"""Task CRUD MCP tools.

Tasks are notes with a non-null `status` — same model, different filter.
Wrappers call services/notes.py for CRUD with is_task=True and add the
task-specific fields (status, priority, due_date, parent_id), plus
services/task_logs.py for add_task_log.

There is no delete_task — matches the existing fable-mcp surface.
Cancel by updating status to "cancelled".

Sentinels (preserved from existing fable-mcp):
  - status="" / priority="" / title="" / body="" → "leave unchanged" on update
  - status="todo" is the default on create (creates a task; non-null status is
    what makes a Note a Task)
  - priority="none" sets explicit no-priority; priority="" is "leave unchanged"
  - project_id=0 / milestone_id=0 / parent_id=0 → "no association" on create,
    "leave unchanged" on update; on update, -1 clears the FK (sets it NULL)
"""
from __future__ import annotations

from scribe.mcp._context import current_user_id
from scribe.services import access as access_svc
from scribe.services import dedup as dedup_svc
from scribe.services import notes as notes_svc
from scribe.services import planning as planning_svc
from scribe.services import rulebooks as rulebooks_svc
from scribe.services import systems as systems_svc
from scribe.services import task_logs as task_logs_svc
from scribe.services import trash as trash_svc


async def list_tasks(
    limit: int = 20,
    offset: int = 0,
    status: str = "",
    project_id: int = 0,
    kind: str = "",
) -> dict:
    """List tasks in Scribe.

    Args:
        status: Filter by status — one of: todo, in_progress, done, cancelled. Omit for all.
        project_id: Filter to a specific project. PASS THE ACTIVE PROJECT'S ID
            whenever a project is in scope so you list that project's tasks, not
            every project's. 0 = no filter (all projects — use only for a
            deliberate cross-project view).
        kind: Filter by task kind — 'work', 'plan', or 'issue'. Omit (empty) for all kinds.

    Results are ordered by last-updated descending.
    """
    uid = current_user_id()
    rows, total = await notes_svc.list_notes(
        uid,
        is_task=True,
        status=status or None,
        project_id=project_id or None,
        task_kind=kind or None,
        limit=max(1, min(limit, 100)),
        offset=max(0, offset),
    )
    return {"tasks": [n.to_dict() for n in rows], "total": total}


async def get_task(task_id: int) -> dict:
    """Fetch a single Scribe task by ID.

    Returns id, title, body, status, priority, tags, project_id, milestone_id,
    parent_id, parent_title, due_date, created_at, updated_at. For legacy
    kind=plan tasks, the response also includes applicable_rules +
    subscribed_rulebooks from the task's project's rulebook subscriptions (new
    plans are milestones — use get_milestone for those).

    A task another user shared with you also carries `shared`, `owner` and
    `permission` — it's their work item, not one you took on.
    """
    uid = current_user_id()
    loaded = await notes_svc.get_note_for_user(uid, task_id)
    note = loaded[0] if loaded else None
    if note is None or note.deleted_at is not None:
        raise ValueError(f"task {task_id} not found")
    data = note.to_dict()
    parent_title = None
    if note.parent_id:
        parent_loaded = await notes_svc.get_note_for_user(uid, note.parent_id)
        if parent_loaded is not None:
            parent_title = parent_loaded[0].title
    data["parent_title"] = parent_title

