"""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


async def fable_list_milestones(project_id: int) -> dict:
    """List milestones for a Fable 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 fable_create_milestone(
    project_id: int,
    title: str,
    description: str = "",
    status: str = "active",
) -> dict:
    """Create a milestone within a Fable 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 fable_update_milestone(
    project_id: int,
    milestone_id: int,
    title: str = "",
    description: str = "",
    status: str = "",
    order_index: int = -1,
) -> dict:
    """Update a Fable 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()


def register(mcp) -> None:
    for fn in (
        fable_list_milestones,
        fable_create_milestone,
        fable_update_milestone,
    ):
        mcp.tool(name=fn.__name__)(fn)