# [DEF:backend.src.core.database:Module]
#
# @TIER:      STANDARD
# @SEMANTICS: database, postgresql, sqlalchemy, session, persistence
# @PURPOSE:   Configures database connection and session management (PostgreSQL-first).
# @LAYER:     Core
# @RELATION:  DEPENDS_ON -> sqlalchemy
# @RELATION:  DEPENDS_ON -> backend.src.models.mapping
# @RELATION:  DEPENDS_ON -> backend.src.core.auth.config
#
# @INVARIANT: A single engine instance is used for the entire application.

# [SECTION: IMPORTS]
from sqlalchemy import create_engine, inspect, text
from sqlalchemy.orm import sessionmaker
from ..models.mapping import Base
# Import models to ensure they're registered with Base
from ..models import task as _task_models  # noqa: F401
from ..models import auth as _auth_models  # noqa: F401
from ..models import config as _config_models  # noqa: F401
from ..models import llm as _llm_models  # noqa: F401
from ..models import assistant as _assistant_models  # noqa: F401
from ..models import profile as _profile_models  # noqa: F401
from .logger import belief_scope, logger
from .auth.config import auth_config
import os
from pathlib import Path
# [/SECTION]

# [DEF:BASE_DIR:Variable]
# @PURPOSE: Base directory for the backend.
BASE_DIR = Path(__file__).resolve().parent.parent.parent
# [/DEF:BASE_DIR:Variable]

# [DEF:DATABASE_URL:Constant]
# @PURPOSE: URL for the main application database.
DEFAULT_POSTGRES_URL = os.getenv(
    "POSTGRES_URL",
    "postgresql+psycopg2://postgres:postgres@localhost:5432/ss_tools",
)
DATABASE_URL = os.getenv("DATABASE_URL", DEFAULT_POSTGRES_URL)
# [/DEF:DATABASE_URL:Constant]

# [DEF:TASKS_DATABASE_URL:Constant]
# @PURPOSE: URL for the tasks execution database.
# Defaults to DATABASE_URL to keep task logs in the same PostgreSQL instance.
TASKS_DATABASE_URL = os.getenv("TASKS_DATABASE_URL", DATABASE_URL)
# [/DEF:TASKS_DATABASE_URL:Constant]

# [DEF:AUTH_DATABASE_URL:Constant]
# @PURPOSE: URL for the authentication database.
AUTH_DATABASE_URL = os.getenv("AUTH_DATABASE_URL", auth_config.AUTH_DATABASE_URL)
# [/DEF:AUTH_DATABASE_URL:Constant]

# [DEF:engine:Variable]
def _build_engine(db_url: str):
    with belief_scope("_build_engine"):
        if db_url.startswith("sqlite"):
            return create_engine(db_url, connect_args={"check_same_thread": False})
        return create_engine(db_url, pool_pre_ping=True)


# @PURPOSE: SQLAlchemy engine for mappings database.
engine = _build_engine(DATABASE_URL)
# [/DEF:engine:Variable]

# [DEF:tasks_engine:Variable]
# @PURPOSE: SQLAlchemy engine for tasks database.
tasks_engine = _build_engine(TASKS_DATABASE_URL)
# [/DEF:tasks_engine:Variable]

# [DEF:auth_engine:Variable]
# @PURPOSE: SQLAlchemy engine for authentication database.
auth_engine = _build_engine(AUTH_DATABASE_URL)
# [/DEF:auth_engine:Variable]

# [DEF:SessionLocal:Class]
# @TIER: TRIVIAL
# @PURPOSE: A session factory for the main mappings database.
# @PRE: engine is initialized.
SessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=engine)
# [/DEF:SessionLocal:Class]

# [DEF:TasksSessionLocal:Class]
# @TIER: TRIVIAL
# @PURPOSE: A session factory for the tasks execution database.
# @PRE: tasks_engine is initialized.
TasksSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=tasks_engine)
# [/DEF:TasksSessionLocal:Class]

# [DEF:AuthSessionLocal:Class]
# @TIER: TRIVIAL
# @PURPOSE: A session factory for the authentication database.
# @PRE: auth_engine is initialized.
AuthSessionLocal = sessionmaker(autocommit=False, autoflush=False, bind=auth_engine)
# [/DEF:AuthSessionLocal:Class]

