"""Milestone CRUD MCP tools — thin wrappers over services/milestones.py.

Mirrors existing fable-mcp milestone tool contracts: list/create/update. The
existing surface has no fable_get_milestone or fable_delete_milestone — kept
that way for parity.

Sentinels:
  - title="" / description="" / status="" → "leave unchanged" on update
  - order_index=-1 → "leave unchanged" on update (0 is a valid order_index)
  - status="active" default on create
"""
from __future__ import annotations

from fabledassistant.mcp._context import current_user_id
from fabledassistant.services import milestones as milestones_svc
from fabledassistant.services import trash as trash_svc


async def list_milestones(project_id: int) -> dict:
    """List milestones for a Scribe project, ordered by order_index.

    Returns id, title, description, status (active/done), order_index,
    and task counts.
    """
    uid = current_user_id()
    rows = await milestones_svc.get_project_milestone_summary(uid, project_id)
    return {"milestones": rows}


async def create_milestone(
    project_id: int,
    title: str,
    description: str = "",
    status: str = "active",
) -> dict:
    """Create a milestone within a Scribe project.

    Args:
        project_id: The project this milestone belongs to (required).
        title: Milestone name (required).
        description: Optional description of what this milestone covers.
        status: active (default) or done.
    """
    uid = current_user_id()
    milestone = await milestones_svc.create_milestone(
        uid,
        project_id=project_id,
        title=title,
        description=description or None,
        status=status,
    )
    return milestone.to_dict()


async def update_milestone(
    project_id: int,
    milestone_id: int,
    title: str = "",
    description: str = "",
    status: str = "",
    order_index: int = -1,
) -> dict:
    """Update a Scribe milestone. Only explicitly provided fields are changed.

    Args:
        project_id: Project the milestone belongs to (preserved for API parity;
            ownership scoping is enforced by user_id at the service layer).
        milestone_id: ID of the milestone to update.
        title: New title, or omit to leave unchanged.
        description: New description, or omit to leave unchanged.
        status: New status — active or done.
        order_index: New display position (0-based). Use -1 to leave unchanged.
    """
    uid = current_user_id()
    fields: dict = {}
    if title:
        fields["title"] = title
    if description:
        fields["description"] = description
    if status:
        fields["status"] = status
    if order_index >= 0:
        fields["order_index"] = order_index
    milestone = await milestones_svc.update_milestone(uid, milestone_id, **fields)
    if milestone is None:
        raise ValueError(f"milestone {milestone_id} not found")
    return milestone.to_dict()


async def delete_milestone(milestone_id: int) -> dict:
    """Move a milestone to the trash (recoverable). Its tasks go with it as one batch.
    Restore via restore(batch_id)."""
    uid = current_user_id()
    batch = await trash_svc.delete(uid, "milestone", milestone_id)
    if batch is None:
        raise ValueError(f"milestone {milestone_id} not found")
    return {"deleted_batch_id": batch,
            "message": f"Milestone {milestone_id} + its tasks moved to trash. Restore with restore('{batch}')."}


def register(mcp) -> None:
    for fn in (
        list_milestones,
        create_milestone,
        update_milestone,
        delete_milestone,
    ):
        mcp.tool(name=fn.__name__)(fn)