429 lines
20 KiB
Markdown
429 lines
20 KiB
Markdown
# NTech
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[🇷🇸 Srpska verzija](Readme_sr.md)
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<img width="1440" height="754" alt="image" src="https://github.com/user-attachments/assets/2ea0746f-2f8e-46f7-9551-06e49c0e61ed" />
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A business application for computer repair shop management, parts inventory tracking, and sales. Built with Go, it runs in the browser and requires no internet connection or external services.
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> ⚠️ The project is under active development. It is not ready for production use.
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**Live demo:** [https://demo.vm-net.in.rs](https://demo.vm-net.in.rs) — log in with `Demo` / `Demo1234` (admin role; password and 2FA changes are disabled in demo mode).
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---
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## About the Project
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NTech is an internal application built for a specific user — a computer repair shop that, in addition to repairs, manages a parts inventory, sales of components and pre-built configurations, as well as client and supplier records.
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The goal is simple: everything the repair shop needs to track is located in one place, without relying on Excel spreadsheets or paper records.
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---
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## How It Works
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**Server-rendered, no build step.** Pages are rendered on the server with Go's `html/template` (auto-escaping, no client-side templating engine). [HTMX](https://htmx.org) swaps page fragments over plain HTTP for SPA-like navigation, and [Alpine.js](https://alpinejs.dev) handles small bits of client-side interactivity (live totals, dynamic form rows, autocomplete). There is no `npm`/webpack build — the browser gets plain HTML/CSS/JS, and a single page load is enough to use the whole app.
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**Single binary, no runtime dependencies.** Templates, static assets (CSS/JS/images) and SQL migrations are embedded into the compiled binary with `go:embed`. Deploying is copying one file (or running one Docker image) — there's no separate asset build, no template files to ship alongside the executable. In development the same code reads straight from disk instead, so template/CSS/JS edits are visible on refresh without a rebuild.
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**Request flow.** `chi` routes each request through a middleware chain — security headers → CSRF (double-submit cookie) → session lookup → role/permission check — before it reaches a handler. Permission checks run at the router level (so a route can't accidentally ship unprotected) and again inside the handler as defense in depth. Handlers talk to the database through a repository layer (plain SQL, no ORM) and pass plain Go structs to templates.
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**Database.** SQLite via a pure-Go driver (`modernc.org/sqlite`, no CGO) is the default and only dependency — a single file, no separate database server to run or back up. Every startup applies any new SQL migration files in order and records them in a `migracije` table, so upgrades are just "replace the binary and restart." An optional PostgreSQL backend (via `pgx/v5`) is planned for multi-user setups.
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**Client-facing public pages.** Two flows don't require a login, only a unique unguessable token in the URL: the service-status page (a client can check repair progress and get a QR code straight from their receipt) and the parts/service proposal approval page (a client accepts or rejects an estimate with a comment). Both are capability-based — whoever has the link has access to that one order, nothing else.
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**Printable documents.** Work orders, pre-invoices, dispatch notes, return slips, and device labels are separate, self-contained HTML pages styled for A4 printing (`@media print`), each with a "Print" button that opens the browser's native print dialog — no PDF library, no headless-browser rendering step. Documents that don't fit one page paginate themselves client-side (measuring content height and inserting page breaks with running page numbers).
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---
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## Features
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### Implemented
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- Initial setup on first run (setup wizard)
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- Database migration system
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- User interface — sidebar navigation, theme system (dark/light), dashboard with statistics
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- User login — server-side sessions, account locking
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- Two-factor authentication (TOTP) — activation with a QR code; secret encrypted at rest (AES-256-GCM, key kept outside the database)
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- Backup (one-time) codes for 2FA — generated on activation, stored as bcrypt hashes; a fallback to TOTP at login
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- Brute-force protection — IP locking after 5 failed attempts within 15 minutes
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- CSRF protection — double-submit cookie pattern, automatic token injection into all forms
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- Security HTTP headers (CSP, X-Frame-Options, Referrer-Policy, nosniff...)
