import logging
import os
import sys
from logging.config import fileConfig

from alembic import context
from dotenv import load_dotenv
from sqlalchemy import engine_from_config, pool

if os.environ.get("DB_HOST", None) is None:
    os.environ["DB_HOST"] = "127.0.0.1"

dotenv_path = os.path.join(os.path.dirname(__file__), "../../.env")
if os.path.exists(dotenv_path):
    print("Loading env from .env")
    load_dotenv(dotenv_path=dotenv_path)

try:
    from anubis.app import create_app
except ImportError:
    sys.path.append(os.getcwd())
    from anubis.app import create_app

app = create_app()

# this is the Alembic Config object, which provides
# access to the values within the .ini file in use.
config = context.config

# Interpret the config file for Python logging.
# This line sets up loggers basically.
fileConfig(config.config_file_name, disable_existing_loggers=False)
logger = logging.getLogger("alembic.env")

# add your model's MetaData object here
# for 'autogenerate' support
# from myapp import mymodel
# target_metadata = mymodel.Base.metadata

with app.app_context():
    config.set_main_option(
        "sqlalchemy.url",
        str(app.extensions["migrate"].db.engine.url).replace("%", "%%"),
    )
    target_metadata = app.extensions["migrate"].db.metadata


# other values from the config, defined by the needs of env.py,
# can be acquired:
# my_important_option = config.get_main_option("my_important_option")
# ... etc.


def run_migrations_offline():
    """Run migrations in 'offline' mode.

    This configures the context with just a URL
    and not an Engine, though an Engine is acceptable
    here as well.  By skipping the Engine creation
    we don't even need a DBAPI to be available.

    Calls to context.execute() here emit the given string to the
    script output.

    """
    url = config.get_main_option("sqlalchemy.url")
    context.configure(url=url, target_metadata=target_metadata, literal_binds=True)

    with context.begin_transaction():
        context.run_migrations()


def run_migrations_online():
    """Run migrations in 'online' mode.

    In this scenario we need to create an Engine
    and associate a connection with the context.

    """

    # this callback is used to prevent an auto-migration from being generated
    # when there are no changes to the schema
    # reference: http://alembic.zzzcomputing.com/en/latest/cookbook.html
    def process_revision_directives(context, revision, directives):
        if getattr(config.cmd_opts, "autogenerate", False):
            script = directives[0]
            if script.upgrade_ops.is_empty():
                directives[:] = []
                logger.info("No changes in schema detected.")

    connectable = engine_from_config(
        config.get_section(config.config_ini_section),
        prefix="sqlalchemy.",
        poolclass=pool.NullPool,
    )

    with connectable.connect() as connection:
        context.configure(
            connection=connection,
            target_metadata=target_metadata,
            process_revision_directives=process_revision_directives,
            **app.extensions["migrate"].configure_args
        )

        with context.begin_transaction():
            context.run_migrations()


with app.app_context():
    if context.is_offline_mode():
        run_migrations_offline()
    else:
        run_migrations_online()
