from __future__ import annotations

import importlib
import logging
from importlib.metadata import entry_points
from pathlib import Path
from typing import Any

from pydantic import BaseModel

from core.base import BaseWorker
from core.plugin_types import HYDROGEN_API_VERSION, EmptyPluginConfig
from core.schemas import ModuleManifest
from core.schemas.config import Config, ResolvedConfig
from core.schemas.modules import LoadedModule, LoadedWorker, ModuleLoadResult
from reporting.models import PluginRuntimeError

logger = logging.getLogger(__name__)


def load_module(package_name: str) -> LoadedModule | None:
    module = importlib.import_module(package_name)
    raw_manifest = getattr(module, "MANIFEST", None)

    if raw_manifest is None:
        logger.warning("module package %s does not export MANIFEST", package_name)
        return None

    manifest = ModuleManifest.model_validate(raw_manifest)
    if manifest.api_version != HYDROGEN_API_VERSION:
        raise ValueError(
            f"module package {package_name} targets api_version={manifest.api_version}, "
            f"expected {HYDROGEN_API_VERSION}"
        )

    builder = getattr(module, "build_worker", None)

    if builder is None:
        logger.warning("module package %s does not export build_worker", package_name)
        return None

    if not callable(builder):
        logger.warning("build_worker in package %s is not callable", package_name)
        return None

    config_model = getattr(module, "CONFIG_MODEL", None)
    if config_model is None:
        config_model = getattr(getattr(builder, "__self__", None), "config_model", None)
    if config_model is None:
        config_model = EmptyPluginConfig
    if not isinstance(config_model, type) or not issubclass(config_model, BaseModel):
        raise TypeError(f"module package {package_name} exports invalid CONFIG_MODEL")

    return LoadedModule(
        package_name=package_name,
        manifest=manifest,
        build_worker=builder,
        config_model=config_model,
    )


def build_worker(
    loaded_module: LoadedModule, config: BaseModel | dict[str, Any]
) -> LoadedWorker | None:
    worker = loaded_module.build_worker(config)
    if not isinstance(worker, BaseWorker):
        logger.warning(
            "build_worker in package %s did not return BaseWorker", loaded_module.package_name
        )
        return None

    return LoadedWorker(worker=worker, manifest=loaded_module.manifest, config=config)


def discover_modules(path: Path, config: Config, package_prefix: str = "modules") -> list[str]:
    package_names: list[str] = []

    if path.exists():
        for entry in path.iterdir():
            if not entry.is_dir() or entry.name.startswith("__"):
                continue
            if not (entry / "__init__.py").exists():
                continue
            package_names.append(f"{package_prefix}.{entry.name}")

    package_names.extend(config.plugin_packages.modules)

    try:
        module_entry_points = entry_points(group="hydrogen.modules")
    except TypeError:
        module_entry_points = entry_points().select(group="hydrogen.modules")

    for module_entry_point in module_entry_points:
        package_names.append(module_entry_point.value.partition(":")[0])

    return list(dict.fromkeys(package_names))


def load_modules(path: Path, config: Config, package_prefix: str = "modules") -> ModuleLoadResult:
    workers: list[LoadedWorker] = []
    errors: list[PluginRuntimeError] = []

    for package_name in discover_modules(path, config, package_prefix):
        try:
            module = load_module(package_name)
            if module is None:
                continue

            if module.manifest.category in config.exclude_categories:
                logger.info(
                    "module %s was skipped due to config exclusion", module.manifest.identifier
                )
                continue

            module_config = config.modules.get(module.manifest.identifier, {})
            validated_config = module.config_model.model_validate(module_config)
            worker = build_worker(module, validated_config)
            if worker is not None:
                workers.append(worker)
                logger.info("module %s has been successfully loaded!", module.manifest.identifier)
        except Exception as exc:
            logger.exception("failed to load module package %s", package_name)
            errors.append(
                PluginRuntimeError(
                    plugin_kind="module",
                    plugin_name=package_name,
                    stage="load",
                    message=str(exc),
                )
            )

    return ModuleLoadResult(loaded_workers=workers, errors=errors)


def load_prevalidated_workers(
    loaded_modules: list[LoadedModule],
    resolved_config: ResolvedConfig,
) -> ModuleLoadResult:
    workers: list[LoadedWorker] = []
    errors: list[PluginRuntimeError] = []

    for loaded_module in loaded_modules:
        if loaded_module.manifest.category in resolved_config.exclude_categories:
            continue

        module_config = resolved_config.modules.get(loaded_module.manifest.identifier)
        if module_config is None:
            continue

        try:
            worker = build_worker(loaded_module, module_config)
            if worker is None:
                errors.append(
                    PluginRuntimeError(
                        plugin_kind="module",
                        plugin_name=loaded_module.manifest.identifier,
                        stage="build_worker",
                        message="build_worker returned an invalid worker instance",
                    )
                )
                continue
            workers.append(worker)
        except Exception as exc:
            logger.exception("failed to build worker for module %s", loaded_module.package_name)
            errors.append(
                PluginRuntimeError(
                    plugin_kind="module",
                    plugin_name=loaded_module.manifest.identifier,
                    stage="build_worker",
                    message=str(exc),
                )
            )

    return ModuleLoadResult(loaded_workers=workers, errors=errors)


def load_module_descriptors(
    path: Path, config: Config, package_prefix: str = "modules"
) -> tuple[list[LoadedModule], list[PluginRuntimeError]]:
    modules: list[LoadedModule] = []
    errors: list[PluginRuntimeError] = []

    for package_name in discover_modules(path, config, package_prefix):
        try:
            module = load_module(package_name)
            if module is not None:
                modules.append(module)
        except Exception as exc:
            logger.exception("failed to discover module package %s", package_name)
            errors.append(
                PluginRuntimeError(
                    plugin_kind="module",
                    plugin_name=package_name,
                    stage="discovery",
                    message=str(exc),
                )
            )

    return modules, errors