Nyan Lin Paing
109 lines
9.1 KiB
Markdown
109 lines
9.1 KiB
Markdown
# EV Booking System — Business Domain Reference
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Reference doc for business rules and domain vocabulary. Pull this up alongside `tickets.md` while working any ticket — it explains *why* a rule exists, not how to code it (see the architecture plan for implementation shape).
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---
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## 1. Glossary
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| Term | Meaning |
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|---|---|
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| **EV Company** | A vehicle operator/fleet owner. Plain reference data — not a tenant (see §4). |
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| **Destination** | A city/town served by routes. Used as both origin and endpoint. |
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| **Pickup Location** | A physical point within a Destination where customers board. |
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| **Dropoff Location** | A physical point within a Destination where customers alight. |
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| **Departure Time Slot** | A shared catalog of times (e.g. "06:00 AM"); attached to routes via a pivot, not owned by one route. |
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| **EV Route** | Company + From Destination + To Destination + Pickup + Dropoff + round-trip flag + one or more Time Slots + pricing per Vehicle Option. |
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| **Vehicle Option** | What the customer books: `front_seat`, `back_seat`, or `whole_vehicle`. Not a numbered seat — see §2. |
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| **Booking** | A customer's reservation of one Vehicle Option on one Route + Date + Time Slot. |
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| **Payment** | One attempt to pay for a Booking through a gateway (may retry after failure). |
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| **Refund** | A reversal against a specific successful Payment (not against the Booking directly). |
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---
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## 2. Vehicle Options & Inventory (the core domain quirk)
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Unlike a bus-booking system, **there is no seat map and no capacity tracking in v1**:
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- Any number of customers can book the same Route + Date + Time Slot. The system does not check whether a "Whole Vehicle" or "Back Seat" is already taken by someone else.
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- The **only rule enforced in code** is: **max 1 Front Seat per booking** (a single booking cannot request more than one front seat — this is a per-booking constraint, not a per-trip inventory check).
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- Back Seat and Whole Vehicle availability are controlled by **blunt config toggles**, not database rows:
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- `BOOKING_BACK_SEAT_ENABLED` — whether Back Seat can be selected at all right now.
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- `BOOKING_WHOLE_VEHICLE_ENABLED` — whether Whole Vehicle can be selected at all right now.
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- `BOOKING_FRONT_SEAT_MAX_PER_BOOKING` — currently `1`, expressed as config in case it ever needs to change.
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- This is a **deliberate v1 simplification**, not an oversight. Real per-route/date/time-slot capacity holding (e.g. "only 1 Whole Vehicle booking allowed per trip") is an explicitly deferred future phase — see §7.
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- Consequence: double-booking of "Whole Vehicle" is possible by design until that future phase ships. Admins reconcile manually via the Filament Booking list (filterable by route + date + time).
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**Do not build seat inventory, seat locking, or availability-checking logic against real capacity in current-phase tickets** unless a ticket explicitly says so — it's out of scope until the "Future Scalability" phase.
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---
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## 3. Pricing
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- `RoutePricing` holds one price per (Route, Vehicle Option) pair.
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- When a Booking is created, the resolved price is **snapshotted** onto `bookings.price` and never re-read from `RoutePricing` again. If admin edits pricing later, existing bookings keep their original price. This is intentional — historical bookings must never silently reprice.
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---
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## 4. Tenancy
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- **Single tenant.** EV Companies are just rows in a table that the one admin team manages — there is no per-company admin login isolation, no data scoping by company for admin users, and no Spatie Permission "teams" feature in v1.
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- If multi-tenant admin isolation is ever needed, it layers onto the existing role/permission tables later without migrating the core booking/route schema (see architecture plan §30).
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---
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## 5. Booking Lifecycle (status machine)
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```
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pending_payment ──(payment succeeds)──▶ confirmed
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pending_payment ──(customer/admin cancels, no payment yet)──▶ cancelled
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confirmed ──(refund processed)──▶ cancelled
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pending_payment ──(TTL expiry, future phase)──▶ expired
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```
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- A Booking is created `pending_payment` — it exists before any money moves.
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- It only becomes `confirmed` once the linked Payment succeeds (via the KBZ webhook, not client-reported success — see §6).
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- Cancelling a `confirmed` (paid) Booking must go through the Refund flow first — never flip status to `cancelled` on a paid booking without a corresponding refund attempt.
