// Enterprise AST analysis framework
package ast

import (
    "fmt"
    "go/ast"
    "go/parser"
    "go/token"
    "go/types"
    "log"
    "path/filepath"
    "strings"
    "sync"
    
    "golang.org/x/tools/go/analysis"
    "golang.org/x/tools/go/analysis/passes/inspect"
    "golang.org/x/tools/go/ast/inspector"
    "golang.org/x/tools/go/packages"
)

// EnterpriseASTAnalyzer provides comprehensive AST analysis capabilities
type EnterpriseASTAnalyzer struct {
    fileSet        *token.FileSet
    packages       []*packages.Package
    typeInfo       *types.Info
    inspector      *inspector.Inspector
    
    // Analysis configuration
    config         *AnalysisConfig
    metrics        *AnalysisMetrics
    
    // Concurrent analysis
    workers        int
    resultsChan    chan AnalysisResult
    errorsChan     chan error
    
    // Custom passes
    passes         []AnalysisPass
    passResults    map[string]interface{}
    mutex          sync.RWMutex
}

type AnalysisConfig struct {
    EnableMetrics       bool
    EnableProfiling     bool
    EnableCaching       bool
    MaxConcurrency     int
    OutputFormat       string
    IncludePatterns    []string
    ExcludePatterns    []string
    SecurityChecks     bool
    PerformanceChecks  bool
    QualityChecks      bool
}

type AnalysisMetrics struct {
    FilesAnalyzed      int64
    FunctionsAnalyzed  int64
    LinesOfCode        int64
    CyclomaticComplexity int64
    SecurityIssues     int64
    PerformanceIssues  int64
    QualityIssues      int64
    AnalysisTime       time.Duration
}

// Custom analysis pass interface
type AnalysisPass interface {
    Name() string
    Description() string
    Requires() []string
    Run(analyzer *EnterpriseASTAnalyzer, pkg *packages.Package) (interface{}, error)
}

// Create new enterprise AST analyzer
func NewEnterpriseASTAnalyzer(config *AnalysisConfig) *EnterpriseASTAnalyzer {
    return &EnterpriseASTAnalyzer{
        fileSet:     token.NewFileSet(),
        config:      config,
        metrics:     &AnalysisMetrics{},
        workers:     config.MaxConcurrency,
        resultsChan: make(chan AnalysisResult, 1000),
        errorsChan:  make(chan error, 100),
        passResults: make(map[string]interface{}),
        passes:      make([]AnalysisPass, 0),
    }
}

// Load packages for analysis
func (eaa *EnterpriseASTAnalyzer) LoadPackages(patterns []string) error {
    cfg := &packages.Config{
        Mode: packages.NeedName | packages.NeedFiles | packages.NeedCompiledGoFiles |
              packages.NeedImports | packages.NeedTypes | packages.NeedTypesSizes |
              packages.NeedSyntax | packages.NeedTypesInfo,
        Fset:    eaa.fileSet,
        ParseFile: eaa.parseFileWithMetrics,
    }
    
    pkgs, err := packages.Load(cfg, patterns...)
    if err != nil {
        return fmt.Errorf("failed to load packages: %w", err)
    }
    
    // Validate packages
    for _, pkg := range pkgs {
        if len(pkg.Errors) > 0 {
            for _, err := range pkg.Errors {
                log.Printf("Package error in %s: %v", pkg.PkgPath, err)
            }
        }
    }
    
    eaa.packages = pkgs
    
    // Create inspector for efficient AST traversal
    var files []*ast.File
    for _, pkg := range pkgs {
        files = append(files, pkg.Syntax...)
    }
    eaa.inspector = inspector.New(files)
    
    return nil
}

// Parse file with metrics collection
func (eaa *EnterpriseASTAnalyzer) parseFileWithMetrics(fset *token.FileSet, filename string, src []byte) (*ast.File, error) {
    start := time.Now()
    
    file, err := parser.ParseFile(fset, filename, src, parser.ParseComments)
    if err != nil {
        return nil, err
    }
    
    // Update metrics
    eaa.mutex.Lock()
    eaa.metrics.FilesAnalyzed++
    eaa.metrics.LinesOfCode += int64(fset.Position(file.End()).Line)
    eaa.mutex.Unlock()
    
    if eaa.config.EnableProfiling {
        log.Printf("Parsed %s in %v", filename, time.Since(start))
    }
    
    return file, nil
}

// Register analysis pass
func (eaa *EnterpriseASTAnalyzer) RegisterPass(pass AnalysisPass) {
    eaa.passes = append(eaa.passes, pass)
}

// Run comprehensive analysis
func (eaa *EnterpriseASTAnalyzer) RunAnalysis() (*EnterpriseAnalysisReport, error) {
    start := time.Now()
    defer func() {
        eaa.metrics.AnalysisTime = time.Since(start)
    }()
    
