#!/usr/bin/env ruby
# typed: ignore

require "erb"
require "fileutils"
require "yaml"

module Prism
  module Template
    SERIALIZE_ONLY_SEMANTICS_FIELDS = ENV.fetch("PRISM_SERIALIZE_ONLY_SEMANTICS_FIELDS", false)
    REMOVE_ON_ERROR_TYPES = SERIALIZE_ONLY_SEMANTICS_FIELDS
    CHECK_FIELD_KIND = ENV.fetch("CHECK_FIELD_KIND", false)

    JAVA_BACKEND = ENV["PRISM_JAVA_BACKEND"] || "truffleruby"
    JAVA_STRING_TYPE = JAVA_BACKEND == "jruby" ? "org.jruby.RubySymbol" : "String"

    COMMON_FLAGS_COUNT = 2

    class Error
      attr_reader :name

      def initialize(name)
        @name = name
      end
    end

    class Warning
      attr_reader :name

      def initialize(name)
        @name = name
      end
    end

    # This module contains methods for escaping characters in JavaDoc comments.
    module JavaDoc
      ESCAPES = {
        "'" => "'",
        "\"" => """,
        "@" => "@",
        "&" => "&",
        "<" => "&lt;",
        ">" => "&gt;"
      }.freeze

      def self.escape(value)
        value.gsub(/['&"<>@]/, ESCAPES)
      end
    end

    # A comment attached to a field or node.
    class ConfigComment
      attr_reader :value

      def initialize(value)
        @value = value
      end

      def each_line(&block)
        value.each_line { |line| yield line.prepend(" ").rstrip }
      end

      def each_java_line(&block)
        ConfigComment.new(JavaDoc.escape(value)).each_line(&block)
      end
    end

    # This represents a field on a node. It contains all of the necessary
    # information to template out the code for that field.
    class Field
      attr_reader :name, :comment, :options

      def initialize(name:, comment: nil, **options)
        @name = name
        @comment = comment
        @options = options
      end

      def each_comment_line(&block)
        ConfigComment.new(comment).each_line(&block) if comment
      end

      def each_comment_java_line(&block)
        ConfigComment.new(comment).each_java_line(&block) if comment
      end

      def semantic_field?
        true
      end

      def should_be_serialized?
        SERIALIZE_ONLY_SEMANTICS_FIELDS ? semantic_field? : true
      end
    end

    # Some node fields can be specialized if they point to a specific kind of
    # node and not just a generic node.
    class NodeKindField < Field
      def initialize(kind:, **options)
        @kind = kind
        super(**options)
      end

      def c_type
        if specific_kind
          "pm_#{specific_kind.gsub(/(?<=.)[A-Z]/, "_\\0").downcase}"
        else
          "pm_node"
        end
      end

      def ruby_type
        specific_kind || "Node"
      end

      def java_type
        specific_kind || "Node"
      end

      def java_cast
        if specific_kind
          "(Nodes.#{@kind}) "
        else
          ""
        end
      end

      def specific_kind
        @kind unless @kind.is_a?(Array)
      end

      def union_kind
        @kind if @kind.is_a?(Array)
      end
    end

    # This represents a field on a node that is itself a node. We pass them as
    # references and store them as references.
    class NodeField < NodeKindField
      def rbs_class
        if specific_kind
          specific_kind
        elsif union_kind
          union_kind.join(" | ")
        else
          "Prism::node"
        end
      end

      def rbi_class
        if specific_kind
          "Prism::#{specific_kind}"
        elsif union_kind
          "T.any(#{union_kind.map { |kind| "Prism::#{kind}" }.join(", ")})"
        else
          "Prism::Node"
        end
      end

      def check_field_kind
        if union_kind
          "[#{union_kind.join(', ')}].include?(#{name}.class)"
        else
          "#{name}.is_a?(#{ruby_type})"
        end
      end
    end