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---
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## 6. Payment Domain (ported from `bnf_event`, refined)
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The existing KBZ Mini App payment code at `/home/marcspecta/company_projects/bnf_event` (`app/Strategies/Payments/KBZMiniApp.php`, `KBZPay.php`, `BasePayment.php`, `app/Services/PaymentService.php`) is the reference implementation being ported and refined — **read it before starting any Payment-module ticket.**
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**What's being kept (business logic, still true in the new system):**
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- KBZ's signing scheme: flatten the request array (excluding `sign`/`sign_type`) into sorted `key=val` pairs joined by `&`, append `&key={merchant_key}`, SHA-256 hash, uppercase. Every request sets `sign_type = "SHA256"`.
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- Three KBZ API operations matter: `kbz.payment.precreate` (start payment), `kbz.payment.queryorder` (poll/verify status), `kbz.payment.refund` (reverse a payment). All are outbound HTTPS calls; refund additionally requires **mTLS** (client cert + key + CA bundle).
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- Client-driven confirmation pattern as a fallback/defense-in-depth: after the client reports payment complete, the server **re-verifies by calling `queryorder`** rather than trusting the client payload blindly.
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- Refund reason is a required, human-readable string sent to KBZ and stored for audit.
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**What's changing (the agreed refinements — see architecture plan §17–19, §34):**
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- Old: 3x duplicated `switch($payment_type)` at each call site to pick a gateway class. New: a `PaymentGatewayFactory` resolves `PaymentGatewayInterface` implementations by `PaymentMethod` enum, registered once.
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- Old: raw associative arrays passed through `PaymentInterface` methods. New: typed DTOs (`PaymentRequestData`, `PaymentResultData`, `RefundResultData`).
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- Old: KBZ credentials (merchant code, keys, URLs) lived in a DB singleton `payment_setting` table, editable via admin UI. New: `.env` + `config/services.php` (`KBZ_*` vars) — no DB table, no Filament resource for secrets.
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- Old: payment/refund state overloaded onto the `orders` table (`payment_status` int, `order_status` string, `payment_remark` text) with no structured history. New: dedicated `payments` + `refunds` tables (`refunds.payment_id` FK to `payments.id`), each with a proper status enum.
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- Old: refund amount was effectively hardcoded to full-amount (the `refund_amount` param was commented out in `KBZMiniApp::refund`). New: `RefundBookingAction` explicitly supports **partial refunds**, validated against the remaining refundable balance on the Payment.
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- Old: no real inbound webhook — only client-driven confirmation + server-side re-verification. New: add a genuine **signed inbound webhook** (`POST /api/v1/webhooks/kbz`) that verifies KBZ's signature before processing — confirm KBZ's actual inbound-webhook signature spec as part of the Phase 5 webhook ticket (flagged risk, KBZ's spec was never implemented in the old code, only referenced by a `notify_url` config value).
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- Old: status transitions applied inline inside `BasePayment::paymentStatusChange()`, tightly coupling the gateway class to booking-status logic. New: gateway strategies only return a `PaymentResultData`/`RefundResultData` — booking-status changes happen in **listeners** reacting to `PaymentCompleted` / `PaymentFailed` / `RefundProcessed` domain events, keeping the gateway strategy ignorant of the Booking module.
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**Webhook idempotency**: KBZ may retry the notify webhook. The handler must check the Payment's current status before transitioning it — never assume a webhook call is the first/only delivery.
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---
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## 7. Deferred / Future (do not build yet)
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- Real per-route/date/time-slot capacity holding + availability checks (see §2).
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- DB row locking (`SELECT ... FOR UPDATE`) for booking concurrency — only needed once real inventory exists.
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- Multi-tenant admin isolation (Spatie Permission "teams").
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- Multiple payment gateways beyond KBZ (the factory is designed to support this later with zero call-site changes).
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- Booking auto-expiry TTL job for stale `pending_payment` bookings.
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- Customer notifications (booking confirmation, payment status push).
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---
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## 8. External Actors & Access Boundaries
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- **Mini App / Mobile App**: customer-facing clients, authenticate via Sanctum token, full customer ability set (create/view/cancel own bookings, initiate payment).
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- **FastAPI AI Agent** (external service, owns Gemini/tool-calling — Laravel has zero AI SDK code): authenticates via a Sanctum token scoped to a **restricted ability set** — `route:read`, `booking:create`, `booking:read` only. It must **never** be able to refund, cancel someone else's booking, or write catalog/pricing data. It never touches the database directly, only `/api/v1`.
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- **Filament Admin**: session-based, role-gated (`super_admin`, `admin`, `support`), the only place catalog/pricing mutation and refund initiation happen for staff.
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