    // Create worker pool for concurrent analysis
    var wg sync.WaitGroup
    semaphore := make(chan struct{}, eaa.workers)
    
    // Run analysis passes
    for _, pass := range eaa.passes {
        for _, pkg := range eaa.packages {
            wg.Add(1)
            go func(p AnalysisPass, pkg *packages.Package) {
                defer wg.Done()
                semaphore <- struct{}{}
                defer func() { <-semaphore }()
                
                result, err := p.Run(eaa, pkg)
                if err != nil {
                    eaa.errorsChan <- fmt.Errorf("pass %s failed on package %s: %w", 
                                                p.Name(), pkg.PkgPath, err)
                    return
                }
                
                eaa.mutex.Lock()
                eaa.passResults[fmt.Sprintf("%s:%s", p.Name(), pkg.PkgPath)] = result
                eaa.mutex.Unlock()
            }(pass, pkg)
        }
    }
    
    // Wait for all analysis to complete
    go func() {
        wg.Wait()
        close(eaa.resultsChan)
        close(eaa.errorsChan)
    }()
    
    // Collect results and errors
    var results []AnalysisResult
    var errors []error
    
    for {
        select {
        case result, ok := <-eaa.resultsChan:
            if !ok {
                goto done
            }
            results = append(results, result)
        case err, ok := <-eaa.errorsChan:
            if !ok {
                goto done
            }
            errors = append(errors, err)
        }
    }
    
done:
    return &EnterpriseAnalysisReport{
        Metrics:     eaa.metrics,
        Results:     results,
        Errors:      errors,
        PassResults: eaa.passResults,
        Timestamp:   time.Now(),
    }, nil
}

// Advanced function complexity analysis
type ComplexityAnalysisPass struct {
    maxComplexity int
    reportFunc    func(string, int, token.Position)
}

func NewComplexityAnalysisPass(maxComplexity int) *ComplexityAnalysisPass {
    return &ComplexityAnalysisPass{
        maxComplexity: maxComplexity,
    }
}

func (cap *ComplexityAnalysisPass) Name() string {
    return "complexity_analysis"
}

func (cap *ComplexityAnalysisPass) Description() string {
    return "Analyzes cyclomatic complexity of functions and methods"
}

func (cap *ComplexityAnalysisPass) Requires() []string {
    return []string{}
}

func (cap *ComplexityAnalysisPass) Run(analyzer *EnterpriseASTAnalyzer, pkg *packages.Package) (interface{}, error) {
    complexities := make(map[string]int)
    
    // Analyze each file in the package
    for _, file := range pkg.Syntax {
        ast.Inspect(file, func(n ast.Node) bool {
            switch node := n.(type) {
            case *ast.FuncDecl:
                if node.Body != nil {
                    complexity := cap.calculateComplexity(node.Body)
                    funcName := getFunctionName(node)
                    complexities[funcName] = complexity
                    
                    // Update global metrics
                    analyzer.mutex.Lock()
                    analyzer.metrics.FunctionsAnalyzed++
                    analyzer.metrics.CyclomaticComplexity += int64(complexity)
                    analyzer.mutex.Unlock()
                    
                    // Report high complexity
                    if complexity > cap.maxComplexity {
                        pos := analyzer.fileSet.Position(node.Pos())
                        if cap.reportFunc != nil {
                            cap.reportFunc(funcName, complexity, pos)
                        }
                    }
                }
            }
            return true
        })
    }
    
    return complexities, nil
}

// Calculate cyclomatic complexity
func (cap *ComplexityAnalysisPass) calculateComplexity(block *ast.BlockStmt) int {
    complexity := 1 // Base complexity
    
    ast.Inspect(block, func(n ast.Node) bool {
        switch n.(type) {
        case *ast.IfStmt, *ast.ForStmt, *ast.RangeStmt, *ast.SwitchStmt, 
             *ast.TypeSwitchStmt, *ast.SelectStmt:
            complexity++
        case *ast.CaseClause:
            complexity++
        case *ast.CommClause:
            complexity++
        }
        return true
    })
    
    return complexity
}

// Security vulnerability analysis pass
type SecurityAnalysisPass struct {
    vulnerabilityRules []SecurityRule
    reportFunc        func(SecurityIssue)
}

type SecurityRule struct {
    ID          string
    Name        string
    Description string
    Severity    Severity
    Checker     func(ast.Node, *types.Info) []SecurityIssue
}

type SecurityIssue struct {
    RuleID      string
    Severity    Severity
    Message     string
    Position    token.Position
    Suggestion  string
}

type Severity int

const (
    SeverityInfo Severity = iota
    SeverityWarning
    SeverityError
    SeverityCritical
)

func NewSecurityAnalysisPass() *SecurityAnalysisPass {
    pass := &SecurityAnalysisPass{
        vulnerabilityRules: make([]SecurityRule, 0),
    }
    
