/**
 * Sync Helper Functions
 * Utility functions for sync operations including dependency ordering
 */

import { EntityType, ENTITY_DEPENDENCIES } from '../types/sync';

/**
 * Get entities in dependency order (parents before children)
 * @param entities List of entities to sync
 * @returns Ordered list of entities respecting dependencies
 */
export function getEntitySyncOrder(entities: EntityType[]): EntityType[] {
  const ordered: EntityType[] = [];
  const visited = new Set<EntityType>();
  const visiting = new Set<EntityType>();

  function visit(entity: EntityType) {
    if (visited.has(entity)) return;
    if (visiting.has(entity)) {
      throw new Error(`Circular dependency detected for entity: ${entity}`);
    }

    visiting.add(entity);

    // Visit dependencies first
    const dependencies = ENTITY_DEPENDENCIES[entity] || [];
    for (const dep of dependencies) {
      if (entities.includes(dep)) {
        visit(dep);
      }
    }

    visiting.delete(entity);
    visited.add(entity);
    ordered.push(entity);
  }

  // Visit all entities
  for (const entity of entities) {
    visit(entity);
  }

  return ordered;
}

/**
 * Get all entities in default sync order
 * @returns All entities in dependency order
 */
export function getAllEntitiesInOrder(): EntityType[] {
  return getEntitySyncOrder([
    EntityType.COMPANIES,
    EntityType.RESOURCES,
    EntityType.STATUSES,
    EntityType.ISSUE_TYPES,
    EntityType.SUB_ISSUE_TYPES,
    EntityType.WORK_TYPES,
    EntityType.QUEUES,
    EntityType.PRIORITIES,
    EntityType.TICKET_CATEGORIES,
    EntityType.CONTACTS,
    EntityType.PROJECTS,
    EntityType.PROJECT_PHASES,
    EntityType.TICKETS,
    EntityType.TICKET_NOTES,
    EntityType.TASKS,
    EntityType.CONFIGURATION_ITEMS,
    EntityType.CONTRACTS,
    EntityType.CONTRACT_SERVICES,
    EntityType.AUTOTASK_SERVICES,
    EntityType.BILLING_ITEMS,
    EntityType.TIME_ENTRIES,
    EntityType.TAG_GROUPS,
    EntityType.TAGS,
    EntityType.COMPANY_TEAMS,
  ]);
}

/**
 * Build filter for contract services (requires contractID filter — fetch all via contractIDs)
 * @returns Query filter array for active contract services
 */
export function buildContractServicesFilter(): Array<{ field: string; op: string; value: any }> {
  return [
    {
      field: 'contractID',
      op: 'gt',
      value: 0,
    },
  ];
}

/**
 * Get table name for entity type
 * @param entity Entity type
 * @returns PostgreSQL table name
 */
export function getTableName(entity: EntityType): string {
  return entity;
}

/**
 * Get Autotask API entity name
 * @param entity Entity type
 * @returns Autotask API entity name (PascalCase)
 */
export function getAutotaskEntityName(entity: EntityType): string {
  const mapping: Record<EntityType, string> = {
    [EntityType.COMPANIES]: 'Companies',
    [EntityType.TICKETS]: 'Tickets',
    [EntityType.TASKS]: 'Tasks',
    [EntityType.PROJECTS]: 'Projects',
    [EntityType.RESOURCES]: 'Resources',
    [EntityType.STATUSES]: 'Statuses',
    [EntityType.ISSUE_TYPES]: 'IssueTypes',
    [EntityType.SUB_ISSUE_TYPES]: 'SubIssueTypes',
    [EntityType.WORK_TYPES]: 'WorkTypes',
    [EntityType.QUEUES]: 'Queues',
    [EntityType.PRIORITIES]: 'Priorities',
    [EntityType.TICKET_CATEGORIES]: 'TicketCategories',
    [EntityType.BILLING_ITEMS]: 'BillingItems',
    [EntityType.CONFIGURATION_ITEMS]: 'ConfigurationItems',
    [EntityType.CONTACTS]: 'Contacts',
    [EntityType.CONTRACTS]: 'Contracts',
    [EntityType.CONTRACT_SERVICES]: 'ContractServices',
    [EntityType.AUTOTASK_SERVICES]: 'Services',
    [EntityType.TIME_ENTRIES]: 'TimeEntries',
    [EntityType.TICKET_NOTES]: 'TicketNotes',
    [EntityType.TAG_GROUPS]: 'TagGroups',
    [EntityType.TAGS]: 'Tags',
    [EntityType.PROJECT_PHASES]: 'Phases',
    [EntityType.COMPANY_CATEGORIES]: 'CompanyCategories',
    [EntityType.COMPANY_TYPES]: 'CompanyTypes',
    [EntityType.COMPANY_TEAMS]: 'CompanyTeams',
  };

