"""Search services shared by REST routes and the AI tool layer."""

from __future__ import annotations

from collections.abc import Callable
from typing import Any


def search_vaults(
    q: str,
    vault: str = "all",
    tag: str | None = None,
    limit: int = 50,
    offset: int = 0,
    is_allowed: Callable[[str], bool] | None = None,
    username: str | None = None,
) -> dict[str, Any]:
    """Full-text search with pagination, returned as the API response payload.

    ``is_allowed`` (#194) filters the raw hits **before** pagination, so a
    restricted vault set neither distorts ``total`` nor the returned page.
    The tool layer filters on its own and leaves it as ``None``.

    ``username`` (#196) : les documents **reçus** par cet utilisateur via un
    partage dirigé sont ajoutés aux résultats (lecture seule, sans indexer
    les fichiers d'autrui — le contenu est lu à la volée et mis en cache
    TF-IDF côté index, pas sur disque).
    """
    from backend.search import search

    all_results = search(q, vault_filter=vault, tag_filter=tag)
    if is_allowed is not None:
        all_results = [r for r in all_results if is_allowed(r.get("vault", ""))]

    if username is not None:
        all_results = all_results + _shared_results(username, q, vault)

    total = len(all_results)
    page = all_results[offset: offset + limit]
    return {
        "query": q,
        "vault_filter": vault,
        "tag_filter": tag,
        "count": len(page),
        "total": total,
        "offset": offset,
        "limit": limit,
        "results": page,
    }


def _shared_results(username: str, q: str, vault: str) -> list[dict[str, Any]]:
    """Search results for documents shared TO *username* (#196).

    Reads the shared file content on the fly (read-only, source vault on
    disk) and returns hits shaped exactly like ordinary search results so
    the frontend can open them via the normal share page.
    """
    from pathlib import Path

    from backend.indexer import get_vault_data
    from backend.services.paths import resolve_safe_path
    from backend.share import list_shares

    out: list[dict[str, Any]] = []
    if not q:
        return out
    q_lower = q.lower()

    for s in list_shares(user=username):
        if s.get("created_by") == username:
            continue  # own share — already indexed in its own vault
        if vault not in ("all", f"home-{username}"):
            continue
        data = get_vault_data(s["vault"])
        if not data:
            continue
        try:
            fp = resolve_safe_path(Path(data["path"]), s["path"])
            if not fp.exists() or fp.suffix.lower() != ".md":
                continue
            raw = fp.read_text(encoding="utf-8", errors="replace")
        except Exception:
            continue
        title = fp.stem
        occurrences = raw.lower().count(q_lower)
        if q_lower in title.lower():
            occurrences += 1
        if occurrences == 0:
            continue
        out.append({
            "vault": f"home-{username}",
            "path": f"Partage/{fp.name}",
            "title": title,
            "tags": [],
            "score": min(occurrences, 10),
            "snippet": _snippet(raw, q_lower),
            "modified": None,
            "share_token": s["token"],
        })
    return out


def _snippet(text: str, q_lower: str, width: int = 160) -> str:
    """Small excerpt around the first match (#196, shared-file search)."""
    idx = text.lower().find(q_lower)
    if idx < 0:
        return text[:width]
    start = max(0, idx - width // 2)
    return "…" + text[start:start + width].replace("\n", " ") + "…"


def list_tags(vault: str | None = None) -> dict[str, int]:
    """Return tag → count, optionally restricted to a single vault."""
    from backend.search import get_all_tags

    return get_all_tags(vault_filter=vault)


def advanced_search_vaults(
    query: str = "",
    vault: str = "all",
    tag: str | None = None,
    limit: int = 50,
    offset: int = 0,
    sort: str = "relevance",
    case_sensitive: bool = False,
    whole_word: bool = False,
    regex: bool = False,
    include_paths: str | None = None,
    exclude_paths: str | None = None,
    created: str | None = None,
    modified: str | None = None,
    size: str | None = None,
    semantic: bool = False,
) -> dict[str, Any]:
    """Advanced full-text search (TF-IDF, facets, operators).

    When ``semantic`` is True, the TF-IDF ranking is fused with the embedding
    (semantic) ranking via RRF. No permission filtering is applied: callers
    that need it (the tool layer) filter the ``results`` list themselves.
    """
    from backend.search import advanced_search

    return advanced_search(
        query,
        vault_filter=vault,
        tag_filter=tag,
        limit=limit,
        offset=offset,
        sort_by=sort,
        case_sensitive=case_sensitive,
        whole_word=whole_word,
        regex=regex,
        include_paths=include_paths,
        exclude_paths=exclude_paths,
        created=created,
        modified=modified,
        size=size,
        semantic=semantic,
    )


def search_paths(q: str, vault: str = "all") -> dict[str, Any]:
    """Search files and directories by path substring using the path index.

    No permission filtering is applied: callers that need it (the tool layer)
    filter the ``results`` list themselves.
    """
    from backend.indexer import path_index

    if not q:
        return {"query": q, "vault_filter": vault, "results": []}

    query_lower = q.lower()
    results: list[dict[str, Any]] = []

    vaults_to_search = [vault] if vault != "all" else list(path_index.keys())

    for vault_name in vaults_to_search:
        for entry in path_index.get(vault_name, []):
            if query_lower in entry["name"].lower() or query_lower in entry["path"].lower():
                results.append({
                    "vault": vault_name,
                    "path": entry["path"],
                    "name": entry["name"],
                    "type": entry["type"],
                    "matched_path": entry["path"],
                })

    return {"query": q, "vault_filter": vault, "results": results}


def list_paths(vault: str, limit: int = 5000) -> dict[str, Any]:
    """Return a flat, capped list of every indexed path in a vault.

    Backs the AI assistant ``@`` mention menu: fetching the whole path index
    once lets the client filter files/directories instantly instead of issuing
    a request per keystroke.

    Args:
        vault: Vault name.
        limit: Maximum number of entries returned.

    Returns:
        ``{"vault", "count", "results": [{vault, path, name, type}]}``.
    """
    from backend.indexer import path_index

    entries = path_index.get(vault, [])
    results = [
        {
            "vault": vault,
            "path": entry["path"],
            "name": entry["name"],
            "type": entry["type"],
        }
        for entry in entries[: max(0, limit)]
    ]
    return {"vault": vault, "count": len(results), "results": results}