jsonpath.rb

# frozen_string_literal: true

require 'strscan'
require 'multi_json'
require 'jsonpath/proxy'
require 'jsonpath/dig'
require 'jsonpath/enumerable'
require 'jsonpath/version'
require 'jsonpath/parser'

# JsonPath: initializes the class with a given JsonPath and parses that path
# into a token array.
class JsonPath
  PATH_ALL = '$..*'

  DEFAULT_OPTIONS = {
    :default_path_leaf_to_null => false,
    :symbolize_keys => false,
    :use_symbols => false,
    :allow_send => true,
    :max_nesting => 100
  }

  attr_accessor :path

  def initialize(path, opts = {})
    @opts = DEFAULT_OPTIONS.merge(opts)
    scanner = StringScanner.new(path.strip)
    @path = []
    until scanner.eos?
      if (token = scanner.scan(/\$\B|@\B|\*|\.\./))
        @path << token
      elsif (token = scanner.scan(/[$@a-zA-Z0-9:{}_-]+/))
        @path << "['#{token}']"
      elsif (token = scanner.scan(/'(.*?)'/))
        @path << "[#{token}]"
      elsif (token = scanner.scan(/\[/))
        @path << find_matching_brackets(token, scanner)
      elsif (token = scanner.scan(/\]/))
        raise ArgumentError, 'unmatched closing bracket'
      elsif (token = scanner.scan(/\(.*\)/))
        @path << token
      elsif scanner.scan(/\./)
        nil
      elsif (token = scanner.scan(/[><=] \d+/))
        @path.last << token
      elsif (token = scanner.scan(/./))
        @path.last << token
      else
        raise ArgumentError, "character '#{scanner.peek(1)}' not supported in query"
      end
    end
  end

  def find_matching_brackets(token, scanner)
    count = 1
    until count.zero?
      if (t = scanner.scan(/\[/))
        token << t
        count += 1
      elsif (t = scanner.scan(/\]/))
        token << t
        count -= 1
      elsif (t = scanner.scan(/[^\[\]]+/))
        token << t
      elsif scanner.eos?
        raise ArgumentError, 'unclosed bracket'
      end
    end
    token
  end

  def join(join_path)
    res = deep_clone
    res.path += JsonPath.new(join_path).path
    res
  end

  def on(obj_or_str, opts = {})
    a = enum_on(obj_or_str).to_a
    if opts[:symbolize_keys]
      a.map! do |e|
        e.each_with_object({}) { |(k, v), memo| memo[k.to_sym] = v; }
      end
    end
    a
  end
  
  def self.fetch_all_path(obj)
    all_paths = ['$']
    find_path(obj, '$', all_paths, obj.class == Array)
    return all_paths
  end

  def self.find_path(obj, root_key, all_paths, is_array = false)
    obj.each do |key, value|
      table_params = { key: key, root_key: root_key}
      is_loop = value.class == Array || value.class == Hash
      if is_loop
        path_exp = construct_path(table_params)
        all_paths << path_exp
        find_path(value, path_exp, all_paths, value.class == Array)
      elsif is_array
        table_params[:index] = obj.find_index(key)
        path_exp = construct_path(table_params)
        find_path(key, path_exp, all_paths, key.class == Array) if key.class == Hash || key.class == Array
        all_paths << path_exp
      else
        all_paths << construct_path(table_params)
      end
    end
  end

  def self.construct_path(table_row)
    if table_row[:index]
      return table_row[:root_key] + '['+ table_row[:index].to_s + ']'
    else
      return table_row[:root_key] + '.'+ table_row[:key]
    end
  end

  def first(obj_or_str, *args)
    enum_on(obj_or_str).first(*args)
  end

  def enum_on(obj_or_str, mode = nil)
    JsonPath::Enumerable.new(self, self.class.process_object(obj_or_str, @opts), mode,
                             @opts)
  end
  alias [] enum_on

  def self.on(obj_or_str, path, opts = {})
    new(path, opts).on(process_object(obj_or_str))
  end

  def self.for(obj_or_str)
    Proxy.new(process_object(obj_or_str))
  end

  private

  def self.process_object(obj_or_str, opts = {})
    obj_or_str.is_a?(String) ? MultiJson.decode(obj_or_str, max_nesting: opts[:max_nesting]) : obj_or_str
  end

  def deep_clone
    Marshal.load Marshal.dump(self)
  end
end