package financial

import (
	"testing"
)

func TestSensitivityAnalyzer_AnalyzeSensitivity(t *testing.T) {
	config := DefaultConfig()
	npvCalc := NewNPVCalculator()
	sa := NewSensitivityAnalyzer(config, npvCalc)

	basic := &EconomicAnalysis{
		NPV:           100000.0,
		AnnualSavings: 15000.0,
		CapexRequired: 50000.0,
		OpexPerYear:   2000.0,
	}

	assumptions := &EconomicAssumptions{
		DiscountRate:     0.08,
		ProjectLifeYears: 10,
	}

	scenarios := sa.AnalyzeSensitivity(basic, assumptions)

	// Should have scenarios for: discount_rate (-20%, -10%, +10%, +20%),
	// capex (-20%, -10%, +10%, +20%), annual_savings (-20%, -10%, +10%, +20%),
	// opex (-20%, -10%, +10%, +20%), project_life (-20%, +20%),
	// co2_price (-50%, +50%, +100%)
	expectedCount := 4 + 4 + 4 + 4 + 2 + 3 // 21 scenarios
	if len(scenarios) != expectedCount {
		t.Errorf("AnalyzeSensitivity() returned %d scenarios, want %d", len(scenarios), expectedCount)
	}

	// Check that scenarios have proper structure
	for i, scenario := range scenarios {
		if scenario.VariableName == "" {
			t.Errorf("Scenario %d: VariableName is empty", i)
		}
		if scenario.BaseValue <= 0 {
			t.Errorf("Scenario %d: BaseValue is not positive: %v", i, scenario.BaseValue)
		}
		if scenario.RiskLevel == "" {
			t.Errorf("Scenario %d: RiskLevel is empty", i)
		}
	}
}

func TestSensitivityAnalyzer_CalculateRiskLevel(t *testing.T) {
	config := DefaultConfig()
	npvCalc := NewNPVCalculator()
	sa := NewSensitivityAnalyzer(config, npvCalc)

	tests := []struct {
		name     string
		impact   float64
		expected string
	}{
		{"Low impact", 0.05, "low"},          // < 0.3
		{"Medium impact", 0.45, "medium"},    // 0.3-0.6
		{"High impact", 0.7, "high"},         // 0.6-0.8
		{"Critical impact", 0.9, "critical"}, // > 0.8
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			impl := sa.(*SensitivityAnalyzerImpl)
			result := impl.calculateRiskLevel(tt.impact)

			if result != tt.expected {
				t.Errorf("calculateRiskLevel(%v) = %v, want %v", tt.impact, result, tt.expected)
			}
		})
	}
}

func TestSensitivityAnalyzer_DiscountRateSensitivity(t *testing.T) {
	config := DefaultConfig()
	npvCalc := NewNPVCalculator()
	sa := NewSensitivityAnalyzer(config, npvCalc)

	basic := &EconomicAnalysis{
		NPV:           100000.0,
		AnnualSavings: 15000.0,
		CapexRequired: 50000.0,
		OpexPerYear:   2000.0,
	}

	assumptions := &EconomicAssumptions{
		DiscountRate:     0.08,
		ProjectLifeYears: 10,
	}

	scenarios := sa.AnalyzeSensitivity(basic, assumptions)

	// Find discount rate scenarios
	var discountScenarios []SensitivityScenario
	for _, scenario := range scenarios {
		if scenario.VariableName == "discount_rate" {
			discountScenarios = append(discountScenarios, scenario)
		}
	}

	if len(discountScenarios) != 4 {
		t.Errorf("Expected 4 discount rate scenarios, got %d", len(discountScenarios))
	}

	// Check that base value matches assumptions
	for _, scenario := range discountScenarios {
		if scenario.BaseValue != 0.08 {
			t.Errorf("Discount rate scenario base value = %v, want 0.08", scenario.BaseValue)
		}
	}
}

func TestSensitivityAnalyzer_CO2PriceSensitivity(t *testing.T) {
	config := DefaultConfig()
	npvCalc := NewNPVCalculator()
	sa := NewSensitivityAnalyzer(config, npvCalc)

	basic := &EconomicAnalysis{
		NPV:           100000.0,
		AnnualSavings: 15000.0,
		CapexRequired: 50000.0,
		OpexPerYear:   2000.0,
	}

	assumptions := &EconomicAssumptions{
		DiscountRate:     0.08,
		ProjectLifeYears: 10,
	}

	scenarios := sa.AnalyzeSensitivity(basic, assumptions)

	// Find CO2 price scenarios
	var co2Scenarios []SensitivityScenario
	for _, scenario := range scenarios {
		if scenario.VariableName == "co2_price" {
			co2Scenarios = append(co2Scenarios, scenario)
		}
	}

	if len(co2Scenarios) != 3 {
		t.Errorf("Expected 3 CO2 price scenarios, got %d", len(co2Scenarios))
	}

	// Check that base value is €25/tonne
	for _, scenario := range co2Scenarios {
		if scenario.BaseValue != 25.0 {
			t.Errorf("CO2 price scenario base value = %v, want 25.0", scenario.BaseValue)
		}
	}
}