    // Register default security rules
    pass.registerDefaultRules()
    
    return pass
}

func (sap *SecurityAnalysisPass) Name() string {
    return "security_analysis"
}

func (sap *SecurityAnalysisPass) Description() string {
    return "Analyzes code for security vulnerabilities and unsafe patterns"
}

func (sap *SecurityAnalysisPass) Requires() []string {
    return []string{}
}

func (sap *SecurityAnalysisPass) Run(analyzer *EnterpriseASTAnalyzer, pkg *packages.Package) (interface{}, error) {
    var issues []SecurityIssue
    
    for _, file := range pkg.Syntax {
        ast.Inspect(file, func(n ast.Node) bool {
            for _, rule := range sap.vulnerabilityRules {
                ruleIssues := rule.Checker(n, pkg.TypesInfo)
                for _, issue := range ruleIssues {
                    issue.Position = analyzer.fileSet.Position(n.Pos())
                    issues = append(issues, issue)
                    
                    if sap.reportFunc != nil {
                        sap.reportFunc(issue)
                    }
                    
                    // Update metrics
                    analyzer.mutex.Lock()
                    analyzer.metrics.SecurityIssues++
                    analyzer.mutex.Unlock()
                }
            }
            return true
        })
    }
    
    return issues, nil
}

// Register default security rules
func (sap *SecurityAnalysisPass) registerDefaultRules() {
    // SQL injection detection
    sap.vulnerabilityRules = append(sap.vulnerabilityRules, SecurityRule{
        ID:          "SEC001",
        Name:        "SQL Injection",
        Description: "Detects potential SQL injection vulnerabilities",
        Severity:    SeverityCritical,
        Checker:     sap.checkSQLInjection,
    })
    
    // Hardcoded credentials
    sap.vulnerabilityRules = append(sap.vulnerabilityRules, SecurityRule{
        ID:          "SEC002", 
        Name:        "Hardcoded Credentials",
        Description: "Detects hardcoded passwords, tokens, and secrets",
        Severity:    SeverityError,
        Checker:     sap.checkHardcodedCredentials,
    })
    
    // Unsafe HTTP usage
    sap.vulnerabilityRules = append(sap.vulnerabilityRules, SecurityRule{
        ID:          "SEC003",
        Name:        "Unsafe HTTP",
        Description: "Detects unsafe HTTP usage and missing security headers",
        Severity:    SeverityWarning,
        Checker:     sap.checkUnsafeHTTP,
    })
    
    // Weak cryptography
    sap.vulnerabilityRules = append(sap.vulnerabilityRules, SecurityRule{
        ID:          "SEC004",
        Name:        "Weak Cryptography",
        Description: "Detects usage of weak cryptographic algorithms",
        Severity:    SeverityError,
        Checker:     sap.checkWeakCryptography,
    })
}

// SQL injection checker
func (sap *SecurityAnalysisPass) checkSQLInjection(node ast.Node, typeInfo *types.Info) []SecurityIssue {
    var issues []SecurityIssue
    
    if call, ok := node.(*ast.CallExpr); ok {
        if fun, ok := call.Fun.(*ast.SelectorExpr); ok {
            // Check for database query methods
            if isDBQueryMethod(fun.Sel.Name) {
                for _, arg := range call.Args {
                    if sap.isStringConcatenation(arg) || sap.isUnvalidatedInput(arg) {
                        issues = append(issues, SecurityIssue{
                            RuleID:     "SEC001",
                            Severity:   SeverityCritical,
                            Message:    "Potential SQL injection vulnerability detected",
                            Suggestion: "Use parameterized queries or prepared statements",
                        })
                    }
                }
            }
        }
    }
    
    return issues
}

// Hardcoded credentials checker
func (sap *SecurityAnalysisPass) checkHardcodedCredentials(node ast.Node, typeInfo *types.Info) []SecurityIssue {
    var issues []SecurityIssue
    
    if lit, ok := node.(*ast.BasicLit); ok && lit.Kind == token.STRING {
        value := strings.Trim(lit.Value, `"`)
        if sap.looksLikeCredential(value) {
            issues = append(issues, SecurityIssue{
                RuleID:     "SEC002",
                Severity:   SeverityError,
                Message:    "Potential hardcoded credential detected",
                Suggestion: "Use environment variables or secure credential storage",
            })
        }
    }
    
    return issues
}

// Unsafe HTTP checker
func (sap *SecurityAnalysisPass) checkUnsafeHTTP(node ast.Node, typeInfo *types.Info) []SecurityIssue {
    var issues []SecurityIssue
    
    if call, ok := node.(*ast.CallExpr); ok {
        if fun, ok := call.Fun.(*ast.SelectorExpr); ok {
            // Check for HTTP client without TLS verification
            if fun.Sel.Name == "Get" || fun.Sel.Name == "Post" {
                if len(call.Args) > 0 {
                    if url, ok := call.Args[0].(*ast.BasicLit); ok {
                        if strings.Contains(url.Value, "http://") {
                            issues = append(issues, SecurityIssue{
                                RuleID:     "SEC003",
                                Severity:   SeverityWarning,
                                Message:    "Unsafe HTTP usage detected",
                                Suggestion: "Use HTTPS for secure communication",
                            })
                        }
                    }
                }
            }
        }
    }
    
