"""MCP tools for the Scribe Rulebook system.

Sixteen tools: rulebook/topic/rule CRUD + subscription management. Thin
wrappers over services/rulebooks.py — ownership is enforced in the service.

Destructive ops (delete_*) require confirmed=True; otherwise return a
preview-style warning. Mirrors the pattern in delete_event and the design
spec.
"""
from __future__ import annotations

from fabledassistant.mcp._context import current_user_id
from fabledassistant.services import rulebooks as rulebooks_svc
from fabledassistant.services import trash as trash_svc


# ── Rulebook CRUD ───────────────────────────────────────────────────────

async def list_rulebooks() -> dict:
    """List all rulebooks owned by the current user.

    Returns id, title, description for each.
    """
    uid = current_user_id()
    rows = await rulebooks_svc.list_rulebooks(uid)
    return {"rulebooks": [rb.to_dict() for rb in rows]}


async def get_rulebook(rulebook_id: int) -> dict:
    """Fetch a rulebook by id with its full topic list."""
    uid = current_user_id()
    rb = await rulebooks_svc.get_rulebook(rulebook_id, uid)
    if rb is None:
        raise ValueError(f"rulebook {rulebook_id} not found")
    topics = await rulebooks_svc.list_topics(rulebook_id, uid)
    data = rb.to_dict()
    data["topics"] = [t.to_dict() for t in topics]
    return data


async def create_rulebook(title: str, description: str = "") -> dict:
    """Create a new rulebook.

    Args:
        title: Rulebook name (e.g. "FabledSword family").
        description: Optional short description of what this rulebook covers.
    """
    uid = current_user_id()
    rb = await rulebooks_svc.create_rulebook(
        user_id=uid, title=title, description=description,
    )
    return rb.to_dict()


async def update_rulebook(
    rulebook_id: int, title: str = "", description: str = "",
    always_on: bool | None = None,
) -> dict:
    """Update an existing rulebook. Only non-empty fields are changed.

    Args:
        rulebook_id: Rulebook to update.
        title: New title. Empty string leaves unchanged.
        description: New description. Empty string leaves unchanged.
        always_on: When True, rules in this rulebook are loaded at session
            start by list_always_on_rules regardless of project context.
            Pass None to leave unchanged.
    """
    uid = current_user_id()
    fields: dict = {}
    if title:
        fields["title"] = title
    if description:
        fields["description"] = description
    if always_on is not None:
        fields["always_on"] = always_on
    rb = await rulebooks_svc.update_rulebook(rulebook_id, uid, **fields)
    if rb is None:
        raise ValueError(f"rulebook {rulebook_id} not found")
    return rb.to_dict()


async def delete_rulebook(rulebook_id: int, confirmed: bool = False) -> dict:
    """Permanently delete a rulebook (cascades to all its topics and rules).

    Pass confirmed=True to actually delete. Without confirmation, returns a
    preview describing what will be cascaded.
    """
    uid = current_user_id()
    rb = await rulebooks_svc.get_rulebook(rulebook_id, uid)
    if rb is None:
        raise ValueError(f"rulebook {rulebook_id} not found")
    if not confirmed:
        topics = await rulebooks_svc.list_topics(rulebook_id, uid)
        rule_count = 0
        for t in topics:
            rule_count += len(await rulebooks_svc.list_rules(uid, topic_id=t.id))
        return {
            "warning": (
                f"Rulebook {rulebook_id} ('{rb.title}') contains "
                f"{len(topics)} topics and {rule_count} rules; all will be "
                f"deleted. Pass confirmed=True to proceed."
            ),
            "confirmed_required": True,
        }
    batch = await trash_svc.delete(uid, "rulebook", rulebook_id)
    return {"deleted": rulebook_id, "deleted_batch_id": batch,
            "message": f"Moved to trash. Restore with restore('{batch}')."}


# ── Topic CRUD ─────────────────────────────────────────────────────────

async def list_topics(rulebook_id: int) -> dict:
    """List topics inside a rulebook."""
    uid = current_user_id()
    rows = await rulebooks_svc.list_topics(rulebook_id, uid)
    return {"topics": [t.to_dict() for t in rows]}


async def create_topic(
    rulebook_id: int, title: str,
    description: str = "", order_index: int = 0,
) -> dict:
    """Create a topic within a rulebook.

