import argparse
import os
import subprocess
from typing import Any

from django.conf import settings
from django.core.exceptions import ValidationError
from django.core.management import call_command
from django.core.management.base import BaseCommand, CommandError, CommandParser

from zerver.forms import check_subdomain_available
from zerver.lib.import_realm import do_import_realm


class Command(BaseCommand):
    help = """Import extracted Zulip database dump directories into a fresh Zulip instance.

This command should be used only on a newly created, empty Zulip instance to
import a database dump from one or more JSON files."""

    def add_arguments(self, parser: CommandParser) -> None:
        parser.add_argument(
            "--destroy-rebuild-database",
            action="store_true",
            help="Destroys and rebuilds the databases prior to import.",
        )

        parser.add_argument(
            "--import-into-nonempty",
            action="store_true",
            help="Import into an existing nonempty database.",
        )

        parser.add_argument(
            "--allow-reserved-subdomain",
            action="store_true",
            help="Allow use of reserved subdomains",
        )

        parser.add_argument("subdomain", metavar="<subdomain>", help="Subdomain")

        parser.add_argument(
            "export_paths",
            nargs="+",
            metavar="<export path>",
            help="list of export directories to import",
        )
        parser.add_argument(
            "--processes",
            default=settings.DEFAULT_DATA_EXPORT_IMPORT_PARALLELISM,
            help="Number of processes to use for uploading Avatars to S3 in parallel",
        )
        parser.formatter_class = argparse.RawTextHelpFormatter

    def do_destroy_and_rebuild_database(self, db_name: str) -> None:
        call_command("flush", verbosity=0, interactive=False)
        subprocess.check_call([os.path.join(settings.DEPLOY_ROOT, "scripts/setup/flush-memcached")])

    def handle(self, *args: Any, **options: Any) -> None:
        num_processes = int(options["processes"])
        if num_processes < 1:
            raise CommandError("You must have at least one process.")

        subdomain = options["subdomain"]

        if options["destroy_rebuild_database"]:
            print("Rebuilding the database!")
            db_name = settings.DATABASES["default"]["NAME"]
            self.do_destroy_and_rebuild_database(db_name)
        elif options["import_into_nonempty"]:
            print("NOTE: The argument 'import_into_nonempty' is now the default behavior.")

        allow_reserved_subdomain = False

        if options["allow_reserved_subdomain"]:
            allow_reserved_subdomain = True

        try:
            check_subdomain_available(subdomain, allow_reserved_subdomain)
        except ValidationError as e:
            raise CommandError(
                e.messages[0]
                + "\nPass --allow-reserved-subdomain to override subdomain restrictions."
            )

        paths = []
        for path in options["export_paths"]:
            path = os.path.realpath(os.path.expanduser(path))
            if not os.path.exists(path):
                raise CommandError(f"Directory not found: '{path}'")
            if not os.path.isdir(path):
                raise CommandError(
                    "Export file should be folder; if it's a tarball, please unpack it first."
                )
            paths.append(path)

        for path in paths:
            print(f"Processing dump: {path} ...")
            do_import_realm(path, subdomain, num_processes)