"""Load JSON items from the local info/*.txt files and upsert into MongoDB."""

from __future__ import annotations

import json
import os
import re
import sys
from pathlib import Path
from typing import Any, Dict, Iterable, List

from pymongo import MongoClient, UpdateOne
from pymongo.collection import Collection
from pymongo.results import BulkWriteResult


DEFAULT_INFO_DIR = Path(__file__).resolve().parent.parent / "info"
MONGO_URI = os.getenv("MONGO_URI", "mongodb://localhost:27017")
MONGO_DB = os.getenv("MONGO_DB", "haier")
MONGO_COLLECTION = os.getenv("MONGO_COLLECTION", "info_items")
BATCH_SIZE = 500

_TRAILING_COMMA_RE = re.compile(r",\s*([}\]])")


def _strip_noise(text: str) -> str:
    """Remove BOM, null bytes, and whitespace noise."""
    return text.replace("\ufeff", "").replace("\x00", "").strip()


def _remove_trailing_commas(text: str) -> str:
    """Best-effort removal of dangling commas before closing braces/brackets."""
    return _TRAILING_COMMA_RE.sub(r"\1", text)


def _as_ndjson_array(text: str) -> str:
    """Wrap newline-delimited JSON objects into an array string if applicable."""
    lines = [line.strip() for line in text.splitlines() if line.strip()]
    if lines and all(line.startswith("{") and line.endswith("}") for line in lines):
        return "[" + ",".join(lines) + "]"
    return text


def parse_json_text(raw: str) -> List[Dict[str, Any]]:
    """Parse possibly messy JSON text into a list of dictionaries."""
    cleaned = _strip_noise(raw)
    candidates = [cleaned]

    cleaned_trailing = _remove_trailing_commas(cleaned)
    if cleaned_trailing != cleaned:
        candidates.append(cleaned_trailing)

    ndjson_wrapped = _as_ndjson_array(cleaned)
    if ndjson_wrapped != cleaned:
        candidates.append(ndjson_wrapped)

    if cleaned and not cleaned.lstrip().startswith("["):
        candidates.append("[" + cleaned + "]")

    last_error: Exception | None = None
    for candidate in candidates:
        try:
            parsed = json.loads(candidate)
        except json.JSONDecodeError as exc:  # pragma: no cover - defensive path
            last_error = exc
            continue

        if isinstance(parsed, dict):
            return [parsed]
        if isinstance(parsed, list):
            return [item for item in parsed if isinstance(item, dict)]

        last_error = ValueError("Parsed JSON is not a dict or list")

    raise ValueError(f"Unable to parse JSON content: {last_error}")


def load_items(path: Path) -> List[Dict[str, Any]]:
    """Parse one info file into a list of dictionaries and tag the source file."""
    text = path.read_text(encoding="utf-8", errors="ignore")
    items = parse_json_text(text)
    for item in items:
        item.setdefault("_source_file", path.name)
    return items


def iter_files(info_dir: Path) -> Iterable[Path]:
    """Yield info txt files in deterministic order for repeatable ingest."""
    yield from sorted(info_dir.glob("*.txt"))


def bulk_upsert(
    collection: Collection, items: List[Dict[str, Any]]
) -> BulkWriteResult | None:
    """Upsert items by id into MongoDB using bulk_write for throughput."""
    operations: List[UpdateOne] = []
    for item in items:
        key = {"id": item.get("id")}
        operations.append(UpdateOne(key, {"$set": item}, upsert=True))
    if not operations:
        return None
    return collection.bulk_write(operations, ordered=False)


def ingest(info_dir: Path) -> None:
    """Process all info files under info_dir and upsert their records."""
    client = MongoClient(MONGO_URI)
    collection = client[MONGO_DB][MONGO_COLLECTION]
    collection.create_index("id", unique=True)

    total_files = 0
    total_items = 0
    for file_path in iter_files(info_dir):
        total_files += 1
        items = load_items(file_path)
        total_items += len(items)

        for start in range(0, len(items), BATCH_SIZE):
            batch = items[start : start + BATCH_SIZE]
            bulk_upsert(collection, batch)

        print(f"{file_path.name}: {len(items)} items upserted")

    print(f"Completed. Files: {total_files}, items processed: {total_items}.")


def main(argv: List[str]) -> int:
    """CLI entry point; accepts optional info directory argument."""
    info_dir = Path(os.getenv("INFO_DIR", DEFAULT_INFO_DIR))
    if len(argv) > 1:
        info_dir = Path(argv[1])

    if not info_dir.exists():
        print(f"Info directory does not exist: {info_dir}", file=sys.stderr)
        return 1

    ingest(info_dir)
    return 0


if __name__ == "__main__":
    raise SystemExit(main(sys.argv))