import { z } from 'zod';

// ============================================================================
// CORE ENTITY INTERFACES
// ============================================================================

/**
 * Asset entity representing basic asset information
 */
export interface Asset {
  assetID: number;
  assetCode: string;
  assetType: string;
  brandModel: string;
  serialNumber: string;
  assetCondition: string;
}

/**
 * System Details entity representing technical specifications linked to assets
 */
export interface SystemDetails {
  systemDetailsID: number;
  assetID: number;
  systemModel: string;
  processor: string;
  installedRAM: string;
  graphics: string;
  screenResolution: string;
  diskModel: string;
  diskSize: string;
  manufacturer: string;
}

/**
 * Asset Assignment entity representing employee assignment tracking
 */
export interface AssetAssignment {
  assignmentID: number;
  assetID: number;
  employeeID: number;
  employeeName: string;
  assetCode: string;
  assignedDate: string; // ISO 8601 format
  returnedDate: string | null; // ISO 8601 format
  remarks: string;
}

/**
 * Asset Item entity representing individual components/items attached to an asset
 */
export interface AssetItem {
  itemID: number;
  assetID: number;
  itemType: string;
  itemName: string;
  quantity: number;
  specifications: string;
  serialNumber?: string;
  condition: string;
  notes?: string;
  addedDate: string; // ISO 8601 format
}

// ============================================================================
// API REQUEST/RESPONSE TYPES
// ============================================================================

/**
 * Request type for creating a new asset (excludes auto-generated ID)
 */
export interface AssetCreateRequest {
  assetCode: string;
  assetType: string;
  brandModel: string;
  serialNumber: string;
  assetCondition: string;
  purchaseDate?: string;
  warrantyExpiry?: string;
  purchaseCost?: number;
  currentValue?: number;
  location?: string;
  notes?: string;
}

/**
 * Request type for updating an existing asset
 */
export interface AssetUpdateRequest {
  assetID: number;
  assetCode: string;
  assetType: string;
  brandModel: string;
  serialNumber: string;
  assetCondition: string;
}

/**
 * Request type for creating new system details (excludes auto-generated ID)
 */
export interface SystemDetailsCreateRequest {
  assetID: number;
  systemModel: string;
  processor: string;
  installedRAM: string;
  graphics: string;
  screenResolution: string;
  diskModel: string;
  diskSize: string;
  manufacturer: string;
}

/**
 * Request type for updating existing system details
 */
export interface SystemDetailsUpdateRequest {
  systemDetailsID: number;
  assetID: number;
  systemModel: string;
  processor: string;
  installedRAM: string;
  graphics: string;
  screenResolution: string;
  diskModel: string;
  diskSize: string;
  manufacturer: string;
}

/**
 * Request type for creating a new asset assignment (excludes auto-generated ID)
 */
export interface AssetAssignmentCreateRequest {
  assetID: number;
  employeeID: number;
  employeeName: string;
  assetCode: string;
  assignedDate: string; // ISO 8601 format
  returnedDate: string | null; // ISO 8601 format
  remarks: string;
}

/**
 * Request type for updating an existing asset assignment
 */
export interface AssetAssignmentUpdateRequest {
  assignmentID: number;
  assetID: number;
  employeeID: number;
  employeeName: string;
  assetCode: string;
  assignedDate: string; // ISO 8601 format
  returnedDate: string | null; // ISO 8601 format
  remarks: string;
}

/**
 * Request type for creating a new asset item (excludes auto-generated ID)
 */
export interface AssetItemCreateRequest {
  assetID: number;
  itemType: string;
  itemName: string;
  quantity: number;
  specifications: string;
  serialNumber?: string;
  condition: string;
  notes?: string;
  addedDate: string; // ISO 8601 format
}

/**
 * Request type for updating an existing asset item
 */
export interface AssetItemUpdateRequest {
  itemID: number;
  assetID: number;
  itemType: string;
  itemName: string;
  quantity: number;
  specifications: string;
  serialNumber?: string;
  condition: string;
  notes?: string;
  addedDate: string; // ISO 8601 format
}

// ============================================================================
// ENUM TYPES AND CONSTANTS
// ============================================================================

