HeatGuard/internal/heat/budget_test.go

package heat

import (
	"testing"
)

func TestComputeRoomBudget(t *testing.T) {
	input := BudgetInput{
		Devices: []Device{
			{WattsIdle: 65, WattsTypical: 200, WattsPeak: 450, DutyCycle: 1.0},
		},
		DeviceMode: ModeTypical,
		Occupants: []Occupant{
			{Count: 1, Activity: Sedentary},
		},
		Solar: SolarParams{
			AreaSqm:           15,
			WindowFraction:    0.15,
			SHGC:              0.6,
			ShadingFactor:     1.0,
			OrientationFactor: 0.8,
			CloudFactor:       0.9,
			SunshineFraction:  0.8,
			PeakIrradiance:    800,
		},
		Ventilation: VentilationParams{
			ACH:          1.0,
			VolumeCubicM: 45,
			OutdoorTempC: 35,
			IndoorTempC:  25,
			RhoCp:        1.2,
		},
		ACCapacityBTUH: 8000,
	}

	result := ComputeRoomBudget(input)

	// Internal: 200 (device) + 100 (occupant) = 300W
	if !almostEqual(result.InternalGainsW, 300, tolerance) {
		t.Errorf("InternalGainsW = %v, want 300", result.InternalGainsW)
	}

	// Solar: 800 * 0.8 * (15*0.15) * 0.6 * 1.0 * 0.9 * 0.8 = 800*0.8*2.25*0.6*0.9*0.8 = 622.08
	if !almostEqual(result.SolarGainW, 622.08, 0.1) {
		t.Errorf("SolarGainW = %v, want ~622.08", result.SolarGainW)
	}

	// Ventilation: 1 * 45 * 1200 * 10 / 3600 = 150W
	if !almostEqual(result.VentilationGainW, 150, tolerance) {
		t.Errorf("VentilationGainW = %v, want 150", result.VentilationGainW)
	}

	// Total gain = 300 + 622.08 + 150 = 1072.08W
	expectedTotal := 300 + 622.08 + 150.0
	if !almostEqual(result.TotalGainW, expectedTotal, 0.1) {
		t.Errorf("TotalGainW = %v, want %v", result.TotalGainW, expectedTotal)
	}

	// TotalGainBTUH
	expectedBTUH := WattsToBTUH(expectedTotal)
	if !almostEqual(result.TotalGainBTUH, expectedBTUH, 1) {
		t.Errorf("TotalGainBTUH = %v, want %v", result.TotalGainBTUH, expectedBTUH)
	}

	// Headroom = 8000 - totalGainBTUH
	expectedHeadroom := 8000 - expectedBTUH
	if !almostEqual(result.HeadroomBTUH, expectedHeadroom, 1) {
		t.Errorf("HeadroomBTUH = %v, want %v", result.HeadroomBTUH, expectedHeadroom)
	}

	// Status should be comfortable (headroom > 20% of 8000 = 1600)
	if result.Status != Comfortable {
		t.Errorf("Status = %v, want Comfortable", result.Status)
	}
}

func TestBudgetStatus(t *testing.T) {
	tests := []struct {
		name       string
		totalGainW float64
		acBTUH     float64
		want       BudgetStatus
	}{
		{
			name:       "comfortable: headroom > 20% of AC",
			totalGainW: 500,
			acBTUH:     8000,
			want:       Comfortable,
		},
		{
			name:       "marginal: headroom 0-20% of AC",
			totalGainW: 2000,
			acBTUH:     8000,
			want:       Marginal,
		},
		{
			name:       "overloaded: negative headroom",
			totalGainW: 3000,
			acBTUH:     8000,
			want:       Overloaded,
		},
		{
			name:       "no AC at all, hot outdoor",
			totalGainW: 500,
			acBTUH:     0,
			want:       Overloaded,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			input := BudgetInput{
				Devices:        nil,
				DeviceMode:     ModeIdle,
				Occupants:      nil,
				Solar:          SolarParams{},
				Ventilation:    VentilationParams{RhoCp: 1.2, OutdoorTempC: 30, IndoorTempC: 25, VolumeCubicM: 50},
				ACCapacityBTUH: tt.acBTUH,
			}
			// Manually set gains via devices to control the total
			input.Devices = []Device{
				{WattsIdle: tt.totalGainW, WattsTypical: tt.totalGainW, WattsPeak: tt.totalGainW, DutyCycle: 1.0},
			}
			result := ComputeRoomBudget(input)
			if result.Status != tt.want {
				t.Errorf("Status = %v, want %v (headroom=%v)", result.Status, tt.want, result.HeadroomBTUH)
			}
		})
	}
}

func TestBudgetStatus_NoACVentilation(t *testing.T) {
	tests := []struct {
		name       string
		devices    []Device
		solar      SolarParams
		vent       VentilationParams
		acBTUH     float64
		want       BudgetStatus
	}{
		{
			name:    "no AC, net cooling via ventilation",
			devices: nil,
			vent: VentilationParams{
				ACH: 1.0, VolumeCubicM: 45, OutdoorTempC: 10, IndoorTempC: 25, RhoCp: 1.2,
			},
			acBTUH: 0,
			want:   Comfortable,
		},
		{
			name: "no AC, cold outdoor, ventilation can solve gains",
			devices: []Device{
				{WattsIdle: 500, WattsTypical: 500, WattsPeak: 500, DutyCycle: 1.0},
			},
			vent: VentilationParams{
				ACH: 0.5, VolumeCubicM: 50, OutdoorTempC: -4, IndoorTempC: 23, RhoCp: 1.2,
			},
			acBTUH: 0,
			want:   Marginal,
		},
		{
			name: "no AC, hot outdoor, delta >= 0",
			devices: []Device{
				{WattsIdle: 500, WattsTypical: 500, WattsPeak: 500, DutyCycle: 1.0},
			},
			vent: VentilationParams{
				ACH: 0.5, VolumeCubicM: 50, OutdoorTempC: 30, IndoorTempC: 25, RhoCp: 1.2,
			},
			acBTUH: 0,
			want:   Overloaded,
		},
		{
			name: "no AC, warm outdoor, vent cannot solve massive gains",
			devices: []Device{
				{WattsIdle: 3000, WattsTypical: 3000, WattsPeak: 3000, DutyCycle: 1.0},
			},
			vent: VentilationParams{
				ACH: 0.5, VolumeCubicM: 50, OutdoorTempC: 20, IndoorTempC: 25, RhoCp: 1.2,
			},
			acBTUH: 0,
			want:   Overloaded,
		},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := ComputeRoomBudget(BudgetInput{
				Devices:        tt.devices,
				DeviceMode:     ModeIdle,
				Solar:          tt.solar,
				Ventilation:    tt.vent,
				ACCapacityBTUH: tt.acBTUH,
			})
			if result.Status != tt.want {
				t.Errorf("Status = %v, want %v (totalW=%.1f, headroom=%.1f)",
					result.Status, tt.want, result.TotalGainW, result.HeadroomBTUH)
			}
		})
	}
}