  return mapping[entity] || entity;
}

/**
 * Check if entity is a picklist type
 * @param entity Entity type
 * @returns True if entity is a picklist
 */
export function isPicklistEntity(entity: EntityType): boolean {
  return [
    EntityType.STATUSES,
    EntityType.ISSUE_TYPES,
    EntityType.SUB_ISSUE_TYPES,
    EntityType.WORK_TYPES,
    EntityType.QUEUES,
    EntityType.PRIORITIES,
    EntityType.TICKET_CATEGORIES,
    EntityType.COMPANY_TYPES,
  ].includes(entity);
}

/**
 * Get field name for last modified date in Autotask
 * @param entity Entity type
 * @returns Field name for filtering by last modified date
 */
export function getLastModifiedField(entity: EntityType): string {
  const mapping: Record<EntityType, string> = {
    [EntityType.COMPANIES]: 'lastActivityDate',
    [EntityType.TICKETS]: 'lastActivityDate',
    [EntityType.TASKS]: 'lastActivityDateTime',
    [EntityType.PROJECTS]: 'lastActivityDateTime',
    [EntityType.RESOURCES]: 'lastModifiedDate',
    [EntityType.CONFIGURATION_ITEMS]: 'lastModifiedTime',
    [EntityType.CONTACTS]: 'lastModifiedDate',
    [EntityType.CONTRACTS]: 'lastModifiedDateTime',
    [EntityType.CONTRACT_SERVICES]: 'lastModifiedDate',
    [EntityType.AUTOTASK_SERVICES]: 'lastModifiedDate',
    [EntityType.BILLING_ITEMS]: 'itemDate',
    [EntityType.TIME_ENTRIES]: 'lastModifiedDateTime',
    [EntityType.TICKET_NOTES]: 'lastActivityDate',
    [EntityType.STATUSES]: 'lastModifiedDate',
    [EntityType.ISSUE_TYPES]: 'lastModifiedDate',
    [EntityType.SUB_ISSUE_TYPES]: 'lastModifiedDate',
    [EntityType.WORK_TYPES]: 'lastModifiedDate',
    [EntityType.QUEUES]: 'lastModifiedDate',
    [EntityType.PRIORITIES]: 'lastModifiedDate',
    [EntityType.TICKET_CATEGORIES]: 'lastModifiedDate',
    [EntityType.TAG_GROUPS]: 'lastModifiedDate',
    [EntityType.TAGS]: 'lastModifiedDateTime',
    [EntityType.PROJECT_PHASES]: 'lastActivityDateTime',
    [EntityType.COMPANY_CATEGORIES]: 'lastModifiedDate',
    [EntityType.COMPANY_TYPES]: 'lastModifiedDate',
    [EntityType.COMPANY_TEAMS]: 'lastModifiedDate', // No date field; incremental not supported
  };