/**
 * Valid asset condition values
 */
export type AssetCondition = 'Excellent' | 'Good' | 'Fair' | 'Poor';

/**
 * Common asset types
 */
export type AssetType =
  | 'Laptop'
  | 'Desktop'
  | 'Monitor'
  | 'Keyboard'
  | 'Mouse'
  | 'Wired Mouse'
  | 'Wireless Mouse'
  | 'Laptop Stand'
  | 'Extended Screen'
  | 'Printer'
  | 'Scanner'
  | 'Tablet'
  | 'Phone'
  | 'Other';

/**
 * Asset condition options for dropdowns
 */
export const ASSET_CONDITIONS: AssetCondition[] = ['Excellent', 'Good', 'Fair', 'Poor'];

/**
 * Asset type options for dropdowns
 */
export const ASSET_TYPES: AssetType[] = [
  'Laptop',
  'Desktop',
  'Monitor',
  'Keyboard',
  'Mouse',
  'Wired Mouse',
  'Wireless Mouse',
  'Laptop Stand',
  'Extended Screen',
  'Printer',
  'Scanner',
  'Tablet',
  'Phone',
  'Other'
];

/**
 * Asset item types
 */
export type AssetItemType =
  | 'RAM'
  | 'Storage'
  | 'Battery'
  | 'Charger'
  | 'Cable'
  | 'Adapter'
  | 'Keyboard'
  | 'Mouse'
  | 'Webcam'
  | 'Headset'
  | 'Docking Station'
  | 'Monitor'
  | 'Other';

/**
 * Asset item type options for dropdowns
 */
export const ASSET_ITEM_TYPES: AssetItemType[] = [
  'RAM',
  'Storage',
  'Battery',
  'Charger',
  'Cable',
  'Adapter',
  'Keyboard',
  'Mouse',
  'Webcam',
  'Headset',
  'Docking Station',
  'Monitor',
  'Other'
];

// ============================================================================
// ZOD VALIDATION SCHEMAS
// ============================================================================

/**
 * Zod schema for Asset validation
 */
export const AssetSchema = z.object({
  assetID: z.number().int().positive().optional(),
  assetCode: z.string()
    .min(1, 'Asset code is required')
    .max(20, 'Asset code must be 20 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Asset code cannot be empty or contain only spaces'
    })
    .refine(val => /^[A-Za-z0-9\-_]+$/.test(val.trim()), {
      message: 'Asset code can only contain letters, numbers, hyphens, and underscores'
    }),
  assetType: z.string()
    .min(1, 'Asset type is required')
    .max(50, 'Asset type must be 50 characters or less')
    .refine(val => ASSET_TYPES.includes(val as AssetType), {
      message: 'Please select a valid asset type from the list'
    }),
  brandModel: z.string()
    .min(1, 'Brand model is required')
    .max(100, 'Brand model must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Brand model cannot be empty or contain only spaces'
    }),
  serialNumber: z.string()
    .min(1, 'Serial number is required')
    .max(50, 'Serial number must be 50 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Serial number cannot be empty or contain only spaces'
    })
    .refine(val => /^[A-Za-z0-9\-_]+$/.test(val.trim()), {
      message: 'Serial number can only contain letters, numbers, hyphens, and underscores'
    }),
  assetCondition: z.enum(['Excellent', 'Good', 'Fair', 'Poor'], {
    errorMap: () => ({ message: 'Asset condition must be Excellent, Good, Fair, or Poor' })
  }),
});

/**
 * Zod schema for Asset creation (excludes ID)
 */
export const AssetCreateSchema = AssetSchema.omit({ assetID: true });

/**
 * Zod schema for Asset updates (requires ID and assetCode)
 */
export const AssetUpdateSchema = AssetSchema.required({ assetID: true, assetCode: true });

