module DeepMerge

# File lib/deep_merge/core.rb, line 238
def self.clear_or_nil(obj)
  if obj.respond_to?(:clear)
    obj.clear
  else
    obj = nil
  end
  obj
end

# File lib/deep_merge/core.rb, line 78
def self.deep_merge!(source, dest, options = {})
  # turn on this line for stdout debugging text
  merge_debug = options[:merge_debug] || false
  overwrite_unmergeable = !options[:preserve_unmergeables]
  knockout_prefix = options[:knockout_prefix] || nil
  raise InvalidParameter, "knockout_prefix cannot be an empty string in deep_merge!" if knockout_prefix == ""
  raise InvalidParameter, "overwrite_unmergeable must be true if knockout_prefix is specified in deep_merge!" if knockout_prefix && !overwrite_unmergeable
  # if present: we will split and join arrays on this char before merging
  array_split_char = options[:unpack_arrays] || false
  # request that we avoid merging arrays
  overwrite_arrays = options[:overwrite_arrays] || false
  # request that we sort together any arrays when they are merged
  sort_merged_arrays = options[:sort_merged_arrays] || false
  # request that arrays of hashes are merged together
  merge_hash_arrays = options[:merge_hash_arrays] || false
  # request to extend existing arrays, instead of overwriting them
  extend_existing_arrays = options[:extend_existing_arrays] || false
  # request that arrays keep duplicate elements
  keep_array_duplicates = options[:keep_array_duplicates] || false
  # request that nil values are merged or skipped (Skipped/false by default)
  merge_nil_values = options[:merge_nil_values] || false

  di = options[:debug_indent] || ''
  # do nothing if source is nil
  return dest if !merge_nil_values && source.nil?
  # if dest doesn't exist, then simply copy source to it
  if !(dest) && overwrite_unmergeable
    dest = source; return dest
  end

