##
## $Release:$
## $Copyright$
##

require 'erubis/util'

module Erubis


  ##
  ## convert
  ##
  module Converter

    attr_accessor :preamble, :postamble, :escape

    def self.supported_properties    # :nodoc:
      return [
              [:preamble,  nil,    "preamble (no preamble when false)"],
              [:postamble, nil,    "postamble (no postamble when false)"],
              [:escape,    nil,    "escape expression or not in default"],
             ]
    end

    def init_converter(properties={})
      @preamble  = properties[:preamble]
      @postamble = properties[:postamble]
      @escape    = properties[:escape]
    end

    ## convert input string into target language
    def convert(input)
      codebuf = ""    # or []
      @preamble.nil? ? add_preamble(codebuf) : (@preamble && (codebuf << @preamble))
      convert_input(codebuf, input)
      @postamble.nil? ? add_postamble(codebuf) : (@postamble && (codebuf << @postamble))
      @_proc = nil    # clear cached proc object
      return codebuf  # or codebuf.join()
    end

    protected

    ##
    ## detect spaces at beginning of line
    ##
    def detect_spaces_at_bol(text, is_bol)
      lspace = nil
      if text.empty?
        lspace = "" if is_bol
      elsif text[-1] == ?\n
        lspace = ""
      else
        rindex = text.rindex(?\n)
        if rindex
          s = text[rindex+1..-1]
          if s =~ /\A[ \t]*\z/
            lspace = s
            #text = text[0..rindex]
            text[rindex+1..-1] = ''
          end
        else
          if is_bol && text =~ /\A[ \t]*\z/
            #lspace = text
            #text = nil
            lspace = text.dup
            text[0..-1] = ''
          end
        end
      end
      return lspace
    end

    ##
    ## (abstract) convert input to code
    ##
    def convert_input(codebuf, input)
      not_implemented
    end

  end


  module Basic
  end


  ##
  ## basic converter which supports '<% ... %>' notation.
  ##
  module Basic::Converter
    include Erubis::Converter

    def self.supported_properties    # :nodoc:
      return [
              [:pattern,  '<% %>', "embed pattern"],
              [:trim,      true,   "trim spaces around <% ... %>"],
             ]
    end

    attr_accessor :pattern, :trim

    def init_converter(properties={})
      super(properties)
      @pattern = properties[:pattern]
      @trim    = properties[:trim] != false
    end

    protected

    ## return regexp of pattern to parse eRuby script
    def pattern_regexp(pattern)
      @prefix, @postfix = pattern.split()   # '<% %>' => '<%', '%>'
      #return /(.*?)(^[ \t]*)?#{@prefix}(=+|\#)?(.*?)-?#{@postfix}([ \t]*\r?\n)?/m
      #return /(^[ \t]*)?#{@prefix}(=+|\#)?(.*?)-?#{@postfix}([ \t]*\r?\n)?/m
      return /#{@prefix}(=+|-|\#|%)?(.*?)([-=])?#{@postfix}([ \t]*\r?\n)?/m
    end
    module_function :pattern_regexp

    #DEFAULT_REGEXP = /(.*?)(^[ \t]*)?<%(=+|\#)?(.*?)-?%>([ \t]*\r?\n)?/m
    #DEFAULT_REGEXP = /(^[ \t]*)?<%(=+|\#)?(.*?)-?%>([ \t]*\r?\n)?/m
    #DEFAULT_REGEXP = /<%(=+|\#)?(.*?)-?%>([ \t]*\r?\n)?/m
    DEFAULT_REGEXP = pattern_regexp('<% %>')