/**
 * Zod schema for System Details validation
 */
export const SystemDetailsSchema = z.object({
  systemDetailsID: z.number().int().positive().optional(),
  assetID: z.number().int().positive('Asset ID must be a positive number'),
  systemModel: z.string()
    .min(1, 'System model is required')
    .max(100, 'System model must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'System model cannot be empty or contain only spaces'
    }),
  processor: z.string()
    .min(1, 'Processor information is required')
    .max(100, 'Processor must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Processor information cannot be empty or contain only spaces'
    }),
  installedRAM: z.string()
    .min(1, 'RAM information is required')
    .max(50, 'RAM must be 50 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'RAM information cannot be empty or contain only spaces'
    }),
  graphics: z.string()
    .min(1, 'Graphics information is required')
    .max(100, 'Graphics must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Graphics information cannot be empty or contain only spaces'
    }),
  screenResolution: z.string()
    .min(1, 'Screen resolution is required')
    .max(50, 'Screen resolution must be 50 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Screen resolution cannot be empty or contain only spaces'
    })
    .refine(val => /^\d+x\d+$/.test(val.trim()) || val === 'custom', {
      message: 'Screen resolution must be in format "1920x1080" or select from the dropdown'
    }),
  diskModel: z.string()
    .min(1, 'Disk model is required')
    .max(100, 'Disk model must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Disk model cannot be empty or contain only spaces'
    }),
  diskSize: z.string()
    .min(1, 'Disk size is required')
    .max(50, 'Disk size must be 50 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Disk size cannot be empty or contain only spaces'
    }),
  manufacturer: z.string()
    .min(1, 'Manufacturer is required')
    .max(100, 'Manufacturer must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Manufacturer cannot be empty or contain only spaces'
    }),
});

/**
 * Zod schema for System Details creation (excludes ID)
 */
export const SystemDetailsCreateSchema = SystemDetailsSchema.omit({ systemDetailsID: true });

/**
 * Zod schema for System Details updates (requires ID)
 */
export const SystemDetailsUpdateSchema = SystemDetailsSchema.required({ systemDetailsID: true });

/**
 * Base Zod schema for Asset Assignment validation (without refinements)
 */
const AssetAssignmentBaseSchema = z.object({
  assignmentID: z.number().int().positive().optional(),
  assetID: z.number().int().positive('Asset ID must be a positive number'),
  employeeID: z.number().int().positive('Employee ID must be a positive number'),
  employeeName: z.string()
    .min(1, 'Employee name is required')
    .max(100, 'Employee name must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Employee name cannot be empty or contain only spaces'
    }),
  assetCode: z.string()
    .min(1, 'Asset code is required')
    .max(20, 'Asset code must be 20 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Asset code cannot be empty or contain only spaces'
    }),
  assignedDate: z.string().datetime('Assigned date must be in ISO 8601 format'),
  returnedDate: z.string().datetime('Returned date must be in ISO 8601 format').nullable(),
  remarks: z.string()
    .min(1, 'Remarks are required')
    .max(500, 'Remarks must be 500 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Remarks cannot be empty or contain only spaces'
    }),
});

/**
 * Zod schema for Asset Assignment validation (with date validation refinement)
 */
export const AssetAssignmentSchema = AssetAssignmentBaseSchema.refine(data => {
  // If both dates are provided, returned date must be after assigned date
  if (data.returnedDate && data.assignedDate) {
    const assignedDate = new Date(data.assignedDate);
    const returnedDate = new Date(data.returnedDate);
    return returnedDate > assignedDate;
  }
  return true;
}, {
  message: 'Returned date must be after the assigned date',
  path: ['returnedDate']
});

/**
 * Zod schema for Asset Assignment creation (excludes ID)
 */
export const AssetAssignmentCreateSchema = AssetAssignmentBaseSchema.omit({ assignmentID: true }).refine(data => {
  // If both dates are provided, returned date must be after assigned date
  if (data.returnedDate && data.assignedDate) {
    const assignedDate = new Date(data.assignedDate);
    const returnedDate = new Date(data.returnedDate);
    return returnedDate > assignedDate;
  }
  return true;
}, {
  message: 'Returned date must be after the assigned date',
  path: ['returnedDate']
});

/**
 * Zod schema for Asset Assignment updates (requires ID)
 */
export const AssetAssignmentUpdateSchema = AssetAssignmentBaseSchema.required({ assignmentID: true }).refine(data => {
  // If both dates are provided, returned date must be after assigned date
  if (data.returnedDate && data.assignedDate) {
    const assignedDate = new Date(data.assignedDate);
    const returnedDate = new Date(data.returnedDate);
    return returnedDate > assignedDate;
  }
  return true;
}, {
  message: 'Returned date must be after the assigned date',
  path: ['returnedDate']
});

