"""
Startmigration command, version 2.
"""

import sys
import os
import re
import string
import random
import inspect
from optparse import make_option

try:
    set
except NameError:
    from sets import Set as set

from django.core.management.base import BaseCommand
from django.core.management.color import no_style
from django.db import models
from django.conf import settings

from south.migration import Migrations
from south.exceptions import NoMigrations
from south.creator import changes, actions, freezer
from south.management.commands.datamigration import Command as DataCommand

class Command(DataCommand):
    option_list = DataCommand.option_list + (
        make_option('--add-model', action='append', dest='added_model_list', type='string',
            help='Generate a Create Table migration for the specified model.  Add multiple models to this migration with subsequent --model parameters.'),
        make_option('--add-field', action='append', dest='added_field_list', type='string',
            help='Generate an Add Column migration for the specified modelname.fieldname - you can use this multiple times to add more than one column.'),
        make_option('--add-index', action='append', dest='added_index_list', type='string',
            help='Generate an Add Index migration for the specified modelname.fieldname - you can use this multiple times to add more than one column.'),
        make_option('--initial', action='store_true', dest='initial', default=False,
            help='Generate the initial schema for the app.'),
        make_option('--auto', action='store_true', dest='auto', default=False,
            help='Attempt to automatically detect differences from the last migration.'),
        make_option('--empty', action='store_true', dest='empty', default=False,
            help='Make a blank migration.'),
    )
    help = "Creates a new template schema migration for the given app"
    usage_str = "Usage: ./manage.py schemamigration appname migrationname [--empty] [--initial] [--auto] [--add-model ModelName] [--add-field ModelName.field_name] [--stdout]"
    
    def handle(self, app=None, name="", added_model_list=None, added_field_list=None, freeze_list=None, initial=False, auto=False, stdout=False, added_index_list=None, verbosity=1, empty=False, **options):
        
        # Any supposed lists that are None become empty lists
        added_model_list = added_model_list or []
        added_field_list = added_field_list or []
        added_index_list = added_index_list or []
        freeze_list = freeze_list or []

        # --stdout means name = -
        if stdout:
            name = "-"
	
        # Only allow valid names
        if re.search('[^_\w]', name) and name != "-":
            self.error("Migration names should contain only alphanumeric characters and underscores.")
        
        # Make sure options are compatable
        if initial and (added_model_list or added_field_list or auto):
            self.error("You cannot use --initial and other options together\n" + self.usage_str)
        
        if auto and (added_model_list or added_field_list or initial):
            self.error("You cannot use --auto and other options together\n" + self.usage_str)
        
        if not app:
            self.error("You must provide an app to create a migration for.\n" + self.usage_str)
        
        # Get the Migrations for this app (creating the migrations dir if needed)
        migrations = Migrations(app, force_creation=True, verbose_creation=verbosity > 0)
        
        # What actions do we need to do?
        if auto:
            # Get the old migration
            try:
                last_migration = migrations[-1]
            except IndexError:
                self.error("You cannot use --auto on an app with no migrations. Try --initial.")
            # Make sure it has stored models
            if migrations.app_label() not in getattr(last_migration.migration_class(), "complete_apps", []):
                self.error("You cannot use automatic detection, since the previous migration does not have this whole app frozen.\nEither make migrations using '--freeze %s' or set 'SOUTH_AUTO_FREEZE_APP = True' in your settings.py." % migrations.app_label())
            # Alright, construct two model dicts to run the differ on.
            old_defs = dict(
                (k, v) for k, v in last_migration.migration_class().models.items()
                if k.split(".")[0] == migrations.app_label()
            )
            new_defs = dict(
                (k, v) for k, v in freezer.freeze_apps([migrations.app_label()]).items()
                if k.split(".")[0] == migrations.app_label()
            )
            change_source = changes.AutoChanges(
                migrations = migrations,
                old_defs = old_defs,
                old_orm = last_migration.orm(),
                new_defs = new_defs,
            )
        
        elif initial:
            # Do an initial migration
            change_source = changes.InitialChanges(migrations)
        
        else:
            # Read the commands manually off of the arguments
            if (added_model_list or added_field_list or added_index_list):
                change_source = changes.ManualChanges(
                    migrations,
                    added_model_list,
                    added_field_list,
                    added_index_list,
                )
            elif empty:
                change_source = None
            else:
                print >>sys.stderr, "You have not passed any of --initial, --auto, --empty, --add-model, --add-field or --add-index."
                sys.exit(1)
        
        # if not name, there's an error
        if not name:
            if change_source:
                name = change_source.suggest_name()
            if not name:
                self.error("You must provide a name for this migration\n" + self.usage_str)
        
        # See what filename is next in line. We assume they use numbers.
        new_filename = migrations.next_filename(name)
        
        # Get the actions, and then insert them into the actions lists
        forwards_actions = []
        backwards_actions = []
        if change_source:
            for action_name, params in change_source.get_changes():
                # Run the correct Action class
                try:
                    action_class = getattr(actions, action_name)
                except AttributeError:
                    raise ValueError("Invalid action name from source: %s" % action_name)
                else:
                    action = action_class(**params)
                    action.add_forwards(forwards_actions)
                    action.add_backwards(backwards_actions)
                    print >>sys.stderr, action.console_line()
        
        # Nowt happen? That's not good for --auto.
        if auto and not forwards_actions:
            self.error("Nothing seems to have changed.")
        
        # Work out which apps to freeze
        apps_to_freeze = self.calc_frozen_apps(migrations, freeze_list)
        
        # So, what's in this file, then?
        file_contents = MIGRATION_TEMPLATE % {
            "forwards": "\n".join(forwards_actions or ["pass"]), 
            "backwards": "\n".join(backwards_actions or ["pass"]), 
            "frozen_models":  freezer.freeze_apps_to_string(apps_to_freeze),
            "complete_apps": apps_to_freeze and "complete_apps = [%s]" % (", ".join(map(repr, apps_to_freeze))) or ""
        }
        
        # - is a special name which means 'print to stdout'
        if name == "-":
            print file_contents
        # Write the migration file if the name isn't -
        else:
            fp = open(os.path.join(migrations.migrations_dir(), new_filename), "w")
            fp.write(file_contents)
            fp.close()
            if empty:
                print >>sys.stderr, "Created %s. You must now edit this migration and add the code for each direction." % new_filename
            else:
                print >>sys.stderr, "Created %s. You can now apply this migration with: ./manage.py migrate %s" % (new_filename, app)


MIGRATION_TEMPLATE = """# encoding: utf-8
import datetime
from south.db import db
from south.v2 import SchemaMigration
from django.db import models

class Migration(SchemaMigration):

    def forwards(self, orm):
        %(forwards)s


    def backwards(self, orm):
        %(backwards)s


    models = %(frozen_models)s

    %(complete_apps)s
"""