    public

    def convert_input(src, input)
      pat = @pattern
      regexp = pat.nil? || pat == '<% %>' ? DEFAULT_REGEXP : pattern_regexp(pat)
      pos = 0
      is_bol = true     # is beginning of line
      input.scan(regexp) do |indicator, code, tailch, rspace|
        match = Regexp.last_match()
        len  = match.begin(0) - pos
        text = input[pos, len]
        pos  = match.end(0)
        ch   = indicator ? indicator[0] : nil
        lspace = ch == ?= ? nil : detect_spaces_at_bol(text, is_bol)
        is_bol = rspace ? true : false
        add_text(src, text) if text && !text.empty?
        ## * when '<%= %>', do nothing
        ## * when '<% %>' or '<%# %>', delete spaces iff only spaces are around '<% %>'
        if ch == ?=              # <%= %>
          rspace = nil if tailch && !tailch.empty?
          add_text(src, lspace) if lspace
          add_expr(src, code, indicator)
          add_text(src, rspace) if rspace
        elsif ch == ?\#          # <%# %>
          n = code.count("\n") + (rspace ? 1 : 0)
          if @trim && lspace && rspace
            add_stmt(src, "\n" * n)
          else
            add_text(src, lspace) if lspace
            add_stmt(src, "\n" * n)
            add_text(src, rspace) if rspace
          end
        elsif ch == ?%           # <%% %>
          s = "#{lspace}#{@prefix||='<%'}#{code}#{tailch}#{@postfix||='%>'}#{rspace}"
          add_text(src, s)
        else                     # <% %>
          if @trim && lspace && rspace
            add_stmt(src, "#{lspace}#{code}#{rspace}")
          else
            add_text(src, lspace) if lspace
            add_stmt(src, code)
            add_text(src, rspace) if rspace
          end
        end
      end
      #rest = $' || input                        # ruby1.8
      rest = pos == 0 ? input : input[pos..-1]   # ruby1.9
      add_text(src, rest)
    end

    ## add expression code to src
    def add_expr(src, code, indicator)
      case indicator
      when '='
        @escape ? add_expr_escaped(src, code) : add_expr_literal(src, code)
      when '=='
        @escape ? add_expr_literal(src, code) : add_expr_escaped(src, code)
      when '==='
        add_expr_debug(src, code)
      end
    end

  end


  module PI
  end

  ##
  ## Processing Instructions (PI) converter for XML.
  ## this class converts '<?rb ... ?>' and '${...}' notation.
  ##
  module PI::Converter
    include Erubis::Converter

    def self.desc   # :nodoc:
      "use processing instructions (PI) instead of '<% %>'"
    end

    def self.supported_properties    # :nodoc:
      return [
              [:trim,      true,   "trim spaces around <% ... %>"],
              [:pi,        'rb',   "PI (Processing Instrunctions) name"],
              [:embchar,   '@',    "char for embedded expression pattern('@{...}@')"],
              [:pattern,  '<% %>', "embed pattern"],
             ]
    end

    attr_accessor :pi, :prefix

    def init_converter(properties={})
      super(properties)
      @trim    = properties.fetch(:trim, true)
      @pi      = properties[:pi] if properties[:pi]
      @embchar = properties[:embchar] || '@'
      @pattern = properties[:pattern]
      @pattern = '<% %>' if @pattern.nil?  #|| @pattern == true
    end

    def convert(input)
      code = super(input)
      return @header || @footer ? "#{@header}#{code}#{@footer}" : code
    end

    protected

    def convert_input(codebuf, input)
      unless @regexp
        @pi ||= 'e'
        ch = Regexp.escape(@embchar)
        if @pattern
          left, right = @pattern.split(' ')
          @regexp = /<\?#{@pi}(?:-(\w+))?(\s.*?)\?>([ \t]*\r?\n)?|#{ch}(!*)?\{(.*?)\}#{ch}|#{left}(=+)(.*?)#{right}/m
        else
          @regexp = /<\?#{@pi}(?:-(\w+))?(\s.*?)\?>([ \t]*\r?\n)?|#{ch}(!*)?\{(.*?)\}#{ch}/m
        end
      end
      #
      is_bol = true
      pos = 0
      input.scan(@regexp) do |pi_arg, stmt, rspace,
                              indicator1, expr1, indicator2, expr2|
        match = Regexp.last_match
        len = match.begin(0) - pos
        text = input[pos, len]
        pos = match.end(0)
        lspace = stmt ? detect_spaces_at_bol(text, is_bol) : nil
        is_bol = stmt && rspace ? true : false
        add_text(codebuf, text) # unless text.empty?
        #
        if stmt
          if @trim && lspace && rspace
            add_pi_stmt(codebuf, "#{lspace}#{stmt}#{rspace}", pi_arg)
          else
            add_text(codebuf, lspace) if lspace
            add_pi_stmt(codebuf, stmt, pi_arg)
            add_text(codebuf, rspace) if rspace
          end
        else
          add_pi_expr(codebuf, expr1 || expr2, indicator1 || indicator2)
        end
      end
      #rest = $' || input                        # ruby1.8
      rest = pos == 0 ? input : input[pos..-1]   # ruby1.9
      add_text(codebuf, rest)
    end

