#!/usr/bin/env python
import dataclasses
import importlib
import os
import pathlib
import re

import click
from django.apps import apps

from sentry.runner import configure

configure()


@dataclasses.dataclass
class MigrationMeta:
    number: int
    name: str
    path: str

    @property
    def full_name(self) -> str:
        return f"{self.number:04}_{self.name}"

    @classmethod
    def from_filename(cls, filepath: str) -> "MigrationMeta":
        filename = os.path.basename(filepath)
        name, _ = filename.split(".", 2)
        number, name = name.split("_", 1)
        number = int(number)
        return cls(number=number, name=name, path=filepath)


def load_module(filepath: str):
    module_name = os.path.basename(filepath)
    spec = importlib.util.spec_from_loader(
        module_name, importlib.machinery.SourceFileLoader(module_name, filepath)
    )
    module = importlib.util.module_from_spec(spec)
    spec.loader.exec_module(module)
    return module


def find_migration(migrations_path: str, migration: str) -> MigrationMeta:
    matches = list(pathlib.Path(migrations_path).glob(f"*{migration}*"))
    if len(matches) > 1:
        click.echo(f"Found multiple migrations matching {migration}")
        for match in matches:
            click.echo(f"- {match}")
        click.echo("Try again with a more specific pattern")
        raise click.Abort()

    if len(matches) == 0:
        click.echo(f"Could not find migration matching {migration}")
        raise click.Abort()

    return MigrationMeta.from_filename(str(matches[0].resolve()))


def find_highest_migration(migrations_path: str, renamed_migration: MigrationMeta) -> MigrationMeta:
    highest = 0
    found = None
    matches = list(pathlib.Path(migrations_path).glob("[0-9]*"))
    for match in matches:
        meta = MigrationMeta.from_filename(str(match.resolve()))
        if meta.number > highest and meta.full_name != renamed_migration.full_name:
            highest = meta.number
            found = meta
    if not found:
        click.echo("Could not find the head migration")
        raise click.Abort()

    click.echo(f"> Current head migration is {found.full_name}")
    return found


@click.command()
@click.argument("migration", required=True)
@click.argument("app_label", default="sentry")
def main(migration: str, app_label: str):
    """
    Update a migration to the top of the migration history.

    migration - The name or number of the migration.
    app_label - The name of the django app the migration is in. Defaults to sentry

    Will do the following:

    - Rename the migration file.
    - Update `dependencies` in the migration to point at the highest migration.
    - Update the name of the related tests/migration if it exists.
    - Update migrations_lockfile.txt.

    """
    app_path = apps.get_app_config(app_label).path
    migrations_path = os.path.join(app_path, "migrations")

    migration_meta = find_migration(migrations_path, migration)
    current_head = find_highest_migration(migrations_path, migration_meta)

    # Create an instance of the migration so that we can read instance properties.
    module = load_module(migration_meta.path)
    migration_instance = module.Migration("", app_label)
    dependencies = migration_instance.dependencies

    new_name = migration_meta.full_name.replace(
        str(migration_meta.number), str(current_head.number + 1)
    )
    click.echo(f"> Updating migration {migration_meta.full_name} to {new_name}")
    with open(migration_meta.path) as f:
        contents = f.read()
        for dep in dependencies:
            if dep[0] == app_label:
                contents = contents.replace(dep[1], current_head.full_name)
    with open(migration_meta.path, "w") as f:
        f.write(contents)

    # Rename the file.
    os.rename(migration_meta.path, os.path.join(migrations_path, f"{new_name}.py"))
    click.echo("> Migration file rename complete")

    # Update lockfile
    lockfile = os.path.join(app_path, "..", "..", "migrations_lockfile.txt")
    with open(lockfile) as f:
        contents = f.read()
        contents = contents.replace(current_head.full_name, new_name)
    with open(lockfile, "w") as f:
        f.write(contents)
    click.echo("> Updated migrations_lockfile.txt")

    # Rename test if it exists.
    test_file_prefix = f"*{migration_meta.number}*"
    migration_test_path = os.path.join(app_path, "..", "..", "tests", "sentry", "migrations")
    matches = list(pathlib.Path(migration_test_path).glob(test_file_prefix))
    if len(matches) == 1:
        click.echo("> Updating migration test file to & from attributes")
        test_path = str(matches[0].resolve())
        with open(test_path) as f:
            contents = f.read()
            contents = re.sub(
                r"(migrate_from\s+=\s+\")([^\"]+)(\")",
                lambda matches: f"{matches.group(1)}{current_head.full_name}{matches.group(3)}",
                contents,
            )
            contents = re.sub(
                r"(migrate_to\s+=\s+\")([^\"]+)(\")",
                lambda matches: f"{matches.group(1)}{new_name}{matches.group(3)}",
                contents,
            )
        with open(test_path, "w") as f:
            f.write(contents)
        click.echo("> Renaming test file")
        os.rename(
            str(matches[0].resolve()), os.path.join(migration_test_path, f"test_{new_name}.py")
        )
    else:
        click.echo("> Could not find a migration test file")

    click.echo("All done!")


if __name__ == "__main__":
    main()