package ucca

import (
	"sort"
	"strings"
)

// Evaluate runs all YAML rules against the intake
func (e *PolicyEngine) Evaluate(intake *UseCaseIntake) *AssessmentResult {
	result := &AssessmentResult{
		Feasibility:             FeasibilityYES,
		RiskLevel:               RiskLevelMINIMAL,
		Complexity:              ComplexityLOW,
		RiskScore:               0,
		TriggeredRules:          []TriggeredRule{},
		RequiredControls:        []RequiredControl{},
		RecommendedArchitecture: []PatternRecommendation{},
		ForbiddenPatterns:       []ForbiddenPattern{},
		ExampleMatches:          []ExampleMatch{},
		DSFARecommended:         false,
		Art22Risk:               false,
		TrainingAllowed:         TrainingYES,
	}

	hasBlock := false
	hasWarn := false
	controlSet := make(map[string]bool)
	patternPriority := make(map[string]int)
	triggeredRuleIDs := make(map[string]bool)
	needsEscalation := false

	priority := 1
	for _, rule := range e.config.Rules {
		if rule.Condition.Aggregate != "" {
			continue
		}

		if e.evaluateCondition(&rule.Condition, intake) {
			triggeredRuleIDs[rule.ID] = true

			triggered := TriggeredRule{
				Code:        rule.ID,
				Category:    rule.Category,
				Title:       rule.Title,
				Description: rule.Description,
				Severity:    parseSeverity(rule.Severity),
				ScoreDelta:  rule.Effect.RiskAdd,
				GDPRRef:     rule.GDPRRef,
				Rationale:   rule.Rationale,
			}
			result.TriggeredRules = append(result.TriggeredRules, triggered)
			result.RiskScore += rule.Effect.RiskAdd

			switch parseSeverity(rule.Severity) {
			case SeverityBLOCK:
				hasBlock = true
			case SeverityWARN:
				hasWarn = true
			}

			if rule.Effect.Feasibility != "" {
				switch rule.Effect.Feasibility {
				case "NO":
					result.Feasibility = FeasibilityNO
				case "CONDITIONAL":
					if result.Feasibility != FeasibilityNO {
						result.Feasibility = FeasibilityCONDITIONAL
					}
				case "YES":
					if result.Feasibility != FeasibilityNO && result.Feasibility != FeasibilityCONDITIONAL {
						result.Feasibility = FeasibilityYES
					}
				}
			}

			for _, ctrlID := range rule.Effect.ControlsAdd {
				if !controlSet[ctrlID] {
					controlSet[ctrlID] = true
					if ctrl, ok := e.config.Controls[ctrlID]; ok {
						result.RequiredControls = append(result.RequiredControls, RequiredControl{
							ID:          ctrl.ID,
							Title:       ctrl.Title,
							Description: ctrl.Description,
							Severity:    parseSeverity(rule.Severity),
							Category:    categorizeControl(ctrl.ID),
							GDPRRef:     ctrl.GDPRRef,
						})
					}
				}
			}

			for _, patternID := range rule.Effect.SuggestedPatterns {
				if _, exists := patternPriority[patternID]; !exists {
					patternPriority[patternID] = priority
					priority++
				}
			}

			if rule.Effect.Escalation {
				needsEscalation = true
			}
			if rule.Effect.Art22Risk {
				result.Art22Risk = true
			}
		}
	}

	if hasBlock {
		result.Feasibility = FeasibilityNO
	} else if hasWarn && result.Feasibility != FeasibilityNO {
		result.Feasibility = FeasibilityCONDITIONAL
	}

	result.RiskLevel = e.calculateRiskLevel(result.RiskScore)
	result.Complexity = e.calculateComplexity(result)
	result.DSFARecommended = e.shouldRecommendDSFA(intake, result)
	result.TrainingAllowed = e.determineTrainingAllowed(intake)
	result.RecommendedArchitecture = e.buildPatternRecommendations(patternPriority)
	result.ExampleMatches = MatchExamples(intake)
	result.Summary = e.generateSummary(result, intake)
	result.Recommendation = e.generateRecommendation(result, intake)
	if result.Feasibility == FeasibilityNO {
		result.AlternativeApproach = e.generateAlternative(result, intake, triggeredRuleIDs)
	}

