# Architecture and System Design

**Sistema de Remuneración Variable, Compensación y Comisiones - Hoteles Estelar**

---

## 1. Technical Stack Selection

To keep resource footprint low on the self-hosted VPS while providing a premium, modern user experience, we recommend a unified **Next.js Full-Stack App Router** architecture.

* **Frontend**: Next.js App Router (React + TypeScript).
* **Styling**: Vanilla CSS with a structured design system (CSS variables, dark/light theme tokens, premium layout aesthetics, smooth CSS micro-animations).
* **Backend**: Next.js API Routes (Node.js runtime).
* **ORM**: Prisma ORM (provides type-safe database queries and automated schema migrations).
* **Database**: PostgreSQL (hosted on the existing `postgres` Docker stack).
* **Excel Processing**: `xlsx` (SheetJS) for high-performance parser logic.
* **Authentication**: NextAuth.js or custom lightweight JWT session cookies.
* **Hosting**: Docker container integrated into the Dockge stack manager, reverse proxied by Caddy with split DNS resolving over WireGuard VPN for security-sensitive areas.

---

## 2. System Architecture

```mermaid
graph TD
    User([Colaborador / Líder / Admin]) -->|HTTPS| Caddy[Caddy Reverse Proxy]
    Caddy -->|Internal Network| NextJS[Next.js Full-Stack App]
    
    subgraph NextJS Container
        UI[React Frontend / Vanilla CSS] <--> API[API Routes / Controllers]
        Engine[Settlement Engine] <--> API
        Parser[Excel Parser] <--> API
    end

    API -->|Prisma Client| DB[(PostgreSQL)]
    Jobs[Integration CRON Jobs] -->|Fetch Sales| API
    External[External PMS / ERP / CRM] -->|API Push / Pull| Jobs
```

---

## 3. Database Schema Design (Entity-Relationship Diagram)

```mermaid
erDiagram
    REGIONS ||--o{ HOTELS : contains
    HOTELS ||--o{ USERS : houses
    USERS ||--o{ GOALS : achieves
    USERS ||--o{ SALES_RESULTS : generates
    USERS ||--o{ SETTLEMENTS : receives
    
    COMPENSATION_PLANS ||--o{ CALCULATION_RULES : dictates
    COMPENSATION_PLANS ||--o{ SETTLEMENTS : calculates
    
    USERS ||--o{ AUDIT_LOGS : executes
    USERS ||--o{ NOTIFICATIONS : receives

    REGIONS {
        int id PK
        string name
        string code
    }

    HOTELS {
        int id PK
        string name
        string code
        int region_id FK
        string status
    }

    USERS {
        int id PK
        string username
        string email
        string password_hash
        string role "ADMIN | DIRECTOR | GERENTE | LIDER | ANALISTA | CONSULTA | COLABORADOR"
        int hotel_id FK
        string area
        string status "ACTIVE | INACTIVE"
        datetime created_at
    }

    COMPENSATION_PLANS {
        int id PK
        string name
        string code UK
        datetime validity_start
        datetime validity_end
        string type "PERCENTAGE | SCALE | CONDITIONAL | FIXED"
        string formula "JSON or string representation"
        decimal meta_amount
        decimal percentage_rate
        decimal max_cap
        string status "DRAFT | ACTIVE | INACTIVE"
        int version
        int created_by FK
        datetime created_at
    }

    CALCULATION_RULES {
        int id PK
        int plan_id FK
        string type "TIER | BONUS"
        decimal min_achievement "percentage"
        decimal max_achievement "percentage"
        decimal rate "multiplier or percentage"
        decimal payout_amount "fixed payment"
    }

    GOALS {
        int id PK
        string target_type "INDIVIDUAL | TEAM | HOTEL"
        int target_id "user_id, team_id, or hotel_id"
        string period "YYYY-MM"
        decimal amount
        datetime created_at
    }

    SALES_RESULTS {
        int id PK
        string source "EXCEL | API"
        int hotel_id FK
        int user_id FK "colaborador"
        string period "YYYY-MM"
        decimal amount
        int sales_count
        string status "PENDING | PROCESSED"
        int uploaded_by FK
        datetime created_at
    }

    SETTLEMENTS {
        int id PK
        string period "YYYY-MM"
        int plan_id FK
        int user_id FK
        decimal sales_amount
        decimal goal_amount
        decimal achievement_percentage
        decimal calculated_commission
        decimal calculated_bonus
        decimal total_payout
        string status "SIMULATED | PENDING | APPROVED | REJECTED"
        int approved_by FK
        datetime approved_at
        string rejection_reason
        datetime created_at
    }

    AUDIT_LOGS {
        int id PK
        int user_id FK
        string action "CREATE | UPDATE | DELETE | APPROVE | REJECT | LOGIN"
        string target_table
        int target_id
        json previous_value
        json new_value
        string ip_address
        datetime created_at
    }

    NOTIFICATIONS {
        int id PK
        int user_id FK
        string title
        string message
        string status "UNREAD | READ"
        string type "EMAIL | PUSH"
        datetime sent_at
    }
```

---

## 4. Key Business Logic: Settlement & Calculation Engine

The engine computes commissions based on the formula:

$$\text{Achievement \%} = \left( \frac{\text{Sales Amount}}{\text{Goal Amount}} \right) \times 100$$

### Calculation Flow:
1. **Fetch inputs**: Get sales results, goals, and matching active compensation plan for the collaborator for the period `YYYY-MM`.
2. **Determine Achievement Level**: Check against the plan's `CALCULATION_RULES` (tiers).
3. **Calculate Commission**:
   - *Fixed Rate*: $\text{Sales} \times \text{percentage\_rate}$.
   - *Tiers/Scales*: Apply rate corresponding to the achievement level tier.
4. **Apply Caps**: If calculated commission exceeds the plan's `max_cap`, set it to `max_cap`.
5. **Add Special Bonuses**: If the collaborator achieves certain thresholds (e.g., >100% meta), add the specific tier's fixed `payout_amount` as a bonus.
6. **Generate Output**: Store as a `SETTLEMENT` entry in `SIMULATED` status.

---

## 5. Security & Access Control Model (RBAC)

We define role-based access restrictions as follows:

| Role | Access Level | Restrictions |
| :--- | :--- | :--- |
| **Administrador** | Full system write & read. | None. |
| **Director Comercial** | Reads all dashboards & reports. Can configure metadata. | Cannot calculate or approve. |
| **Gerente Hotel** | Reads data, sales, and settlements for their specific Hotel. | Restricted to `hotel_id`. |
| **Líder Comercial** | Triggers simulations, views dashboards. Approves/Rejects settlements. | Restricted to their region/team. |
| **Analista Financiero** | Reviews calculations. Exports consolidated PDF/Excel reports. | Cannot approve. |
| **Consulta** | Read-only. | No mutations allowed. |
| **Colaborador** | Consults own history & dashboard. | Restricted to `user_id`. |