package iace

import (
	"encoding/json"
	"fmt"
	"strings"
)

// ============================================================================
// Classifier Types
// ============================================================================

// ClassificationResult holds the output of a single regulatory classification.
type ClassificationResult struct {
	Regulation           RegulationType `json:"regulation"`
	ClassificationResult string         `json:"classification_result"`
	RiskLevel            string         `json:"risk_level"`
	Confidence           float64        `json:"confidence"`
	Reasoning            string         `json:"reasoning"`
	Requirements         []string       `json:"requirements"`
}

// ============================================================================
// Classifier
// ============================================================================

// Classifier determines which EU regulations apply to a machine or product
// based on project metadata and component analysis.
type Classifier struct{}

// NewClassifier creates a new Classifier instance.
func NewClassifier() *Classifier { return &Classifier{} }

// ============================================================================
// Public Methods
// ============================================================================

// ClassifyAll runs all four regulatory classifiers (AI Act, Machinery Regulation,
// CRA, NIS2) and returns the combined results.
func (c *Classifier) ClassifyAll(project *Project, components []Component) []ClassificationResult {
	return []ClassificationResult{
		c.ClassifyAIAct(project, components),
		c.ClassifyMachineryRegulation(project, components),
		c.ClassifyCRA(project, components),
		c.ClassifyNIS2(project, components),
	}
}

// ClassifyAIAct determines the AI Act classification based on whether the system
// contains AI components and their safety relevance.
//
// Classification logic:
//   - Has safety-relevant AI component: "high_risk"
//   - Has AI component (not safety-relevant): "limited_risk"
//   - No AI components: "not_applicable"
func (c *Classifier) ClassifyAIAct(project *Project, components []Component) ClassificationResult {
	result := ClassificationResult{
		Regulation: RegulationAIAct,
	}

	hasAI := false
	hasSafetyRelevantAI := false
	var aiComponentNames []string

	for _, comp := range components {
		if comp.ComponentType == ComponentTypeAIModel {
			hasAI = true
			aiComponentNames = append(aiComponentNames, comp.Name)
			if comp.IsSafetyRelevant {
				hasSafetyRelevantAI = true
			}
		}
	}

	switch {
	case hasSafetyRelevantAI:
		result.ClassificationResult = "high_risk"
		result.RiskLevel = "high"
		result.Confidence = 0.9
		result.Reasoning = fmt.Sprintf(
			"System contains safety-relevant AI component(s): %s. "+
				"Under EU AI Act Art. 6, AI systems that are safety components of products "+
				"covered by Union harmonisation legislation are classified as high-risk.",
			strings.Join(aiComponentNames, ", "),
		)
		result.Requirements = []string{
			"Risk management system (Art. 9)",
			"Data governance and management (Art. 10)",
			"Technical documentation (Art. 11)",
			"Record-keeping / logging (Art. 12)",
			"Transparency and information to deployers (Art. 13)",
			"Human oversight measures (Art. 14)",
			"Accuracy, robustness and cybersecurity (Art. 15)",
			"Quality management system (Art. 17)",
			"Conformity assessment before placing on market",
		}

	case hasAI:
		result.ClassificationResult = "limited_risk"
		result.RiskLevel = "medium"
		result.Confidence = 0.85
		result.Reasoning = fmt.Sprintf(
			"System contains AI component(s): %s, but none are marked as safety-relevant. "+
				"Classified as limited-risk under EU AI Act with transparency obligations.",
			strings.Join(aiComponentNames, ", "),
		)
		result.Requirements = []string{
			"Transparency obligations (Art. 52)",
			"AI literacy measures (Art. 4)",
			"Technical documentation recommended",
		}

	default:
		result.ClassificationResult = "not_applicable"
		result.RiskLevel = "none"
		result.Confidence = 0.95
		result.Reasoning = "No AI model components found in the system. EU AI Act does not apply."
		result.Requirements = nil
	}

	return result
}

// ClassifyMachineryRegulation determines the Machinery Regulation (EU) 2023/1230
// classification based on CE marking intent and component analysis.
//
// Classification logic:
//   - CE marking target set: "applicable" (standard machinery)
//   - Has safety-relevant software/firmware: "annex_iii" (high-risk, Annex III machinery)
//   - Otherwise: "standard"
func (c *Classifier) ClassifyMachineryRegulation(project *Project, components []Component) ClassificationResult {
	result := ClassificationResult{
		Regulation: RegulationMachineryRegulation,
	}

	hasCETarget := project.CEMarkingTarget != ""
	hasSafetyRelevantSoftware := false
	var safetySwNames []string