    return issues
}

// Weak cryptography checker
func (sap *SecurityAnalysisPass) checkWeakCryptography(node ast.Node, typeInfo *types.Info) []SecurityIssue {
    var issues []SecurityIssue
    
    if call, ok := node.(*ast.CallExpr); ok {
        if fun, ok := call.Fun.(*ast.SelectorExpr); ok {
            weakAlgorithms := map[string]bool{
                "MD5":    true,
                "SHA1":   true,
                "DES":    true,
                "RC4":    true,
            }
            
            if weakAlgorithms[fun.Sel.Name] {
                issues = append(issues, SecurityIssue{
                    RuleID:     "SEC004",
                    Severity:   SeverityError,
                    Message:    fmt.Sprintf("Weak cryptographic algorithm %s detected", fun.Sel.Name),
                    Suggestion: "Use stronger algorithms like SHA-256, AES, or modern alternatives",
                })
            }
        }
    }
    
    return issues
}

// Helper functions
func getFunctionName(fn *ast.FuncDecl) string {
    if fn.Recv != nil && len(fn.Recv.List) > 0 {
        // Method
        if recv := fn.Recv.List[0].Type; recv != nil {
            return fmt.Sprintf("%s.%s", types.ExprString(recv), fn.Name.Name)
        }
    }
    // Function
    return fn.Name.Name
}

func isDBQueryMethod(name string) bool {
    dbMethods := map[string]bool{
        "Query":     true,
        "QueryRow":  true,
        "Exec":      true,
        "Prepare":   true,
    }
    return dbMethods[name]
}

func (sap *SecurityAnalysisPass) isStringConcatenation(expr ast.Expr) bool {
    if binary, ok := expr.(*ast.BinaryExpr); ok {
        return binary.Op == token.ADD
    }
    return false
}

func (sap *SecurityAnalysisPass) isUnvalidatedInput(expr ast.Expr) bool {
    // Simplified check - in practice, would need data flow analysis
    if ident, ok := expr.(*ast.Ident); ok {
        name := strings.ToLower(ident.Name)
        return strings.Contains(name, "input") || 
               strings.Contains(name, "param") ||
               strings.Contains(name, "user")
    }
    return false
}

func (sap *SecurityAnalysisPass) looksLikeCredential(value string) bool {
    value = strings.ToLower(value)
    
    // Check for common credential patterns
    credentialPatterns := []string{
        "password", "passwd", "pwd",
        "secret", "key", "token",
        "api_key", "apikey",
        "access_key", "accesskey",
        "private_key", "privatekey",
    }
    
    for _, pattern := range credentialPatterns {
        if strings.Contains(value, pattern) && len(value) > 8 {
            return true
        }
    }
    
    // Check for patterns that look like encoded secrets
    if len(value) > 20 && (isBase64Like(value) || isHexLike(value)) {
        return true
    }
    
    return false
}

func isBase64Like(s string) bool {
    // Simple heuristic for base64-like strings
    return strings.ContainsAny(s, "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=") &&
           len(s)%4 == 0
}

func isHexLike(s string) bool {
    // Simple heuristic for hex strings
    for _, r := range s {
        if !((r >= '0' && r <= '9') || (r >= 'a' && r <= 'f') || (r >= 'A' && r <= 'F')) {
            return false
        }
    }
    return len(s) >= 16 && len(s)%2 == 0
}

// Results and reporting structures
type AnalysisResult struct {
    PassName    string
    PackagePath string
    Data        interface{}
    Timestamp   time.Time
}

type EnterpriseAnalysisReport struct {
    Metrics     *AnalysisMetrics
    Results     []AnalysisResult
    Errors      []error
    PassResults map[string]interface{}
    Timestamp   time.Time
}

// Enterprise optimization framework
package optimization

import (
    "fmt"
    "go/ast"
    "go/constant"
    "go/token"
    "go/types"
    "strings"
    "sync"
    
    "golang.org/x/tools/go/analysis"
    "golang.org/x/tools/go/ssa"
)

// EnterpriseOptimizer provides advanced optimization capabilities
type EnterpriseOptimizer struct {
    passes          []OptimizationPass
    ssaProgram      *ssa.Program
    typeInfo        *types.Info
    fileSet         *token.FileSet
    
    // Optimization configuration
    config          *OptimizationConfig
    statistics      *OptimizationStatistics
    
