module ActiveRecord::Import::PostgreSQLAdapter

def add_column_for_on_duplicate_key_update( column, options = {} ) # :nodoc:
  arg = options[:on_duplicate_key_update]
  if arg.is_a?( Hash )
    columns = arg.fetch( :columns ) { arg[:columns] = [] }
    case columns
    when Array then columns << column.to_sym unless columns.include?( column.to_sym )
    when Hash then columns[column.to_sym] = column.to_sym
    end
  elsif arg.is_a?( Array )
    arg << column.to_sym unless arg.include?( column.to_sym )
  end
end

def database_version
  defined?(postgresql_version) ? postgresql_version : super
end

def duplicate_key_update_error?(exception) # :nodoc:
  exception.is_a?(ActiveRecord::StatementInvalid) && exception.to_s.include?('duplicate key')
end

def insert_many( sql, values, options = {}, *args ) # :nodoc:
  number_of_inserts = 1
  returned_values = {}
  ids = []
  results = []
  base_sql, post_sql = if sql.is_a?( String )
    [sql, '']
  elsif sql.is_a?( Array )
    [sql.shift, sql.join( ' ' )]
  end
  sql2insert = base_sql + values.join( ',' ) + post_sql
  selections = returning_selections(options)
  if selections.blank? || (options[:no_returning] && !options[:recursive])
    insert( sql2insert, *args )
  else
    returned_values = if selections.size > 1
      # Select composite columns
      db_result = select_all( sql2insert, *args )
      { values: db_result.rows, columns: db_result.columns }
    else
      { values: select_values( sql2insert, *args ) }
    end
    clear_query_cache if query_cache_enabled
  end
  if options[:returning].blank?
    ids = Array(returned_values[:values])
  elsif options[:primary_key].blank?
    options[:returning_columns] ||= returned_values[:columns]
    results = Array(returned_values[:values])
  else
    # split primary key and returning columns
    ids, results, options[:returning_columns] = split_ids_and_results(returned_values, options)
  end
  ActiveRecord::Import::Result.new([], number_of_inserts, ids, results)
end

def next_value_for_sequence(sequence_name)
  %{nextval('#{sequence_name}')}
end

def post_sql_statements( table_name, options ) # :nodoc:
  sql = []
  if supports_on_duplicate_key_update?
    # Options :recursive and :on_duplicate_key_ignore are mutually exclusive
    if (options[:ignore] || options[:on_duplicate_key_ignore]) && !options[:on_duplicate_key_update] && !options[:recursive]
      sql << sql_for_on_duplicate_key_ignore( table_name, options[:on_duplicate_key_ignore] )
    end
  elsif logger && options[:on_duplicate_key_ignore] && !options[:on_duplicate_key_update]
    logger.warn "Ignoring on_duplicate_key_ignore because it is not supported by the database."
  end
  sql += super(table_name, options)
  selections = returning_selections(options)
  unless selections.blank? || (options[:no_returning] && !options[:recursive])
    sql << " RETURNING #{selections.join(', ')}"
  end
  sql
end

def returning_selections(options)
  selections = []
  column_names = Array(options[:model].column_names)
  selections += Array(options[:primary_key]) if options[:primary_key].present?
  selections += Array(options[:returning]) if options[:returning].present?
  selections.map do |selection|
    column_names.include?(selection.to_s) ? "\"#{selection}\"" : selection
  end
end

def split_ids_and_results( selections, options )
  ids = []
  returning_values = []
  columns = Array(selections[:columns])
  values = Array(selections[:values])
  id_indexes = Array(options[:primary_key]).map { |key| columns.index(key) }
  returning_columns = columns.reject.with_index { |_, index| id_indexes.include?(index) }
  returning_indexes = returning_columns.map { |column| columns.index(column) }
  values.each do |value|
    value_array = Array(value)
    ids << id_indexes.map { |index| value_array[index] }
    returning_values << returning_indexes.map { |index| value_array[index] }
  end
  ids.map!(&:first) if id_indexes.size == 1
  returning_values.map!(&:first) if returning_columns.size == 1
  [ids, returning_values, returning_columns]
end

def sql_for_conflict_target( args = {} )
  constraint_name = args[:constraint_name]
  conflict_target = args[:conflict_target]
  index_predicate = args[:index_predicate]
  if constraint_name.present?
    "ON CONSTRAINT #{constraint_name} "
  elsif conflict_target.present?
    sql = '(' + Array( conflict_target ).reject( &:blank? ).join( ', ' ) + ') '
    sql += "WHERE #{index_predicate} " if index_predicate
    sql
  end
end

def sql_for_default_conflict_target( table_name, primary_key )
  conflict_target = Array(primary_key).join(', ')
  "(#{conflict_target}) " if conflict_target.present?
end

def sql_for_on_duplicate_key_ignore( table_name, *args ) # :nodoc:
  arg = args.first
  conflict_target = sql_for_conflict_target( arg ) if arg.is_a?( Hash )
  " ON CONFLICT #{conflict_target}DO NOTHING"
end

def sql_for_on_duplicate_key_update( table_name, *args ) # :nodoc:
  arg, primary_key, locking_column = args
  arg = { columns: arg } if arg.is_a?( Array ) || arg.is_a?( String )
  return unless arg.is_a?( Hash )
  sql = ' ON CONFLICT '.dup
  conflict_target = sql_for_conflict_target( arg )
  columns = arg.fetch( :columns, [] )
  condition = arg[:condition]
  if columns.respond_to?( :empty? ) && columns.empty?
    return sql << "#{conflict_target}DO NOTHING"
  end
  conflict_target ||= sql_for_default_conflict_target( table_name, primary_key )
  unless conflict_target
    raise ArgumentError, 'Expected :conflict_target or :constraint_name to be specified'
  end
  sql << "#{conflict_target}DO UPDATE SET "
  if columns.is_a?( Array )
    sql << sql_for_on_duplicate_key_update_as_array( table_name, locking_column, columns )
  elsif columns.is_a?( Hash )
    sql << sql_for_on_duplicate_key_update_as_hash( table_name, locking_column, columns )
  elsif columns.is_a?( String )
    sql << columns
  else
    raise ArgumentError, 'Expected :columns to be an Array or Hash'
  end
  sql << " WHERE #{condition}" if condition.present?
  sql
end

def sql_for_on_duplicate_key_update_as_array( table_name, locking_column, arr ) # :nodoc:
  results = arr.map do |column|
    qc = quote_column_name( column )
    "#{qc}=EXCLUDED.#{qc}"
  end
  increment_locking_column!(table_name, results, locking_column)
  results.join( ',' )
end

def sql_for_on_duplicate_key_update_as_hash( table_name, locking_column, hsh ) # :nodoc:
  results = hsh.map do |column1, column2|
    qc1 = quote_column_name( column1 )
    qc2 = quote_column_name( column2 )
    "#{qc1}=EXCLUDED.#{qc2}"
  end
  increment_locking_column!(table_name, results, locking_column)
  results.join( ',' )
end

def supports_on_duplicate_key_update?
  database_version >= MIN_VERSION_FOR_UPSERT
end

def supports_setting_primary_key_of_imported_objects?
  true
end