require 'cgi'
require 'action_controller/vendor/xml_simple'

# Static methods for parsing the query and request parameters that can be used in
# a CGI extension class or testing in isolation.
class CGIMethods #:nodoc:
  public
    # Returns a hash with the pairs from the query string. The implicit hash construction that is done in
    # parse_request_params is not done here.
    def CGIMethods.parse_query_parameters(query_string)
      parsed_params = {}
  
      query_string.split(/[&;]/).each { |p| 
        k, v = p.split('=',2)
        v = nil if (!v.nil? && v.empty?)

        k = CGI.unescape(k) unless k.nil?
        v = CGI.unescape(v) unless v.nil?

        keys = split_key(k)
        last_key = keys.pop
        last_key = keys.pop if (use_array = last_key.empty?)
        parent = keys.inject(parsed_params) {|h, k| h[k] ||= {}}
        
        if use_array then (parent[last_key] ||= []) << v
        else parent[last_key] = v
        end
      }
  
      return parsed_params
    end

    # Returns the request (POST/GET) parameters in a parsed form where pairs such as "customer[address][street]" / 
    # "Somewhere cool!" are translated into a full hash hierarchy, like
    # { "customer" => { "address" => { "street" => "Somewhere cool!" } } }
    def CGIMethods.parse_request_parameters(params)
      parsed_params = {}

      for key, value in params
        value = [value] if key =~ /.*\[\]$/
        CGIMethods.build_deep_hash(
          CGIMethods.get_typed_value(value[0]),
          parsed_params, 
          CGIMethods.get_levels(key)
        )
      end
    
      return parsed_params
    end

    def self.parse_formatted_request_parameters(format, raw_post_data)
      case format
        when :xml
          return XmlSimple.xml_in(raw_post_data, 'ForceArray' => false)
        when :yaml
          return YAML.load(raw_post_data)
      end
    rescue Object => e
      { "exception" => "#{e.message} (#{e.class})", "backtrace" => e.backtrace, 
        "raw_post_data" => raw_post_data, "format" => format }
    end

  private

    # Splits the given key into several pieces. Example keys are 'name', 'person[name]',
    # 'person[name][first]', and 'people[]'. In each instance, an Array instance is returned.
    # 'person[name][first]' produces ['person', 'name', 'first']; 'people[]' produces ['people', '']
    def CGIMethods.split_key(key)
      if /^([^\[]+)((?:\[[^\]]*\])+)$/ =~ key
        keys = [$1]
        
        keys.concat($2[1..-2].split(']['))
        keys << '' if key[-2..-1] == '[]' # Have to add it since split will drop empty strings
        
        return keys
      else
        return [key]
      end
    end
    
    def CGIMethods.get_typed_value(value)
      if value.respond_to?(:content_type) && !value.content_type.empty?
        # Uploaded file
        value
      elsif value.respond_to?(:read)
        # Value as part of a multipart request
        value.read
      elsif value.class == Array
        value.collect { |v| CGIMethods.get_typed_value(v) }
      else
        # Standard value (not a multipart request)
        value.to_s
      end
    end
  
    PARAMS_HASH_RE = /^([^\[]+)(\[.*\])?(.)?.*$/
    def CGIMethods.get_levels(key)
      all, main, bracketed, trailing = PARAMS_HASH_RE.match(key).to_a
      if main.nil?
        []
      elsif trailing
        [key]
      elsif bracketed
        [main] + bracketed.slice(1...-1).split('][')
      else
        [main]
      end
    end

    def CGIMethods.build_deep_hash(value, hash, levels)
      if levels.length == 0
        value
      elsif hash.nil?
        { levels.first => CGIMethods.build_deep_hash(value, nil, levels[1..-1]) }
      else
        hash.update({ levels.first => CGIMethods.build_deep_hash(value, hash[levels.first], levels[1..-1]) })
      end
    end
end