"""Match the runtime's legacy-first persistence configuration precedence."""

import os
from pathlib import Path


def postgres_connection_string(config) -> str | None:
    if not shared_postgres_configured(config):
        return None
    checkpoint = getattr(config, "checkpointer", None)
    if checkpoint is not None:
        return getattr(checkpoint, "connection_string", None)
    return getattr(config.database, "postgres_url", None)


def shared_postgres_configured(config) -> bool:
    database = getattr(config, "database", None)
    if getattr(database, "backend", None) not in {"postgres", "mysql"}:
        return False
    checkpoint = getattr(config, "checkpointer", None)
    if checkpoint is None:
        return database.backend == "postgres"
    raw = os.getenv("DEER_FLOW_USE_PG_CHECKPOINTER")
    enabled = raw.strip().lower() not in {"0", "false", "no", "off"} if raw else getattr(checkpoint, "use_postgres", True)
    return checkpoint.type == "postgres" and enabled


def sqlite_checkpoint_path(config) -> str | None:
    from deerflow.runtime.checkpointer.async_provider import _sqlite_conn_str_for_postgres_fallback, _use_postgres_enabled
    from deerflow.runtime.store._sqlite_utils import resolve_sqlite_conn_str

    checkpoint = getattr(config, "checkpointer", None)
    if checkpoint is None:
        return None
    if checkpoint.type == "sqlite":
        raw = getattr(checkpoint, "connection_string", None) or "store.db"
    elif checkpoint.type == "postgres" and not _use_postgres_enabled(checkpoint):
        raw = _sqlite_conn_str_for_postgres_fallback(checkpoint)
    else:
        return None
    return resolve_sqlite_conn_str(raw)


def shared_storage_configured(config) -> bool:
    if shared_postgres_configured(config):
        return True
    if getattr(getattr(config, "database", None), "backend", None) not in {"mysql", "postgres"}:
        return False
    path = sqlite_checkpoint_path(config)
    return bool(path and path != ":memory:" and not path.startswith("file:"))


def validate_sqlite_mount(config, mountinfo: str | None = None) -> None:
    """SQLite databases and WAL sidecars must live on one shared local directory."""
    path = sqlite_checkpoint_path(config)
    if path is None:
        return
    database = Path(path).resolve()
    content = mountinfo if mountinfo is not None else Path("/proc/self/mountinfo").read_text()
    for line in content.splitlines():
        left, right = line.split(" - ", 1)
        mount = Path(left.split()[4].replace("\\040", " "))
        # A single-file bind does not share the -wal/-shm files.
        if mount != Path("/") and mount in database.parents:
            if right.split()[0] in {"nfs", "nfs4", "cifs", "smb3", "9p"}:
                raise RuntimeError("SQLite Worker requires a shared local directory, not a network filesystem")
            return
    raise RuntimeError("SQLite Worker requires the database directory to be persistently mounted in every container")