  return mapping[entity] || 'lastModifiedDate';
}

/**
 * Get active status field name for entity
 * @param entity Entity type
 * @returns Field name for active status
 */
export function getActiveField(entity: EntityType): string | null {
  const mapping: Record<EntityType, string | null> = {
    [EntityType.COMPANIES]: 'isActive',
    [EntityType.TICKETS]: null, // Use status field instead
    [EntityType.TASKS]: null, // Use status field instead
    [EntityType.PROJECTS]: null, // Use status field instead
    [EntityType.RESOURCES]: 'isActive',
    [EntityType.CONFIGURATION_ITEMS]: 'isActive',
    [EntityType.CONTACTS]: 'isActive',
    [EntityType.CONTRACTS]: null, // Use status field instead
    [EntityType.CONTRACT_SERVICES]: null,
    [EntityType.AUTOTASK_SERVICES]: 'isActive',
    [EntityType.BILLING_ITEMS]: null,
    [EntityType.TIME_ENTRIES]: null, // Time entries don't have active status
    [EntityType.TICKET_NOTES]: null, // Ticket notes don't have active status
    [EntityType.STATUSES]: 'isActive',
    [EntityType.ISSUE_TYPES]: 'isActive',
    [EntityType.SUB_ISSUE_TYPES]: 'isActive',
    [EntityType.WORK_TYPES]: 'isActive',
    [EntityType.QUEUES]: 'isActive',
    [EntityType.PRIORITIES]: 'isActive',
    [EntityType.TICKET_CATEGORIES]: 'isActive',
    [EntityType.TAG_GROUPS]: 'isActive',
    [EntityType.TAGS]: 'isActive',
    [EntityType.PROJECT_PHASES]: null, // No active field on phases
    [EntityType.COMPANY_CATEGORIES]: 'isActive',
    [EntityType.COMPANY_TYPES]: 'isActive',
    [EntityType.COMPANY_TEAMS]: null,
  };

  return mapping[entity] || null;
}

/**
 * Build Autotask query filter for incremental sync
 * @param entity Entity type
 * @param lastSyncTime Last successful sync timestamp
 * @returns Query filter array
 */
export function buildIncrementalFilter(
  entity: EntityType,
  lastSyncTime: Date
): Array<{ field: string; op: string; value: any }> {
  const lastModifiedField = getLastModifiedField(entity);
  
  return [
    {
      field: lastModifiedField,
      op: 'gte',
      value: lastSyncTime.toISOString(),
    },
  ];
}

/**
 * Build Autotask query filter for active records only
 * @param entity Entity type
 * @returns Query filter array or null if no active field
 */
export function buildActiveFilter(
  entity: EntityType
): Array<{ field: string; op: string; value: any }> | null {
  const activeField = getActiveField(entity);
  
  if (!activeField) {
    return null;
  }

  return [
    {
      field: activeField,
      op: 'eq',
      value: true,
    },
  ];
}

/**
 * Build date range filter for entities to limit sync to recent records
 * @param entity Entity type
 * @param yearsBack Number of years to look back (default: 2)
 * @returns Query filter array or null if entity doesn't support date filtering
 */
export function buildDateRangeFilter(
  entity: EntityType,
  yearsBack: number = 2
): Array<{ field: string; op: string; value: any }> | null {
  // Only apply date range filters to time-based entities
  // Note: TIME_ENTRIES removed because Autotask API doesn't support date filtering on TimeEntry
  const timeBasedEntities = [
    EntityType.TICKETS,
    EntityType.TICKET_NOTES,
    EntityType.TASKS,
  ];

  if (!timeBasedEntities.includes(entity)) {
    return null;
  }

  // Define which entities should have date range filters and which field to use
  const dateFieldMapping: Record<EntityType, string | null> = {
    [EntityType.TICKETS]: 'createDate',
    [EntityType.TASKS]: 'createDateTime',
    [EntityType.TIME_ENTRIES]: 'createDate', // TimeEntry uses createDate for filtering
    [EntityType.PROJECTS]: 'startDateTime',
    [EntityType.BILLING_ITEMS]: 'itemDate',
    [EntityType.CONTRACTS]: 'startDate',
    [EntityType.CONTRACT_SERVICES]: null,
    [EntityType.AUTOTASK_SERVICES]: null,
    [EntityType.COMPANIES]: null,
    [EntityType.RESOURCES]: null,
    [EntityType.CONTACTS]: null,
    [EntityType.CONFIGURATION_ITEMS]: null,
    [EntityType.TICKET_NOTES]: 'lastActivityDate',
    [EntityType.TAG_GROUPS]: null,
    [EntityType.TAGS]: null,
    [EntityType.STATUSES]: null,
    [EntityType.ISSUE_TYPES]: null,
    [EntityType.SUB_ISSUE_TYPES]: null,
    [EntityType.WORK_TYPES]: null,
    [EntityType.QUEUES]: null,
    [EntityType.PRIORITIES]: null,
    [EntityType.TICKET_CATEGORIES]: null,
    [EntityType.PROJECT_PHASES]: null,
    [EntityType.COMPANY_CATEGORIES]: null,
    [EntityType.COMPANY_TYPES]: null,
    [EntityType.COMPANY_TEAMS]: null,
  };

