class DidYouMean::TreeSpellChecker

# File lib/did_you_mean/tree_spell_checker.rb, line 9
def initialize(dictionary:, separator: '/', augment: nil)
  @dictionary = dictionary
  @separator = separator
  @augment = augment
end

# File lib/did_you_mean/tree_spell_checker.rb, line 15
def correct(input)
  plausibles = plausible_dimensions(input)
  return fall_back_to_normal_spell_check(input) if plausibles.empty?

  suggestions = find_suggestions(input, plausibles)
  return fall_back_to_normal_spell_check(input) if suggestions.empty?

  suggestions
end

# File lib/did_you_mean/tree_spell_checker.rb, line 25
def dictionary_without_leaves
  @dictionary_without_leaves ||= dictionary.map { |word| word.split(separator)[0..-2] }.uniq
end

# File lib/did_you_mean/tree_spell_checker.rb, line 33
def dimensions
  @dimensions ||= tree_depth.times.map do |index|
                    dictionary_without_leaves.map { |element| element[index] }.compact.uniq
                  end
end

# File lib/did_you_mean/tree_spell_checker.rb, line 39
def find_leaves(path)
  path_with_separator = "#{path}#{separator}"

  dictionary
    .select {|str| str.include?(path_with_separator) }
    .map {|str| str.gsub(path_with_separator, '') }
end

# File lib/did_you_mean/tree_spell_checker.rb, line 47
def plausible_dimensions(input)
  input.split(separator)[0..-2]
    .map
    .with_index { |element, index| correct_element(dimensions[index], element) if dimensions[index] }
    .compact
end

# File lib/did_you_mean/tree_spell_checker.rb, line 54
def possible_paths(states)
  states.map { |state| state.join(separator) }
end

# File lib/did_you_mean/tree_spell_checker.rb, line 29
def tree_depth
  @tree_depth ||= dictionary_without_leaves.max { |a, b| a.size <=> b.size }.size
end

# File lib/did_you_mean/tree_spell_checker.rb, line 93
def correct_element(names, element)
  return names if names.size == 1

  str = normalize(element)

  return [str] if names.include?(str)

  ::DidYouMean::SpellChecker.new(dictionary: names).correct(str)
end

# File lib/did_you_mean/tree_spell_checker.rb, line 68
def fall_back_to_normal_spell_check(input)
  return [] unless augment

  ::DidYouMean::SpellChecker.new(dictionary: dictionary).correct(input)
end

# File lib/did_you_mean/tree_spell_checker.rb, line 74
def find_ideas(paths, leaf)
  paths.flat_map do |path|
    names = find_leaves(path)
    ideas = correct_element(names, leaf)

    ideas_to_paths(ideas, leaf, names, path)
  end.compact
end

# File lib/did_you_mean/tree_spell_checker.rb, line 60
def find_suggestions(input, plausibles)
  states = plausibles[0].product(*plausibles[1..-1])
  paths  = possible_paths(states)
  leaf   = input.split(separator).last

  find_ideas(paths, leaf)
end

# File lib/did_you_mean/tree_spell_checker.rb, line 83
def ideas_to_paths(ideas, leaf, names, path)
  if ideas.empty?
    nil
  elsif names.include?(leaf)
    ["#{path}#{separator}#{leaf}"]
  else
    ideas.map {|str| "#{path}#{separator}#{str}" }
  end
end

# File lib/did_you_mean/tree_spell_checker.rb, line 103
def normalize(str)
  str.downcase!
  str.tr!('@', ' ') if str.include?('@')
  str
end