	_ = needsEscalation
	return result
}

// evaluateCondition recursively evaluates a condition against the intake
func (e *PolicyEngine) evaluateCondition(cond *ConditionDef, intake *UseCaseIntake) bool {
	if len(cond.AllOf) > 0 {
		for _, subCond := range cond.AllOf {
			if !e.evaluateCondition(&subCond, intake) {
				return false
			}
		}
		return true
	}

	if len(cond.AnyOf) > 0 {
		for _, subCond := range cond.AnyOf {
			if e.evaluateCondition(&subCond, intake) {
				return true
			}
		}
		return false
	}

	if cond.Field != "" {
		return e.evaluateFieldCondition(cond.Field, cond.Operator, cond.Value, intake)
	}

	return false
}

// evaluateFieldCondition evaluates a single field comparison
func (e *PolicyEngine) evaluateFieldCondition(field, operator string, value interface{}, intake *UseCaseIntake) bool {
	fieldValue := e.getFieldValue(field, intake)
	if fieldValue == nil {
		return false
	}

	switch operator {
	case "equals":
		return e.compareEquals(fieldValue, value)
	case "not_equals":
		return !e.compareEquals(fieldValue, value)
	case "in":
		return e.compareIn(fieldValue, value)
	case "contains":
		return e.compareContains(fieldValue, value)
	default:
		return false
	}
}

// getFieldValue extracts a field value from the intake using dot notation
func (e *PolicyEngine) getFieldValue(field string, intake *UseCaseIntake) interface{} {
	parts := strings.Split(field, ".")
	if len(parts) == 0 {
		return nil
	}

	switch parts[0] {
	case "data_types":
		if len(parts) < 2 {
			return nil
		}
		return e.getDataTypeValue(parts[1], intake)
	case "purpose":
		if len(parts) < 2 {
			return nil
		}
		return e.getPurposeValue(parts[1], intake)
	case "automation":
		return string(intake.Automation)
	case "outputs":
		if len(parts) < 2 {
			return nil
		}
		return e.getOutputsValue(parts[1], intake)
	case "hosting":
		if len(parts) < 2 {
			return nil
		}
		return e.getHostingValue(parts[1], intake)
	case "model_usage":
		if len(parts) < 2 {
			return nil
		}
		return e.getModelUsageValue(parts[1], intake)
	case "domain":
		return string(intake.Domain)
	case "retention":
		if len(parts) < 2 {
			return nil
		}
		return e.getRetentionValue(parts[1], intake)
	}

	return nil
}

func (e *PolicyEngine) getDataTypeValue(field string, intake *UseCaseIntake) interface{} {
	switch field {
	case "personal_data":
		return intake.DataTypes.PersonalData
	case "article_9_data":
		return intake.DataTypes.Article9Data
	case "minor_data":
		return intake.DataTypes.MinorData
	case "license_plates":
		return intake.DataTypes.LicensePlates
	case "images":
		return intake.DataTypes.Images
	case "audio":
		return intake.DataTypes.Audio
	case "location_data":
		return intake.DataTypes.LocationData
	case "biometric_data":
		return intake.DataTypes.BiometricData
	case "financial_data":
		return intake.DataTypes.FinancialData
	case "employee_data":
		return intake.DataTypes.EmployeeData
	case "customer_data":
		return intake.DataTypes.CustomerData
	case "public_data":
		return intake.DataTypes.PublicData
	}
	return nil
}

func (e *PolicyEngine) getPurposeValue(field string, intake *UseCaseIntake) interface{} {
	switch field {
	case "customer_support":
		return intake.Purpose.CustomerSupport
	case "marketing":
		return intake.Purpose.Marketing
	case "analytics":
		return intake.Purpose.Analytics
	case "automation":
		return intake.Purpose.Automation
	case "evaluation_scoring":
		return intake.Purpose.EvaluationScoring
	case "decision_making":
		return intake.Purpose.DecisionMaking
	case "profiling":
		return intake.Purpose.Profiling
	case "research":
		return intake.Purpose.Research
	case "internal_tools":
		return intake.Purpose.InternalTools
	case "public_service":
		return intake.Purpose.PublicService
	}
	return nil
}

func (e *PolicyEngine) getOutputsValue(field string, intake *UseCaseIntake) interface{} {
	switch field {
	case "recommendations_to_users":
		return intake.Outputs.RecommendationsToUsers
	case "rankings_or_scores":
		return intake.Outputs.RankingsOrScores
	case "legal_effects":
		return intake.Outputs.LegalEffects
	case "access_decisions":
		return intake.Outputs.AccessDecisions
	case "content_generation":
		return intake.Outputs.ContentGeneration
	case "data_export":
		return intake.Outputs.DataExport
	}
	return nil
}

func (e *PolicyEngine) getHostingValue(field string, intake *UseCaseIntake) interface{} {
	switch field {
	case "provider":
		return intake.Hosting.Provider
	case "region":
		return intake.Hosting.Region
	case "data_residency":
		return intake.Hosting.DataResidency
	}
	return nil
}