    // Cache for optimization results
    optimizationCache map[string]OptimizationResult
    cacheMutex        sync.RWMutex
}

type OptimizationConfig struct {
    EnableInlining          bool
    EnableConstantFolding   bool
    EnableDeadCodeElimination bool
    EnableLoopOptimizations bool
    EnableSSAOptimizations  bool
    MaxInliningDepth        int
    OptimizationLevel       int
    TargetArch              string
    EnableProfiling         bool
}

type OptimizationStatistics struct {
    InlinedFunctions        int64
    FoldedConstants         int64
    EliminatedDeadCode      int64
    OptimizedLoops          int64
    ReducedInstructions     int64
    OptimizationTime        time.Duration
}

type OptimizationPass interface {
    Name() string
    Description() string
    RequiresSSA() bool
    Run(optimizer *EnterpriseOptimizer, fn *ssa.Function) OptimizationResult
}

type OptimizationResult struct {
    PassName            string
    FunctionName        string
    OptimizationsApplied []string
    InstructionsReduced  int
    Performance         PerformanceMetrics
}

type PerformanceMetrics struct {
    EstimatedSpeedup    float64
    MemoryReduction     int64
    InstructionReduction int
}

// Create new enterprise optimizer
func NewEnterpriseOptimizer(config *OptimizationConfig) *EnterpriseOptimizer {
    return &EnterpriseOptimizer{
        config:            config,
        statistics:        &OptimizationStatistics{},
        optimizationCache: make(map[string]OptimizationResult),
        passes:            make([]OptimizationPass, 0),
    }
}

// Register optimization pass
func (eo *EnterpriseOptimizer) RegisterPass(pass OptimizationPass) {
    eo.passes = append(eo.passes, pass)
}

// Function inlining optimization pass
type InliningOptimizationPass struct {
    maxDepth        int
    maxComplexity   int
    inlineHeuristic InlineHeuristic
}

type InlineHeuristic func(*ssa.Function) bool

func NewInliningOptimizationPass(maxDepth, maxComplexity int) *InliningOptimizationPass {
    return &InliningOptimizationPass{
        maxDepth:      maxDepth,
        maxComplexity: maxComplexity,
        inlineHeuristic: defaultInlineHeuristic,
    }
}

func (iop *InliningOptimizationPass) Name() string {
    return "function_inlining"
}

func (iop *InliningOptimizationPass) Description() string {
    return "Inlines small functions to reduce call overhead"
}

func (iop *InliningOptimizationPass) RequiresSSA() bool {
    return true
}

func (iop *InliningOptimizationPass) Run(optimizer *EnterpriseOptimizer, fn *ssa.Function) OptimizationResult {
    result := OptimizationResult{
        PassName:     iop.Name(),
        FunctionName: fn.Name(),
    }
    
    // Find inlining candidates
    candidates := iop.findInliningCandidates(fn)
    
    for _, candidate := range candidates {
        if iop.shouldInline(candidate) {
            if iop.performInlining(fn, candidate) {
                result.OptimizationsApplied = append(result.OptimizationsApplied, 
                    fmt.Sprintf("Inlined function %s", candidate.Name()))
                result.InstructionsReduced += iop.estimateInliningBenefit(candidate)
                
                optimizer.statistics.InlinedFunctions++
            }
        }
    }
    
    return result
}

// Find functions that can be inlined
func (iop *InliningOptimizationPass) findInliningCandidates(fn *ssa.Function) []*ssa.Function {
    var candidates []*ssa.Function
    
    // Traverse function body to find call instructions
    for _, block := range fn.Blocks {
        for _, instr := range block.Instrs {
            if call, ok := instr.(*ssa.Call); ok {
                if callee := call.Call.StaticCallee(); callee != nil {
                    candidates = append(candidates, callee)
                }
            }
        }
    }
    
    return candidates
}

// Determine if function should be inlined
func (iop *InliningOptimizationPass) shouldInline(fn *ssa.Function) bool {
    // Check heuristics
    if !iop.inlineHeuristic(fn) {
        return false
    }
    
    // Check size constraints
    if iop.calculateComplexity(fn) > iop.maxComplexity {
        return false
    }
    
    // Check for recursion
    if iop.isRecursive(fn) {
        return false
    }
    
    return true
}

// Default inlining heuristic
func defaultInlineHeuristic(fn *ssa.Function) bool {
    // Simple heuristic: inline small leaf functions
    return len(fn.Blocks) <= 3 && len(fn.Params) <= 4
}

// Calculate function complexity for inlining decisions
func (iop *InliningOptimizationPass) calculateComplexity(fn *ssa.Function) int {
    complexity := 0
    
    for _, block := range fn.Blocks {
        complexity += len(block.Instrs)
        
        // Add penalty for control flow
        if len(block.Succs) > 1 {
            complexity += 2
        }
    }
    
    return complexity
}

// Check if function is recursive
func (iop *InliningOptimizationPass) isRecursive(fn *ssa.Function) bool {
    for _, block := range fn.Blocks {
        for _, instr := range block.Instrs {
            if call, ok := instr.(*ssa.Call); ok {
                if callee := call.Call.StaticCallee(); callee == fn {
                    return true
                }
            }
        }
    }
    return false
}

