require 'ripper'
require 'temple'
require 'haml_parser/ast'
require_relative 'attribute_compiler'
require_relative 'error'
require_relative 'filter_compilers'
require_relative 'helpers'
require_relative 'rails_helpers'
require_relative 'text_compiler'

module Faml
  class Compiler < Temple::Parser
    DEFAULT_AUTO_CLOSE_TAGS = %w[
      area base basefont br col command embed frame hr img input isindex keygen
      link menuitem meta param source track wbr
    ]
    DEFAULT_PRESERVE_TAGS = %w[pre textarea code]

    define_options(
      autoclose: DEFAULT_AUTO_CLOSE_TAGS,
      format: :html,
      preserve: DEFAULT_PRESERVE_TAGS,
      use_html_safe: false,
      filename: nil,
      extend_helpers: false,
    )

    def initialize(*)
      super
      @text_compiler = TextCompiler.new
      @filename = options[:filename]
    end

    def call(ast)
      compile(ast)
    rescue Error => e
      if @filename && e.lineno
        e.backtrace.unshift "#{@filename}:#{e.lineno}"
      end
      raise e
    end

    def self.find_and_preserve(input)
      # Taken from the original haml code
      re = %r{<(#{options[:preserve].map(&Regexp.method(:escape)).join('|')})([^>]*)>(.*?)(<\/\1>)}im
      input.to_s.gsub(re) do |s|
        m = s.match(re) # Can't rely on $1, etc. existing since Rails' SafeBuffer#gsub is incompatible
        "<#{m[1]}#{m[2]}>#{Helpers.preserve(m[3])}</#{m[1]}>"
      end
    end

    private

    def compile(ast)
      case ast
      when HamlParser::Ast::Root
        compile_root(ast)
      when HamlParser::Ast::Doctype
        compile_doctype(ast)
      when HamlParser::Ast::HtmlComment
        compile_html_comment(ast)
      when HamlParser::Ast::HamlComment
        compile_haml_comment(ast)
      when HamlParser::Ast::Empty
        [:multi]
      when HamlParser::Ast::Element
        compile_element(ast)
      when HamlParser::Ast::Script
        compile_script(ast)
      when HamlParser::Ast::SilentScript
        compile_silent_script(ast)
      when HamlParser::Ast::Text
        compile_text(ast)
      when HamlParser::Ast::Filter
        compile_filter(ast)
      else
        raise "InternalError: Unknown AST node #{ast.class}: #{ast.inspect}"
      end
    end

    def compile_root(ast)
      temple = [:multi]
      if options[:extend_helpers]
        temple << [:code, "extend ::#{helper_module.name}"]
      end
      compile_children(ast, temple)
      temple
    end

    def helper_module
      if options[:use_html_safe]
        RailsHelpers
      else
        Helpers
      end
    end

    def compile_children(ast, temple)
      ast.children.each do |c|
        temple << compile(c)
        if need_newline?(c)
          temple << [:mknl]
        end
        unless suppress_code_newline?(c)
          temple << [:newline]
        end
      end
    end

    def need_newline?(child)
      case child
      when HamlParser::Ast::Script
        child.children.empty?
      when HamlParser::Ast::SilentScript, HamlParser::Ast::HamlComment, HamlParser::Ast::Empty
        false
      when HamlParser::Ast::Element
        !child.nuke_outer_whitespace
      when HamlParser::Ast::Filter
        FilterCompilers.find(child.name).need_newline?
      else
        true
      end
    end

    def suppress_code_newline?(ast)
      ast.is_a?(HamlParser::Ast::Script) ||
        ast.is_a?(HamlParser::Ast::SilentScript) ||
        (ast.is_a?(HamlParser::Ast::Element) && suppress_code_newline?(ast.oneline_child)) ||
        (ast.is_a?(HamlParser::Ast::Element) && !ast.children.empty?) ||
        (ast.is_a?(HamlParser::Ast::HtmlComment) && !ast.conditional.empty?)
    end

    def compile_text(ast)
      @text_compiler.compile(ast.text, ast.lineno, escape_html: ast.escape_html)
    end

    # html5 and html4 is deprecated in temple.
    DEFAULT_DOCTYPE = {
      html: 'html',
      html5: 'html',
      html4: 'transitional',
      xhtml: 'transitional',
    }.freeze

    def compile_doctype(ast)
      doctype = ast.doctype.downcase
      if doctype.empty?
        doctype = DEFAULT_DOCTYPE[options[:format]]
      end
      [:haml, :doctype, doctype]
    end

    def compile_html_comment(ast)
      if ast.children.empty?
        if ast.conditional.empty?
          [:html, :comment, [:static, " #{ast.comment} "]]
        else
          [:html, :comment, [:static, "[#{ast.conditional}]> #{ast.comment} <![endif]"]]
        end
      else
        temple = [:multi]
        if ast.conditional.empty?
          temple << [:mknl]
        else
          temple << [:static, "[#{ast.conditional}]>"] << [:mknl] << [:newline]
        end
        compile_children(ast, temple)
        unless ast.conditional.empty?
          temple << [:static, '<![endif]']
        end
        [:multi, [:html, :comment, temple]]
      end
    end

    def compile_haml_comment(ast)
      [:multi].concat([[:newline]] * ast.children.size)
    end

    def compile_element(ast)
      temple = [
        :haml, :tag,
        ast.tag_name,
        self_closing?(ast),
        AttributeCompiler.new.compile(ast),
      ]

      if ast.oneline_child
        temple << compile(ast.oneline_child)
      elsif !ast.children.empty?
        temple << compile_element_children(ast)
      end

      if ast.nuke_outer_whitespace
        [:multi, [:rmnl], temple]
      else
        temple
      end
    rescue UnparsableRubyCode => e
      unless e.lineno
        e.lineno = ast.lineno
      end
      raise e
    end

    def self_closing?(ast)
      ast.self_closing || options[:autoclose].include?(ast.tag_name)
    end

    def compile_element_children(ast)
      children = [:multi]
      unless nuke_inner_whitespace?(ast)
        children << [:mknl]
      end
      children << [:newline]
      compile_children(ast, children)
      if nuke_inner_whitespace?(ast)
        children << [:rmnl]
      end
      children
    end

    def nuke_inner_whitespace?(ast)
      ast.nuke_inner_whitespace || options[:preserve].include?(ast.tag_name)
    end

    def compile_script(ast)
      sym = unique_name
      temple = [:multi]
      if ast.children.empty?
        temple << [:code, "#{sym} = (#{ast.script}"] << [:newline] << [:code, ')']
      else
        temple << [:code, "#{sym} = #{ast.script}"] << [:newline]
        compile_children(ast, temple)
        temple << [:code, 'end']
      end
      if !ast.escape_html && ast.preserve
        temple << [:haml, :preserve, sym]
      else
        temple << [:escape, ast.escape_html, [:dynamic, "#{sym}.to_s"]]
      end
      temple
    end

    SKIP_END_KEYWORDS = %w[elsif else when rescue ensure].freeze

    def compile_silent_script(ast)
      temple = [:multi]
      if SKIP_END_KEYWORDS.include?(ast.keyword)
        temple << [:rmend]
      end
      temple << [:code, ast.script] << [:newline]
      compile_children(ast, temple)
      if !ast.children.empty? || ast.keyword
        temple << [:mkend]
      end
      temple
    end

    def compile_filter(ast)
      FilterCompilers.find(ast.name).compile(ast)
    rescue FilterCompilers::NotFound => e
      unless e.lineno
        e.lineno = ast.lineno
      end
      raise e
    end
  end
end