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- Login attempt logging — history by user, IP, reason, date
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- Users and roles — admin panel, user management
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- Inventory — items, categories, filtering, critical stock levels, per-item stock card, supplier links, item transfers
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- Barcode (EAN) per item — searchable by barcode in inventory; in the sales screen, scanning a barcode (any USB/Bluetooth scanner that types + Enter) looks the item up and adds it to the order automatically
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- Service orders:
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- Intake form, status bar, archive
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- Diagnostic workflow — fault description, technician notes, work done, diagnostic fee
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- Parts and services — used items deducted from stock; suggested items (proposal to client)
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- Client proposal approval — client receives a public link (QR code) to accept or reject a parts/service proposal with a comment
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- Public status tracking via QR code — the device label and every printed document carry a QR code the client scans with their phone; it opens a mobile-optimized page (no login, no app) showing the current repair status, which they can revisit any time by the same link/code
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- Documents — work order, pre-invoice (estimate), dispatch note, return slip, device label (QR + Code128 barcode)
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- Pickup with payment — tracks payment method and advance amount
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- Guarantee period, expected completion date, technician assignment, client notes
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- Sales orders — items, calculation, receipt with company and client details
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- Services catalog — service price list used for billing in service orders
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- Expenses — expense records with category and amount
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- Procurement — records of purchases from suppliers
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- Sales price calculation on procurement — markup (global, per category, per item), landed costs (customs, shipping...) allocated across items, two-way markup↔price computation; respects VAT-payer status
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- Price revaluation (nivelacija) — sales price changes with an audit trail (old→new, reason, source, user)
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- Company profile and modules — features toggle based on company type and VAT-payer status
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- VAT records (KIR/KPR) — books of issued and received invoices, auto-filled from sales and procurement
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- VAT calculation per period + mapping to the PP-PDV form; imports (customs declaration) tracked in fields 006/106
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- VAT rate code list
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- **Fiscalization (ESIR/L-PFR)** — full Go client for the Teron fiscal device API: connection test, invoice issuing (sale/service, including advances and refunds on cancellation), daily till summary, end-of-day closure, PDF fiscal reports, QR-code invoice verification (public `/v/` page), automatic retry on failed fiscalization with a visible error state, and a card-emulator status/reset panel (talks to the signing device over TCP). Currently verified against the Teron mock server (`Fisk/`); not yet tested against real certified hardware.
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- Clients and suppliers — contact database
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- Reminders — records with deadlines
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- Reports — revenue overview, inventory status, inventory value report, stock movement list, stocktake (physical count)
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- Settings — company name, address, Tax ID (PIB), logo; theme toggle
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- Background images — login page and app, with blur, transparency and glass effect
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- Personal theme and background — each user can set their own theme and background image
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- Permission matrix (RBAC) — admin panel for permissions by role; enforced at the route level (both mutations and views) and in handlers
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- Flash messages — one-time feedback after an action
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- Automatic SQLite backup — with configurable number of retained copies; restore from a copy (safe, with no downtime)
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- Charts — monthly revenue on reports (Chart.js)
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- Structured logging — `log/slog` (JSON in production, text in development); separate auth log in fail2ban format
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- Automated tests — unit and integration over a SQLite database (crypto, RBAC, login flows, form validators, reports)
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- **Demo mode** (`NTECH_ENV=demo`) — auto-created demo user, pre-filled login form, restricted backup count, blocked password/2FA changes
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### In Progress
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- **Fiscalization on real hardware** — the full flow (issuing, refunds, daily till, closure, reports) is implemented and verified against the Teron mock server; testing against a real certified L-PFR device is still pending.
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### Planned
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- KPO book and double-entry bookkeeping (optional, later phase)
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- PostgreSQL support (for multi-user environments)
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- WebAuthn / Passkey login (database schema is already prepared)
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- Notifications (email / WhatsApp) — deferred to a later phase
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- Barcode scanning via camera — deferred to a later phase
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---
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## Technologies
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| Technology | Role |
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| [Go](https://go.dev) | backend language |
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| [chi](https://github.com/go-chi/chi) | HTTP router |
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| [html/template](https://pkg.go.dev/html/template) | server-side templates |
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| [HTMX](https://htmx.org) | dynamic HTML over HTTP |
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| [Alpine.js](https://alpinejs.dev) | client-side UI logic |
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| [SQLite](https://sqlite.org) + [modernc.org/sqlite](https://gitlab.com/cznic/sqlite) | main database (pure Go, no CGO) |
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| [PostgreSQL](https://www.postgresql.org) + [pgx/v5](https://github.com/jackc/pgx) | optional production database |
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---
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## Running the Application
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### Requirements
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- Go 1.26 or newer
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- Git
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### Steps
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```bash
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# 1. Clone the repository
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git clone <repository-url>
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cd GoNtech
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# 2. Run in development mode (reads files from disk, no HTTPS required)
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go run ./cmd/ntech
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```
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The application opens at `http://localhost:8080`. On first run the setup wizard starts automatically.
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### Production Build
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Use the interactive build script:
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```bash
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./start.sh
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```
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It asks for the version, environment (production/development), platform (Linux/Windows/both), optional UPX compression, and whether to push a Docker image to Gitea and GitHub Container Registry.
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Or build manually:
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```bash
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CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build \
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-ldflags "-X main.Verzija=1.0.0 -s -w" \
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-trimpath \
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-o ntech ./cmd/ntech
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```
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The result is a single static binary with no external dependencies.
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---
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## Environment Variables
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The application reads environment variables on startup. In development, place them in `ntech.env` alongside the SQLite database file. In production/demo the program creates `ntech.env` automatically in the same directory as the database.