    Args:
        rulebook_id: Rulebook to add the topic to.
        title: Topic name (e.g. "git-workflow").
        description: Optional description.
        order_index: Display order (0-based; default 0).
    """
    uid = current_user_id()
    topic = await rulebooks_svc.create_topic(
        rulebook_id=rulebook_id, user_id=uid,
        title=title, description=description, order_index=order_index,
    )
    return topic.to_dict()


async def update_topic(
    topic_id: int, title: str = "",
    description: str = "", order_index: int = -1,
) -> dict:
    """Update a topic. Sentinels: title="" / description="" leave unchanged;
    order_index=-1 leaves unchanged.
    """
    uid = current_user_id()
    fields: dict = {}
    if title:
        fields["title"] = title
    if description:
        fields["description"] = description
    if order_index >= 0:
        fields["order_index"] = order_index
    topic = await rulebooks_svc.update_topic(topic_id, uid, **fields)
    if topic is None:
        raise ValueError(f"topic {topic_id} not found")
    return topic.to_dict()


async def delete_topic(topic_id: int, confirmed: bool = False) -> dict:
    """Delete a topic and all its rules. Requires confirmed=True."""
    uid = current_user_id()
    topic = await rulebooks_svc.get_topic(topic_id, uid)
    if topic is None:
        raise ValueError(f"topic {topic_id} not found")
    if not confirmed:
        rules = await rulebooks_svc.list_rules(uid, topic_id=topic_id)
        return {
            "warning": (
                f"Topic {topic_id} ('{topic.title}') contains {len(rules)} "
                f"rules; all will be deleted. Pass confirmed=True to proceed."
            ),
            "confirmed_required": True,
        }
    batch = await trash_svc.delete(uid, "topic", topic_id)
    return {"deleted": topic_id, "deleted_batch_id": batch,
            "message": f"Moved to trash. Restore with restore('{batch}')."}


# ── Rule CRUD ──────────────────────────────────────────────────────────

async def list_rules(
    rulebook_id: int = 0, topic_id: int = 0, project_id: int = 0,
) -> dict:
    """List rules — filter by rulebook, topic, and/or project.

    Args:
        rulebook_id: 0 = no filter; positive = restrict to that rulebook.
        topic_id: 0 = no filter; positive = restrict to that topic.
        project_id: 0 = no filter; positive = restrict to rules applicable
            to that project (via its rulebook subscriptions).

    All filters are AND-combined; ownership-scoped.
    """
    uid = current_user_id()
    rows = await rulebooks_svc.list_rules(
        user_id=uid,
        rulebook_id=rulebook_id or None,
        topic_id=topic_id or None,
        project_id=project_id or None,
    )
    return {
        "rules": [
            {
                "id": r.id, "title": r.title, "statement": r.statement,
                "topic_id": r.topic_id,
            }
            for r in rows
        ],
        "total": len(rows),
    }


async def list_always_on_rules() -> dict:
    """Return all rules from rulebooks flagged always_on for the current user.

    Call this at session start. Treat the returned rules as binding for the
    session — they apply regardless of which project (if any) is in scope.
    Pair with get_project(id).applicable_rules when working on a specific
    project to also load that project's subscription-derived rules.
    """
    uid = current_user_id()
    rules = await rulebooks_svc.list_always_on_rules(uid)
    return {
        "rules": [
            {
                "id": r.id, "title": r.title, "statement": r.statement,
                "topic_id": r.topic_id,
            }
            for r in rules
        ],
        "total": len(rules),
    }


async def get_rule(rule_id: int) -> dict:
    """Fetch a rule by id — full statement + why + how_to_apply."""
    uid = current_user_id()
    rule = await rulebooks_svc.get_rule(rule_id, uid)
    if rule is None:
        raise ValueError(f"rule {rule_id} not found")
    return rule.to_dict()


async def create_rule(
    topic_id: int, title: str, statement: str,
    why: str = "", how_to_apply: str = "", order_index: int = 0,
) -> dict:
    """Create a new rule under a topic (cross-project rulebook rule).

    Args:
        topic_id: The topic to attach the rule to.
        title: A short imperative title (e.g. "dev is home").
        statement: The actionable instruction (required). 1-2 sentences.
        why: Optional rationale — the reason the rule exists.
        how_to_apply: Optional operationalization — when / where it kicks in.
        order_index: Display order within the topic (default 0).

