import re
from pathlib import Path

from alembic import op


_DOLLAR_TAG_RE = re.compile(r"\$\w+\$")
_SQL_DIRECTORY = Path(__file__).parent / "versions" / "sql"


def _split_statements(sql: str) -> list[str]:
    statements: list[str] = []
    current: list[str] = []
    dollar_tag: str | None = None

    for line in sql.splitlines():
        stripped = line.strip()
        if stripped.startswith("--"):
            continue

        if dollar_tag is None:
            match = _DOLLAR_TAG_RE.search(stripped)
            if match:
                dollar_tag = match.group(0)
        elif stripped.startswith(dollar_tag):
            dollar_tag = None

        current.append(line)
        if dollar_tag is None and stripped.endswith(";"):
            statements.append("\n".join(current))
            current = []

    if remaining := "\n".join(current).strip():
        statements.append(remaining)

    return statements


def run_sql_file_migration(filename: str) -> None:
    """Execute statements from a SQL file in alembic/versions/sql."""
    sql = (_SQL_DIRECTORY / filename).read_text(encoding="utf-8")
    for statement in _split_statements(sql):
        if stripped := statement.rstrip(";").strip():
            op.execute(stripped)