/**
 * Client-side validation for entity submissions
 * Prevents missing required fields before database calls
 */

export interface ValidationResult {
  valid: boolean;
  missingFields: string[];
  errorMessage?: string;
}

export interface SlugValidationResult extends ValidationResult {
  suggestedSlug?: string;
}

/**
 * Validates slug format matching database constraints
 * Pattern: lowercase alphanumeric with hyphens only
 * No consecutive hyphens, no leading/trailing hyphens
 */
export function validateSlugFormat(slug: string): SlugValidationResult {
  if (!slug) {
    return { 
      valid: false, 
      missingFields: ['slug'], 
      errorMessage: 'Slug is required' 
    };
  }

  // Must match DB regex: ^[a-z0-9]+(-[a-z0-9]+)*$
  const slugRegex = /^[a-z0-9]+(-[a-z0-9]+)*$/;
  if (!slugRegex.test(slug)) {
    const suggested = slug
      .toLowerCase()
      .replace(/[^a-z0-9-]/g, '-')
      .replace(/-+/g, '-')
      .replace(/^-|-$/g, '');
    
    return {
      valid: false,
      missingFields: ['slug'],
      errorMessage: 'Slug must be lowercase alphanumeric with hyphens only (no spaces or special characters)',
      suggestedSlug: suggested
    };
  }

  // Length constraints
  if (slug.length < 2) {
    return { 
      valid: false, 
      missingFields: ['slug'], 
      errorMessage: 'Slug too short (minimum 2 characters)' 
    };
  }
  if (slug.length > 100) {
    return { 
      valid: false, 
      missingFields: ['slug'], 
      errorMessage: 'Slug too long (maximum 100 characters)' 
    };
  }

  // Reserved slugs that could conflict with routes
  const reserved = [
    'admin', 'api', 'auth', 'new', 'edit', 'delete', 'create', 
    'update', 'null', 'undefined', 'settings', 'profile', 'login',
    'logout', 'signup', 'dashboard', 'moderator', 'moderation'
  ];
  if (reserved.includes(slug)) {
    return { 
      valid: false, 
      missingFields: ['slug'], 
      errorMessage: `'${slug}' is a reserved slug and cannot be used`,
      suggestedSlug: `${slug}-1`
    };
  }

  return { valid: true, missingFields: [] };
}

/**
 * Validates required fields for park creation
 */
export function validateParkCreateFields(data: any): ValidationResult {
  const missingFields: string[] = [];
  
  if (!data.name?.trim()) missingFields.push('name');
  if (!data.slug?.trim()) missingFields.push('slug');
  if (!data.park_type) missingFields.push('park_type');
  if (!data.status) missingFields.push('status');
  
  if (missingFields.length > 0) {
    return {
      valid: false,
      missingFields,
      errorMessage: `Missing required fields for park creation: ${missingFields.join(', ')}`
    };
  }
  
  // Validate slug format
  if (data.slug?.trim()) {
    const slugValidation = validateSlugFormat(data.slug.trim());
    if (!slugValidation.valid) {
      return slugValidation;
    }
  }
  
  return { valid: true, missingFields: [] };
}

/**
 * Validates required fields for ride creation
 */
export function validateRideCreateFields(data: any): ValidationResult {
  const missingFields: string[] = [];
  
  if (!data.name?.trim()) missingFields.push('name');
  if (!data.slug?.trim()) missingFields.push('slug');
  if (!data.category) missingFields.push('category');
  if (!data.status) missingFields.push('status');
  
  if (missingFields.length > 0) {
    return {
      valid: false,
      missingFields,
      errorMessage: `Missing required fields for ride creation: ${missingFields.join(', ')}`
    };
  }
  
  // Validate slug format
  if (data.slug?.trim()) {
    const slugValidation = validateSlugFormat(data.slug.trim());
    if (!slugValidation.valid) {
      return slugValidation;
    }
  }
  
  return { valid: true, missingFields: [] };
}

/**
 * Validates required fields for company creation
 */
export function validateCompanyCreateFields(data: any): ValidationResult {
  const missingFields: string[] = [];
  
  if (!data.name?.trim()) missingFields.push('name');
  if (!data.slug?.trim()) missingFields.push('slug');
  if (!data.company_type) missingFields.push('company_type');
  
  if (missingFields.length > 0) {
    return {
      valid: false,
      missingFields,
      errorMessage: `Missing required fields for company creation: ${missingFields.join(', ')}`
    };
  }
  
  // Validate slug format
  if (data.slug?.trim()) {
    const slugValidation = validateSlugFormat(data.slug.trim());
    if (!slugValidation.valid) {
      return slugValidation;
    }
  }
  
  return { valid: true, missingFields: [] };
}

/**
 * Validates required fields for ride model creation
 */
export function validateRideModelCreateFields(data: any): ValidationResult {
  const missingFields: string[] = [];
  
  if (!data.name?.trim()) missingFields.push('name');
  if (!data.slug?.trim()) missingFields.push('slug');
  if (!data.manufacturer_id) missingFields.push('manufacturer_id');
  if (!data.category) missingFields.push('category');
  
  if (missingFields.length > 0) {
    return {
      valid: false,
      missingFields,
      errorMessage: `Missing required fields for ride model creation: ${missingFields.join(', ')}`
    };
  }
  
  // Validate slug format
  if (data.slug?.trim()) {
    const slugValidation = validateSlugFormat(data.slug.trim());
    if (!slugValidation.valid) {
      return slugValidation;
    }
  }
  
  return { valid: true, missingFields: [] };
}

/**
 * Helper to throw validation error if validation fails
 */
export function assertValid(result: ValidationResult): void {
  if (!result.valid) {
    throw new Error(result.errorMessage);
  }
}