import csv

import csvs

def import_csv(db, table, stream, use_copy_from=True, has_row_num=True):

    def log(msg, level=1): db.log_debug(msg, level)

    # Get format info

    info = csvs.stream_info(stream, parse_header=True)

    dialect = info.dialect

    if csvs.is_tsv(dialect): use_copy_from = False

    col_names = map(strings.to_unicode, info.header)

    for i, col in enumerate(col_names): # replace empty column names

        if col == '': col_names[i] = 'column_'+str(i)

    # Select schema and escape names

    def esc_name(name): return db.esc_name(name)

    typed_cols = [sql_gen.TypedCol(v, 'text') for v in col_names]

    log('Creating table')

    sql.create_table(db, table, typed_cols, has_pkey=False, col_indexes=False)

    # Load the data

    def load_():

        if use_copy_from:

            log('Using COPY FROM')

            # Create COPY FROM statement

            copy_from = ('COPY '+table.to_str(db)+' FROM STDIN DELIMITER '

                +db.esc_value(dialect.delimiter)+' NULL '+db.esc_value(''))

            assert not csvs.is_tsv(dialect)

            copy_from += ' CSV'

            if dialect.quoting != csv.QUOTE_NONE:

                quote_str = db.esc_value(dialect.quotechar)

                copy_from += ' QUOTE '+quote_str

                if dialect.doublequote: copy_from += ' ESCAPE '+quote_str

            copy_from += ';\n'

            log(copy_from, level=2)

            db.db.cursor().copy_expert(copy_from, stream)

        else:

            log('Using INSERT')

            cols_ct = len(col_names)

            for row in csvs.make_reader(stream, dialect):

                row = map(strings.to_unicode, row)

                util.list_set_length(row, cols_ct) # truncate extra cols

                sql.insert(db, table, row, cacheable=False, log_level=5)

    sql.with_savepoint(db, load_)

    if has_row_num: sql.add_row_num(db, table)

    cleanup_table(db, table)