"""Task specification the worker consumes.

MVP source is a JSON file matching what the activity-core issue-core sink
emits per rule action (task_template/description/target_repo/labels), plus
executor-specific fields. A future source polls issue-core directly.
"""

from __future__ import annotations

import json
from dataclasses import dataclass, field
from pathlib import Path


class TaskSpecError(ValueError):
    pass


@dataclass
class TaskSpec:
    title: str
    description: str
    target_repo: Path
    agent: str = "coach"
    labels: list[str] = field(default_factory=list)
    hub_task_id: str | None = None
    completion_event_type: str = "executor_run"
    timeout_seconds: int = 900

    @classmethod
    def from_file(cls, path: str | Path) -> "TaskSpec":
        raw = json.loads(Path(path).read_text())
        missing = {"title", "description", "target_repo"} - set(raw)
        if missing:
            raise TaskSpecError(f"task spec missing field(s): {', '.join(sorted(missing))}")
        target = Path(raw["target_repo"]).expanduser()
        if not (target / ".git").is_dir():
            raise TaskSpecError(f"target_repo is not a git repository: {target}")
        return cls(
            title=str(raw["title"]),
            description=str(raw["description"]),
            target_repo=target,
            agent=str(raw.get("agent", "coach")),
            labels=[str(label) for label in raw.get("labels", [])],
            hub_task_id=raw.get("hub_task_id"),
            completion_event_type=str(raw.get("completion_event_type", "executor_run")),
            timeout_seconds=int(raw.get("timeout_seconds", 900)),
        )