package maximizer

import "testing"

func newTestOptimizer(t *testing.T) *Optimizer {
	t.Helper()
	rules := loadTestRules(t)
	eval := NewEvaluator(rules)
	return NewOptimizer(eval)
}

// --- Golden Test Cases ---

func TestGC01_HRFullAutomationBlocked(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		AutomationLevel:    AutoFull,
		DecisionBinding:    BindingFullyBinding,
		DecisionImpact:     ImpactHigh,
		Domain:             DomainHR,
		DataType:           DataPersonal,
		HumanInLoop:        HILNone,
		Explainability:     ExplainNone,
		RiskClassification: RiskMinimal,
		LegalBasis:         LegalContract,
		ModelType:          ModelBlackboxLLM,
		DeploymentScope:    ScopeExternal,
	}

	result := opt.Optimize(config)
	if result.OriginalCompliant {
		t.Fatal("expected original to be non-compliant")
	}
	if result.MaxSafeConfig == nil {
		t.Fatal("expected an optimized variant")
	}

	max := result.MaxSafeConfig
	if max.Config.AutomationLevel == AutoFull {
		t.Error("optimizer must change automation_level from full")
	}
	if max.Config.HumanInLoop != HILRequired {
		t.Errorf("expected human_in_loop=required, got %s", max.Config.HumanInLoop)
	}
	if max.Config.DecisionBinding == BindingFullyBinding {
		t.Error("expected decision_binding to change from fully_binding")
	}
	// Verify the optimized config is actually compliant
	if !max.Evaluation.IsCompliant {
		t.Errorf("MaxSafeConfig is not compliant: violations=%+v", max.Evaluation.Violations)
	}
}

func TestGC02_HRRankingWithHumanReviewAllowed(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		AutomationLevel:      AutoAssistive,
		DecisionBinding:      BindingHumanReview,
		DecisionImpact:       ImpactHigh,
		Domain:               DomainHR,
		DataType:             DataPersonal,
		HumanInLoop:          HILRequired,
		Explainability:       ExplainBasic,
		RiskClassification:   RiskMinimal,
		LegalBasis:           LegalContract,
		TransparencyRequired: true,
		LoggingRequired:      true,
		ModelType:            ModelBlackboxLLM,
		DeploymentScope:      ScopeExternal,
	}

	result := opt.Optimize(config)
	// Should be allowed with conditions (requirements from high-risk classification)
	if result.MaxSafeConfig == nil {
		t.Fatal("expected a variant")
	}
}

func TestGC05_SensitiveDataWithoutLegalBasis(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		DataType:        DataSensitive,
		LegalBasis:      LegalLegitimateInterest,
		DecisionImpact:  ImpactHigh,
		Domain:          DomainHR,
		AutomationLevel: AutoAssistive,
		HumanInLoop:     HILRequired,
		DecisionBinding: BindingHumanReview,
	}

	result := opt.Optimize(config)
	if result.OriginalCompliant {
		t.Error("expected non-compliant: sensitive data with legitimate_interest")
	}
	if result.MaxSafeConfig == nil {
		t.Fatal("expected optimized variant")
	}
	if result.MaxSafeConfig.Config.LegalBasis != LegalConsent {
		t.Errorf("expected legal_basis=consent, got %s", result.MaxSafeConfig.Config.LegalBasis)
	}
}

func TestGC16_ProhibitedPracticeBlocked(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		RiskClassification: RiskProhibited,
		DeploymentScope:    ScopePublic,
	}

	result := opt.Optimize(config)
	if result.OriginalCompliant {
		t.Error("expected non-compliant for prohibited")
	}
	// Prohibited = no optimization possible
	if len(result.Variants) > 0 {
		t.Error("expected no variants for prohibited classification")
	}
}

func TestGC18_OptimizerMinimalChange(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		AutomationLevel:    AutoFull,
		DecisionBinding:    BindingFullyBinding,
		DecisionImpact:     ImpactHigh,
		Domain:             DomainHR,
		DataType:           DataPersonal,
		HumanInLoop:        HILNone,
		Explainability:     ExplainBasic,
		RiskClassification: RiskMinimal,
		LegalBasis:         LegalContract,
		ModelType:          ModelStatistical,
		DeploymentScope:    ScopeInternal,
	}

	result := opt.Optimize(config)
	if result.MaxSafeConfig == nil {
		t.Fatal("expected optimized variant")
	}

	max := result.MaxSafeConfig
	// Domain must NOT change
	if max.Config.Domain != DomainHR {
		t.Errorf("optimizer must not change domain: got %s", max.Config.Domain)
	}
	// Explainability was already basic, should stay
	if max.Config.Explainability != ExplainBasic {
		t.Errorf("optimizer should keep explainability=basic, got %s", max.Config.Explainability)
	}
	// Model type should not change unnecessarily
	if max.Config.ModelType != ModelStatistical {
		t.Errorf("optimizer should not change model_type unnecessarily, got %s", max.Config.ModelType)
	}
}

