# Phase 1 Implementation Complete - Database Foundation

## Date: April 28, 2026
## Status: ✅ COMPLETE & TESTED

---

## Overview
Phase 1 establishes the database and model layer for the core business logic (tier access control, loan requests, M-Pesa integration, and advanced repayment tracking). All changes maintain backward compatibility with existing web and mobile API users.

---

## Database Changes

### 1. Users Table Enhancements
**Migration:** `2026_04_28_101503_add_tier_access_to_users_table.php`

**New Columns:**
- `accessible_tier_id` (BIGINT, FK to tiers) — Highest tier user can access; defaults to tier 1
- `mpesa_phone` (VARCHAR 20) — M-Pesa phone number for disbursements
- `admin_pin_hash` (VARCHAR 255) — Hashed admin PIN (only for admin users)

**Backward Compatibility:** ✅ All fields are nullable; existing users unaffected

---

### 2. Loan Requests Table (New)
**Migration:** `2026_04_28_101521_create_loan_requests_table.php`

**Purpose:** Track loan requests from submission through approval and disbursement

**Columns:**
- `id` — Primary key
- `user_id` (FK) — User requesting loan
- `tier_id` (FK) — Requested tier
- `requested_amount` (DECIMAL 12,2) — Amount user requested
- `approved_amount` (DECIMAL 12,2, nullable) — Amount admin approved
- `status` (ENUM: pending, approved, rejected, disbursed) — Request lifecycle
- `admin_notes` (TEXT, nullable) — Admin comments
- `approved_by` (FK to users, nullable) — Which admin approved
- `approved_at` (TIMESTAMP, nullable) — When approved
- `mpesa_code` (VARCHAR 255, nullable) — M-Pesa receipt reference
- `mpesa_transaction_id` (VARCHAR 255, nullable) — M-Pesa transaction ID
- `callback_data` (JSON, nullable) — Full M-Pesa callback
- `created_at`, `updated_at` — Timestamps

**Indexes:** status, user_id for fast filtering

---

### 3. Repayments Table Enhancements
**Migration:** `2026_04_28_101534_add_installment_tracking_to_repayments_table.php`

**New Columns:**
- `installment_number` (INT) — Sequential number (1, 2, 3, ...) for tracking order
- `is_active` (BOOLEAN, default true) — Whether visible/actionable to user
- `paid_at` (TIMESTAMP, nullable) — When fully paid

**Purpose:** Support individual installment tracking, partial payments, and multi-installment visibility

**Backward Compatibility:** ✅ New fields populated automatically during repayment generation

---

### 4. Transactions Table Enhancements
**Migration:** `2026_04_28_101552_add_mpesa_to_transactions_table.php`

**New Columns:**
- `mpesa_code` (VARCHAR 255, nullable) — M-Pesa receipt code
- `mpesa_transaction_id` (VARCHAR 255, nullable) — M-Pesa reference ID
- `callback_data` (JSON, nullable) — Full callback payload
- `processed_at` (TIMESTAMP, nullable) — When transaction was processed
- `repayment_id` (BIGINT, FK, nullable) — Links payment to specific installment

**Purpose:** Store M-Pesa transaction details for audit trail and reconciliation

**Backward Compatibility:** ✅ All new fields nullable; existing transactions unaffected

**Indexes:** mpesa_code, mpesa_transaction_id for transaction lookup

---

### 5. Settings Table (Seeded)
**Migration:** `2026_04_28_101812_add_phase1_settings.php`

**Default Settings Added:**
```php
'tier_progression_threshold' => '3'              // Completed loans to unlock next tier
'late_payment_fine_amount' => '100'             // KSH per 24 hours
'fine_calculation_period_hours' => '24'         // Hours between fine increments
'default_tier_id' => '1'                        // First tier for new users
'laf_fee_percentage' => '2.00'                  // % of loan amount
'registration_fee_amount' => '500.00'           // Fixed fee
'default_interest_rate' => '25.00'              // % per annum
'admin_pin_length' => '4'                       // Admin PIN digit count
```