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`ntech.env` is **never committed** to Git.
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| Variable | Default | Description |
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| ---------------- | ------------- | ----------------------------------------------------------------- |
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| `NTECH_ENV` | `development` | Mode: `development`, `production`, or `demo` |
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| `NTECH_PORT` | `8080` | HTTP port |
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| `NTECH_DB` | `sqlite` | Database type: `sqlite` or `postgres` |
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| `NTECH_SQLITE` | `ntech.db` | Path to the SQLite file |
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| `NTECH_DSN` | — | PostgreSQL connection string |
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| `NTECH_SECRET` | — | Session signing key (min. 32 bytes); auto-generated if missing |
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| `NTECH_TOTP_KEY` | — | AES-256 key for TOTP secret encryption; auto-generated if missing |
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| `BE_ENABLED` | `true` | Enables the built-in card-emulator (fiscalization signing device) |
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| `BE_PORT` | `4567` | TCP port for the built-in card-emulator |
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`NTECH_SECRET` and `NTECH_TOTP_KEY` are generated automatically on the first run and saved to `ntech.env`. **Back this file up** — losing `NTECH_TOTP_KEY` invalidates all 2FA secrets stored in the database.
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---
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## Docker Deployment
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Docker images are published to:
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- `ghcr.io/dalibor31/ntech:latest`
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- `git.vm-net.in.rs/dasko/ntech:latest`
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### Production
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```yaml
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# docker-compose.yml
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services:
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ntech:
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image: ghcr.io/dalibor31/ntech:latest
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restart: unless-stopped
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environment:
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NTECH_ENV: production
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NTECH_PORT: "8000"
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NTECH_SQLITE: /app/data/ntech.db
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volumes:
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- ./data:/app/data # database + ntech.env (secrets)
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- ./uploads:/app/uploads # uploaded images
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- ./logs:/app/logs # structured + auth logs
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- ./backups:/app/backups # automatic database backups
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ports:
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- "8000:8000"
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```
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On the **first start** the setup wizard runs and creates the first admin user. After that, `./data/ntech.env` contains the auto-generated secrets — **back it up**.
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Place the app behind a reverse proxy (Caddy, nginx) that terminates HTTPS. Secure cookies require HTTPS.
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Example Caddy config:
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```
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your.domain.com {
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reverse_proxy ntech:8000
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}
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```
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### With Teron L-PFR Mock (Fiscalization Testing)
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The `Fisk/` directory contains a Python mock server that simulates a [Teron](https://teron.rs) L-PFR fiscal device (port 4566). It implements the Teron HTTP API — invoice signing, PDV calculation, QR code generation, and per-type counters — without requiring real hardware or a certificate.
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Use it alongside NTech for fiscalization development and testing:
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```yaml
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# docker-compose.yml
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services:
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ntech:
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image: ghcr.io/dalibor31/ntech:latest
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container_name: ntech
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restart: unless-stopped
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ports:
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- "8000:8000"
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environment:
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NTECH_ENV: production
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NTECH_PORT: "8000"
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NTECH_SQLITE: /app/data/ntech.db
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volumes:
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- ./data:/app/data
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- ./uploads:/app/web/static/uploads
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- ./logs:/var/log/ntech
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- ./backups:/app/backups
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networks:
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- ntech-net
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teron-mock:
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image: ghcr.io/dalibor31/ntech-fisk:latest
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container_name: teron_mock
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restart: unless-stopped
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environment:
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- BE_HOST=ntech # NTech service name on the shared network — required so the
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- BE_PORT=4567 # mock can read company data (name/PIB/address) from the card emulator
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- VERIFY_HOST=https://ntech.your-domain.com # takes precedence over the "verify_host" setting
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# in NTech's UI (the mock can't see ntech.db) —
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# without it the QR links to sandbox.suf.purs.gov.rs
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# and is sparse instead of encoding the full invoice
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volumes:
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- teron-data:/app/data
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networks:
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- ntech-net
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volumes:
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teron-data:
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networks:
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ntech-net:
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```
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The `teron-mock` service is reachable from `ntech` at `http://teron-mock:4566` over the internal Docker network — the port is not exposed to the host.
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`BE_HOST`/`BE_PORT` must point to the NTech container's card emulator (`internal/be`, TCP port 4567). Without them, `teron-mock` defaults to `127.0.0.1:4567`, which inside its own container never reaches NTech — the mock then silently falls back to placeholder company data ("Test Company DOO", TIN `RS000000000`) instead of your real business profile.