    For a rule that applies to a single project only, use create_project_rule
    instead — no rulebook+topic ceremony required.
    """
    uid = current_user_id()
    rule = await rulebooks_svc.create_rule(
        topic_id=topic_id, user_id=uid,
        title=title, statement=statement,
        why=why, how_to_apply=how_to_apply, order_index=order_index,
    )
    return rule.to_dict()


async def create_project_rule(
    project_id: int, statement: str, title: str = "",
    why: str = "", how_to_apply: str = "", order_index: int = 0,
) -> dict:
    """Create a rule scoped to a single project (no rulebook needed).

    Use this when a rule only applies to one project — it bypasses the
    Rulebook -> Topic -> Rule ceremony. The rule is returned in get_project's
    applicable_rules (under project_rules) and in list_rules(project_id=...).

    Args:
        project_id: The project to attach the rule to.
        statement: The actionable instruction (required). 1-2 sentences.
        title: Short imperative title. If empty, derived from the first ~50
            characters of statement.
        why: Optional rationale — the reason the rule exists.
        how_to_apply: Optional operationalization — when / where it kicks in.
        order_index: Display order within the project's rule list (default 0).
    """
    uid = current_user_id()
    derived_title = title.strip() or statement.strip().split(".")[0][:50]
    rule = await rulebooks_svc.create_project_rule(
        project_id=project_id, user_id=uid,
        title=derived_title, statement=statement,
        why=why, how_to_apply=how_to_apply, order_index=order_index,
    )
    return rule.to_dict()


async def update_rule(
    rule_id: int, title: str = "", statement: str = "",
    why: str = "", how_to_apply: str = "", order_index: int = -1,
) -> dict:
    """Update a rule. Empty strings / order_index=-1 leave fields unchanged."""
    uid = current_user_id()
    fields: dict = {}
    if title:
        fields["title"] = title
    if statement:
        fields["statement"] = statement
    if why:
        fields["why"] = why
    if how_to_apply:
        fields["how_to_apply"] = how_to_apply
    if order_index >= 0:
        fields["order_index"] = order_index
    rule = await rulebooks_svc.update_rule(rule_id, uid, **fields)
    if rule is None:
        raise ValueError(f"rule {rule_id} not found")
    return rule.to_dict()


async def delete_rule(rule_id: int, confirmed: bool = False) -> dict:
    """Permanently delete a rule. Requires confirmed=True."""
    uid = current_user_id()
    rule = await rulebooks_svc.get_rule(rule_id, uid)
    if rule is None:
        raise ValueError(f"rule {rule_id} not found")
    if not confirmed:
        return {
            "warning": (
                f"Rule {rule_id} ('{rule.title}') will be permanently deleted. "
                f"Pass confirmed=True to proceed."
            ),
            "confirmed_required": True,
        }
    batch = await trash_svc.delete(uid, "rule", rule_id)
    return {"deleted": rule_id, "deleted_batch_id": batch,
            "message": f"Moved to trash. Restore with restore('{batch}')."}


# ── Subscriptions ──────────────────────────────────────────────────────

async def subscribe_project_to_rulebook(
    project_id: int, rulebook_id: int,
) -> dict:
    """Subscribe a project to a rulebook. Its rules will apply to that project."""
    uid = current_user_id()
    await rulebooks_svc.subscribe_project(
        project_id=project_id, rulebook_id=rulebook_id, user_id=uid,
    )
    return {"project_id": project_id, "rulebook_id": rulebook_id, "subscribed": True}


async def unsubscribe_project_from_rulebook(
    project_id: int, rulebook_id: int,
) -> dict:
    """Remove a project's subscription to a rulebook."""
    uid = current_user_id()
    await rulebooks_svc.unsubscribe_project(
        project_id=project_id, rulebook_id=rulebook_id, user_id=uid,
    )
    return {"project_id": project_id, "rulebook_id": rulebook_id, "subscribed": False}


def register(mcp) -> None:
    for fn in (
        list_rulebooks, get_rulebook, create_rulebook, update_rulebook, delete_rulebook,
        list_topics, create_topic, update_topic, delete_topic,
        list_rules, list_always_on_rules, get_rule,
        create_rule, create_project_rule, update_rule, delete_rule,
        subscribe_project_to_rulebook, unsubscribe_project_from_rulebook,
    ):
        mcp.tool(name=fn.__name__)(fn)