    # Legacy kind=plan tasks predate milestone-as-plan; still surface their
    # project's rules on read so the historical plans stay useful.
    if data.get("task_kind") == "plan" and note.project_id:
        applicable = await rulebooks_svc.get_applicable_rules(
            project_id=note.project_id, user_id=uid,
        )
        data["applicable_rules"] = applicable["rules"]
        data["subscribed_rulebooks"] = applicable["subscribed_rulebooks"]
        data["applicable_rules_truncated"] = applicable["truncated"]
        data["project_rules"] = applicable.get("project_rules", [])
        data["suppressed_rules"] = applicable.get("suppressed_rules", [])
        data["suppressed_topics"] = applicable.get("suppressed_topics", [])
    data.update(await access_svc.describe_provenance(uid, note))
    return data


async def create_task(
    title: str,
    body: str = "",
    status: str = "todo",
    priority: str = "",
    project_id: int = 0,
    milestone_id: int = 0,
    parent_id: int = 0,
    tags: list[str] | None = None,
    kind: str = "work",
    system_ids: list[int] | None = None,
    arose_from_id: int = 0,
    force: bool = False,
) -> dict:
    """Create a new task in Scribe.

    Args:
        title: Task title (required).
        body: Markdown description / notes for the task.
        status: Initial status — one of: todo (default), in_progress, done, cancelled.
        priority: One of: low, medium, high, or 'none'. Omit (empty string) to leave unset.
        project_id: Associate with a project (0 = no project).
        milestone_id: Place within a project milestone (0 = no milestone).
        parent_id: Make this a sub-task of another task (0 = top-level).
        tags: List of plain-string tags without # prefix.
        kind: 'work' (default) or 'issue'. An issue is corrective work — a
            problem you fixed or are fixing; record symptom → root cause → fix
            in the body. (Plans are milestones now — call start_planning to begin
            a plan; 'plan' is not a valid kind here.)
        system_ids: Ids of the project's Systems (reusable subsystem/area
            objects; see list_systems / create_system) to associate this task with.
        arose_from_id: For an issue, the id of the task/feature it arose from
            (provenance). 0 = none.
        force: Bypass the near-duplicate gate. By default, if a title- or
            meaning-similar task already exists in the same project, creation is
            BLOCKED and the existing task's id is returned so you update it
            instead. Set true only for a genuinely distinct task.

    Returns the created task, OR — when a near-duplicate is found and force is
    false — {"duplicate": true, "existing_id": ..., "message": ...} (nothing
    created).
    """
    uid = current_user_id()
    if kind == "plan":
        raise ValueError(
            "kind=plan is retired — a plan is now a milestone. Call "
            "start_planning(project_id, title) to begin a plan (it creates the "
            "milestone + seeds the design), then create each step as its own "
            "task with create_task(milestone_id=<that milestone>)."
        )
    if not force:
        dup = await dedup_svc.find_duplicate_note(
            uid, title, body, project_id=project_id or None,
            is_task=True, note_type="note",
        )
        if dup is not None:
            return dedup_svc.duplicate_response(dup, "task")
    note = await notes_svc.create_note(
        uid,
        title=title,
        body=body,
        status=status,
        priority=priority or None,
        project_id=project_id or None,
        milestone_id=milestone_id or None,
        parent_id=parent_id or None,
        tags=tags,
        task_kind=kind,
        arose_from_id=arose_from_id or None,
    )
    if system_ids:
        await systems_svc.set_record_systems(uid, note.id, system_ids)
    data = note.to_dict()
    if system_ids:
        data["systems"] = [
            s.to_dict() for s in await systems_svc.list_record_systems(uid, note.id)
        ]
    return data


async def update_task(
    task_id: int,
    title: str = "",
    body: str = "",
    status: str = "",
    priority: str = "",
    project_id: int = 0,
    milestone_id: int = 0,
    system_ids: list[int] | None = None,
    arose_from_id: int = 0,
) -> dict:
    """Update an existing Scribe task. Only explicitly provided fields are changed.

