from pathlib import Path

import yaml
from django.conf import settings


REQUIRED_FIELDS = [
    ("id",),
    ("name",),
    ("description",),
    ("agent", "role"),
    ("agent", "goal"),
    ("agent", "instructions"),
    ("rag", "enabled"),
    ("tools",),
    ("output", "type"),
    ("audit", "enabled"),
]


class ScenarioNotFound(KeyError):
    pass


class ScenarioValidationError(ValueError):
    pass


def _get_nested(config: dict, path: tuple[str, ...]):
    value = config
    for key in path:
        if not isinstance(value, dict) or key not in value:
            raise ScenarioValidationError("缺失必填字段: " + ".".join(path))
        value = value[key]
    return value


def validate_scenario(config: dict) -> dict:
    for field_path in REQUIRED_FIELDS:
        _get_nested(config, field_path)
    return config


def _scenario_files() -> list[Path]:
    config_dir = Path(settings.SCENARIO_CONFIG_DIR)
    if not config_dir.exists():
        return []
    return sorted([*config_dir.glob("*.yaml"), *config_dir.glob("*.yml")])


def list_scenarios() -> list[dict]:
    scenarios = []
    for path in _scenario_files():
        with path.open("r", encoding="utf-8") as file:
            config = yaml.safe_load(file) or {}
        scenarios.append(validate_scenario(config))
    return scenarios


def get_scenario(scenario_id: str) -> dict:
    for scenario in list_scenarios():
        if scenario["id"] == scenario_id:
            return scenario
    raise ScenarioNotFound(f"场景不存在: {scenario_id}")