import numpy as np
from recommendations.Costs import Costs


class SolarPvRecommendations:
    # Approximate area of the solar panels
    SOLAR_PANEL_AREA = 1.6
    # Wattage per panel - this is based on the average wattage of a solar panel being between 250w and 420w
    SOLAR_PANEL_WATTAGE = 250

    def __init__(self, property_instance):
        """
        :param property_instance: Instance of the Property class, for the home associated to property_id
        """

        self.property = property_instance
        self.costs = Costs(self.property)

        self.recommendation = []

    def recommend(self):
        """
        We check if a property is potentially suitable for solar PV based on the following criteria:
        - The property is a house or bungalow
        - The property has a flat or pitched roof
        - The property does not have existing solar pv
        :return:
        """

        is_valid_property_type = self.property.data["property-type"] in ["House", "Bungalow"]
        is_valid_roof_type = (
            self.property.roof["is_flat"] or self.property.roof["is_pitched"] or self.property.roof["is_roof_room"]
        )
        # If there is no existing solar PV, the photo-supply field will be None or a missing value
        has_no_existing_solar_pv = self.property.data["photo-supply"] in [
            None, 0, self.property.DATA_ANOMALY_MATCHES
        ]

        if not is_valid_property_type or not is_valid_roof_type or not has_no_existing_solar_pv:
            return

        # We now have a property which is potentially suitable for solar PV
        number_solar_panels = np.floor(self.property.solar_pv_roof_area / self.SOLAR_PANEL_AREA)
        solar_panel_wattage = number_solar_panels * self.SOLAR_PANEL_WATTAGE

        roof_coverage_percent = round(self.property.solar_pv_percentage * 100)

        # Given the wattage, we estimate the cost of the solar PV system. This is based on the MCS database
        # of solar PV installations
        cost_result = self.costs.solar_pv(wattage=solar_panel_wattage)

        kw = np.floor(solar_panel_wattage / 100) / 10

        self.recommendation = [
            {
                "parts": [],
                "type": "solar_pv",
                "description": f"Install a {kw} kilowatt-peak (kWp) solar photovoltaic (PV) panel system on "
                               f"{roof_coverage_percent}% the roof",
                "starting_u_value": None,
                "new_u_value": None,
                "sap_points": None,
                **cost_result,
                # This is required for simulating the SAP impact. solar_pv_percentage is between 0 & 1 so we scale
                # back up here
                "photo_supply": 100 * self.property.solar_pv_percentage
            }
        ]