from pgtoolkit.toolbase import SimpleTool
from pgtoolkit import pgbrowser
from pycolib.prettysize import prettysize_short
from pycolib.ansicolor import highlight


class BigTablesTool(SimpleTool):

    """List largest tables.

    Reads size statistics of tables and indexes from pgcatalog.

    """

    def __init__(self):
        SimpleTool.__init__(self, name='bigtables')

    def specify_args(self):
        SimpleTool.specify_args(self)
        self.parser.add_argument('-n', '--limit', metavar='NUM', dest='limit', type=int, default=5, help='Show NUM biggest tables.')
        self.parser.add_argument('-v', '--details', dest='details', action='store_true', help='Show sizes of data and individual indexes.')

    def main(self):
        browser = pgbrowser.PgBrowser(self.pgm.get_conn('target'))

        # scan all tables from all shemas, remember names and sizes
        all_tables = []
        all_indexes = []
        schemas = browser.list_schemas()
        for schema in schemas:
            tables = browser.list_tables(schema['name'])
            for table in tables:
                table_name = '%s.%s' % (schema['name'], table['name'])
                indexes = browser.list_indexes(table['name'], schema['name'])
                for index in indexes:
                    all_indexes.append({'name': index['name'], 'table': table_name, 'size': index['size']})
                all_tables.append({'name': table_name, 'size': table['size'], 'indexes': indexes})

        # print names and sizes of 20 largest tables
        for table in sorted(all_tables, reverse=True, key=lambda x: x['size'])[:self.args.limit]:
            size_of_indexes = sum(index['size'] for index in table['indexes'])
            print(highlight(1) + prettysize_short(table['size'] + size_of_indexes, trailing_zeros=True).rjust(8) + highlight(0),
                  '(total)'.ljust(8),
                  highlight(1) + table['name'] + highlight(0), sep='  ')
            if self.args.details:
                print(prettysize_short(table['size'], trailing_zeros=True).rjust(8),
                      '(data)'.ljust(8), sep='  ')
                for index in sorted(table['indexes'], reverse=True, key=lambda x: x['size']):
                    print(prettysize_short(index['size'], trailing_zeros=True).rjust(8),
                          '(index)'.ljust(8), index['name'], sep='  ')
            print()


cls = BigTablesTool