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
}