"""Eager module loading for immutable runtime immunity (Issue #5 Phase 4).

Ensures all dependencies (loop, delegation, agents, external packages)
are loaded into sys.modules at loop startup, preventing mid-flight disk
modifications from triggering lazy-import syntax/EOF errors (B-13).
"""

from __future__ import annotations

import importlib
import os
import sys
from typing import List, Sequence

# Framework version locked with framework constants
FRAMEWORK_VERSION = "4.8.8"

CORE_MODULES: Sequence[str] = (
    # Standard library modules
    "atexit",
    "argparse",
    "copy",
    "glob",
    "hashlib",
    "json",
    "os",
    "pathlib",
    "re",
    "shutil",
    "signal",
    "sqlite3",
    "subprocess",
    "sys",
    "tempfile",
    "time",
    "typing",
    # Framework loop modules
    "lib_py.loop.parser",
    "lib_py.loop.checkpoint",
    "lib_py.loop.runner",
    "lib_py.loop.attribution",
    "lib_py.loop.autocomplete",
    "lib_py.loop.evidence",
    "lib_py.loop.policy",
    "lib_py.loop.shadow",
    "lib_py.loop.store",
    "lib_py.loop.watcher",
    # Delegation and common modules
    "lib_py.ints",
    "lib_py.paths",
    "lib_py.state",
    "lib_py.atomic_yaml",
    "lib_py.workspace_uuid",
    "lib_py.verify_session",
    "lib_py.layout",
    "lib_py.delegation.engine",
    "lib_py.delegation.finalize",
    "lib_py.delegation.job_subscriber",
    "lib_py.delegation.mqtt_common",
    "lib_py.delegation.notifier",
    "lib_py.delegation.publish_event",
    "lib_py.delegation.publisher",
    "lib_py.delegation.registry",
    "lib_py.delegation.service",
    "lib_py.delegation.cli",
    # Agent adapter registry
    "lib_py.agents.base",
    "lib_py.agents.registry",
    "lib_py.agents.input_region",
    "lib_py.agents.sanitize",
)

OPTIONAL_MODULES: Sequence[str] = (
    "yaml",
    "paho.mqtt",
    "paho.mqtt.client",
)


def verify_framework_version(expected_version: str = FRAMEWORK_VERSION) -> None:
    """Verifies that MAM_VERSION matches framework version if set."""
    env_version = os.environ.get("MAM_VERSION")
    if env_version and env_version != expected_version:
        raise RuntimeError(
            f"MAM_VERSION mismatch: expected {expected_version}, got {env_version} in environment."
        )


def eager_load(
    modules: Sequence[str] = CORE_MODULES,
    optional_modules: Sequence[str] = OPTIONAL_MODULES,
) -> List[str]:
    """Eagerly imports all modules into sys.modules.

    Returns the list of successfully loaded module names.
    """
    verify_framework_version()

    # Ensure PYTHONDONTWRITEBYTECODE is set for isolation
    sys.dont_write_bytecode = True
    os.environ["PYTHONDONTWRITEBYTECODE"] = "1"

    loaded: List[str] = []
    for mod_name in modules:
        if mod_name not in sys.modules:
            try:
                importlib.import_module(mod_name)
            except Exception as exc:
                raise RuntimeError(f"Failed to eager load {mod_name}: {exc}") from exc
        loaded.append(mod_name)

    for opt_mod in optional_modules:
        if opt_mod not in sys.modules:
            try:
                importlib.import_module(opt_mod)
                loaded.append(opt_mod)
            except (ImportError, ModuleNotFoundError):
                pass

    return loaded


def is_eager_loaded(modules: Sequence[str] = CORE_MODULES) -> bool:
    """Returns True if all required core modules are present in sys.modules."""
    return all(mod in sys.modules for mod in modules)