# frozen_string_literal: true

module DeadEnd
  # Represents a single line of code of a given source file
  #
  # This object contains metadata about the line such as
  # amount of indentation. An if it is empty or not.
  #
  # While a given search for syntax errors is being performed
  # state about the search can be stored in individual lines such
  # as :valid or :invalid.
  #
  # Visibility of lines can be toggled on and off.
  #
  # Example:
  #
  #   line = CodeLine.new(line: "def foo\n", index: 0)
  #   line.line_number => 1
  #   line.empty? # => false
  #   line.visible? # => true
  #   line.mark_invisible
  #   line.visible? # => false
  #
  # A CodeBlock is made of multiple CodeLines
  #
  # Marking a line as invisible indicates that it should not be used
  # for syntax checks. It's essentially the same as commenting it out
  #
  # Marking a line as invisible also lets the overall program know
  # that it should not check that area for syntax errors.
  class CodeLine
    TRAILING_SLASH = ("\\" + $/).freeze

    def self.parse(source)
      source.lines.map.with_index do |line, index|
        CodeLine.new(line: line, index: index)
      end
    end

    attr_reader :line, :index, :indent, :original_line

    def initialize(line:, index:)
      @original_line = line.freeze
      @line = @original_line
      if line.strip.empty?
        @empty = true
        @indent = 0
      else
        @empty = false
        @indent = SpaceCount.indent(line)
      end
      @index = index
      @status = nil # valid, invalid, unknown
      @invalid = false

      lex_detect!
    end

    private def lex_detect!
      lex_array = LexAll.new(source: line)
      kw_count = 0
      end_count = 0
      lex_array.each_with_index do |lex, index|
        next unless lex.type == :on_kw

        case lex.token
        when "if", "unless", "while", "until"
          # Only count if/unless when it's not a "trailing" if/unless
          # https://github.com/ruby/ruby/blob/06b44f819eb7b5ede1ff69cecb25682b56a1d60c/lib/irb/ruby-lex.rb#L374-L375
          kw_count += 1 unless lex.expr_label?
        when "def", "case", "for", "begin", "class", "module", "do"
          kw_count += 1
        when "end"
          end_count += 1
        end
      end

      @is_comment = lex_array.detect { |lex| lex.type != :on_sp }&.type == :on_comment
      return if @is_comment
      @is_kw = (kw_count - end_count) > 0
      @is_end = (end_count - kw_count) > 0
      @is_trailing_slash = lex_array.last.token == TRAILING_SLASH
    end

    alias_method :original, :original_line

    def trailing_slash?
      @is_trailing_slash
    end

    def indent_index
      @indent_index ||= [indent, index]
    end

    def <=>(other)
      index <=> other.index
    end

    def is_comment?
      @is_comment
    end

    def not_comment?
      !is_comment?
    end

    def is_kw?
      @is_kw
    end

    def is_end?
      @is_end
    end

    def mark_invisible
      @line = ""
      self
    end

    def mark_visible
      @line = @original_line
      self
    end

    def visible?
      !line.empty?
    end

    def hidden?
      !visible?
    end

    def line_number
      index + 1
    end
    alias_method :number, :line_number

    def not_empty?
      !empty?
    end

    def empty?
      @empty
    end

    def to_s
      line
    end
  end
end