  const dateField = dateFieldMapping[entity];
  
  if (!dateField) {
    return null;
  }

  // Calculate date from X years ago
  // Convert years to milliseconds for accurate calculation (including fractional years)
  const cutoffDate = new Date();
  const millisecondsPerYear = 365.25 * 24 * 60 * 60 * 1000; // Account for leap years
  const millisecondsBack = yearsBack * millisecondsPerYear;
  cutoffDate.setTime(cutoffDate.getTime() - millisecondsBack);

  console.log(`Date range filter: ${dateField} >= ${cutoffDate.toISOString()} (${yearsBack} years back)`);

  return [
    {
      field: dateField,
      op: 'gte',
      value: cutoffDate.toISOString(),
    },
  ];
}

/**
 * Build special filter for contracts (requires status filter)
 * @returns Query filter array for active contracts
 */
export function buildContractsFilter(): Array<{ field: string; op: string; value: any }> {
  // Contracts API requires a filter. Use status = 1 for Active contracts
  // Status values: 1 = Active, others are inactive/expired
  return [
    {
      field: 'status',
      op: 'eq',
      value: 1,
    },
  ];
}

/**
 * Build filter for project phases (Phases endpoint requires a filter)
 * @returns Query filter array for all phases
 */
export function buildProjectPhasesFilter(): Array<{ field: string; op: string; value: any }> {
  return [
    {
      field: 'id',
      op: 'gt',
      value: 0,
    },
  ];
}

/**
 * Build special filter for projects (requires status filter)
 * @returns Query filter array for active projects
 */
export function buildProjectsFilter(): Array<{ field: string; op: string; value: any }> {
  // Projects API requires a filter. Use status = 1 for New/Active projects
  // Status values: 1 = New, others include Complete, Cancelled, etc.
  // To get all active projects, we should filter for status NOT equal to Complete (5)
  return [
    {
      field: 'status',
      op: 'noteq',
      value: 5, // 5 = Complete
    },
  ];
}

/**
 * Build special filter for time entries (requires filter)
 * @param yearsBack Number of years to look back (default: 2)
 * @returns Query filter array for time entries
 */
export function buildTimeEntriesFilter(yearsBack: number = 2): Array<{ field: string; op: string; value: any }> {
  // TimeEntries API requires a filter. Use lastModifiedDateTime so that edits
  // to existing entries (e.g. hours changed, notes updated) are picked up even
  // if the dateWorked is in the past or future.
  // We still bound it by yearsBack to avoid a full scan on first load.
  const cutoffDate = new Date();
  const millisecondsPerYear = 365.25 * 24 * 60 * 60 * 1000;
  const millisecondsBack = yearsBack * millisecondsPerYear;
  cutoffDate.setTime(cutoffDate.getTime() - millisecondsBack);

  console.log(`TimeEntries filter: lastModifiedDateTime >= ${cutoffDate.toISOString()} (${yearsBack} years back)`);

  return [
    {
      field: 'lastModifiedDateTime',
      op: 'gte',
      value: cutoffDate.toISOString(),
    },
  ];
}

