feat: initial commit of Git Automation CLI

- Add comprehensive Git workflow automation tools
- Include branch management utilities
- Add commit helpers with conventional commit support
- Implement GitHub integration for PR management
- Add configuration management system
- Include comprehensive test coverage
- Add professional documentation and examples

internal/validation/validation.go

@@ -0,0 +1,182 @@
+package validation
+
+import (
+	"context"
+	"fmt"
+	"regexp"
+	"strings"
+	"github.com/iwasforcedtobehere/git-automation-cli/internal/git"
+)
+
+// ValidationResult represents the result of a validation
+type ValidationResult struct {
+	IsValid bool
+	Errors  []string
+}
+
+// NewValidationResult creates a new validation result
+func NewValidationResult() *ValidationResult {
+	return &ValidationResult{
+		IsValid: true,
+		Errors:  make([]string, 0),
+	}
+}
+
+// AddError adds an error to the validation result
+func (vr *ValidationResult) AddError(format string, args ...interface{}) {
+	vr.IsValid = false
+	vr.Errors = append(vr.Errors, fmt.Sprintf(format, args...))
+}
+
+// GetErrors returns all validation errors as a single string
+func (vr *ValidationResult) GetErrors() string {
+	return strings.Join(vr.Errors, "\n")
+}
+
+// ValidateGitRepository checks if the current directory is a Git repository
+func ValidateGitRepository(ctx context.Context) *ValidationResult {
+	result := NewValidationResult()
+	
+	if _, err := git.CurrentBranch(ctx); err != nil {
+		result.AddError("not a git repository or no branch found")
+	}
+	
+	return result
+}
+
+// ValidateBranchName checks if a branch name is valid
+func ValidateBranchName(name string) *ValidationResult {
+	result := NewValidationResult()
+	
+	// Check if branch name is empty
+	if name == "" {
+		result.AddError("branch name cannot be empty")
+		return result
+	}
+	
+	// Check for invalid characters
+	if strings.Contains(name, "..") || strings.Contains(name, " ") || 
+		strings.Contains(name, ":") || strings.Contains(name, "?") || 
+		strings.Contains(name, "*") || strings.Contains(name, "[") || 
+		strings.Contains(name, "@") || strings.Contains(name, "\\") {
+		result.AddError("branch name contains invalid characters")
+	}
+	
+	// Check if branch name starts with a dot
+	if strings.HasPrefix(name, ".") {
+		result.AddError("branch name cannot start with a dot")
+	}
+	
+	// Check if branch name ends with a slash
+	if strings.HasSuffix(name, "/") {
+		result.AddError("branch name cannot end with a slash")
+	}
+	
+	// Check for consecutive slashes
+	if strings.Contains(name, "//") {
+		result.AddError("branch name cannot contain consecutive slashes")
+	}
+	
+	// Check if branch name is a valid refname
+	// Git refname rules: must contain at least one /
+	if !strings.Contains(name, "/") && name != "HEAD" && 
+		name != "main" && name != "master" {
+		// This is not necessarily an error, but a warning
+		// We'll allow it but log a warning
+	}
+	
+	return result
+}
+
+// ValidateCommitMessage checks if a commit message is valid
+func ValidateCommitMessage(message string) *ValidationResult {
+	result := NewValidationResult()
+	
+	// Check if commit message is empty
+	if strings.TrimSpace(message) == "" {
+		result.AddError("commit message cannot be empty")
+		return result
+	}
+	
+	// Check if commit message is too long
+	if len(message) > 72 {
+		result.AddError("commit message should be 72 characters or less")
+	}
+	
+	// Check if commit message starts with a whitespace
+	if strings.HasPrefix(message, " ") {
+		result.AddError("commit message should not start with whitespace")
+	}
+	
+	return result
+}
+
+// ValidateConventionalCommit checks if a commit message follows the conventional commit format
+func ValidateConventionalCommit(message string) *ValidationResult {
+	result := NewValidationResult()
+	
+	// Conventional commit format: type(scope): description
+	// Example: feat(auth): add login functionality
+	
+	// Check if commit message is empty
+	if strings.TrimSpace(message) == "" {
+		result.AddError("commit message cannot be empty")
+		return result
+	}
+	
+	// Regex pattern for conventional commit
+	pattern := `^(\w+)(\([^)]+\))?(!)?:\s.+`
+	matched, err := regexp.MatchString(pattern, message)
+	if err != nil {
+		result.AddError("error validating conventional commit format: %v", err)
+		return result
+	}
+	
+	if !matched {
+		result.AddError("commit message does not follow conventional commit format")
+		result.AddError("expected format: type(scope): description")
+		result.AddError("example: feat(auth): add login functionality")
+	}
+	
+	return result
+}
+
+// ValidateGitHubToken checks if a GitHub token is valid
+func ValidateGitHubToken(token string) *ValidationResult {
+	result := NewValidationResult()
+	
+	// Check if token is empty
+	if token == "" {
+		result.AddError("GitHub token cannot be empty")
+		return result
+	}
+	
+	// Check if token starts with "ghp_" (personal access token) or "gho_" (OAuth token)
+	if !strings.HasPrefix(token, "ghp_") && !strings.HasPrefix(token, "gho_") {
+		result.AddError("GitHub token should start with 'ghp_' or 'gho_'")
+	}
+	
+	// Check token length (GitHub tokens are typically 40 characters long)
+	if len(token) != 40 {
+		result.AddError("GitHub token should be 40 characters long")
+	}
+	
+	return result
+}
+
+// ValidateWorkingDirectory checks if the working directory is clean
+func ValidateWorkingDirectory(ctx context.Context) *ValidationResult {
+	result := NewValidationResult()
+	
+	clean, err := git.IsCleanWorkingDir(ctx)
+	if err != nil {
+		result.AddError("failed to check working directory: %v", err)
+		return result
+	}
+	
+	if clean {
+		result.AddError("no changes to commit")
+	}
+	
+	return result
+}