import os
import json
import re
from typing import List, Dict, Any, Optional

from fastapi import UploadFile


def list_files_by_ext(root_dir: str, exts: List[str]) -> List[str]:
    if not root_dir or not os.path.exists(root_dir):
        return []
    found = []
    for base, _, files in os.walk(root_dir):
        for file_name in files:
            ext = os.path.splitext(file_name)[1].lower()
            if ext in exts:
                found.append(os.path.join(base, file_name))
    return sorted(found)


def parse_json_from_text(text: str) -> Any:
    if not text:
        return None
    try:
        return json.loads(text)
    except Exception:
        pass
    match = re.search(r"\{[\s\S]*\}", text)
    if match:
        try:
            return json.loads(match.group(0))
        except Exception:
            return None
    match = re.search(r"\[[\s\S]*\]", text)
    if match:
        try:
            return json.loads(match.group(0))
        except Exception:
            return None
    return None


def extract_evidence_text_from_ocr(ocr_text: str) -> Dict[str, Any]:
    parsed = parse_json_from_text(ocr_text)
    lines = []
    if isinstance(parsed, list):
        for item in parsed:
            if not isinstance(item, dict):
                continue
            label = item.get("block_label")
            content = item.get("block_content")
            if not content or not isinstance(content, str):
                continue
            if label in {"text", "paragraph_title", "table", "header"}:
                cleaned = content.strip()
                if cleaned:
                    lines.append(cleaned)
    text = "\n".join(lines)
    return {"text": text, "lines": lines}


def normalize_filename(name: str) -> str:
    base = os.path.basename(name)
    return base.replace("..", "_")


async def save_uploads(files: Optional[List[UploadFile]], target_dir: str) -> List[str]:
    if not files:
        return []
    os.makedirs(target_dir, exist_ok=True)
    saved = []
    for file in files:
        if not file or not file.filename:
            continue
        file_path = os.path.join(target_dir, normalize_filename(file.filename))
        content = await file.read()
        with open(file_path, "wb") as f:
            f.write(content)
        saved.append(file_path)
    return saved