define [], ->
  # Formats the {where: condition} Eve REST query parameter. Each key
  # in the condition parameters is quoted. The condition value is
  # unquoted for numbers, escape-quoted otherwise. A non-numeric
  # condition value is converted to a string before being quoted.
  #
  # Examples:
  #     where({number: 2}) => {where:"{\"number: 2}"
  #
  #     where({project: QIN}) => {where:"{\"project: \"QIN\"}"
  #
  # TODO - add moment parameter date conversion.
  #
  # TODO - add object parameter embedded document conversion, e.g.:
  #   where({session: {number: 3}}) => {where:"{\"session.number\": 3}"
  #
  # @param params the input parameters
  # @returns the REST condition query parameter
  where: (params) ->
    # @param field the request field
    # @param value the request value
    # @returns the formatted Eve {where: condition}
    formatFieldCondition = (field, value) ->
      if typeof value is 'number'
        condValue = value
      else
        condValue = "\"#{ value }\""
      # Return the field condition.
      "\"#{ field }\":#{ condValue }"

    # Format the field conditions.
    fieldConds = (formatFieldCondition(pair...) for pair in _.toPairs(params))
    cond = fieldConds.join(',')

    # Return the {where: condition} object.
    where: "{#{ cond }}"

  # Formats the {field: flag} Eve REST query projection parameter.
  # The fields argument can be a single field name or an array of
  # field names.
  #
  # @param fields the Javascript camelCase data properties to select
  # @returns the formatted Eve {projection: critierion}
  map: (fields) ->
    # The input can be a single field name.
    if _.isString(fields)
      fields = [fields]
    # Format the field name: flag entries.
    flags = fields.map (field) -> "\"#{ field }\": 1"
    criterion = flags.join(',')

    # Return the {projection: critierion} object.
    projection: "{#{ criterion }}"

  # Formats the {field: flag} Eve REST query projection parameter.
  #
  # @param fields the Javascript camelCase data properties to exclude
  # @returns the formatted Eve {projection: critierion}
  omit: (fields) ->
    # Format the field name: flag entries.
    flags = fields.map (field) -> "\"#{ field }\": 0"
    critierion = flags.join(',')

    # Return the {projection: critierion} object.
    projection: "{#{ critierion }}"