    # This represents a field on a node that is itself a node and can be
    # optionally null. We pass them as references and store them as references.
    class OptionalNodeField < NodeKindField
      def rbs_class
        if specific_kind
          "#{specific_kind}?"
        elsif union_kind
          [*union_kind, "nil"].join(" | ")
        else
          "Prism::node?"
        end
      end

      def rbi_class
        if specific_kind
          "T.nilable(Prism::#{specific_kind})"
        elsif union_kind
          "T.nilable(T.any(#{union_kind.map { |kind| "Prism::#{kind}" }.join(", ")}))"
        else
          "T.nilable(Prism::Node)"
        end
      end

      def check_field_kind
        if union_kind
          "[#{union_kind.join(', ')}, NilClass].include?(#{name}.class)"
        else
          "#{name}.nil? || #{name}.is_a?(#{ruby_type})"
        end
      end
    end

    # This represents a field on a node that is a list of nodes. We pass them as
    # references and store them directly on the struct.
    class NodeListField < NodeKindField
      def rbs_class
        if specific_kind
          "Array[#{specific_kind}]"
        elsif union_kind
          "Array[#{union_kind.join(" | ")}]"
        else
          "Array[Prism::node]"
        end
      end

      def rbi_class
        if specific_kind
          "T::Array[Prism::#{specific_kind}]"
        elsif union_kind
          "T::Array[T.any(#{union_kind.map { |kind| "Prism::#{kind}" }.join(", ")})]"
        else
          "T::Array[Prism::Node]"
        end
      end

      def java_type
        "#{super}[]"
      end

      def check_field_kind
        if union_kind
          "#{name}.all? { |n| [#{union_kind.join(', ')}].include?(n.class) }"
        else
          "#{name}.all? { |n| n.is_a?(#{ruby_type}) }"
        end
      end
    end

    # This represents a field on a node that is the ID of a string interned
    # through the parser's constant pool.
    class ConstantField < Field
      def rbs_class
        "Symbol"
      end

      def rbi_class
        "Symbol"
      end

      def java_type
        JAVA_STRING_TYPE
      end
    end

    # This represents a field on a node that is the ID of a string interned
    # through the parser's constant pool and can be optionally null.
    class OptionalConstantField < Field
      def rbs_class
        "Symbol?"
      end

      def rbi_class
        "T.nilable(Symbol)"
      end

      def java_type
        JAVA_STRING_TYPE
      end
    end

    # This represents a field on a node that is a list of IDs that are associated
    # with strings interned through the parser's constant pool.
    class ConstantListField < Field
      def rbs_class
        "Array[Symbol]"
      end

      def rbi_class
        "T::Array[Symbol]"
      end

      def java_type
        "#{JAVA_STRING_TYPE}[]"
      end
    end

    # This represents a field on a node that is a string.
    class StringField < Field
      def rbs_class
        "String"
      end

      def rbi_class
        "String"
      end

      def java_type
        "byte[]"
      end
    end

    # This represents a field on a node that is a location.
    class LocationField < Field
      def semantic_field?
        false
      end

      def rbs_class
        "Location"
      end

      def rbi_class
        "Prism::Location"
      end

      def java_type
        "Location"
      end
    end

    # This represents a field on a node that is a location that is optional.
    class OptionalLocationField < Field
      def semantic_field?
        false
      end

      def rbs_class
        "Location?"
      end

      def rbi_class
        "T.nilable(Prism::Location)"
      end

      def java_type
        "Location"
      end
    end

    # This represents an integer field.
    class UInt8Field < Field
      def rbs_class
        "Integer"
      end

      def rbi_class
        "Integer"
      end

      def java_type
        "int"
      end
    end

    # This represents an integer field.
    class UInt32Field < Field
      def rbs_class
        "Integer"
      end

      def rbi_class
        "Integer"
      end

      def java_type
        "int"
      end
    end

    # This represents an arbitrarily-sized integer. When it gets to Ruby it will
    # be an Integer.
    class IntegerField < Field
      def rbs_class
        "Integer"
      end

      def rbi_class
        "Integer"
      end

      def java_type
        "Object"
      end
    end

    # This represents a double-precision floating point number. When it gets to
    # Ruby it will be a Float.
    class DoubleField < Field
      def rbs_class
        "Float"
      end

      def rbi_class
        "Float"
      end

      def java_type
        "double"
      end
    end

    # This class represents a node in the tree, configured by the config.yml file
    # in YAML format. It contains information about the name of the node and the
    # various child nodes it contains.
    class NodeType
      attr_reader :name, :type, :human, :flags, :fields, :newline, :comment

      def initialize(config, flags)
        @name = config.fetch("name")

        type = @name.gsub(/(?<=.)[A-Z]/, "_\\0")
        @type = "PM_#{type.upcase}"
        @human = type.downcase