---

## Model Changes

### 1. User Model (`app/Models/User.php`)
**Updated Fillable:**
```php
'accessible_tier_id', 'mpesa_phone', 'admin_pin_hash'
```

**New Relationships:**
```php
public function accessibleTier()              // Current max tier
public function loanRequests()                // Requests submitted by user
public function approvedLoanRequests()        // Requests approved by this admin
```

---

### 2. LoanRequest Model (New)
**Location:** `app/Models/LoanRequest.php`

**Relationships:**
```php
public function user()          // User who made request
public function tier()          // Tier requested
public function approvedBy()    // Admin who approved (nullable)
public function loan()          // Resulting loan after approval (hasOne)
```

**Casts:**
```php
'requested_amount' => 'decimal:2'
'approved_amount' => 'decimal:2'
'approved_at' => 'datetime'
'callback_data' => 'array'
```

---

### 3. Repayment Model (`app/Models/Repayment.php`)
**Updated Fillable:**
```php
'installment_number', 'is_active', 'paid_at'
```

---

### 4. Transaction Model (`app/Models/Transaction.php`)
**Updated Fillable:**
```php
'repayment_id', 'mpesa_code', 'mpesa_transaction_id', 'callback_data', 'processed_at'
```

**New Relationship:**
```php
public function repayment()     // Payment for specific installment
```

**Updated Casts:**
```php
'callback_data' => 'array'
'processed_at' => 'datetime'
```

---

## Test Data Seeder Updates

### Tier Updates
Changed from generic tiers (Bronze, Silver, Gold, Platinum) to **BIASHARA tiers**:

| Tier | Amount Range | Duration | Interest |
|------|--------------|----------|----------|
| BIASHARA 1 | 8,000 - 20,000 | 5 weeks | 25% p.a. |
| BIASHARA 2 | 24,000 - 30,000 | 7 weeks | 25% p.a. |
| BIASHARA 3 | 32,000 - 100,000 | 8 weeks | 25% p.a. |
| BIASHARA 4 | 110,000 - 150,000 | 10 weeks | 25% p.a. |
| BIASHARA 5 | 160,000 - 200,000 | 12 weeks | 25% p.a. |

### User Creation
- 15 total users (1 existing admin + 14 new)
- Each new user:
  - `accessible_tier_id` = 1 (BIASHARA 1, default)
  - `mpesa_phone` = Generated Kenyan format (254XXXXXXX)
  - Role = 'user'

### Repayment Tracking
- Each repayment now includes:
  - `installment_number` — Sequential (1, 2, 3, ...)
  - `is_active` — Always true in test data
  - `paid_at` — Set when status is 'paid'
  
### Transaction Tracking
- Paid transactions now include:
  - `repayment_id` — Link to specific installment
  - `processed_at` — Transaction completion time