// Perform actual inlining
func (iop *InliningOptimizationPass) performInlining(caller, callee *ssa.Function) bool {
    // This is a simplified implementation
    // Real inlining requires complex SSA graph manipulation
    
    // Find call sites
    callSites := iop.findCallSites(caller, callee)
    
    for _, callSite := range callSites {
        // Replace call with inlined body
        if iop.replaceCallWithInlinedBody(caller, callSite, callee) {
            return true
        }
    }
    
    return false
}

// Constant folding optimization pass
type ConstantFoldingPass struct {
    foldedConstants int
}

func NewConstantFoldingPass() *ConstantFoldingPass {
    return &ConstantFoldingPass{}
}

func (cfp *ConstantFoldingPass) Name() string {
    return "constant_folding"
}

func (cfp *ConstantFoldingPass) Description() string {
    return "Evaluates constant expressions at compile time"
}

func (cfp *ConstantFoldingPass) RequiresSSA() bool {
    return true
}

func (cfp *ConstantFoldingPass) Run(optimizer *EnterpriseOptimizer, fn *ssa.Function) OptimizationResult {
    result := OptimizationResult{
        PassName:     cfp.Name(),
        FunctionName: fn.Name(),
    }
    
    // Find constant expressions
    for _, block := range fn.Blocks {
        for i, instr := range block.Instrs {
            if folded := cfp.tryFoldInstruction(instr); folded != nil {
                // Replace instruction with constant
                block.Instrs[i] = folded
                result.OptimizationsApplied = append(result.OptimizationsApplied,
                    fmt.Sprintf("Folded constant expression"))
                result.InstructionsReduced++
                cfp.foldedConstants++
            }
        }
    }
    
    optimizer.statistics.FoldedConstants += int64(cfp.foldedConstants)
    return result
}

// Try to fold instruction if it operates on constants
func (cfp *ConstantFoldingPass) tryFoldInstruction(instr ssa.Instruction) ssa.Instruction {
    switch inst := instr.(type) {
    case *ssa.BinOp:
        return cfp.foldBinaryOperation(inst)
    case *ssa.UnOp:
        return cfp.foldUnaryOperation(inst)
    case *ssa.Convert:
        return cfp.foldConversion(inst)
    }
    return nil
}

// Fold binary operations
func (cfp *ConstantFoldingPass) foldBinaryOperation(binop *ssa.BinOp) ssa.Instruction {
    x, xOk := binop.X.(*ssa.Const)
    y, yOk := binop.Y.(*ssa.Const)
    
    if !xOk || !yOk {
        return nil
    }
    
    // Evaluate constant expression
    result := constant.BinaryOp(x.Value, binop.Op, y.Value)
    if result == nil {
        return nil
    }
    
    // Create new constant instruction
    constInstr := &ssa.Const{
        Value: result,
    }
    constInstr.SetType(binop.Type())
    
    return constInstr
}

// Fold unary operations
func (cfp *ConstantFoldingPass) foldUnaryOperation(unop *ssa.UnOp) ssa.Instruction {
    x, ok := unop.X.(*ssa.Const)
    if !ok {
        return nil
    }
    
    result := constant.UnaryOp(unop.Op, x.Value, 0)
    if result == nil {
        return nil
    }
    
    constInstr := &ssa.Const{
        Value: result,
    }
    constInstr.SetType(unop.Type())
    
    return constInstr
}

// Fold type conversions
func (cfp *ConstantFoldingPass) foldConversion(conv *ssa.Convert) ssa.Instruction {
    x, ok := conv.X.(*ssa.Const)
    if !ok {
        return nil
    }
    
    // Try to convert constant
    if converted := constant.Convert(x.Value, &types.Basic{}, 0); converted != nil {
        constInstr := &ssa.Const{
            Value: converted,
        }
        constInstr.SetType(conv.Type())
        return constInstr
    }
    
    return nil
}

// Dead code elimination pass
type DeadCodeEliminationPass struct {
    eliminatedInstructions int
}

func NewDeadCodeEliminationPass() *DeadCodeEliminationPass {
    return &DeadCodeEliminationPass{}
}

func (dcep *DeadCodeEliminationPass) Name() string {
    return "dead_code_elimination"
}

func (dcep *DeadCodeEliminationPass) Description() string {
    return "Removes unreachable code and unused variables"
}

func (dcep *DeadCodeEliminationPass) RequiresSSA() bool {
    return true
}

func (dcep *DeadCodeEliminationPass) Run(optimizer *EnterpriseOptimizer, fn *ssa.Function) OptimizationResult {
    result := OptimizationResult{
        PassName:     dcep.Name(),
        FunctionName: fn.Name(),
    }
    