        @fields =
          config.fetch("fields", []).map do |field|
            type = field_type_for(field.fetch("type"))

            options = field.transform_keys(&:to_sym)
            options.delete(:type)

            # If/when we have documentation on every field, this should be
            # changed to use fetch instead of delete.
            comment = options.delete(:comment)

            if kinds = options[:kind]
              kinds = [kinds] unless kinds.is_a?(Array)
              kinds = kinds.map do |kind|
                case kind
                when "non-void expression"
                  # the actual list of types would be way too long
                  "Node"
                when "pattern expression"
                  # the list of all possible types is too long with 37+ different classes
                  "Node"
                when Hash
                  kind = kind.fetch("on error")
                  REMOVE_ON_ERROR_TYPES ? nil : kind
                else
                  kind
                end
              end.compact
              if kinds.size == 1
                kinds = kinds.first
                kinds = nil if kinds == "Node"
              end
              options[:kind] = kinds
            else
              if type < NodeKindField
                raise "Missing kind in config.yml for field #{@name}##{options.fetch(:name)}"
              end
            end

            type.new(comment: comment, **options)
          end

        @flags = config.key?("flags") ? flags.fetch(config.fetch("flags")) : nil
        @newline = config.fetch("newline", true)
        @comment = config.fetch("comment")
      end

      def each_comment_line(&block)
        ConfigComment.new(comment).each_line(&block)
      end

      def each_comment_java_line(&block)
        ConfigComment.new(comment).each_java_line(&block)
      end

      def semantic_fields
        @semantic_fields ||= @fields.select(&:semantic_field?)
      end

      # Should emit serialized length of node so implementations can skip
      # the node to enable lazy parsing.
      def needs_serialized_length?
        name == "DefNode"
      end

      private

      def field_type_for(name)
        case name
        when "node"       then NodeField
        when "node?"      then OptionalNodeField
        when "node[]"     then NodeListField
        when "string"     then StringField
        when "constant"   then ConstantField
        when "constant?"  then OptionalConstantField
        when "constant[]" then ConstantListField
        when "location"   then LocationField
        when "location?"  then OptionalLocationField
        when "uint8"      then UInt8Field
        when "uint32"     then UInt32Field
        when "integer"    then IntegerField
        when "double"     then DoubleField
        else raise("Unknown field type: #{name.inspect}")
        end
      end
    end

    # This represents a token in the lexer.
    class Token
      attr_reader :name, :value, :comment

      def initialize(config)
        @name = config.fetch("name")
        @value = config["value"]
        @comment = config.fetch("comment")
      end
    end

    # Represents a set of flags that should be internally represented with an enum.
    class Flags
      # Represents an individual flag within a set of flags.
      class Flag
        attr_reader :name, :camelcase, :comment

        def initialize(config)
          @name = config.fetch("name")
          @camelcase = @name.split("_").map(&:capitalize).join
          @comment = config.fetch("comment")
        end
      end

      attr_reader :name, :human, :values, :comment

      def initialize(config)
        @name = config.fetch("name")
        @human = @name.gsub(/(?<=.)[A-Z]/, "_\\0").downcase
        @values = config.fetch("values").map { |flag| Flag.new(flag) }
        @comment = config.fetch("comment")
      end

      def self.empty
        new("name" => "", "values" => [], "comment" => "")
      end
    end

    class << self
      # This templates out a file using ERB with the given locals. The locals are
      # derived from the config.yml file.
      def render(name, write_to: nil)
        filepath = "templates/#{name}.erb"
        template = File.expand_path("../#{filepath}", __dir__)

        erb = read_template(template)
        extension = File.extname(filepath.gsub(".erb", ""))

        heading =
          case extension
          when ".rb"
            <<~HEADING
            # frozen_string_literal: true

