# Complex Facade Patterns Sample

## Overview
This sample demonstrates advanced facade pattern implementations for enterprise scenarios including multi-layer facades, composition patterns, and complex system integration.

## Multi-Layer Facade Architecture

```al
// Business Service Layer Facade
codeunit 50200 "Sales Order Service Facade"
{
    var
        DocumentFacade: Codeunit "Document Processing Facade";
        ValidationFacade: Codeunit "Sales Validation Facade";
        IntegrationFacade: Codeunit "External Integration Facade";

    procedure ProcessSalesOrder(var SalesHeader: Record "Sales Header"): Boolean
    begin
        if not ValidationFacade.ValidateOrder(SalesHeader) then
            exit(false);

        if not DocumentFacade.ProcessDocument(SalesHeader) then
            exit(false);

        if SalesHeader."External Integration Required" then
            IntegrationFacade.NotifyExternalSystems(SalesHeader);

        exit(true);
    end;

    procedure CreateCompleteOrder(CustomerNo: Code[20]; Items: List of [Text]): Code[20]
    var
        SalesHeader: Record "Sales Header";
        OrderBuilder: Codeunit "Sales Order Builder";
    begin
        // Composite operation using multiple facades
        SalesHeader := OrderBuilder.CreateHeader(CustomerNo);
        OrderBuilder.AddItems(SalesHeader, Items);

        ValidationFacade.ValidateCompleteOrder(SalesHeader);
        DocumentFacade.FinalizeDocument(SalesHeader);

        exit(SalesHeader."No.");
    end;
}
```

## Facade Composition Pattern

```al
// Document Processing Facade (Lower Level)
codeunit 50201 "Document Processing Facade"
{
    var
        NumberSeriesMgmt: Codeunit "Number Series Management";
        DocumentValidation: Codeunit "Document Validation";
        StatusMgmt: Codeunit "Document Status Management";

    procedure ProcessDocument(var SalesHeader: Record "Sales Header"): Boolean
    var
        ProcessingContext: Record "Document Processing Context";
    begin
        ProcessingContext := CreateProcessingContext(SalesHeader);

        if not ValidateDocumentStructure(SalesHeader) then
            exit(false);

        AssignDocumentNumbers(SalesHeader);
        UpdateDocumentStatus(SalesHeader, ProcessingContext);
        LogProcessingActivity(SalesHeader, ProcessingContext);

        exit(true);
    end;

    local procedure CreateProcessingContext(SalesHeader: Record "Sales Header"): Record "Document Processing Context"
    var
        Context: Record "Document Processing Context";
    begin
        Context."Document Type" := SalesHeader."Document Type";
        Context."Document No." := SalesHeader."No.";
        Context."Processing Started" := CurrentDateTime;
        Context."User ID" := UserId;
        Context.Insert();
        exit(Context);
    end;
}
```

## Context-Aware Facade

```al
codeunit 50202 "Context Aware Sales Facade"
{
    procedure ProcessOrderByContext(var SalesHeader: Record "Sales Header"; Context: Enum "Processing Context"): Boolean
    var
        Strategy: Interface "Processing Strategy";
    begin
        Strategy := GetProcessingStrategy(Context);
        exit(Strategy.ProcessOrder(SalesHeader));
    end;

    local procedure GetProcessingStrategy(Context: Enum "Processing Context"): Interface "Processing Strategy"
    var
        StandardStrategy: Codeunit "Standard Processing Strategy";
        ExpressStrategy: Codeunit "Express Processing Strategy";
        BulkStrategy: Codeunit "Bulk Processing Strategy";
    begin
        case Context of
            Context::Standard:
                exit(StandardStrategy);
            Context::Express:
                exit(ExpressStrategy);
            Context::Bulk:
                exit(BulkStrategy);
        end;
    end;
}
```

## Enterprise Integration Facade

```al
codeunit 50203 "Enterprise Integration Facade"
{
    var
        ERPConnector: Codeunit "ERP System Connector";
        CRMConnector: Codeunit "CRM System Connector";
        EDIProcessor: Codeunit "EDI Message Processor";

    procedure SynchronizeCustomer(CustomerNo: Code[20]): Boolean
    var
        Customer: Record Customer;
        SyncResult: Record "Integration Sync Result";
    begin
        if not Customer.Get(CustomerNo) then
            exit(false);

        // Coordinate multiple system integrations
        SyncResult := InitializeSyncResult(CustomerNo);

        if Customer."CRM Integration Enabled" then
            UpdateCRMSyncResult(SyncResult, CRMConnector.SyncCustomer(Customer));

        if Customer."ERP Integration Enabled" then
            UpdateERPSyncResult(SyncResult, ERPConnector.SyncCustomer(Customer));

        if Customer."EDI Integration Enabled" then
            UpdateEDISyncResult(SyncResult, EDIProcessor.ProcessCustomerUpdate(Customer));

        exit(SyncResult."Overall Success");
    end;

    procedure ProcessBulkIntegration(var Customers: Record Customer): Integer
    var
        SuccessCount: Integer;
        Customer: Record Customer;
    begin
        Customers.FindSet();
        repeat
            if SynchronizeCustomer(Customers."No.") then
                SuccessCount += 1;
        until Customers.Next() = 0;

        exit(SuccessCount);
    end;
}
```

