"""Snippet MCP tools: record reusable functions/components for later recall.

A snippet is a Note with note_type='snippet' (see services/snippets.py). Because
snippets are ordinary embedded notes, once recorded they surface through the same
semantic search + title-first auto-inject as everything else — so a reusable
thing recorded once can be recalled before it's re-written as a one-off.

The tools wrap services/snippets.py, mirroring the note/process tools (dedup gate
on create, System association passthrough).
"""
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 snippets as snippets_svc
from scribe.services import systems as systems_svc


async def list_snippets(
    q: str = "", tag: str = "", limit: int = 50, project_id: int = 0,
) -> dict:
    """List recorded snippets (reusable functions/components).

    Args:
        q: Free-text search across name + body (optional). Matches on meaning as
            well as wording, so describe what you need the code to DO.
        tag: Filter to a single tag, e.g. a language like "python" (optional).
        limit: Max results (1-100).
        project_id: Narrow to one project. 0 (default) searches every project —
            usually what you want, since a helper you need here may well have
            been written somewhere else.

    Returns {"snippets": [{id, title, tags, preview}], "total": int}. The title
    reads "name — when to reach for it"; open one in full with get_snippet(id).

    An entry marked `shared: true` with an `owner` belongs to someone else — one
    person's suggestion, not settled practice here. Weigh it on its merits and
    attribute it when you use it. Searching (passing `q`) also reaches snippets
    shared directly with the operator; browsing without a query deliberately
    does not, so those stay out of ambient results until asked for.
    """
    uid = current_user_id()
    items, total = await snippets_svc.list_snippets(
        uid, q=q or None, tag=tag, limit=max(1, min(limit, 100)),
        project_id=project_id or None,
    )
    return {
        "snippets": await access_svc.label_shared_items(uid, items),
        "total": total,
    }


async def create_snippet(
    name: str,
    code: str,
    language: str = "",
    signature: str = "",
    when_to_use: str = "",
    repo: str = "",
    path: str = "",
    symbol: str = "",
    locations: list[dict] | None = None,
    tags: list[str] | None = None,
    project_id: int = 0,
    system_ids: list[int] | None = None,
    force: bool = False,
) -> dict:
    """Record a reusable function/component so future sessions can RECALL it
    instead of writing a fresh one-off.

    Reach for this the moment you build (or notice) something reusable: a helper,
    a hook, a component, a pattern worth repeating. Recording it once makes it
    surface automatically when a similar problem comes up later. Before writing a
    new utility, search first — a snippet may already exist.

    Args:
        name: Short name of the function/component, e.g. "useDebouncedRef".
        code: The code itself (required).
        language: Language/format, e.g. "python", "vue", "sql". Becomes a tag and
            the code-fence language.
        signature: One-line signature/interface, e.g. "debounce(fn, ms) -> fn".
        when_to_use: One line on when to reach for it — this becomes part of the
            title, so it's what a recall menu shows. Keep it sharp.
        repo/path/symbol: Canonical location of the reference implementation.
        locations: Several locations at once, as [{"repo","path","symbol"}, ...],
            when you already know the thing lives in more than one place. Takes
            precedence over the single repo/path/symbol shorthand.
        tags: Extra plain-string tags (language + "snippet" are added for you).
        project_id: Associate with a project (0 = no project). Snippets surface
            proactively within their project; search finds them across projects.
        system_ids: Ids of the project's Systems to associate this snippet with.
        force: Bypass the near-duplicate gate (see below).

    Returns the created snippet (including a parsed `snippet` field), OR — when a
    near-duplicate snippet already exists and force is false — {"duplicate": true,
    "existing_id": ..., "message": ...} and nothing is created. When that happens
    and it really is the same reusable thing found in another place, prefer
    merge_snippets(existing_id, [new...]) — or record then merge — to unify them
    into ONE canonical record (which then carries every call site as a location),
    rather than forcing a second copy with force=true.
    """
    if not (name or "").strip() or not (code or "").strip():
        raise ValueError("create_snippet requires a non-empty name and code")
    uid = current_user_id()

    title = snippets_svc.compose_title(name, when_to_use)
    body = snippets_svc.compose_body(
        code=code, language=language, signature=signature,
        when_to_use=when_to_use, repo=repo, path=path, symbol=symbol,
        locations=locations,
    )
    if not force:
        dup = await dedup_svc.find_duplicate_note(
            uid, title, body, project_id=project_id or None,
            is_task=False, note_type=snippets_svc.SNIPPET_NOTE_TYPE,
        )
        if dup is not None:
            return dedup_svc.duplicate_response(dup, "snippet")

    note = await snippets_svc.create_snippet(
        uid, name=name, code=code, language=language, signature=signature,
        when_to_use=when_to_use, repo=repo, path=path, symbol=symbol,
        locations=locations, tags=tags, project_id=project_id or None,
    )
    if system_ids:
        await systems_svc.set_record_systems(uid, note.id, system_ids)
    data = snippets_svc.snippet_to_dict(note)
    if system_ids:
        data["systems"] = [
            s.to_dict() for s in await systems_svc.list_record_systems(uid, note.id)
        ]
    return data


async def get_snippet(snippet_id: int) -> dict:
    """Fetch a snippet by id — the full record: code, signature, location, and a
    parsed `snippet` field of its structured parts.

