from __future__ import annotations
from dataclasses import dataclass
import re
import os
import unicodedata
import yaml
from typing import Tuple, Dict

FRONTMATTER_RE = re.compile(r"^---\s*\n(.*?)\n---\s*\n?", re.DOTALL)  # YAML-Frontmatter am Anfang

@dataclass
class ParsedNote:
    frontmatter: Dict
    body: str
    path: str

def _strip_bom(text: str) -> str:
    return text.lstrip("\ufeff")

def _normalize_text(t: str) -> str:
    # Unicode-NFKC + vereinheitlichte Zeilenenden + Trim
    t = unicodedata.normalize("NFKC", t)
    t = t.replace("\r\n", "\n").replace("\r", "\n")
    return t

def read_markdown(path: str) -> ParsedNote:
    with open(path, "r", encoding="utf-8") as f:
        raw = _strip_bom(f.read())
    raw = _normalize_text(raw)

    m = FRONTMATTER_RE.match(raw)
    front, body = {}, raw
    if m:
        yaml_block = m.group(1)
        body = raw[m.end():]
        try:
            front = yaml.safe_load(yaml_block) or {}
            if not isinstance(front, dict):
                raise ValueError("Frontmatter must be a mapping")
        except yaml.YAMLError as e:
            raise ValueError(f"Invalid YAML frontmatter in {path}: {e}") from e

    return ParsedNote(frontmatter=front, body=body, path=path)

RE_WIKILINK = re.compile(r"\[\[([^\]\|#]+)(?:#[^\]]+)?(?:\|[^\]]+)?\]\]")  # [[id]] | [[id#anchor]] | [[id|label]]

def extract_wikilinks(text: str) -> list[str]:
    return list({m.group(1).strip() for m in RE_WIKILINK.finditer(text)})

def validate_required_frontmatter(fm: dict, required=("title","id","type","status","created")):
    missing = [k for k in required if k not in fm or fm[k] in (None, "")]
    if missing:
        raise ValueError(f"Missing required frontmatter fields: {', '.join(missing)}")

    # einfache Plausibilitäten
    if not isinstance(fm.get("tags", []), (list, tuple)):
        if "tags" in fm and fm["tags"] not in (None, ""):
            raise ValueError("tags must be a list of strings")

def normalize_frontmatter(fm: dict) -> dict:
    # kleinere Normalisierungen ohne die Semantik zu verändern
    out = dict(fm)
    if "tags" in out and isinstance(out["tags"], list):
        out["tags"] = [str(t).strip() for t in out["tags"]]
    if "embedding_exclude" in out:
        out["embedding_exclude"] = bool(out["embedding_exclude"])
    return out