package impact

import (
	"github.com/damirmukimov/city_resource_graph/models/customer"
	"github.com/damirmukimov/city_resource_graph/models/params"
)

// ImpactMetrics represents environmental impact metrics for a given year.
type ImpactMetrics struct {
	CO2Avoided    float64 `json:"co2_avoided"`    // CO₂ avoided (t CO₂/year)
	WaterReused   float64 `json:"water_reused"`   // Water reused (m³/year)
	WasteDiverted float64 `json:"waste_diverted"` // Waste diverted from landfill (t/year)
}

// CalculateImpact computes environmental impact metrics for a given year.
func CalculateImpact(year int, custMetrics customer.CustomerMetrics, p *params.Params) ImpactMetrics {
	ip := p.Impact

	// CO₂ avoided from heat recovery
	// Formula: CO₂ = Heat_MWh × Grid_Factor × HX_Eff × Utilization
	heatMWh := ip.HeatMWh.GetYear(year)
	co2Avoided := heatMWh * ip.GridFactor * ip.HXEff * ip.Utilization

	// Water reused
	// Formula: Water_Reused = Total_Orgs × Water_Per_Org × Reuse_Rate
	waterReuseRate := ip.WaterReuseRate.GetYear(year)
	waterReused := float64(custMetrics.TotalOrgs) * ip.WaterPerOrg * waterReuseRate

	// Waste diverted
	// Formula: Waste_Diverted = Total_Orgs × Waste_Per_Org × Diversion_Rate
	wasteDiversionRate := ip.WasteDiversionRate.GetYear(year)
	wasteDiverted := float64(custMetrics.TotalOrgs) * ip.WastePerOrg * wasteDiversionRate

	return ImpactMetrics{
		CO2Avoided:    co2Avoided,
		WaterReused:   waterReused,
		WasteDiverted: wasteDiverted,
	}
}