from django.db import migrations
from django.db.backends.postgresql.schema import DatabaseSchemaEditor
from django.db.migrations.state import StateApps
from django.db.models import F


def set_initial_value_of_is_private_flag(
    apps: StateApps, schema_editor: DatabaseSchemaEditor
) -> None:
    UserMessage = apps.get_model("zerver", "UserMessage")
    Message = apps.get_model("zerver", "Message")
    if not Message.objects.exists():
        return

    i = 0
    # Total is only used for the progress bar
    total = Message.objects.filter(recipient__type__in=[1, 3]).count()
    processed = 0

    print("\nStart setting initial value for is_private flag...", flush=True)
    while True:
        range_end = i + 10000
        # Can't use [Recipient.PERSONAL, Recipient.HUDDLE] in migration files
        message_ids = list(
            Message.objects.filter(recipient__type__in=[1, 3], id__gt=i, id__lte=range_end)
            .values_list("id", flat=True)
            .order_by("id")
        )
        count = UserMessage.objects.filter(message_id__in=message_ids).update(
            flags=F("flags").bitor(UserMessage.flags.is_private)
        )
        if count == 0 and range_end >= Message.objects.last().id:
            break

        i = range_end
        processed += len(message_ids)
        if total != 0:
            percent = round((processed / total) * 100, 2)
        else:
            percent = 100.00
        print(f"Processed {processed}/{total} {percent}%", flush=True)


class Migration(migrations.Migration):
    atomic = False

    dependencies = [
        ("zerver", "0181_userprofile_change_emojiset"),
    ]

    operations = [
        migrations.RunPython(
            set_initial_value_of_is_private_flag,
            reverse_code=migrations.RunPython.noop,
            elidable=True,
        ),
    ]