class Prism::Pattern

# File lib/prism/pattern.rb, line 63
def initialize(query)
  @query = query
  @compiled = nil
end

# File lib/prism/pattern.rb, line 70
def compile
  result = Prism.parse("case nil\nin #{query}\nend")

  case_match_node = result.value.statements.body.last
  raise CompilationError, case_match_node.inspect unless case_match_node.is_a?(CaseMatchNode)

  in_node = case_match_node.conditions.last
  raise CompilationError, in_node.inspect unless in_node.is_a?(InNode)

  compile_node(in_node.pattern)
end

# File lib/prism/pattern.rb, line 86
def scan(root)
  return to_enum(:scan, root) unless block_given?

  @compiled ||= compile
  queue = [root]

  while (node = queue.shift)
    yield node if @compiled.call(node) # steep:ignore
    queue.concat(node.compact_child_nodes)
  end
end

# File lib/prism/pattern.rb, line 102
def combine_and(left, right)
  ->(other) { left.call(other) && right.call(other) }
end

# File lib/prism/pattern.rb, line 108
def combine_or(left, right)
  ->(other) { left.call(other) || right.call(other) }
end

# File lib/prism/pattern.rb, line 143
def compile_alternation_pattern_node(node)
  combine_or(compile_node(node.left), compile_node(node.right))
end

# File lib/prism/pattern.rb, line 118
def compile_array_pattern_node(node)
  compile_error(node) if !node.rest.nil? || node.posts.any?

  constant = node.constant
  compiled_constant = compile_node(constant) if constant

  preprocessed = node.requireds.map { |required| compile_node(required) }

  compiled_requireds = ->(other) do
    deconstructed = other.deconstruct

    deconstructed.length == preprocessed.length &&
      preprocessed
        .zip(deconstructed)
        .all? { |(matcher, value)| matcher.call(value) }
  end

  if compiled_constant
    combine_and(compiled_constant, compiled_requireds)
  else
    compiled_requireds
  end
end

# File lib/prism/pattern.rb, line 168
def compile_constant_name(node, name)
  if Prism.const_defined?(name, false)
    clazz = Prism.const_get(name)

    ->(other) { clazz === other }
  elsif Object.const_defined?(name, false)
    clazz = Object.const_get(name)

    ->(other) { clazz === other }
  else
    compile_error(node)
  end
end

# File lib/prism/pattern.rb, line 148
def compile_constant_path_node(node)
  parent = node.parent

  if parent.is_a?(ConstantReadNode) && parent.slice == "Prism"
    name = node.name
    raise CompilationError, node.inspect if name.nil?

    compile_constant_name(node, name)
  else
    compile_error(node)
  end
end

# File lib/prism/pattern.rb, line 163
def compile_constant_read_node(node)
  compile_constant_name(node, node.name)
end

# File lib/prism/pattern.rb, line 113
def compile_error(node)
  raise CompilationError, node.inspect
end

# File lib/prism/pattern.rb, line 184
def compile_hash_pattern_node(node)
  compile_error(node) if node.rest
  compiled_constant = compile_node(node.constant) if node.constant

  preprocessed =
    node.elements.to_h do |element|
      key = element.key
      if key.is_a?(SymbolNode)
        [key.unescaped.to_sym, compile_node(element.value)]
      else
        raise CompilationError, element.inspect
      end
    end

  compiled_keywords = ->(other) do
    deconstructed = other.deconstruct_keys(preprocessed.keys)

    preprocessed.all? do |keyword, matcher|
      deconstructed.key?(keyword) && matcher.call(deconstructed[keyword])
    end
  end

  if compiled_constant
    combine_and(compiled_constant, compiled_keywords)
  else
    compiled_keywords
  end
end

# File lib/prism/pattern.rb, line 214
def compile_nil_node(node)
  ->(attribute) { attribute.nil? }
end

# File lib/prism/pattern.rb, line 243
def compile_node(node)
  case node
  when AlternationPatternNode
    compile_alternation_pattern_node(node)
  when ArrayPatternNode
    compile_array_pattern_node(node)
  when ConstantPathNode
    compile_constant_path_node(node)
  when ConstantReadNode
    compile_constant_read_node(node)
  when HashPatternNode
    compile_hash_pattern_node(node)
  when NilNode
    compile_nil_node(node)
  when RegularExpressionNode
    compile_regular_expression_node(node)
  when StringNode
    compile_string_node(node)
  when SymbolNode
    compile_symbol_node(node)
  else
    compile_error(node)
  end
end

# File lib/prism/pattern.rb, line 219
def compile_regular_expression_node(node)
  regexp = Regexp.new(node.unescaped, node.closing[1..])

  ->(attribute) { regexp === attribute }
end

# File lib/prism/pattern.rb, line 227
def compile_string_node(node)
  string = node.unescaped

  ->(attribute) { string === attribute }
end

# File lib/prism/pattern.rb, line 235
def compile_symbol_node(node)
  symbol = node.unescaped.to_sym

  ->(attribute) { symbol === attribute }
end