/**
 * Build special filter for billing items (requires filter)
 * @param yearsBack Number of years to look back (default: 2)
 * @returns Query filter array for billing items
 */
export function buildBillingItemsFilter(yearsBack: number = 2): Array<{ field: string; op: string; value: any }> {
  // BillingItems API requires a filter. Use itemDate to limit the range
  // Calculate date from X years ago
  const cutoffDate = new Date();
  const millisecondsPerYear = 365.25 * 24 * 60 * 60 * 1000;
  const millisecondsBack = yearsBack * millisecondsPerYear;
  cutoffDate.setTime(cutoffDate.getTime() - millisecondsBack);

  console.log(`BillingItems filter: itemDate >= ${cutoffDate.toISOString()} (${yearsBack} years back)`);

  return [
    {
      field: 'itemDate',
      op: 'gte',
      value: cutoffDate.toISOString(),
    },
  ];
}

/**
 * Calculate estimated sync duration based on record count
 * @param recordCount Number of records to sync
 * @param rateLimit Requests per second
 * @param pageSize Records per page
 * @returns Estimated duration in milliseconds
 */
export function estimateSyncDuration(
  recordCount: number,
  rateLimit: number = 10,
  pageSize: number = 500
): number {
  const totalPages = Math.ceil(recordCount / pageSize);
  const secondsNeeded = totalPages / rateLimit;
  const processingOverhead = recordCount * 0.001; // 1ms per record for processing
  
  return (secondsNeeded * 1000) + processingOverhead;
}

/**
 * Format sync duration for display
 * @param milliseconds Duration in milliseconds
 * @returns Formatted duration string
 */
export function formatDuration(milliseconds: number): string {
  const seconds = Math.floor(milliseconds / 1000);
  const minutes = Math.floor(seconds / 60);
  const hours = Math.floor(minutes / 60);

  if (hours > 0) {
    return `${hours}h ${minutes % 60}m`;
  } else if (minutes > 0) {
    return `${minutes}m ${seconds % 60}s`;
  } else {
    return `${seconds}s`;
  }
}

/**
 * Generate unique sync ID
 * @returns Unique sync identifier
 */
export function generateSyncId(): string {
  return `sync_${Date.now()}_${Math.random().toString(36).substring(2, 9)}`;
}

/**
 * Validate entity type
 * @param entity Entity type string
 * @returns True if valid entity type
 */
export function isValidEntityType(entity: string): entity is EntityType {
  return Object.values(EntityType).includes(entity as EntityType);
}

/**
 * Get entity display name
 * @param entity Entity type
 * @returns Human-readable entity name
 */
export function getEntityDisplayName(entity: EntityType): string {
  const mapping: Record<EntityType, string> = {
    [EntityType.COMPANIES]: 'Companies',
    [EntityType.TICKETS]: 'Tickets',
    [EntityType.TASKS]: 'Tasks',
    [EntityType.PROJECTS]: 'Projects',
    [EntityType.RESOURCES]: 'Resources',
    [EntityType.STATUSES]: 'Statuses',
    [EntityType.ISSUE_TYPES]: 'Issue Types',
    [EntityType.SUB_ISSUE_TYPES]: 'Sub-Issue Types',
    [EntityType.WORK_TYPES]: 'Work Types',
    [EntityType.QUEUES]: 'Queues',
    [EntityType.PRIORITIES]: 'Priorities',
    [EntityType.TICKET_CATEGORIES]: 'Ticket Categories',
    [EntityType.BILLING_ITEMS]: 'Billing Items',
    [EntityType.CONFIGURATION_ITEMS]: 'Configuration Items',
    [EntityType.CONTACTS]: 'Contacts',
    [EntityType.CONTRACTS]: 'Contracts',
    [EntityType.CONTRACT_SERVICES]: 'Contract Services',
    [EntityType.AUTOTASK_SERVICES]: 'Autotask Services',
    [EntityType.TIME_ENTRIES]: 'Time Entries',
    [EntityType.TICKET_NOTES]: 'Ticket Notes',
    [EntityType.TAG_GROUPS]: 'Tag Groups',
    [EntityType.TAGS]: 'Tags',
    [EntityType.PROJECT_PHASES]: 'Project Phases',
    [EntityType.COMPANY_CATEGORIES]: 'Company Categories',
    [EntityType.COMPANY_TYPES]: 'Company Types',
    [EntityType.COMPANY_TEAMS]: 'Company Teams',
  };

  return mapping[entity] || entity;
}