Smart Solutions: Record Keeping App

Production WPF desktop application built for Smart Solutions, Peshawar (NTN: 7569020-2), a printing and Haier AC after-sales service business. Designed and developed with specification-driven design, architecture review, implementation, testing, and deployment, by a software engineer with 20+ years of experience.

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The Problem It Solves

Smart Solutions was tracking print orders, Haier AC jobs, and business finances using Excel spreadsheets and manually generated invoices:

Daily transaction log in Excel	Monthly income/expense summary	Manually generated invoice

Manual, error-prone, impossible to audit, and not shareable across multiple PCs. This app replaces the entire workflow with a validated, guided, multi-user desktop application.

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What It Does

Print Business

• Print Orders: customers, multi-line orders with per-sqft and per-piece pricing, vendor assignment, status tracking (Draft → Confirmed → Sent to Vendor → Ready → Delivered)
• PDF Invoices: generated from a FastReport template with business letterhead
• Partial Payments: collect payments over time; balance = total invoiced − sum of payments

Haier AC After-Sales Service

• Haier Jobs: warranty and out-of-warranty repair jobs, technician assignment, job status tracking (Pending → In Progress → Completed)
• Job Payments: same partial payment model as print orders

Business Operations

• Expenses: categorised expense tracking with payment channel breakdown (Cash, Easypaisa, Bank, etc.)
• Financial Reports: income, expense, and profit summaries by date range
• Customer Management: searchable customer list with contact and address details
• Audit Trail: every record stamped with the creating user; full accountability without complex permissions

Setup & Deployment

• First-Run Wizard: guided 3-step setup (database connection → business info → admin PIN) on first launch
• Multi-PC LAN: each PC has its own appsettings.json; all connect to a shared SQL Server on the LAN
• MSIX Installer: distributed as a signed .msix package for clean Windows installation

Lookup Data (all user-managed, nothing hardcoded)

Item categories, item names, vendors, technicians, expense categories, payment channels, and user accounts: all managed via dedicated sidebar pages. No hardcoded lists anywhere.

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Tech Stack

Component	Technology
Runtime	.NET 10, C#
UI Framework	WPF + XAML
MVVM	CommunityToolkit.Mvvm
Database	SQL Server Express 2022
ORM	Entity Framework Core 10 (code-first, migrations)
UI Theme	MaterialDesignInXamlToolkit
PDF / Print	FastReport Community
Packaging	MSIX (single-project)
Tests	xUnit + NSubstitute + FluentAssertions

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Architecture

Three-layer separation (no business logic in the UI layer, no EF in the business layer):

SmartSolutions.Data      16 entities · EF Core migrations · AppDbContext
SmartSolutions.Core       8 services · 10 interfaces · all business logic
SmartSolutions.App       19 ViewModels · 17 Views · Material Design UI · FastReport templates
SmartSolutions.Tests     35 unit tests · NSubstitute mocks · in-memory DB

Key patterns:

• MVVM strictly enforced: [ObservableProperty] and [RelayCommand] from CommunityToolkit; no business logic in code-behind
• IDbContextFactory<AppDbContext> on every service: no shared singleton DbContext, safe for async
• ISessionService singleton: holds the logged-in user in memory for audit trail stamping
• All database calls are async: no .Result or .Wait() anywhere

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Engineering Workflow

This project was built using a structured, specification-driven engineering workflow:

1. Requirements: business problem captured as a structured Product Requirements Document
2. Architecture & design specs: each feature designed and reviewed before any code was written
3. Implementation plans: detailed, task-by-task plans reviewed and confirmed
4. Implementation: built incrementally, reviewed at every milestone
5. Testing: 35-test xUnit suite (services, validation, connection handling) kept green throughout
6. Deployment: MSIX packaging, first-run wizard, per-PC LAN configuration

The product requirements are documented in this repo:

Artifact	Link
Product Requirements Document	docs/PRD.md

Designed and built by a software engineer with 20+ years of experience, going from idea to production-ready app with every spec reviewed and approved before a line of code was written.

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Getting Started

See docs/INSTALL.md for full setup instructions including MSIX certificate install and the first-run wizard walkthrough.

Prerequisites:

• Windows 10 / 11
• SQL Server Express 2022 (on one PC on the LAN)
• .NET 10 Desktop Runtime