            =begin
            This file is generated by the templates/template.rb script and should not be
            modified manually. See #{filepath}
            if you are looking to modify the template
            =end

            HEADING
          when ".rbs"
            <<~HEADING
            # This file is generated by the templates/template.rb script and should not be
            # modified manually. See #{filepath}
            # if you are looking to modify the template

            HEADING
          when ".rbi"
            <<~HEADING
            # typed: strict

            =begin
            This file is generated by the templates/template.rb script and should not be
            modified manually. See #{filepath}
            if you are looking to modify the template
            =end

            HEADING
          else
            <<~HEADING
            /*----------------------------------------------------------------------------*/
            /* This file is generated by the templates/template.rb script and should not  */
            /* be modified manually. See                                                  */
            /* #{filepath + " " * (74 - filepath.size) } */
            /* if you are looking to modify the                                           */
            /* template                                                                   */
            /*----------------------------------------------------------------------------*/

            HEADING
          end

        write_to ||= File.expand_path("../#{name}", __dir__)
        contents = heading + erb.result_with_hash(locals)

        if (extension == ".c" || extension == ".h") && !contents.ascii_only?
          # Enforce that we only have ASCII characters here. This is necessary
          # for non-UTF-8 locales that only allow ASCII characters in C source
          # files.
          contents.each_line.with_index(1) do |line, line_number|
            raise "Non-ASCII character on line #{line_number} of #{write_to}" unless line.ascii_only?
          end
        end

        FileUtils.mkdir_p(File.dirname(write_to))
        File.write(write_to, contents)
      end

      private

      def read_template(filepath)
        template = File.read(filepath, encoding: Encoding::UTF_8)
        erb = erb(template)
        erb.filename = filepath
        erb
      end

      def erb(template)
        ERB.new(template, trim_mode: "-")
      end

      def locals
        @locals ||=
          begin
            config = YAML.load_file(File.expand_path("../config.yml", __dir__))
            flags = config.fetch("flags").to_h { |flags| [flags["name"], Flags.new(flags)] }

            {
              errors: config.fetch("errors").map { |name| Error.new(name) },
              warnings: config.fetch("warnings").map { |name| Warning.new(name) },
              nodes: config.fetch("nodes").map { |node| NodeType.new(node, flags) }.sort_by(&:name),
              tokens: config.fetch("tokens").map { |token| Token.new(token) },
              flags: flags.values
            }
          end
      end
    end

    TEMPLATES = [
      "ext/prism/api_node.c",
      "include/prism/ast.h",
      "include/prism/diagnostic.h",
      "javascript/src/deserialize.js",
      "javascript/src/nodes.js",
      "javascript/src/visitor.js",
      "java/org/prism/Loader.java",
      "java/org/prism/Nodes.java",
      "java/org/prism/AbstractNodeVisitor.java",
      "lib/prism/compiler.rb",
      "lib/prism/dispatcher.rb",
      "lib/prism/dot_visitor.rb",
      "lib/prism/dsl.rb",
      "lib/prism/inspect_visitor.rb",
      "lib/prism/mutation_compiler.rb",
      "lib/prism/node.rb",
      "lib/prism/reflection.rb",
      "lib/prism/serialize.rb",
      "lib/prism/visitor.rb",
      "src/diagnostic.c",
      "src/node.c",
      "src/prettyprint.c",
      "src/serialize.c",
      "src/token_type.c",
      "rbi/prism/dsl.rbi",
      "rbi/prism/node.rbi",
      "rbi/prism/visitor.rbi",
      "sig/prism.rbs",
      "sig/prism/dsl.rbs",
      "sig/prism/mutation_compiler.rbs",
      "sig/prism/node.rbs",
      "sig/prism/visitor.rbs",
      "sig/prism/_private/dot_visitor.rbs"
    ]
  end
end

if __FILE__ == $0
  if ARGV.empty?
    Prism::Template::TEMPLATES.each { |filepath| Prism::Template.render(filepath) }
  else # ruby/ruby
    name, write_to = ARGV
    Prism::Template.render(name, write_to: write_to)
  end
end