# [DEF:_ensure_user_dashboard_preferences_columns:Function]
# @PURPOSE: Applies additive schema upgrades for user_dashboard_preferences table.
# @PRE: bind_engine points to application database where profile table is stored.
# @POST: Missing columns are added without data loss.
def _ensure_user_dashboard_preferences_columns(bind_engine):
    with belief_scope("_ensure_user_dashboard_preferences_columns"):
        table_name = "user_dashboard_preferences"
        inspector = inspect(bind_engine)
        if table_name not in inspector.get_table_names():
            return

        existing_columns = {
            str(column.get("name") or "").strip()
            for column in inspector.get_columns(table_name)
        }

        alter_statements = []
        if "git_username" not in existing_columns:
            alter_statements.append(
                "ALTER TABLE user_dashboard_preferences ADD COLUMN git_username VARCHAR"
            )
        if "git_email" not in existing_columns:
            alter_statements.append(
                "ALTER TABLE user_dashboard_preferences ADD COLUMN git_email VARCHAR"
            )
        if "git_personal_access_token_encrypted" not in existing_columns:
            alter_statements.append(
                "ALTER TABLE user_dashboard_preferences "
                "ADD COLUMN git_personal_access_token_encrypted VARCHAR"
            )
        if "start_page" not in existing_columns:
            alter_statements.append(
                "ALTER TABLE user_dashboard_preferences "
                "ADD COLUMN start_page VARCHAR NOT NULL DEFAULT 'dashboards'"
            )
        if "auto_open_task_drawer" not in existing_columns:
            alter_statements.append(
                "ALTER TABLE user_dashboard_preferences "
                "ADD COLUMN auto_open_task_drawer BOOLEAN NOT NULL DEFAULT TRUE"
            )
        if "dashboards_table_density" not in existing_columns:
            alter_statements.append(
                "ALTER TABLE user_dashboard_preferences "
                "ADD COLUMN dashboards_table_density VARCHAR NOT NULL DEFAULT 'comfortable'"
            )

        if not alter_statements:
            return

        try:
            with bind_engine.begin() as connection:
                for statement in alter_statements:
                    connection.execute(text(statement))
        except Exception as migration_error:
            logger.warning(
                "[database][EXPLORE] Profile preference additive migration failed: %s",
                migration_error,
            )
# [/DEF:_ensure_user_dashboard_preferences_columns:Function]


# [DEF:_ensure_git_server_configs_columns:Function]
# @PURPOSE: Applies additive schema upgrades for git_server_configs table.
# @PRE: bind_engine points to application database.
# @POST: Missing columns are added without data loss.
def _ensure_git_server_configs_columns(bind_engine):
    with belief_scope("_ensure_git_server_configs_columns"):
        table_name = "git_server_configs"
        inspector = inspect(bind_engine)
        if table_name not in inspector.get_table_names():
            return

        existing_columns = {
            str(column.get("name") or "").strip()
            for column in inspector.get_columns(table_name)
        }

        alter_statements = []
        if "default_branch" not in existing_columns:
            alter_statements.append(
                "ALTER TABLE git_server_configs ADD COLUMN default_branch VARCHAR NOT NULL DEFAULT 'main'"
            )

        if not alter_statements:
            return

        try:
            with bind_engine.begin() as connection:
                for statement in alter_statements:
                    connection.execute(text(statement))
        except Exception as migration_error:
            logger.warning(
                "[database][EXPLORE] GitServerConfig preference additive migration failed: %s",
                migration_error,
            )
# [/DEF:_ensure_git_server_configs_columns:Function]


# [DEF:init_db:Function]
# @PURPOSE: Initializes the database by creating all tables.
# @PRE: engine, tasks_engine and auth_engine are initialized.
# @POST: Database tables created in all databases.
# @SIDE_EFFECT: Creates physical database files if they don't exist.
def init_db():
    with belief_scope("init_db"):
        Base.metadata.create_all(bind=engine)
        Base.metadata.create_all(bind=tasks_engine)
        Base.metadata.create_all(bind=auth_engine)
        _ensure_user_dashboard_preferences_columns(engine)
        _ensure_git_server_configs_columns(engine)
# [/DEF:init_db:Function]

# [DEF:get_db:Function]
# @PURPOSE: Dependency for getting a database session.
# @PRE: SessionLocal is initialized.
# @POST:    Session is closed after use.
# @RETURN:  Generator[Session, None, None]
def get_db():
    with belief_scope("get_db"):
        db = SessionLocal()
        try:
            yield db
        finally:
            db.close()
# [/DEF:get_db:Function]

# [DEF:get_tasks_db:Function]
# @PURPOSE: Dependency for getting a tasks database session.
# @PRE: TasksSessionLocal is initialized.
# @POST:    Session is closed after use.
# @RETURN:  Generator[Session, None, None]
def get_tasks_db():
    with belief_scope("get_tasks_db"):
        db = TasksSessionLocal()
        try:
            yield db
        finally:
            db.close()
# [/DEF:get_tasks_db:Function]

# [DEF:get_auth_db:Function]
# @PURPOSE: Dependency for getting an authentication database session.
# @PRE: AuthSessionLocal is initialized.
# @POST:    Session is closed after use.
# @RETURN:  Generator[Session, None, None]
def get_auth_db():
    with belief_scope("get_auth_db"):
        db = AuthSessionLocal()
        try:
            yield db
        finally:
            db.close()
# [/DEF:get_auth_db:Function]

# [/DEF:backend.src.core.database:Module]