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To run as a standalone Docker container:
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```yaml
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# docker-compose.fisk.yml
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services:
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teron-mock:
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image: ghcr.io/dalibor31/ntech-fisk:latest
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container_name: teron_mock
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restart: unless-stopped
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environment:
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- BE_HOST=ntech # adjust to the NTech container's name/hostname on this network
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- BE_PORT=4567
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- VERIFY_HOST=https://ntech.your-domain.com
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ports:
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- "4566:4566"
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volumes:
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- teron-data:/app/data
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volumes:
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teron-data:
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```
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```bash
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docker compose -f docker-compose.fisk.yml up -d
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```
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To run the mock server locally (without Docker):
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```bash
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cd Fisk
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pip install -r requirements.txt
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python server.py
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# or: ./start.sh
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```
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#### Teron Mock Endpoints
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| Method | Path | Description |
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|--------|------|-------------|
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| GET | `/api/status` | Device status and last invoice number |
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| GET | `/api/attention` | Active alerts |
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| POST | `/api/pin` | PIN verification (BE unlock) |
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| GET | `/api/settings` | Device settings |
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| POST | `/api/invoices` | Issue a fiscal invoice |
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| POST | `/api/invoices/final` | Finalize an advance invoice |
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| GET | `/api/invoices/last` | Last issued invoice |
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| GET | `/api/invoices/:invoiceNumber` | Invoice by number |
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| POST | `/api/invoices/search` | Search invoices |
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Counters, signed receipts, QR codes, and JSON invoice data are persisted in `Fisk/data/`.
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---
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### Demo Mode
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Demo mode runs a fully functional copy with a pre-created `Demo` / `Demo1234` admin account. Password and 2FA changes are blocked. Backup is limited to 2 copies.
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```yaml
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# docker-compose.yml (demo)
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services:
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ntech-demo:
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image: ghcr.io/dalibor31/ntech:latest
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restart: unless-stopped
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environment:
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NTECH_ENV: demo
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NTECH_PORT: "8000"
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NTECH_SQLITE: /app/data/ntech.db
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volumes:
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- ./data:/app/data
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- ./uploads:/app/uploads
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- ./logs:/app/logs
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- ./backups:/app/backups
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ports:
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- "8000:8000"
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```
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Demo also requires HTTPS (Caddy or similar) because Secure cookies are enabled.
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---
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### Health Check
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The app exposes an unauthenticated `GET /healthz` endpoint that pings the database and returns `200 OK` (or `503` if the database is unreachable). Use it for a Docker `HEALTHCHECK` or a reverse-proxy/orchestrator liveness probe:
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```yaml
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healthcheck:
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test: ["CMD", "wget", "-qO-", "http://localhost:8000/healthz"]
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interval: 30s
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timeout: 3s
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retries: 3
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```
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---
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## Project Structure
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```
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ntech/
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├── cmd/
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│ └── ntech/ # entry point
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├── internal/
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│ ├── auth/ # login, sessions, fail2ban log
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│ ├── config/ # settings, setup wizard
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│ ├── db/ # database layer
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│ │ └── sqlite/ # SQLite implementation
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│ ├── handler/ # HTTP handlers
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│ ├── middleware/ # CSRF, security headers, authentication
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│ └── model/ # shared data types
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├── web/
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│ ├── static/ # CSS, JavaScript, images, logos
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│ └── templates/ # HTML templates
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├── migrations/ # SQL migrations (001_desc.sql, 002_desc.sql, ...)
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├── logs/ # auth.log and other logs
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├── backups/ # database backups
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├── start.sh # interactive build and Docker push script
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├── Dockerfile
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├── go.mod
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└── go.sum
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```
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---
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## Testing
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The project has unit and integration tests (against a real SQLite database) covering crypto, RBAC, login flows, form validators, and reports.
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```bash
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go test ./...
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```
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Migrations are numbered SQL files (`migrations/NNN_description.sql`) applied in order at startup and tracked in a `migracije` table, so they run exactly once and are safe to ship inside the same binary.
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---
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## Security Notes
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- Sessions are server-side (random token in an `HttpOnly`, `SameSite=Strict` cookie), not JWT — revocation is immediate (delete the row).
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- CSRF tokens and the card-emulator PIN are compared in constant time (`crypto/subtle`).
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- Brute-force locking applies to both the password step and the TOTP/backup-code step, keyed by client IP.
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- `X-Real-IP` / `X-Forwarded-For` are only trusted when the connection itself comes from a loopback or private address (i.e. a reverse proxy on the same host/Docker network) — otherwise the raw connection IP is used, so the header can't be spoofed from the internet to bypass the lockout.
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- TOTP secrets are encrypted at rest (AES-256-GCM); the key (`NTECH_TOTP_KEY`) is kept outside the database.
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- This is a single-tenant, single-organization application by design — there is no cross-tenant data isolation to reason about.
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See [`SECURITY.md`](SECURITY.md) for how to report a vulnerability.
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---
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## License
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[MIT](LICENSE) © Dalibor Marković
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