"""FlowDeck — unified search (v5.0.0).

Powers the Ctrl+K command palette. Searches editor pages and databases
(collections) with SQLite FTS5 when available, falling back to ``LIKE`` scans
otherwise. Results are scoped to the workspaces the current user can access.
"""
from __future__ import annotations

import logging
import re

from app.db import get_conn
from app.migrations import fts5_available

logger = logging.getLogger(__name__)


# ── FTS5 helpers ────────────────────────────────────────────────────────────

def _fts_terms(query: str) -> list[str]:
    """Split a user query into safe FTS5 prefix terms."""
    tokens = re.findall(r"[\wÀ-ÿ]+", query, flags=re.UNICODE)
    return [t.replace('"', '""') for t in tokens if t]


def _fts_match(query: str) -> str | None:
    """Build a MATCH expression, or None when the query is not FTS-safe."""
    terms = _fts_terms(query)
    if not terms:
        return None
    return " AND ".join(f'"{t}"*' for t in terms)


def _has_fts_table(conn) -> bool:
    try:
        row = conn.execute(
            "SELECT 1 FROM sqlite_master WHERE type='table' AND name='pages_fts'"
        ).fetchone()
        return row is not None
    except Exception:
        return False


def _extract_plain_text(content: str, content_format: str) -> str:
    """Return a readable one-line excerpt for a page raw ``content`` value."""
    if not content:
        return ""
    fmt = content_format or "blocks"
    if fmt == "blocks":
        try:
            import json as _json
            blocks = _json.loads(content)
            parts = []
            for b in blocks if isinstance(blocks, list) else []:
                if isinstance(b, dict):
                    text = b.get("content") or b.get("text") or ""
                    if isinstance(text, str) and text.strip():
                        parts.append(text.strip())
                    for child in (b.get("children") or []):
                        if isinstance(child, dict) and (child.get("content") or child.get("text")):
                            parts.append(str(child.get("content") or child.get("text")).strip())
            return " ".join(parts)
        except Exception:
            return content
    if fmt == "file":
        return ""
    return content


def _workspace_name(conn, workspace_id) -> str:
    if not workspace_id:
        return ""
    try:
        row = conn.execute("SELECT name FROM workspaces WHERE id=?", (workspace_id,)).fetchone()
        return row["name"] if row else ""
    except Exception:
        return ""


def _scope_where(user_id: int | None) -> tuple[str, list]:
    """SQL filter restricting results to the user's accessible workspaces."""
    if user_id is None:
        return "1=1", []
    return (
        "(workspace_id IS NULL OR workspace_id IN ("
        " SELECT id FROM workspaces WHERE owner_id = ? "
        " UNION SELECT workspace_id FROM workspace_members WHERE user_id = ?))",
        [user_id, user_id],
    )


# ── Search entry point ──────────────────────────────────────────────────────

def search(query: str, user_id: int | None = None, limit: int = 20) -> dict:
    """Return unified search results: ``{pages: [...], collections: [...]}``."""
    q = (query or "").strip()
    if not q:
        return {"pages": [], "collections": []}

    with get_conn() as conn:
        pages = _search_pages(conn, q, user_id, limit)
        collections = _search_collections(conn, q, user_id, limit)
    return {"pages": pages, "collections": collections}


def _search_pages(conn, query: str, user_id: int | None, limit: int) -> list:
    like = f"%{query}%"
    scope, params = _scope_where(user_id)

    # 1) FTS5 fast path.
    if fts5_available() and _has_fts_table(conn):
        match = _fts_match(query)
        if match:
            try:
                rows = conn.execute(
                    f"""
                    SELECT p.id, p.title, p.content, p.content_format,
                           p.workspace_id, p.content_format
                    FROM pages_fts f
                    JOIN pages p ON p.id = f.rowid
                    WHERE pages_fts MATCH ? AND p.deleted_at IS NULL AND {scope}
                    ORDER BY rank LIMIT ?
                    """,
                    [match, *params, limit],
                ).fetchall()
                return _page_rows_to_results(conn, rows)
            except Exception as exc:  # FTS syntax/edge case → fall through to LIKE
                logger.debug("FTS search failed (%s); fallback to LIKE", exc)

    # 2) LIKE fallback.
    rows = conn.execute(
        f"""
        SELECT p.id, p.title, p.content, p.content_format, p.workspace_id
        FROM pages p
        WHERE p.deleted_at IS NULL AND {scope}
          AND (p.title LIKE ? OR p.content LIKE ?)
        ORDER BY p.updated_at DESC LIMIT ?
        """,
        [*params, like, like, limit],
    ).fetchall()
    return _page_rows_to_results(conn, rows)


def _search_collections(conn, query: str, user_id: int | None, limit: int) -> list:
    like = f"%{query}%"
    scope, params = _scope_where(user_id)
    rows = conn.execute(
        f"""
        SELECT c.id, c.name, c.description, c.icon, c.workspace_id
        FROM collections c
        WHERE {scope}
          AND (c.name LIKE ? OR c.description LIKE ?)
        ORDER BY c.updated_at DESC LIMIT ?
        """,
        [*params, like, like, limit],
    ).fetchall()
    return [
        {
            "id": r["id"],
            "type": "collection",
            "title": r["name"] or "Untitled",
            "subtitle": "Database" + (f" · {_workspace_name(conn, r['workspace_id'])}" if r["workspace_id"] else ""),
            "icon": (r["icon"] or "📋"),
            "url": f"/db/{r['id']}",
        }
        for r in rows
    ]


def _page_rows_to_results(conn, rows) -> list:
    results = []
    for r in rows:
        title = (r["title"] or "Untitled").strip() or "Untitled"
        ws = _workspace_name(conn, r["workspace_id"])
        subtitle = ws or "Page"
        excerpt = _extract_plain_text(r["content"], r["content_format"])
        results.append({
            "id": r["id"],
            "type": "page",
            "title": title,
            "subtitle": subtitle,
            "icon": "file",
            "excerpt": excerpt[:160],
            "url": f"/pages/{r['id']}",
        })
    return results