module ActiveRecord::Import::SQLite3Adapter

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?(sqlite_version) ? sqlite_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 = 0
  base_sql, post_sql = if sql.is_a?( String )
    [sql, '']
  elsif sql.is_a?( Array )
    [sql.shift, sql.join( ' ' )]
  end
  value_sets = ::ActiveRecord::Import::ValueSetsRecordsParser.parse(values,
    max_records: SQLITE_LIMIT_COMPOUND_SELECT)
  transaction(requires_new: true) do
    value_sets.each do |value_set|
      number_of_inserts += 1
      sql2insert = base_sql + value_set.join( ',' ) + post_sql
      insert( sql2insert, *args )
    end
  end
  ActiveRecord::Import::Result.new([], number_of_inserts, [], [])
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]
      sql << sql_for_on_duplicate_key_ignore( options[:on_duplicate_key_ignore] )
    end
  end
  sql + super
end

def pre_sql_statements( options )
  sql = []
  # Options :recursive and :on_duplicate_key_ignore are mutually exclusive
  if !supports_on_duplicate_key_update? && (options[:ignore] || options[:on_duplicate_key_ignore])
    sql << "OR IGNORE"
  end
  sql + super
end

def sql_for_conflict_target( args = {} )
  conflict_target = args[:conflict_target]
  index_predicate = args[:index_predicate]
  if conflict_target.present?
    '(' << Array( conflict_target ).reject( &:blank? ).join( ', ' ) << ') '.tap do |sql|
      sql << "WHERE #{index_predicate} " if index_predicate
    end
  end
end

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

def sql_for_on_duplicate_key_ignore( *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 '
  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( primary_key )
  unless conflict_target
    raise ArgumentError, 'Expected :conflict_target 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_import?
  database_version >= MIN_VERSION_FOR_IMPORT
end

def supports_on_duplicate_key_update?
  database_version >= MIN_VERSION_FOR_UPSERT
end