## Configurable Facade Pattern

```al
codeunit 50204 "Configurable Business Facade"
{
    var
        FacadeConfig: Record "Facade Configuration";

    procedure ProcessBusinessTransaction(TransactionType: Enum "Business Transaction Type"; DataVariant: Variant): Boolean
    var
        ProcessingSteps: List of [Text];
        StepName: Text;
    begin
        LoadConfiguration(TransactionType);
        ProcessingSteps := GetConfiguredSteps();

        foreach StepName in ProcessingSteps do begin
            if not ExecuteProcessingStep(StepName, DataVariant) then
                exit(false);
        end;

        exit(true);
    end;

    local procedure LoadConfiguration(TransactionType: Enum "Business Transaction Type")
    begin
        FacadeConfig.SetRange("Transaction Type", TransactionType);
        FacadeConfig.SetRange(Active, true);
        if not FacadeConfig.FindFirst() then
            Error('No configuration found for transaction type %1', TransactionType);
    end;

    local procedure GetConfiguredSteps(): List of [Text]
    var
        ConfigLine: Record "Facade Configuration Line";
        StepsList: List of [Text];
    begin
        ConfigLine.SetRange("Configuration ID", FacadeConfig."Configuration ID");
        ConfigLine.SetCurrentKey("Step Order");
        if ConfigLine.FindSet() then
            repeat
                StepsList.Add(ConfigLine."Step Name");
            until ConfigLine.Next() = 0;

        exit(StepsList);
    end;
}
```

## Performance-Optimized Facade

```al
codeunit 50205 "Performance Optimized Facade"
{
    var
        CachedResults: Dictionary of [Text, Variant];
        BatchProcessor: Codeunit "Batch Processing Engine";

    procedure ProcessMultipleOrders(var SalesHeaders: Record "Sales Header"): Record "Batch Processing Result"
    var
        BatchJob: Record "Batch Processing Job";
        Result: Record "Batch Processing Result";
    begin
        BatchJob := BatchProcessor.CreateBatchJob('SALES_ORDER_PROCESSING');

        // Add all orders to batch
        SalesHeaders.FindSet();
        repeat
            BatchProcessor.AddToBatch(BatchJob, SalesHeaders);
        until SalesHeaders.Next() = 0;

        // Process batch with optimized resource usage
        Result := BatchProcessor.ExecuteBatch(BatchJob);

        // Clean up resources
        BatchProcessor.CompleteBatch(BatchJob);

        exit(Result);
    end;

    procedure GetCachedCustomerData(CustomerNo: Code[20]): Variant
    var
        CacheKey: Text;
        CustomerData: Variant;
    begin
        CacheKey := 'CUSTOMER_' + CustomerNo;

        if CachedResults.ContainsKey(CacheKey) then
            exit(CachedResults.Get(CacheKey));

        CustomerData := LoadCustomerData(CustomerNo);
        CachedResults.Set(CacheKey, CustomerData);

        exit(CustomerData);
    end;

    procedure ClearCache()
    begin
        Clear(CachedResults);
    end;
}
```

## Error Handling Facade

```al
codeunit 50206 "Error Handling Facade"
{
    procedure ExecuteWithErrorHandling(Operation: Interface "Business Operation"; var ErrorInfo: Record "Error Information"): Boolean
    var
        RetryCount: Integer;
        MaxRetries: Integer;
    begin
        MaxRetries := 3;
        RetryCount := 0;

        repeat
            RetryCount += 1;

            if TryExecuteOperation(Operation) then
                exit(true);

            HandleOperationError(GetLastErrorText(), RetryCount, ErrorInfo);

            if ShouldRetry(ErrorInfo, RetryCount, MaxRetries) then
                Sleep(CalculateRetryDelay(RetryCount))
            else
                exit(false);

        until RetryCount >= MaxRetries;

        exit(false);
    end;

    [TryFunction]
    local procedure TryExecuteOperation(Operation: Interface "Business Operation")
    begin
        Operation.Execute();
    end;

    local procedure ShouldRetry(ErrorInfo: Record "Error Information"; RetryCount: Integer; MaxRetries: Integer): Boolean
    begin
        if RetryCount >= MaxRetries then
            exit(false);

        case ErrorInfo."Error Type" of
            ErrorInfo."Error Type"::"Temporary Network Error",
            ErrorInfo."Error Type"::"Database Timeout":
                exit(true);
            else
                exit(false);
        end;
    end;
}
```

This sample demonstrates complex facade patterns including multi-layer architecture, composition, context-awareness, enterprise integration, configurability, performance optimization, and comprehensive error handling.