"""vault_knowledge_parse — Parsea un Markdown del vault y persiste en knowledge_docs."""

from __future__ import annotations

import json
import re
import sqlite3
import time
from pathlib import Path


def _parse_frontmatter(text: str) -> tuple[dict, str]:
    """Separa YAML frontmatter del cuerpo. Retorna (frontmatter_dict, body)."""
    if not text.startswith("---\n") and not text.startswith("---\r\n"):
        return {}, text

    # Buscar cierre del frontmatter
    end = text.find("\n---", 4)
    if end == -1:
        return {}, text

    yaml_block = text[4:end].strip()
    body = text[end + 4:].lstrip("\n\r")

    try:
        import yaml

        fm = yaml.safe_load(yaml_block) or {}
        if not isinstance(fm, dict):
            fm = {}
    except Exception:
        fm = {}

    return fm, body


def _extract_headings(body: str) -> list[dict]:
    """Extrae headings Markdown (# ... ### ...) del cuerpo."""
    headings = []
    for line in body.splitlines():
        m = re.match(r"^(#{1,6})\s+(.*)", line)
        if m:
            headings.append({"level": len(m.group(1)), "text": m.group(2).strip()})
    return headings


def _extract_title(frontmatter: dict, body: str, basename: str) -> str:
    """Extrae título: frontmatter['title'] > primer H1 > basename."""
    if frontmatter.get("title"):
        return str(frontmatter["title"])
    for line in body.splitlines():
        m = re.match(r"^#\s+(.*)", line)
        if m:
            return m.group(1).strip()
    return basename


def vault_knowledge_parse(
    vault_path: str,
    rel_path: str,
    db_path: str | None = None,
) -> dict:
    """Parsea un archivo Markdown del vault: extrae frontmatter, título, headings y cuerpo.

    Args:
        vault_path: Ruta absoluta a la raiz del vault.
        rel_path: Ruta relativa al archivo Markdown dentro del vault.
        db_path: Override opcional de la ruta a vault_index.db.

    Returns:
        Dict con: rel_path, title, frontmatter, headings, content_text, persisted.

    Raises:
        RuntimeError: Si el archivo no existe o no se puede leer.
    """
    vault = Path(vault_path)
    md_file = vault / rel_path
    if not md_file.exists():
        raise RuntimeError(f"vault_knowledge_parse: archivo no encontrado: {md_file}")

    db = Path(db_path) if db_path else vault / "vault_index.db"

    try:
        text = md_file.read_text(encoding="utf-8")
    except UnicodeDecodeError:
        text = md_file.read_text(encoding="latin-1", errors="replace")

    frontmatter, body = _parse_frontmatter(text)
    headings = _extract_headings(body)
    basename = md_file.stem
    title = _extract_title(frontmatter, body, basename)
    content_text = body

    # Persistir en vault_index.db
    persisted = False
    if db.exists():
        conn = sqlite3.connect(str(db))
        try:
            now = int(time.time())
            conn.execute(
                """
                INSERT INTO knowledge_docs(rel_path, title, frontmatter_json, headings_json, parsed_at)
                VALUES (?, ?, ?, ?, ?)
                ON CONFLICT(rel_path) DO UPDATE SET
                    title=excluded.title,
                    frontmatter_json=excluded.frontmatter_json,
                    headings_json=excluded.headings_json,
                    parsed_at=excluded.parsed_at
                """,
                (
                    rel_path,
                    title,
                    json.dumps(frontmatter, ensure_ascii=False),
                    json.dumps(headings, ensure_ascii=False),
                    now,
                ),
            )
            # Actualizar files_fts (rowid debe coincidir con files)
            conn.execute("DELETE FROM files_fts WHERE rel_path = ?", (rel_path,))
            conn.execute(
                """
                INSERT INTO files_fts(rowid, rel_path, content_text)
                VALUES ((SELECT rowid FROM files WHERE rel_path = ?), ?, ?)
                """,
                (rel_path, rel_path, content_text),
            )
            conn.commit()
            persisted = True
        except Exception:
            conn.rollback()
            raise
        finally:
            conn.close()

    return {
        "rel_path": rel_path,
        "title": title,
        "frontmatter": frontmatter,
        "headings": headings,
        "content_text": content_text,
        "persisted": persisted,
    }