---

## Database Schema Diagram

```
┌─────────────────────────────────────────────────────┐
│                      USERS                           │
├──────────────┬──────────┬──────────────────────────┤
│ id           │ email    │ accessible_tier_id (FK) │
│ name         │ password │ mpesa_phone             │
│ role         │ ...      │ admin_pin_hash          │
└──────────────┴──────────┴──────────────────────────┘
        ↓                       ↓
    ┌───────────────────────────────────────┐
    │        LOAN_REQUESTS (NEW)            │
    ├─────────────────────────────────────┤
    │ id                                   │
    │ user_id (FK) → users                │
    │ tier_id (FK) → tiers                │
    │ requested_amount, approved_amount    │
    │ status: pending|approved|rejected|.. │
    │ approved_by (FK) → users (admin)    │
    │ mpesa_code, mpesa_transaction_id     │
    │ callback_data                        │
    └─────────────────────────────────────┘
        ↓                       ↓
    ┌───────────────────────────────────────┐
    │         LOANS                         │
    ├─────────────────────────────────────┤
    │ user_id (FK)  | tier_id (FK)        │
    │ disbursement_date | status          │
    │ amount | interest | total_payable    │
    └─────────────────────────────────────┘
        ↓
    ┌───────────────────────────────────────┐
    │      REPAYMENTS (ENHANCED)            │
    ├─────────────────────────────────────┤
    │ installment_number ← NEW             │
    │ due_date | amount_due | balance      │
    │ amount_paid | status                 │
    │ is_active ← NEW                      │
    │ paid_at ← NEW                        │
    └─────────────────────────────────────┘
        ↓
    ┌───────────────────────────────────────┐
    │    TRANSACTIONS (ENHANCED)            │
    ├─────────────────────────────────────┤
    │ user_id (FK) | loan_id (FK)         │
    │ repayment_id (FK) ← NEW              │
    │ reference | mpesa_code ← NEW         │
    │ amount | type | status               │
    │ processed_at ← NEW                   │
    │ callback_data ← NEW                  │
    └───────────────────────────────────────┘
```

---

## API & Web Backward Compatibility

### ✅ Mobile API (Sanctum)
- All existing endpoints continue to work
- `/api/login` unchanged
- `/api/tiers`, `/api/loans`, `/api/repayments` unchanged
- New fields added to responses but won't break existing clients

### ✅ Web Portal
- User login/registration unchanged
- Dashboard remains functional
- Loan views remain functional
- New tier access logic will be enforced in Phase 2 services

### ✅ Admin Portal
- Admin login unchanged
- Dashboard remains functional
- Loan management unchanged
- New features (requests, PIN approval) to be implemented in Phase 2

---

## Files Created/Modified

### Created:
- `app/Models/LoanRequest.php` — New model for loan requests
- `database/migrations/2026_04_28_101503_add_tier_access_to_users_table.php`
- `database/migrations/2026_04_28_101521_create_loan_requests_table.php`
- `database/migrations/2026_04_28_101534_add_installment_tracking_to_repayments_table.php`
- `database/migrations/2026_04_28_101552_add_mpesa_to_transactions_table.php`
- `database/migrations/2026_04_28_101812_add_phase1_settings.php`

### Modified:
- `app/Models/User.php` — Added tier access relationships
- `app/Models/Repayment.php` — Updated fillable for installment fields
- `app/Models/Transaction.php` — Updated for M-Pesa tracking
- `database/seeders/TestDataSeeder.php` — Updated to BIASHARA tiers, tier access, installment numbers

---

## Validation Checklist

- [x] All migrations run successfully
- [x] No existing data lost
- [x] New columns properly nullable for backward compatibility
- [x] Foreign keys created with correct cascade behavior
- [x] Test data seeded with 15 users
- [x] BIASHARA tiers created (5 total)
- [x] Users assigned default tier (BIASHARA 1)
- [x] M-Pesa phone numbers generated for all users
- [x] Repayments include installment numbers and active status
- [x] Transactions linked to repayments
- [x] Settings table populated with configuration values
- [x] No API/web route breakage expected
- [x] Models updated with new relationships and casts

---

## What's Next (Phase 2)

Phase 2 will implement the business logic services:
1. **TierAccessService** — Enforce tier access rules, automatic progression
2. **LoanRequestService** — Submission, approval workflow with PIN
3. **RepaymentService** — Enhanced for partial payments, independent installments
4. **AdminService** — PIN validation, user management
5. **MpesaService** — B2C disbursement, STK Push, callback handling

---

## Summary

Phase 1 successfully establishes the database foundation for the complete loan management system. All structural changes are in place while maintaining full backward compatibility with existing web and mobile applications. The system is ready for Phase 2 business logic implementation.

**Database Status:** ✅ Production-ready
**API Status:** ✅ No changes required
**Web Status:** ✅ No changes required
**Mobile Status:** ✅ No changes required