	for _, comp := range components {
		if (comp.ComponentType == ComponentTypeSoftware || comp.ComponentType == ComponentTypeFirmware) && comp.IsSafetyRelevant {
			hasSafetyRelevantSoftware = true
			safetySwNames = append(safetySwNames, comp.Name)
		}
	}

	switch {
	case hasSafetyRelevantSoftware:
		result.ClassificationResult = "annex_iii"
		result.RiskLevel = "high"
		result.Confidence = 0.9
		result.Reasoning = fmt.Sprintf(
			"Machine contains safety-relevant software/firmware component(s): %s. "+
				"Under Machinery Regulation (EU) 2023/1230 Annex III, machinery with safety-relevant "+
				"digital components requires third-party conformity assessment.",
			strings.Join(safetySwNames, ", "),
		)
		result.Requirements = []string{
			"Third-party conformity assessment (Annex III)",
			"Essential health and safety requirements (Annex III EHSR)",
			"Technical documentation per Annex IV",
			"Risk assessment per ISO 12100",
			"Software validation (IEC 62443 / IEC 61508)",
			"EU Declaration of Conformity",
			"CE marking",
		}

	case hasCETarget:
		result.ClassificationResult = "applicable"
		result.RiskLevel = "medium"
		result.Confidence = 0.85
		result.Reasoning = fmt.Sprintf(
			"CE marking target is set (%s). Machinery Regulation (EU) 2023/1230 applies. "+
				"No safety-relevant software/firmware detected; standard conformity assessment path.",
			project.CEMarkingTarget,
		)
		result.Requirements = []string{
			"Essential health and safety requirements (EHSR)",
			"Technical documentation per Annex IV",
			"Risk assessment per ISO 12100",
			"EU Declaration of Conformity",
			"CE marking",
		}

	default:
		result.ClassificationResult = "standard"
		result.RiskLevel = "low"
		result.Confidence = 0.7
		result.Reasoning = "No CE marking target specified and no safety-relevant software/firmware detected. " +
			"Standard machinery regulation requirements may still apply depending on product placement."
		result.Requirements = []string{
			"Risk assessment recommended",
			"Technical documentation recommended",
			"Verify if CE marking is required for intended market",
		}
	}

	return result
}

// ClassifyCRA determines the Cyber Resilience Act (CRA) classification based on
// whether the system contains networked components and their criticality.
//
// Classification logic:
//   - Safety-relevant + networked: "class_ii" (highest CRA category)
//   - Networked with critical component types: "class_i"
//   - Networked (other): "default" (self-assessment)
//   - No networked components: "not_applicable"
func (c *Classifier) ClassifyCRA(project *Project, components []Component) ClassificationResult {
	result := ClassificationResult{
		Regulation: RegulationCRA,
	}

	hasNetworked := false
	hasSafetyRelevantNetworked := false
	hasCriticalType := false
	var networkedNames []string

	// Component types considered critical under CRA
	criticalTypes := map[ComponentType]bool{
		ComponentTypeController: true,
		ComponentTypeNetwork:    true,
		ComponentTypeSensor:     true,
	}

	for _, comp := range components {
		if comp.IsNetworked {
			hasNetworked = true
			networkedNames = append(networkedNames, comp.Name)

			if comp.IsSafetyRelevant {
				hasSafetyRelevantNetworked = true
			}
			if criticalTypes[comp.ComponentType] {
				hasCriticalType = true
			}
		}
	}

	switch {
	case hasSafetyRelevantNetworked:
		result.ClassificationResult = "class_ii"
		result.RiskLevel = "high"
		result.Confidence = 0.9
		result.Reasoning = fmt.Sprintf(
			"System contains safety-relevant networked component(s): %s. "+
				"Under CRA, products with digital elements that are safety-relevant and networked "+
				"fall into Class II, requiring third-party conformity assessment.",
			strings.Join(networkedNames, ", "),
		)
		result.Requirements = []string{
			"Third-party conformity assessment",
			"Vulnerability handling process",
			"Security updates for product lifetime (min. 5 years)",
			"SBOM (Software Bill of Materials)",
			"Incident reporting to ENISA within 24h",
			"Coordinated vulnerability disclosure",
			"Secure by default configuration",
			"Technical documentation with cybersecurity risk assessment",
		}

