"""
Busca full-text via SQLite FTS5 no histórico de sessões.
"""

import sqlite3
from pathlib import Path

from config import DB_PATH, MAX_SEARCH_RESULTS
from models import SearchResult


def _get_connection() -> sqlite3.Connection:
    """Retorna conexão SQLite com FTS5."""
    DB_PATH.parent.mkdir(parents=True, exist_ok=True)
    conn = sqlite3.connect(str(DB_PATH))
    conn.execute("PRAGMA journal_mode=WAL")
    return conn


def init_search_db():
    """Cria tabela FTS5 se não existir."""
    conn = _get_connection()
    conn.execute("""
        CREATE VIRTUAL TABLE IF NOT EXISTS session_search USING fts5(
            session_number,
            date,
            section,
            content,
            tokenize='unicode61'
        )
    """)
    conn.commit()
    conn.close()


def index_session(session_number: int, date: str, sections: dict[str, str]):
    """
    Indexa conteúdo de uma sessão.
    sections: {"topics": "texto", "decisions": "texto", ...}
    """
    conn = _get_connection()
    # Remove entradas antigas da mesma sessão
    conn.execute(
        "DELETE FROM session_search WHERE session_number = ?",
        (str(session_number),),
    )
    for section_name, content in sections.items():
        if content.strip():
            conn.execute(
                "INSERT INTO session_search (session_number, date, section, content) VALUES (?, ?, ?, ?)",
                (str(session_number), date, section_name, content),
            )
    conn.commit()
    conn.close()


def search(query: str, limit: int = MAX_SEARCH_RESULTS) -> list[SearchResult]:
    """Busca full-text no histórico."""
    conn = _get_connection()
    try:
        rows = conn.execute(
            """
            SELECT session_number, date, section, snippet(session_search, 3, '>>>', '<<<', '...', 40)
            FROM session_search
            WHERE session_search MATCH ?
            ORDER BY rank
            LIMIT ?
            """,
            (query, limit),
        ).fetchall()
    except sqlite3.OperationalError:
        # Tabela não existe ou query inválida
        return []
    finally:
        conn.close()

    results = []
    for row in rows:
        results.append(SearchResult(
            session_number=int(row[0]),
            date=row[1],
            section=row[2],
            snippet=row[3],
        ))
    return results


def reindex_all(sessions_dir: Path):
    """Reconstrói índice a partir dos arquivos de sessão."""
    conn = _get_connection()
    conn.execute("DELETE FROM session_search")
    conn.commit()
    conn.close()

    for session_file in sorted(sessions_dir.glob("session-*.md")):
        try:
            num = int(session_file.stem.split("-")[1])
        except (IndexError, ValueError):
            continue

        text = session_file.read_text(encoding="utf-8")
        date = ""
        sections = {}
        current_section = "general"

        for line in text.splitlines():
            if line.startswith("# Sessão") and "—" in line:
                date = line.split("—")[-1].strip()
            elif line.startswith("## "):
                current_section = line[3:].strip().lower()
            else:
                sections.setdefault(current_section, "")
                sections[current_section] += line + "\n"

        index_session(num, date, sections)