"""Typed description of the single workflow run this container exists to execute.

The control plane hands the container exactly one of these (JSON in
OPENSWARM_RUN_SPEC, or a path in OPENSWARM_RUN_SPEC_FILE) and nothing else. Every
field is validated before the backend boots, so a malformed job dies in under a
second instead of burning a machine-minute discovering it.
"""

import json
import os
from datetime import datetime, timedelta, timezone
from typing import List, Literal, Optional

from pydantic import BaseModel, ConfigDict, Field, model_validator
from typeguard import typechecked

from backend.apps.workflows.models import Workflow

SPEC_ENV = "OPENSWARM_RUN_SPEC"
SPEC_FILE_ENV = "OPENSWARM_RUN_SPEC_FILE"

# Headroom the access token must still have on arrival. The control plane refreshes right before dispatch; anything thinner than this means its clock or its queue is broken, and we must not paper over that by refreshing ourselves.
MIN_TOKEN_LIFETIME = timedelta(minutes=2)


class InvalidRunSpec(ValueError):
    """The control plane handed us something we refuse to run."""


class ProviderCredential(BaseModel):
    """One already-refreshed provider credential, spendable but not rotatable.

    `extra="forbid"` is the first of two walls keeping a refresh token out of this
    container: a payload carrying `refreshToken` fails validation here and the run
    dies loudly. See runner.router_credentials for the second wall and the why.
    """

    model_config = ConfigDict(validate_assignment=True, extra="forbid")

    provider: str = Field(min_length=1)
    auth_type: Literal["oauth", "api_key"]
    label: str = "OpenSwarm cloud run"
    access_token: Optional[str] = None
    api_key: Optional[str] = None
    expires_at: Optional[datetime] = None
    scope: Optional[str] = None

    @model_validator(mode="after")
    def p_require_matching_secret(self) -> "ProviderCredential":
        if self.auth_type == "oauth":
            if not self.access_token:
                raise ValueError(f"credential for {self.provider!r} is oauth but carries no access_token")
            if self.expires_at is None:
                raise ValueError(f"credential for {self.provider!r} is oauth but carries no expires_at")
            if self.api_key:
                raise ValueError(f"credential for {self.provider!r} carries both an access_token and an api_key")
        else:
            if not self.api_key:
                raise ValueError(f"credential for {self.provider!r} is api_key but carries no api_key")
            if self.access_token:
                raise ValueError(f"credential for {self.provider!r} carries both an access_token and an api_key")
        return self

    @typechecked
    def remaining_lifetime(self, now: datetime) -> Optional[timedelta]:
        """How long this credential is still good for; None when it cannot expire."""
        if self.expires_at is None:
            return None
        return self.expires_at.astimezone(timezone.utc) - now.astimezone(timezone.utc)


class CallbackTarget(BaseModel):
    """Where the run reports back. The token is a dedicated two-party secret, never a user credential."""

    model_config = ConfigDict(validate_assignment=True, extra="forbid")

    url: str = Field(min_length=1)
    token: str = Field(min_length=1)
    heartbeat_seconds: int = Field(default=30, ge=5, le=300)


class RunSpec(BaseModel):
    model_config = ConfigDict(validate_assignment=True, extra="forbid")

    run_id: str = Field(min_length=1)
    workflow: Workflow
    credentials: List[ProviderCredential] = Field(min_length=1)
    callback: Optional[CallbackTarget] = None
    # Hard wall-clock ceiling. Fly bills by machine-second, so an agent that wedges must cost a bounded amount.
    max_run_seconds: int = Field(default=1800, ge=60, le=7200)

    @typechecked
    def expired_credentials(self, now: datetime) -> List[ProviderCredential]:
        """Credentials too close to expiry to spend. The runner cannot refresh, so this is fatal, not a retry."""
        stale: List[ProviderCredential] = []
        for credential in self.credentials:
            remaining = credential.remaining_lifetime(now)
            if remaining is not None and remaining < MIN_TOKEN_LIFETIME:
                stale.append(credential)
        return stale

    @typechecked
    def workflow_for_disk(self) -> Workflow:
        """The workflow as this container should see it: one run, never a schedule.

        A cloud-executed workflow arrives with its schedule still configured. Left
        enabled, the container's own scheduler would fire it a second time inside
        the box, so the timer is stripped here rather than trusted to stay off.
        """
        copy = self.workflow.model_copy(deep=True)
        copy.schedule.enabled = False
        copy.deleted_at = None
        copy.draft_steps = None
        copy.next_run_at = None
        return copy


@typechecked
def load_run_spec() -> RunSpec:
    """Parse the run spec from the environment, or raise InvalidRunSpec with a legible reason."""
    raw = os.environ.get(SPEC_ENV, "").strip()
    source = SPEC_ENV
    if not raw:
        path = os.environ.get(SPEC_FILE_ENV, "").strip()
        if not path:
            raise InvalidRunSpec(f"no run spec: set {SPEC_ENV} to JSON or {SPEC_FILE_ENV} to a file path")
        source = f"{SPEC_FILE_ENV}={path}"
        try:
            with open(path, "r", encoding="utf-8") as handle:
                raw = handle.read()
        except OSError as exc:
            raise InvalidRunSpec(f"cannot read run spec from {source}: {exc}") from exc

    try:
        return RunSpec.model_validate_json(raw)
    except json.JSONDecodeError as exc:
        raise InvalidRunSpec(f"run spec from {source} is not valid JSON: {exc}") from exc
    except ValueError as exc:
        raise InvalidRunSpec(f"run spec from {source} is not a valid RunSpec: {exc}") from exc