    Args:
        task_id: ID of the task to update.
        title: New title, or omit to leave unchanged.
        body: New markdown body, or omit to leave unchanged.
        status: New status — one of: todo, in_progress, done, cancelled. Drive
            the lifecycle: set in_progress when you start, done when complete —
            don't leave finished work at todo.
        priority: New priority — one of: none, low, medium, high.
        project_id: New project. 0 = leave unchanged, -1 = clear (remove from
            its project; also clears the milestone), positive = set.
        milestone_id: New milestone. 0 = leave unchanged, -1 = clear (remove
            from its milestone), positive = set.
        system_ids: Replace this task's System associations with these ids
            (set-semantics). None = leave unchanged; [] = clear all.
        arose_from_id: Provenance (issue → originating task). 0 = leave unchanged,
            -1 = clear, positive = set.
    """
    uid = current_user_id()
    fields: dict = {}
    if title:
        fields["title"] = title
    if body:
        fields["body"] = body
    if status:
        fields["status"] = status
    if priority:
        fields["priority"] = priority
    # Optional FKs: 0 = leave unchanged, -1 = clear (set NULL), positive = set.
    if project_id == -1:
        fields["project_id"] = None
        fields["milestone_id"] = None  # a milestone can't outlive its project
    elif project_id:
        fields["project_id"] = project_id
    if milestone_id == -1:
        fields["milestone_id"] = None
    elif milestone_id:
        fields["milestone_id"] = milestone_id
    if arose_from_id == -1:
        fields["arose_from_id"] = None
    elif arose_from_id:
        fields["arose_from_id"] = arose_from_id
    note = await notes_svc.update_note(uid, task_id, **fields)
    if note is None:
        raise ValueError(f"task {task_id} not found")
    if system_ids is not None:
        await systems_svc.set_record_systems(uid, task_id, system_ids)
    data = note.to_dict()
    if system_ids is not None:
        data["systems"] = [
            s.to_dict() for s in await systems_svc.list_record_systems(uid, task_id)
        ]
    return data


async def add_task_log(task_id: int, content: str) -> dict:
    """Append a timestamped progress log entry to a Scribe task.

    Use this to record work sessions, decisions, or status updates over time
    without overwriting the task's main body. Each entry is stored separately
    and shown chronologically in the task view.
    """
    uid = current_user_id()
    log = await task_logs_svc.create_log(uid, task_id, content)
    return log.to_dict() if hasattr(log, "to_dict") else {
        "id": log.id, "task_id": log.task_id, "content": log.content,
        "created_at": log.created_at.isoformat() if log.created_at else None,
    }


async def start_planning(project_id: int, title: str) -> dict:
    """Begin a plan in Scribe (the preferred home for plans — not a local .md file).

    Creates a MILESTONE that IS the plan: its `body` is seeded with a design
    template (Goal/Approach/Verification) under the given project, and the call
    returns it together with the project's applicable Rulebook rules and brief
    context. The milestone is the plan container — the individual steps live as
    first-class child tasks under it, not as checkboxes in the body.

    Afterwards:
    - Edit the plan/design with update_milestone(milestone_id, body=...).
    - Create each step as its own task with create_task(milestone_id=<this id>);
      track it with status + add_task_log. Do NOT put steps as checkboxes in the
      milestone body.

    (kind=plan tasks are retired — use this instead. Existing historical
    plan-tasks remain readable but new planning goes through milestones.)

    Args:
        project_id: The project this plan is for.
        title: A short title for the plan/milestone.
    """
    uid = current_user_id()
    return await planning_svc.start_planning(
        user_id=uid, project_id=project_id, title=title,
    )


async def delete_task(task_id: int) -> dict:
    """Move a Scribe task (or plan) to the trash (recoverable). Sub-tasks go with it.
    Restore via restore(batch_id)."""
    uid = current_user_id()
    batch = await trash_svc.delete(uid, "task", task_id)
    if batch is None:
        raise ValueError(f"task {task_id} not found")
    return {"deleted_batch_id": batch,
            "message": f"Task {task_id} moved to trash. Restore with restore('{batch}')."}


def register(mcp) -> None:
    for fn in (
        list_tasks,
        get_task,
        create_task,
        update_task,
        add_task_log,
        start_planning,
        delete_task,
    ):
        mcp.tool(name=fn.__name__)(fn)