func TestGC20_AlreadyCompliantNoChanges(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		AutomationLevel:      AutoAssistive,
		DecisionBinding:      BindingNonBinding,
		DecisionImpact:       ImpactLow,
		Domain:               DomainGeneral,
		DataType:             DataNonPersonal,
		HumanInLoop:          HILRequired,
		Explainability:       ExplainBasic,
		RiskClassification:   RiskMinimal,
		LegalBasis:           LegalContract,
		TransparencyRequired: false,
		LoggingRequired:      false,
		ModelType:            ModelRuleBased,
		DeploymentScope:      ScopeInternal,
	}

	result := opt.Optimize(config)
	if !result.OriginalCompliant {
		t.Error("expected compliant")
	}
	if result.MaxSafeConfig == nil {
		t.Fatal("expected variant")
	}
	if result.MaxSafeConfig.DeltaCount != 0 {
		t.Errorf("expected 0 deltas for compliant config, got %d", result.MaxSafeConfig.DeltaCount)
	}
	if result.MaxSafeConfig.UtilityScore != 100 {
		t.Errorf("expected utility 100, got %d", result.MaxSafeConfig.UtilityScore)
	}
}

// --- Meta Tests ---

func TestMT01_Determinism(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		AutomationLevel: AutoFull,
		DecisionImpact:  ImpactHigh,
		Domain:          DomainHR,
		DataType:        DataPersonal,
		HumanInLoop:     HILNone,
	}

	r1 := opt.Optimize(config)
	r2 := opt.Optimize(config)

	if r1.OriginalCompliant != r2.OriginalCompliant {
		t.Error("determinism failed: different compliance result")
	}
	if len(r1.Variants) != len(r2.Variants) {
		t.Errorf("determinism failed: %d vs %d variants", len(r1.Variants), len(r2.Variants))
	}
	if r1.MaxSafeConfig != nil && r2.MaxSafeConfig != nil {
		if r1.MaxSafeConfig.CompositeScore != r2.MaxSafeConfig.CompositeScore {
			t.Error("determinism failed: different composite scores")
		}
	}
}

func TestMT03_ViolationsReferenceObligations(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		AutomationLevel: AutoFull,
		DecisionImpact:  ImpactHigh,
		DataType:        DataSensitive,
	}

	result := opt.Optimize(config)
	for _, v := range result.OriginalEval.Violations {
		if v.ObligationID == "" {
			t.Errorf("violation %s missing obligation reference", v.RuleID)
		}
	}
	for _, tr := range result.OriginalEval.TriggeredRules {
		if tr.ObligationID == "" {
			t.Errorf("triggered rule %s missing obligation reference", tr.RuleID)
		}
	}
}

func TestMT05_OptimizerMinimality(t *testing.T) {
	opt := newTestOptimizer(t)
	// Config that only violates one dimension
	config := &DimensionConfig{
		AutomationLevel:      AutoAssistive,
		DecisionBinding:      BindingHumanReview,
		DecisionImpact:       ImpactLow,
		Domain:               DomainGeneral,
		DataType:             DataSensitive, // only violation: needs consent
		HumanInLoop:          HILRequired,
		Explainability:       ExplainBasic,
		RiskClassification:   RiskMinimal,
		LegalBasis:           LegalLegitimateInterest, // must change to consent
		TransparencyRequired: false,
		LoggingRequired:      false,
		ModelType:            ModelRuleBased,
		DeploymentScope:      ScopeInternal,
	}

	result := opt.Optimize(config)
	if result.MaxSafeConfig == nil {
		t.Fatal("expected optimized variant")
	}

	// Check that only compliance-related dimensions changed
	for _, d := range result.MaxSafeConfig.Deltas {
		switch d.Dimension {
		case "legal_basis", "transparency_required", "logging_required", "data_type":
			// Expected: legal_basis→consent, transparency, logging for sensitive data
			// data_type→personal is from optimizer meta-rule (reduce unnecessary sensitivity)
		default:
			t.Errorf("unexpected dimension change: %s (%s → %s)", d.Dimension, d.From, d.To)
		}
	}
}

func TestOptimizeProducesRankedVariants(t *testing.T) {
	opt := newTestOptimizer(t)
	config := &DimensionConfig{
		AutomationLevel: AutoFull,
		DecisionImpact:  ImpactHigh,
		Domain:          DomainHR,
		DataType:        DataPersonal,
		HumanInLoop:     HILNone,
		Explainability:  ExplainNone,
		ModelType:       ModelBlackboxLLM,
		DeploymentScope: ScopeExternal,
	}

	result := opt.Optimize(config)
	if len(result.Variants) < 2 {
		t.Skipf("only %d variants generated", len(result.Variants))
	}

	// Verify descending composite score order
	for i := 1; i < len(result.Variants); i++ {
		if result.Variants[i].CompositeScore > result.Variants[i-1].CompositeScore {
			t.Errorf("variants not sorted: [%d]=%.1f > [%d]=%.1f",
				i, result.Variants[i].CompositeScore,
				i-1, result.Variants[i-1].CompositeScore)
		}
	}
}