    #--
    #def convert_input(codebuf, input)
    #  parse_stmts(codebuf, input)
    #  #parse_stmts2(codebuf, input)
    #end
    #
    #def parse_stmts(codebuf, input)
    #  #regexp = pattern_regexp(@pattern)
    #  @pi ||= 'e'
    #  @stmt_pattern ||= /<\?#{@pi}(?:-(\w+))?(\s.*?)\?>([ \t]*\r?\n)?/m
    #  is_bol = true
    #  pos = 0
    #  input.scan(@stmt_pattern) do |pi_arg, code, rspace|
    #    match = Regexp.last_match
    #    len  = match.begin(0) - pos
    #    text = input[pos, len]
    #    pos  = match.end(0)
    #    lspace = detect_spaces_at_bol(text, is_bol)
    #    is_bol = rspace ? true : false
    #    parse_exprs(codebuf, text) # unless text.empty?
    #    if @trim && lspace && rspace
    #      add_pi_stmt(codebuf, "#{lspace}#{code}#{rspace}", pi_arg)
    #    else
    #      add_text(codebuf, lspace)
    #      add_pi_stmt(codebuf, code, pi_arg)
    #      add_text(codebuf, rspace)
    #    end
    #  end
    #  rest = $' || input
    #  parse_exprs(codebuf, rest)
    #end
    #
    #def parse_exprs(codebuf, input)
    #  unless @expr_pattern
    #    ch = Regexp.escape(@embchar)
    #    if @pattern
    #      left, right = @pattern.split(' ')
    #      @expr_pattern = /#{ch}(!*)?\{(.*?)\}#{ch}|#{left}(=+)(.*?)#{right}/
    #    else
    #      @expr_pattern = /#{ch}(!*)?\{(.*?)\}#{ch}/
    #    end
    #  end
    #  pos = 0
    #  input.scan(@expr_pattern) do |indicator1, code1, indicator2, code2|
    #    indicator = indicator1 || indicator2
    #    code = code1 || code2
    #    match = Regexp.last_match
    #    len  = match.begin(0) - pos
    #    text = input[pos, len]
    #    pos  = match.end(0)
    #    add_text(codebuf, text) # unless text.empty?
    #    add_pi_expr(codebuf, code, indicator)
    #  end
    #  rest = $' || input
    #  add_text(codebuf, rest)
    #end
    #++

    def add_pi_stmt(codebuf, code, pi_arg)  # :nodoc:
      case pi_arg
      when nil      ;  add_stmt(codebuf, code)
      when 'header' ;  @header = code
      when 'footer' ;  @footer = code
      when 'comment';  add_stmt(codebuf, "\n" * code.count("\n"))
      when 'value'  ;  add_expr_literal(codebuf, code)
      else          ;  add_stmt(codebuf, code)
      end
    end

    def add_pi_expr(codebuf, code, indicator)  # :nodoc:
      case indicator
      when nil, '', '=='    # @{...}@ or <%== ... %>
        @escape == false ? add_expr_literal(codebuf, code) : add_expr_escaped(codebuf, code)
      when '!', '='         # @!{...}@ or <%= ... %>
        @escape == false ? add_expr_escaped(codebuf, code) : add_expr_literal(codebuf, code)
      when '!!', '==='      # @!!{...}@ or <%=== ... %>
        add_expr_debug(codebuf, code)
      else
        # ignore
      end
    end

  end


end