/**
 * Zod schema for Asset Assignment form editing (excludes ID for form validation)
 * Uses Date objects instead of strings for form compatibility
 */
export const AssetAssignmentFormSchema = z.object({
  assetID: z.number().int().positive('Asset ID must be a positive number'),
  employeeID: z.number().int().positive('Employee ID must be a positive number'),
  employeeName: z.string()
    .min(1, 'Employee name is required')
    .max(100, 'Employee name must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Employee name cannot be empty or contain only spaces'
    }),
  assetCode: z.string()
    .min(1, 'Asset code is required')
    .max(20, 'Asset code must be 20 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Asset code cannot be empty or contain only spaces'
    }),
  assignedDate: z.date({
    required_error: 'Assigned date is required',
    invalid_type_error: 'Assigned date must be a valid date'
  }),
  returnedDate: z.date({
    invalid_type_error: 'Returned date must be a valid date'
  }).nullable(),
  remarks: z.string()
    .min(1, 'Remarks are required')
    .max(500, 'Remarks must be 500 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Remarks cannot be empty or contain only spaces'
    }),
}).refine(data => {
  // If both dates are provided, returned date must be after assigned date
  if (data.returnedDate && data.assignedDate) {
    return data.returnedDate > data.assignedDate;
  }
  return true;
}, {
  message: 'Returned date must be after the assigned date',
  path: ['returnedDate']
});

/**
 * Zod schema for Asset Item validation
 */
export const AssetItemSchema = z.object({
  itemID: z.number().int().positive().optional(),
  assetID: z.number().int().positive('Asset ID must be a positive number'),
  itemType: z.string()
    .min(1, 'Item type is required')
    .max(50, 'Item type must be 50 characters or less'),
  itemName: z.string()
    .min(1, 'Item name is required')
    .max(100, 'Item name must be 100 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Item name cannot be empty or contain only spaces'
    }),
  quantity: z.number().int().positive('Quantity must be a positive number').min(1, 'Quantity must be at least 1'),
  specifications: z.string()
    .min(1, 'Specifications are required')
    .max(200, 'Specifications must be 200 characters or less')
    .refine(val => val.trim().length > 0, {
      message: 'Specifications cannot be empty or contain only spaces'
    }),
  serialNumber: z.string()
    .max(50, 'Serial number must be 50 characters or less')
    .optional(),
  condition: z.enum(['Excellent', 'Good', 'Fair', 'Poor'], {
    errorMap: () => ({ message: 'Condition must be Excellent, Good, Fair, or Poor' })
  }),
  notes: z.string()
    .max(500, 'Notes must be 500 characters or less')
    .optional(),
  addedDate: z.string().datetime('Added date must be in ISO 8601 format'),
});

/**
 * Zod schema for Asset Item creation (excludes ID)
 */
export const AssetItemCreateSchema = AssetItemSchema.omit({ itemID: true });

/**
 * Zod schema for Asset Item updates (requires ID)
 */
export const AssetItemUpdateSchema = AssetItemSchema.required({ itemID: true });

// ============================================================================
// UTILITY TYPES AND INTERFACES
// ============================================================================

/**
 * Generic API response wrapper
 */
export interface AssetManagementApiResponse<T> {
  success: boolean;
  data?: T;
  message?: string;
  error?: string;
}

/**
 * Extended Asset interface with related data for detailed views
 */
export interface AssetWithDetails extends Asset {
  systemDetails?: SystemDetails;
  assignments?: AssetAssignment[];
  currentAssignment?: AssetAssignment;
  items?: AssetItem[];
}

/**
 * Extended System Details interface with asset information
 */
export interface SystemDetailsWithAsset extends SystemDetails {
  asset?: Asset;
}

/**
 * Extended Asset Assignment interface with related entity information
 */
export interface AssetAssignmentWithDetails extends AssetAssignment {
  asset?: Asset;
  employeeEmail?: string;
}

/**
 * Filter options for asset listing
 */
export interface AssetFilter {
  assetType?: string;
  assetCondition?: AssetCondition;
  searchTerm?: string;
  assignmentStatus?: 'assigned' | 'unassigned' | 'all';
}

