from qgis.core import (
    QgsVectorLayer,
    QgsVectorLayerExporter,
    QgsVectorFileWriter
)
import processing
from typing import Dict
from database import build_uri

def load_layer(table_name: str):
    uri = build_uri(table_name)
    print('uri',uri)
    layer = QgsVectorLayer(uri, table_name, "postgres")
    print("Layer valid:", layer.isValid())
    # print("Error:", layer.error().summary())
    # print("FIELDS:", [f.name() for f in layer.fields()])
    return layer

def cleansing_layer(layer: QgsVectorLayer) -> Dict:

    summary = {
        "total_features_before": layer.featureCount(),
        "invalid_geometries_before": 0,
        "invalid_geometries_fixed": 0,
        "duplicates_removed": 0,
    }

    # -------------------------
    # 1. IDENTIFY INVALID GEOMETRY
    # -------------------------
    invalid_ids = []
    for f in layer.getFeatures():
        if not f.geometry().isGeosValid():
            invalid_ids.append(f.id())

    summary["invalid_geometries_before"] = len(invalid_ids)

    # -------------------------
    # 2. FIX INVALID GEOMETRY
    # -------------------------
    fixed = processing.run(
        "native:fixgeometries",
        {
            "INPUT": layer,
            "OUTPUT": "memory:"
        }
    )["OUTPUT"]

    summary["invalid_geometries_fixed"] = len(invalid_ids)

    # -------------------------
    # 3. AUTO DETECT DUPLICATE KEY FIELD
    # -------------------------
    all_fields = [f.name() for f in fixed.fields()]

    print("Detecting key fields:", all_fields)

    key_fields = None

    # (1) Prefer kolom "id"
    if "id" in all_fields:
        key_fields = ["id"]

    # (2) Jika tidak ada, pilih kolom integer pertama
    if key_fields is None:
        int_cols = [f.name() for f in fixed.fields()
                    if f.typeName().lower() in ["int", "integer", "bigint"]]
        if int_cols:
            key_fields = [int_cols[0]]

    # (3) Jika tetap tidak ada, pakai semua kolom
    if key_fields is None:
        key_fields = all_fields

    print("Using key field:", key_fields)

    # -------------------------
    # 4. REMOVE DUPLICATES BY ATTRIBUTE
    # -------------------------
    dedup = processing.run(
        "native:removeduplicatesbyattribute",
        {
            "INPUT": fixed,
            "FIELDS": key_fields,
            "METHOD": 0,
            "OUTPUT": "memory:"
        }
    )["OUTPUT"]

    summary["duplicates_removed"] = (
        fixed.featureCount() - dedup.featureCount()
    )

    # -------------------------
    # 5. TRIM STRING FIELDS
    # -------------------------
    trimmed = processing.run(
        "qgis:refactorfields",
        {
            "INPUT": dedup,
            "FIELDS_MAPPING": [
                {
                    "expression": f"trim(\"{field.name()}\")"
                    if field.typeName().lower() in ["text", "varchar"]
                    else f"\"{field.name()}\"",
                    "name": field.name(),
                    "type": field.type(),
                    "length": field.length(),
                    "precision": field.precision()
                }
                for field in dedup.fields()
            ],
            "OUTPUT": "memory:"
        }
    )["OUTPUT"]

    # -------------------------
    # RESULT
    # -------------------------
    return {
        "summary": summary,
        "clean_layer": trimmed
    }