  puts "#{di}Source class: #{source.class.inspect} :: Dest class: #{dest.class.inspect}" if merge_debug
  if source.kind_of?(Hash)
    puts "#{di}Hashes: #{source.inspect} :: #{dest.inspect}" if merge_debug
    source.each do |src_key, src_value|
      if dest.kind_of?(Hash)
        puts "#{di} looping: #{src_key.inspect} => #{src_value.inspect} :: #{dest.inspect}" if merge_debug
        if dest[src_key]
          puts "#{di} ==>merging: #{src_key.inspect} => #{src_value.inspect} :: #{dest[src_key].inspect}" if merge_debug
          dest[src_key] = deep_merge!(src_value, dest[src_key], options.merge(:debug_indent => di + '  '))
        else # dest[src_key] doesn't exist so we want to create and overwrite it (but we do this via deep_merge!)
          puts "#{di} ==>merging over: #{src_key.inspect} => #{src_value.inspect}" if merge_debug
          # note: we rescue here b/c some classes respond to "dup" but don't implement it (Numeric, TrueClass, FalseClass, NilClass among maybe others)
          begin
            src_dup = src_value.dup # we dup src_value if possible because we're going to merge into it (since dest is empty)
          rescue TypeError
            src_dup = src_value
          end
          if src_dup.kind_of?(Array) && keep_array_duplicates
            # note: in this case the merge will be additive, rather than a bounded set, so we can't simply merge src with itself
            # We need to merge src with an empty array
            src_dup = []
          end
          dest[src_key] = deep_merge!(src_value, src_dup, options.merge(:debug_indent => di + '  '))
        end
      elsif dest.kind_of?(Array) && extend_existing_arrays
        dest.push(source)
      else # dest isn't a hash, so we overwrite it completely (if permitted)
        if overwrite_unmergeable
          puts "#{di}  overwriting dest: #{src_key.inspect} => #{src_value.inspect} -over->  #{dest.inspect}" if merge_debug
          dest = overwrite_unmergeables(source, dest, options)
        end
      end
    end
  elsif source.kind_of?(Array)
    puts "#{di}Arrays: #{source.inspect} :: #{dest.inspect}" if merge_debug
    if overwrite_arrays
      puts "#{di} overwrite arrays" if merge_debug
      dest = source
    else
      # if we are instructed, join/split any source arrays before processing
      if array_split_char
        puts "#{di} split/join on source: #{source.inspect}" if merge_debug
        source = source.join(array_split_char).split(array_split_char)
        if dest.kind_of?(Array)
          dest = dest.join(array_split_char).split(array_split_char)
        end
      end
      # if there's a naked knockout_prefix in source, that means we are to truncate dest
      if knockout_prefix && source.index(knockout_prefix)
        dest = clear_or_nil(dest); source.delete(knockout_prefix)
      end
      if dest.kind_of?(Array)
        if knockout_prefix
          print "#{di} knocking out: " if merge_debug
          # remove knockout prefix items from both source and dest
          source.delete_if do |ko_item|
            retval = false
            item = ko_item.respond_to?(:gsub) ? ko_item.gsub(%r{^#{knockout_prefix}}, "") : ko_item
            if item != ko_item
              print "#{ko_item} - " if merge_debug
              dest.delete(item)
              dest.delete(ko_item)
              retval = true
            end
            retval
          end
          puts if merge_debug
        end
        puts "#{di} merging arrays: #{source.inspect} :: #{dest.inspect}" if merge_debug
        source_all_hashes = source.all? { |i| i.kind_of?(Hash) }
        dest_all_hashes = dest.all? { |i| i.kind_of?(Hash) }
        if merge_hash_arrays && source_all_hashes && dest_all_hashes
          # merge hashes in lists
          list = []
          dest.each_index do |i|
            list[i] = deep_merge!(source[i] || {}, dest[i],
                                  options.merge(:debug_indent => di + '  '))
          end
          list += source[dest.count..-1] if source.count > dest.count
          dest = list
        elsif keep_array_duplicates
          dest = dest.concat(source)
        else
          dest = dest | source
        end
        dest.sort! if sort_merged_arrays
      elsif overwrite_unmergeable
        puts "#{di} overwriting dest: #{source.inspect} -over-> #{dest.inspect}" if merge_debug
        dest = overwrite_unmergeables(source, dest, options)
      end
    end
  else # src_hash is not an array or hash, so we'll have to overwrite dest
    if dest.kind_of?(Array) && extend_existing_arrays
      dest.push(source)
    else
      puts "#{di}Others: #{source.inspect} :: #{dest.inspect}" if merge_debug
      dest = overwrite_unmergeables(source, dest, options)
    end
  end
  puts "#{di}Returning #{dest.inspect}" if merge_debug
  dest
end

# File lib/deep_merge/core.rb, line 212
def self.overwrite_unmergeables(source, dest, options)
  merge_debug = options[:merge_debug] || false
  overwrite_unmergeable = !options[:preserve_unmergeables]
  knockout_prefix = options[:knockout_prefix] || false
  di = options[:debug_indent] || ''
  if knockout_prefix && overwrite_unmergeable
    if source.kind_of?(String) # remove knockout string from source before overwriting dest
      src_tmp = source.gsub(%r{^#{knockout_prefix}},"")
    elsif source.kind_of?(Array) # remove all knockout elements before overwriting dest
      src_tmp = source.delete_if {|ko_item| ko_item.kind_of?(String) && ko_item.match(%r{^#{knockout_prefix}}) }
    else
      src_tmp = source
    end
    if src_tmp == source # if we didn't find a knockout_prefix then we just overwrite dest
      puts "#{di}#{src_tmp.inspect} -over-> #{dest.inspect}" if merge_debug
      dest = src_tmp
    else # if we do find a knockout_prefix, then we just delete dest
      puts "#{di}\"\" -over-> #{dest.inspect}" if merge_debug
      dest = ""
    end
  elsif overwrite_unmergeable
    dest = source
  end
  dest
end