    // Mark live instructions
    liveInstructions := dcep.markLiveInstructions(fn)
    
    // Remove dead instructions
    for _, block := range fn.Blocks {
        var newInstrs []ssa.Instruction
        for _, instr := range block.Instrs {
            if liveInstructions[instr] {
                newInstrs = append(newInstrs, instr)
            } else {
                dcep.eliminatedInstructions++
                result.InstructionsReduced++
            }
        }
        block.Instrs = newInstrs
    }
    
    // Remove unreachable blocks
    reachableBlocks := dcep.findReachableBlocks(fn)
    var newBlocks []*ssa.BasicBlock
    for _, block := range fn.Blocks {
        if reachableBlocks[block] {
            newBlocks = append(newBlocks, block)
        }
    }
    fn.Blocks = newBlocks
    
    if dcep.eliminatedInstructions > 0 {
        result.OptimizationsApplied = append(result.OptimizationsApplied,
            fmt.Sprintf("Eliminated %d dead instructions", dcep.eliminatedInstructions))
    }
    
    optimizer.statistics.EliminatedDeadCode += int64(dcep.eliminatedInstructions)
    return result
}

// Mark instructions that are live (have side effects or are used)
func (dcep *DeadCodeEliminationPass) markLiveInstructions(fn *ssa.Function) map[ssa.Instruction]bool {
    live := make(map[ssa.Instruction]bool)
    worklist := make([]ssa.Instruction, 0)
    
    // Mark initially live instructions (those with side effects)
    for _, block := range fn.Blocks {
        for _, instr := range block.Instrs {
            if dcep.hasSideEffects(instr) {
                live[instr] = true
                worklist = append(worklist, instr)
            }
        }
    }
    
    // Propagate liveness backwards
    for len(worklist) > 0 {
        current := worklist[len(worklist)-1]
        worklist = worklist[:len(worklist)-1]
        
        // Mark operands as live
        for _, operand := range current.Operands(nil) {
            if op := *operand; op != nil {
                if instr, ok := op.(ssa.Instruction); ok && !live[instr] {
                    live[instr] = true
                    worklist = append(worklist, instr)
                }
            }
        }
    }
    
    return live
}

// Check if instruction has side effects
func (dcep *DeadCodeEliminationPass) hasSideEffects(instr ssa.Instruction) bool {
    switch instr.(type) {
    case *ssa.Call, *ssa.Defer, *ssa.Go, *ssa.Panic, *ssa.Return,
         *ssa.Store, *ssa.MapUpdate, *ssa.Send:
        return true
    case *ssa.If, *ssa.Jump, *ssa.RunDefers:
        return true
    default:
        return false
    }
}

// Find reachable basic blocks
func (dcep *DeadCodeEliminationPass) findReachableBlocks(fn *ssa.Function) map[*ssa.BasicBlock]bool {
    reachable := make(map[*ssa.BasicBlock]bool)
    worklist := make([]*ssa.BasicBlock, 0)
    
    if len(fn.Blocks) > 0 {
        entry := fn.Blocks[0]
        reachable[entry] = true
        worklist = append(worklist, entry)
    }
    
    for len(worklist) > 0 {
        current := worklist[len(worklist)-1]
        worklist = worklist[:len(worklist)-1]
        
        for _, succ := range current.Succs {
            if !reachable[succ] {
                reachable[succ] = true
                worklist = append(worklist, succ)
            }
        }
    }
    
    return reachable
}

// Loop optimization pass
type LoopOptimizationPass struct {
    optimizedLoops int
}

func NewLoopOptimizationPass() *LoopOptimizationPass {
    return &LoopOptimizationPass{}
}

func (lop *LoopOptimizationPass) Name() string {
    return "loop_optimization"
}

func (lop *LoopOptimizationPass) Description() string {
    return "Optimizes loops through strength reduction and invariant code motion"
}

func (lop *LoopOptimizationPass) RequiresSSA() bool {
    return true
}

func (lop *LoopOptimizationPass) Run(optimizer *EnterpriseOptimizer, fn *ssa.Function) OptimizationResult {
    result := OptimizationResult{
        PassName:     lop.Name(),
        FunctionName: fn.Name(),
    }
    
    // Find loops in the function
    loops := lop.findLoops(fn)
    
    for _, loop := range loops {
        optimizations := 0
        
        // Apply loop invariant code motion
        if moved := lop.moveLoopInvariantCode(loop); moved > 0 {
            optimizations += moved
            result.OptimizationsApplied = append(result.OptimizationsApplied,
                fmt.Sprintf("Moved %d loop invariant instructions", moved))
        }
        
        // Apply strength reduction
        if reduced := lop.applyStrengthReduction(loop); reduced > 0 {
            optimizations += reduced
            result.OptimizationsApplied = append(result.OptimizationsApplied,
                fmt.Sprintf("Applied strength reduction to %d instructions", reduced))
        }
        
        if optimizations > 0 {
            lop.optimizedLoops++
            result.InstructionsReduced += optimizations
        }
    }
    
    optimizer.statistics.OptimizedLoops += int64(lop.optimizedLoops)
    return result
}

