from django.core.management.base import NoArgsCommand, CommandError

class Command(NoArgsCommand):

    help = "Introspects the database tables in the given database and outputs a Django model module."

    requires_model_validation = False

    def handle_noargs(self, **options):

        try:

            for line in self.handle_inspection():

                print line

        except NotImplementedError:

            raise CommandError("Database inspection isn't supported for the currently selected database backend.")

    def handle_inspection(self):

        from django.db import connection, get_introspection_module

        import keyword

        introspection_module = get_introspection_module()

        table2model = lambda table_name: table_name.title().replace('_', '')

        cursor = connection.cursor()

        yield "# This is an auto-generated Django model module."

        yield "# You'll have to do the following manually to clean this up:"

        yield "#     * Rearrange models' order"

        yield "#     * Make sure each model has one field with primary_key=True"

        yield "# Feel free to rename the models, but don't rename db_table values or field names."

        yield "#"

        yield "# Also note: You'll have to insert the output of 'django-admin.py sqlcustom [appname]'"

        yield "# into your database."

        yield ''

        yield 'from django.db import models'

        yield ''

        for table_name in introspection_module.get_table_list(cursor):

            yield 'class %s(models.Model):' % table2model(table_name)

            try:

                relations = introspection_module.get_relations(cursor, table_name)

            except NotImplementedError:

                relations = {}

            try:

                indexes = introspection_module.get_indexes(cursor, table_name)

            except NotImplementedError:

                indexes = {}

            for i, row in enumerate(introspection_module.get_table_description(cursor, table_name)):

                att_name = row[0].lower()

                comment_notes = [] # Holds Field notes, to be displayed in a Python comment.

                extra_params = {}  # Holds Field parameters such as 'db_column'.

                if ' ' in att_name:

                    extra_params['db_column'] = att_name

                    att_name = att_name.replace(' ', '')

                    comment_notes.append('Field renamed to remove spaces.')

                if keyword.iskeyword(att_name):

                    extra_params['db_column'] = att_name

                    att_name += '_field'

                    comment_notes.append('Field renamed because it was a Python reserved word.')

                if i in relations:

                    rel_to = relations[i][1] == table_name and "'self'" or table2model(relations[i][1])

                    field_type = 'ForeignKey(%s' % rel_to

                    if att_name.endswith('_id'):

                        att_name = att_name[:-3]

                    else:

                        extra_params['db_column'] = att_name

                else:

                    try:

                        field_type = introspection_module.DATA_TYPES_REVERSE[row[1]]

                    except KeyError:

                        field_type = 'TextField'

                        comment_notes.append('This field type is a guess.')

                    # This is a hook for DATA_TYPES_REVERSE to return a tuple of

                    # (field_type, extra_params_dict).

                    if type(field_type) is tuple:

                        field_type, new_params = field_type

                        extra_params.update(new_params)

                    # Add max_length for all CharFields.

                    if field_type == 'CharField' and row[3]:

                        extra_params['max_length'] = row[3]

                    if field_type == 'DecimalField':

                        extra_params['max_digits'] = row[4]

                        extra_params['decimal_places'] = row[5]

                    # Add primary_key and unique, if necessary.

                    column_name = extra_params.get('db_column', att_name)

                    if column_name in indexes:

                        if indexes[column_name]['primary_key']:

                            extra_params['primary_key'] = True

                        elif indexes[column_name]['unique']:

                            extra_params['unique'] = True

                    field_type += '('

                # Don't output 'id = meta.AutoField(primary_key=True)', because

                # that's assumed if it doesn't exist.

                if att_name == 'id' and field_type == 'AutoField(' and extra_params == {'primary_key': True}:

                    continue

                # Add 'null' and 'blank', if the 'null_ok' flag was present in the

                # table description.

                if row[6]: # If it's NULL...

                    extra_params['blank'] = True

                    if not field_type in ('TextField(', 'CharField('):

                        extra_params['null'] = True

                field_desc = '%s = models.%s' % (att_name, field_type)

                if extra_params:

                    if not field_desc.endswith('('):

                        field_desc += ', '

                    field_desc += ', '.join(['%s=%r' % (k, v) for k, v in extra_params.items()])

                field_desc += ')'

                if comment_notes:

                    field_desc += ' # ' + ' '.join(comment_notes)

                yield '    %s' % field_desc

            yield '    class Meta:'

            yield '        db_table = %r' % table_name

            yield ''