/**
 * Sort options for asset listing
 */
export interface AssetSort {
  field: keyof Asset;
  direction: 'asc' | 'desc';
}

/**
 * Pagination options
 */
export interface PaginationOptions {
  page: number;
  limit: number;
}

/**
 * Paginated response wrapper
 */
export interface PaginatedResponse<T> {
  data: T[];
  total: number;
  page: number;
  limit: number;
  totalPages: number;
}

/**
 * Bulk import response interface
 */
export interface BulkImportResponse {
  success: boolean;
  message: string;
  results: {
    successful: number;
    failed: number;
    total: number;
    errors: ImportError[];
    createdAssets: Asset[];
  };
}

/**
 * Import error interface for bulk operations
 */
export interface ImportError {
  index: number;
  asset: AssetCreateRequest;
  error: string;
  field?: string;
}

// ============================================================================
// TYPE GUARDS AND VALIDATION HELPERS
// ============================================================================

/**
 * Type guard to check if an object is a valid Asset
 */
export function isAsset(obj: any): obj is Asset {
  return AssetSchema.safeParse(obj).success;
}

/**
 * Type guard to check if an object is a valid SystemDetails
 */
export function isSystemDetails(obj: any): obj is SystemDetails {
  return SystemDetailsSchema.safeParse(obj).success;
}

/**
 * Type guard to check if an object is a valid AssetAssignment
 */
export function isAssetAssignment(obj: any): obj is AssetAssignment {
  return AssetAssignmentSchema.safeParse(obj).success;
}

/**
 * Validates and transforms API response data to ensure type safety
 */
export function validateAssetApiResponse(data: any): Asset {
  // For API responses, we expect the ID to be present
  const schemaWithRequiredId = AssetSchema.required({ assetID: true });
  const result = schemaWithRequiredId.safeParse(data);
  if (!result.success) {
    console.error('Asset validation failed:', result.error);
    throw new Error(`Invalid asset data: ${result.error.message}`);
  }
  return result.data as Asset;
}

/**
 * Validates and transforms System Details API response data
 */
export function validateSystemDetailsApiResponse(data: any): SystemDetails {
  // For API responses, we expect the ID to be present
  const schemaWithRequiredId = SystemDetailsSchema.required({ systemDetailsID: true });
  const result = schemaWithRequiredId.safeParse(data);
  if (!result.success) {
    console.error('System Details validation failed:', result.error);
    throw new Error(`Invalid system details data: ${result.error.message}`);
  }
  return result.data as SystemDetails;
}

/**
 * Validates and transforms Asset Assignment API response data
 */
export function validateAssetAssignmentApiResponse(data: any): AssetAssignment {
  // For API responses, we expect the ID to be present
  const result = AssetAssignmentSchema.safeParse(data);
  if (!result.success) {
    console.error('Asset Assignment validation failed:', result.error);
    throw new Error(`Invalid asset assignment data: ${result.error.message}`);
  }
  return result.data as AssetAssignment;
}

// ============================================================================
// FORM VALIDATION HELPERS
// ============================================================================

/**
 * Helper to get validation errors for Asset forms
 */
export function getAssetValidationErrors(data: any): Record<string, string> {
  const result = AssetSchema.safeParse(data);
  if (result.success) return {};

  const errors: Record<string, string> = {};
  result.error.errors.forEach(error => {
    const field = error.path.join('.');
    errors[field] = error.message;
  });
  return errors;
}

/**
 * Helper to get validation errors for System Details forms
 */
export function getSystemDetailsValidationErrors(data: any): Record<string, string> {
  const result = SystemDetailsSchema.safeParse(data);
  if (result.success) return {};

  const errors: Record<string, string> = {};
  result.error.errors.forEach(error => {
    const field = error.path.join('.');
    errors[field] = error.message;
  });
  return errors;
}

/**
 * Helper to get validation errors for Asset Assignment forms
 */
export function getAssetAssignmentValidationErrors(data: any): Record<string, string> {
  const result = AssetAssignmentSchema.safeParse(data);
  if (result.success) return {};

  const errors: Record<string, string> = {};
  result.error.errors.forEach(error => {
    const field = error.path.join('.');
    errors[field] = error.message;
  });
  return errors;
}