// Simple loop detection
func (lop *LoopOptimizationPass) findLoops(fn *ssa.Function) []Loop {
    var loops []Loop
    
    // Build dominance tree and find back edges
    domTree := buildDominanceTree(fn)
    
    for _, block := range fn.Blocks {
        for _, succ := range block.Succs {
            if domTree.dominates(succ, block) {
                // Found a back edge, this indicates a loop
                loop := Loop{
                    Header: succ,
                    Blocks: lop.findLoopBlocks(succ, block, domTree),
                }
                loops = append(loops, loop)
            }
        }
    }
    
    return loops
}

type Loop struct {
    Header *ssa.BasicBlock
    Blocks []*ssa.BasicBlock
}

// Loop invariant code motion
func (lop *LoopOptimizationPass) moveLoopInvariantCode(loop Loop) int {
    moved := 0
    
    // Find preheader or create one
    preheader := lop.getOrCreatePreheader(loop)
    
    // Identify invariant instructions
    for _, block := range loop.Blocks {
        for i := len(block.Instrs) - 1; i >= 0; i-- {
            instr := block.Instrs[i]
            
            if lop.isLoopInvariant(instr, loop) && lop.canBeMoved(instr) {
                // Move instruction to preheader
                block.Instrs = append(block.Instrs[:i], block.Instrs[i+1:]...)
                preheader.Instrs = append(preheader.Instrs, instr)
                moved++
            }
        }
    }
    
    return moved
}

// Check if instruction is loop invariant
func (lop *LoopOptimizationPass) isLoopInvariant(instr ssa.Instruction, loop Loop) bool {
    // An instruction is loop invariant if all its operands are either:
    // 1. Constants
    // 2. Defined outside the loop
    // 3. Loop invariant themselves
    
    for _, operand := range instr.Operands(nil) {
        if op := *operand; op != nil {
            if _, isConst := op.(*ssa.Const); isConst {
                continue // Constants are invariant
            }
            
            if defInstr, ok := op.(ssa.Instruction); ok {
                if lop.isDefinedInLoop(defInstr, loop) {
                    return false
                }
            }
        }
    }
    
    return true
}

// Helper functions (simplified implementations)
func (lop *LoopOptimizationPass) canBeMoved(instr ssa.Instruction) bool {
    // Check if instruction can be safely moved (no side effects, etc.)
    switch instr.(type) {
    case *ssa.Call, *ssa.Store, *ssa.Send:
        return false // Has side effects
    default:
        return true
    }
}

func (lop *LoopOptimizationPass) isDefinedInLoop(instr ssa.Instruction, loop Loop) bool {
    instrBlock := instr.Block()
    for _, block := range loop.Blocks {
        if block == instrBlock {
            return true
        }
    }
    return false
}

func (lop *LoopOptimizationPass) getOrCreatePreheader(loop Loop) *ssa.BasicBlock {
    // Simplified: assume first predecessor is preheader
    if len(loop.Header.Preds) > 0 {
        return loop.Header.Preds[0]
    }
    // In practice, would create a new preheader block
    return loop.Header
}

func (lop *LoopOptimizationPass) findLoopBlocks(header, latch *ssa.BasicBlock, domTree *DominanceTree) []*ssa.BasicBlock {
    // Simplified: just return header and latch
    return []*ssa.BasicBlock{header, latch}
}

func (lop *LoopOptimizationPass) applyStrengthReduction(loop Loop) int {
    // Simplified strength reduction implementation
    reduced := 0
    
    // Look for multiplication by constants that can be replaced with shifts/adds
    for _, block := range loop.Blocks {
        for i, instr := range block.Instrs {
            if binop, ok := instr.(*ssa.BinOp); ok && binop.Op == token.MUL {
                if constOp, ok := binop.Y.(*ssa.Const); ok {
                    if val, ok := constant.Int64Val(constOp.Value); ok && isPowerOfTwo(val) {
                        // Replace multiplication with shift
                        // This is a simplified representation
                        reduced++
                    }
                }
            }
        }
    }
    
    return reduced
}

// Helper functions
func isPowerOfTwo(n int64) bool {
    return n > 0 && (n&(n-1)) == 0
}

// Simplified dominance tree
type DominanceTree struct {
    dominators map[*ssa.BasicBlock]*ssa.BasicBlock
}

func buildDominanceTree(fn *ssa.Function) *DominanceTree {
    // Simplified dominance computation
    return &DominanceTree{
        dominators: make(map[*ssa.BasicBlock]*ssa.BasicBlock),
    }
}

func (dt *DominanceTree) dominates(a, b *ssa.BasicBlock) bool {
    // Simplified dominance check
    return dt.dominators[b] == a
}