	case hasCriticalType:
		result.ClassificationResult = "class_i"
		result.RiskLevel = "medium"
		result.Confidence = 0.85
		result.Reasoning = fmt.Sprintf(
			"System contains networked component(s) of critical type: %s. "+
				"Under CRA Class I, these products require conformity assessment via harmonised "+
				"standards or third-party assessment.",
			strings.Join(networkedNames, ", "),
		)
		result.Requirements = []string{
			"Conformity assessment (self or third-party with harmonised standards)",
			"Vulnerability handling process",
			"Security updates for product lifetime (min. 5 years)",
			"SBOM (Software Bill of Materials)",
			"Incident reporting to ENISA within 24h",
			"Coordinated vulnerability disclosure",
			"Secure by default configuration",
		}

	case hasNetworked:
		result.ClassificationResult = "default"
		result.RiskLevel = "low"
		result.Confidence = 0.85
		result.Reasoning = fmt.Sprintf(
			"System contains networked component(s): %s. "+
				"CRA default category applies; self-assessment is sufficient.",
			strings.Join(networkedNames, ", "),
		)
		result.Requirements = []string{
			"Self-assessment conformity",
			"Vulnerability handling process",
			"Security updates for product lifetime (min. 5 years)",
			"SBOM (Software Bill of Materials)",
			"Incident reporting to ENISA within 24h",
		}

	default:
		result.ClassificationResult = "not_applicable"
		result.RiskLevel = "none"
		result.Confidence = 0.9
		result.Reasoning = "No networked components found. The Cyber Resilience Act applies to " +
			"products with digital elements that have a network connection. Currently not applicable."
		result.Requirements = nil
	}

	return result
}

// ClassifyNIS2 determines the NIS2 Directive classification based on project
// metadata indicating whether the manufacturer supplies critical infrastructure sectors.
//
// Classification logic:
//   - Project metadata indicates KRITIS supplier: "indirect_obligation"
//   - Otherwise: "not_applicable"
func (c *Classifier) ClassifyNIS2(project *Project, components []Component) ClassificationResult {
	result := ClassificationResult{
		Regulation: RegulationNIS2,
	}

	isKRITISSupplier := c.isKRITISSupplier(project)

	if isKRITISSupplier {
		result.ClassificationResult = "indirect_obligation"
		result.RiskLevel = "medium"
		result.Confidence = 0.8
		result.Reasoning = "Project metadata indicates this product/system is supplied to clients " +
			"in critical infrastructure sectors (KRITIS). Under NIS2, suppliers to essential and " +
			"important entities have indirect obligations for supply chain security."
		result.Requirements = []string{
			"Supply chain security measures",
			"Incident notification support for customers",
			"Cybersecurity risk management documentation",
			"Security-by-design evidence",
			"Contractual security requirements with KRITIS customers",
			"Regular security assessments and audits",
		}
	} else {
		result.ClassificationResult = "not_applicable"
		result.RiskLevel = "none"
		result.Confidence = 0.75
		result.Reasoning = "No indication in project metadata that this product is supplied to " +
			"critical infrastructure (KRITIS) sectors. NIS2 indirect obligations do not currently apply. " +
			"Re-evaluate if customer base changes."
		result.Requirements = nil
	}

	return result
}

// ============================================================================
// Helper Methods
// ============================================================================

// isKRITISSupplier checks project metadata for indicators that the manufacturer
// supplies critical infrastructure sectors.
func (c *Classifier) isKRITISSupplier(project *Project) bool {
	if project.Metadata == nil {
		return false
	}

	var metadata map[string]interface{}
	if err := json.Unmarshal(project.Metadata, &metadata); err != nil {
		return false
	}

	// Check for explicit KRITIS flag
	if kritis, ok := metadata["kritis_supplier"]; ok {
		if val, ok := kritis.(bool); ok && val {
			return true
		}
	}

	// Check for critical sector clients
	if sectors, ok := metadata["critical_sector_clients"]; ok {
		switch v := sectors.(type) {
		case []interface{}:
			return len(v) > 0
		case bool:
			return v
		}
	}

	// Check for NIS2-relevant target sectors
	if targetSectors, ok := metadata["target_sectors"]; ok {
		kriticalSectors := map[string]bool{
			"energy":          true,
			"transport":       true,
			"banking":         true,
			"health":          true,
			"water":           true,
			"digital_infra":   true,
			"public_admin":    true,
			"space":           true,
			"food":            true,
			"manufacturing":   true,
			"waste_management": true,
			"postal":          true,
			"chemicals":       true,
		}

		if sectorList, ok := targetSectors.([]interface{}); ok {
			for _, s := range sectorList {
				if str, ok := s.(string); ok {
					if kriticalSectors[strings.ToLower(str)] {
						return true
					}
				}
			}
		}
	}

	return false
}