)
      end

      # Replace the given pattern with the given replacement
      #
      # @return [String,nil]
      #
      # @see http://www.ruby-doc.org/core/String.html#method-i-gsub
      #
      # @since 0.3.0
      def gsub(pattern, replacement = nil, &blk)
        if block_given?
          @string.gsub(pattern, &blk)
        else
          @string.gsub(pattern, replacement)
        end
      end

      # Both forms iterate through str, matching the pattern
      #
      # @return [String,nil]
      #
      # @see http://www.ruby-doc.org/core/String.html#method-i-scan
      #
      # @since 0.6.0
      def scan(pattern, &blk)
        @string.scan(pattern, &blk)
      end

      # Replace the rightmost match of <tt>pattern</tt> with <tt>replacement</tt>
      #
      # If the pattern cannot be matched, it returns the original string.
      #
      # This method does NOT mutate the original string.
      #
      # @param pattern [Regexp, String] the pattern to find
      # @param replacement [String, Hanami::Utils::String] the string to replace
      #
      # @return [Hanami::Utils::String] the replaced string
      #
      # @since 0.6.0
      #
      # @example
      #   require 'hanami/utils/string'
      #
      #   string = Hanami::Utils::String.new('authors/books/index')
      #   result = string.rsub(/\//, '#')
      #
      #   puts string
      #     # => #<Hanami::Utils::String:0x007fdb41233ad8 @string="authors/books/index">
      #
      #   puts result
      #     # => #<Hanami::Utils::String:0x007fdb41232ed0 @string="authors/books#index">
      def rsub(pattern, replacement)
        if i = rindex(pattern)
          s    = @string.dup
          s[i] = replacement
          self.class.new s
        else
          self
        end
      end

      # Override Ruby's method_missing in order to provide ::String interface
      #
      # @api private
      # @since 0.3.0
      #
      # @raise [NoMethodError] If doesn't respond to the given method
      def method_missing(m, *args, &blk)
        if respond_to?(m)
          s = @string.__send__(m, *args, &blk)
          s = self.class.new(s) if s.is_a?(::String)
          s
        else
          raise NoMethodError.new(%(undefined method `#{ m }' for "#{ @string }":#{ self.class }))
        end
      end

      # Override Ruby's respond_to_missing? in order to support ::String interface
      #
      # @api private
      # @since 0.3.0
      def respond_to_missing?(m, include_private=false)
        @string.respond_to?(m, include_private)
      end
    end
  end
end