import pandas as pd
import geopandas as gpd
from shapely import wkt
from shapely.errors import WKTReadingError

def process_dataframe_synchronous(df_input, tmp_file):
    """
    Fungsi ini berjalan di thread terpisah (CPU bound).
    Melakukan validasi, cleaning, dan export ke parquet.
    """
    # 1. Copy agar tidak mengubah data asli
    export_df = df_input.copy()

    # =========================================================================
    # TAHAP 1: SAFE WKT LOADING
    # =========================================================================
    def safe_load_wkt(raw):
        if not isinstance(raw, str):
            return None
        try:
            return wkt.loads(raw)
        except (WKTReadingError, Exception):
            return None # Return None jika WKT corrupt

    # Terapkan safe load
    export_df["geom"] = export_df["geometry"].apply(safe_load_wkt)

    # =========================================================================
    # TAHAP 2: FILTER NULL & INVALID GEOMETRY
    # =========================================================================
    # Hapus baris di mana konversi WKT gagal (None)
    export_df = export_df[export_df["geom"].notnull()]
    if export_df.empty:
        raise ValueError("Tidak ada data spasial valid yang ditemukan.")

    # Jadikan GeoDataFrame
    export_df = gpd.GeoDataFrame(export_df, geometry="geom")

    # =========================================================================
    # TAHAP 3: FIX TOPOLOGY (PENTING!)
    # =========================================================================
    # Cek validitas (misal: Polygon yang garisnya menabrak diri sendiri)
    # buffer(0) adalah trik standar GIS untuk memperbaiki topologi ringan
    export_df["geom"] = export_df["geom"].apply(
        lambda g: g.buffer(0) if not g.is_valid else g
    )
    
    # Hapus lagi jika setelah di-fix malah jadi kosong (jarang terjadi, tapi aman)
    export_df = export_df[~export_df["geom"].is_empty]

    # =========================================================================
    # TAHAP 4: FINALISASI (CRS & RENAME)
    # =========================================================================
    export_df = export_df.drop(columns=["geometry"]) # Buang kolom string WKT lama
    export_df = export_df.set_crs("EPSG:4326", allow_override=True)

    # Rename kolom atribut ke UPPERCASE, biarkan 'geom' lowercase
    # .strip() untuk membuang spasi hantu (" ID " -> "ID")
    export_df = export_df.rename(
        columns=lambda c: str(c).strip().upper() if c != "geom" else c
    )

    # Simpan ke Parquet
    export_df.to_parquet(tmp_file)
    
    return len(export_df)

# --- Cara Pemanggilan di Async Function ---
# await asyncio.to_thread(process_dataframe_synchronous, result, tmp_file)