func (e *PolicyEngine) getModelUsageValue(field string, intake *UseCaseIntake) interface{} {
	switch field {
	case "rag":
		return intake.ModelUsage.RAG
	case "finetune":
		return intake.ModelUsage.Finetune
	case "training":
		return intake.ModelUsage.Training
	case "inference":
		return intake.ModelUsage.Inference
	}
	return nil
}

func (e *PolicyEngine) getRetentionValue(field string, intake *UseCaseIntake) interface{} {
	switch field {
	case "store_prompts":
		return intake.Retention.StorePrompts
	case "store_responses":
		return intake.Retention.StoreResponses
	case "retention_days":
		return intake.Retention.RetentionDays
	case "anonymize_after_use":
		return intake.Retention.AnonymizeAfterUse
	}
	return nil
}

func (e *PolicyEngine) compareEquals(fieldValue, expected interface{}) bool {
	if bv, ok := fieldValue.(bool); ok {
		if eb, ok := expected.(bool); ok {
			return bv == eb
		}
	}
	if sv, ok := fieldValue.(string); ok {
		if es, ok := expected.(string); ok {
			return sv == es
		}
	}
	if iv, ok := fieldValue.(int); ok {
		switch ev := expected.(type) {
		case int:
			return iv == ev
		case float64:
			return iv == int(ev)
		}
	}
	return false
}

func (e *PolicyEngine) compareIn(fieldValue, expected interface{}) bool {
	list, ok := expected.([]interface{})
	if !ok {
		return false
	}
	sv, ok := fieldValue.(string)
	if !ok {
		return false
	}
	for _, item := range list {
		if is, ok := item.(string); ok && is == sv {
			return true
		}
	}
	return false
}

func (e *PolicyEngine) compareContains(fieldValue, expected interface{}) bool {
	sv, ok := fieldValue.(string)
	if !ok {
		return false
	}
	es, ok := expected.(string)
	if !ok {
		return false
	}
	return strings.Contains(strings.ToLower(sv), strings.ToLower(es))
}

func (e *PolicyEngine) calculateRiskLevel(score int) RiskLevel {
	t := e.config.Thresholds.Risk
	if score >= t.Unacceptable {
		return RiskLevelUNACCEPTABLE
	}
	if score >= t.High {
		return RiskLevelHIGH
	}
	if score >= t.Medium {
		return RiskLevelMEDIUM
	}
	if score >= t.Low {
		return RiskLevelLOW
	}
	return RiskLevelMINIMAL
}

func (e *PolicyEngine) calculateComplexity(result *AssessmentResult) Complexity {
	controlCount := len(result.RequiredControls)
	if controlCount >= 5 || result.RiskScore >= 50 {
		return ComplexityHIGH
	}
	if controlCount >= 3 || result.RiskScore >= 25 {
		return ComplexityMEDIUM
	}
	return ComplexityLOW
}

func (e *PolicyEngine) shouldRecommendDSFA(intake *UseCaseIntake, result *AssessmentResult) bool {
	if result.RiskLevel == RiskLevelHIGH || result.RiskLevel == RiskLevelUNACCEPTABLE {
		return true
	}
	if intake.DataTypes.Article9Data || intake.DataTypes.BiometricData {
		return true
	}
	if intake.Purpose.Profiling && intake.DataTypes.PersonalData {
		return true
	}
	for _, ctrl := range result.RequiredControls {
		if ctrl.ID == "C_DSFA" {
			return true
		}
	}
	return false
}

func (e *PolicyEngine) determineTrainingAllowed(intake *UseCaseIntake) TrainingAllowed {
	if intake.ModelUsage.Training && intake.DataTypes.PersonalData {
		return TrainingNO
	}
	if intake.ModelUsage.Finetune && intake.DataTypes.PersonalData {
		return TrainingCONDITIONAL
	}
	if intake.DataTypes.MinorData && (intake.ModelUsage.Training || intake.ModelUsage.Finetune) {
		return TrainingNO
	}
	return TrainingYES
}

func (e *PolicyEngine) buildPatternRecommendations(patternPriority map[string]int) []PatternRecommendation {
	type priorityPair struct {
		id       string
		priority int
	}

	pairs := make([]priorityPair, 0, len(patternPriority))
	for id, p := range patternPriority {
		pairs = append(pairs, priorityPair{id, p})
	}
	sort.Slice(pairs, func(i, j int) bool {
		return pairs[i].priority < pairs[j].priority
	})

	recommendations := make([]PatternRecommendation, 0, len(pairs))
	for _, p := range pairs {
		if pattern, ok := e.config.Patterns[p.id]; ok {
			recommendations = append(recommendations, PatternRecommendation{
				PatternID:   pattern.ID,
				Title:       pattern.Title,
				Description: pattern.Description,
				Rationale:   pattern.Benefit,
				Priority:    p.priority,
			})
		}
	}
	return recommendations
}