    If the record belongs to someone else it carries `shared: true` with the
    `owner` and your `permission`. Read that as ONE PERSON'S SUGGESTION, not as
    established practice here: judge it on its merits, say whose it is when you
    reference it, and don't adopt it as the house pattern without checking.
    """
    uid = current_user_id()
    note = await snippets_svc.get_snippet(uid, snippet_id)
    if note is None:
        raise ValueError(f"snippet {snippet_id} not found")
    data = snippets_svc.snippet_to_dict(note)
    data.update(await access_svc.describe_provenance(uid, note))
    return data


async def update_snippet(
    snippet_id: int,
    name: str | None = None,
    code: str | None = None,
    language: str | None = None,
    signature: str | None = None,
    when_to_use: str | None = None,
    repo: str | None = None,
    path: str | None = None,
    symbol: str | None = None,
    locations: list[dict] | None = None,
    tags: list[str] | None = None,
    project_id: int = 0,
    system_ids: list[int] | None = None,
) -> dict:
    """Update a snippet. Only the fields you pass change.

    An omitted field is left alone; an EMPTY STRING clears it — so a stale
    signature, a wrong "when to use", or an obsolete location can be removed, not
    just overwritten. A snippet that surfaces in recall with wrong details is
    worse than none, so correcting downward has to be possible.

    Args:
        locations: Replace the whole location set, as [{"repo","path","symbol"},
            ...]. Pass [] to clear every location. The single repo/path/symbol
            args instead overlay onto the FIRST location, leaving the rest.
        tags: Replaces the extra-tag set (language + "snippet" are re-derived).
        project_id: 0 leaves it unchanged, -1 detaches it from its project, a
            positive id moves it.
    """
    uid = current_user_id()
    if project_id == 0:
        project = snippets_svc.UNSET
    elif project_id < 0:
        project = None
    else:
        project = project_id

    note = await snippets_svc.update_snippet(
        uid, snippet_id,
        name=name, code=code, language=language,
        signature=signature, when_to_use=when_to_use,
        repo=repo, path=path, symbol=symbol,
        locations=locations, tags=tags, project_id=project,
    )
    if note is None:
        raise ValueError(f"snippet {snippet_id} not found")
    if system_ids is not None:
        await systems_svc.set_record_systems(uid, snippet_id, system_ids)
    data = snippets_svc.snippet_to_dict(note)
    if system_ids is not None:
        data["systems"] = [
            s.to_dict() for s in await systems_svc.list_record_systems(uid, snippet_id)
        ]
    return data


async def delete_snippet(snippet_id: int) -> dict:
    """Retire a snippet you recorded — it moves to the trash and is recoverable.

    Reach for this when a snippet is wrong, obsolete, or was never worth keeping.
    A recorded snippet is offered as prior art on every matching turn, so a bad
    one costs more than a missing one. If instead it's a duplicate of something
    that should survive, prefer merge_snippets — that keeps the call sites.
    """
    uid = current_user_id()
    if not await snippets_svc.delete_snippet(uid, snippet_id):
        raise ValueError(f"snippet {snippet_id} not found")
    return {"deleted": True, "id": snippet_id}


async def merge_snippets(target_id: int, source_ids: list[int]) -> dict:
    """Unify duplicate/variant snippets INTO one canonical record — the cure for
    the same reusable thing recorded as several one-offs.

    Keeps the target as the canonical: its name, when-to-use, signature, language
    and code win. The sources' locations and extra tags are folded in — so the
    survivor ends up carrying EVERY call site as a location (which is itself the
    "this is duplicated N times" signal) — and the source records are moved to the
    trash (recoverable). The survivor is re-embedded so recall stops surfacing the
    now-merged duplicates.

    Args:
        target_id: The snippet to keep (the canonical record).
        source_ids: Snippet ids to fold into the target and retire. Ids that
            aren't your snippets are skipped; target_id in the list is ignored.

    Returns the merged canonical snippet (with a parsed `snippet` field) plus
    `merged_ids` — the source ids actually merged and trashed.
    """
    uid = current_user_id()
    ids = [s for s in (source_ids or []) if s != target_id]
    if not ids:
        raise ValueError("merge_snippets requires at least one other source_id")
    result = await snippets_svc.merge_snippets(uid, target_id, ids)
    if result is None:
        raise ValueError(f"snippet {target_id} not found")
    note, merged_ids = result
    data = snippets_svc.snippet_to_dict(note)
    data["merged_ids"] = merged_ids
    return data


def register(mcp) -> None:
    for fn in (
        list_snippets, create_snippet, get_snippet, update_snippet,
        delete_snippet, merge_snippets,
    ):
        mcp.tool(name=fn.__name__)(fn)