Repository interfaces, not databases

4. Activity Diagrams

Activity: Creating a Reservation

flowchart TD
    Start([🚗 Customer wants to rent]) --> Search[🔍 Search available vehicles]
    Search --> Select[📅 Select vehicle and dates]
    Select --> Check{✅ Vehicle available?}
    Check -->|No| Alternatives[💡 Show alternatives]
    Alternatives --> Select
    Check -->|Yes| CalcPrice[💰 Calculate total price]
    CalcPrice --> SelectAddOns[🛠️ Select add-ons]
    SelectAddOns --> Review[📋 Review booking summary]
    Review --> Confirm{🤔 Customer confirms?}
    Confirm -->|No| Cancel([❌ End - Cancelled])
    Confirm -->|Yes| Payment[💳 Process payment]
    Payment --> PaySuccess{✓ Payment OK?}
    PaySuccess -->|No| PaymentFail[⚠️ Show error]
    PaymentFail --> Payment
    PaySuccess -->|Yes| CreateRes[📝 Create reservation]
    CreateRes --> SendEmail[📧 Send confirmation email]
    SendEmail --> End([✅ Reservation confirmed])

    style Start fill:#E1F5FE,stroke:#01579B,stroke-width:3px
    style End fill:#C8E6C9,stroke:#2E7D32,stroke-width:3px
    style Cancel fill:#FFCDD2,stroke:#C62828,stroke-width:3px

    style Search fill:#B3E5FC,stroke:#0277BD,stroke-width:2px
    style Select fill:#B3E5FC,stroke:#0277BD,stroke-width:2px
    style CalcPrice fill:#B3E5FC,stroke:#0277BD,stroke-width:2px
    style SelectAddOns fill:#B3E5FC,stroke:#0277BD,stroke-width:2px
    style Review fill:#B3E5FC,stroke:#0277BD,stroke-width:2px
    style CreateRes fill:#A5D6A7,stroke:#388E3C,stroke-width:2px
    style SendEmail fill:#A5D6A7,stroke:#388E3C,stroke-width:2px

    style Payment fill:#FFE082,stroke:#F57F17,stroke-width:2px
    style PaymentFail fill:#FFAB91,stroke:#D84315,stroke-width:2px
    style Alternatives fill:#CE93D8,stroke:#6A1B9A,stroke-width:2px

    style Check fill:#FFF9C4,stroke:#F9A825,stroke-width:2px
    style Confirm fill:#FFF9C4,stroke:#F9A825,stroke-width:2px
    style PaySuccess fill:#FFF9C4,stroke:#F9A825,stroke-width:2px

Activity: Vehicle Check-Out

flowchart TD
    Start([👤 Customer arrives]) --> GetRes[📋 Retrieve reservation]
    GetRes --> VerifyRes{✓ Valid reservation?}
    VerifyRes -->|No| Error([❌ End - Error])
    VerifyRes -->|Yes| CheckLicense[🪪 Verify driver license]
    CheckLicense --> LicenseOK{✓ License valid?}
    LicenseOK -->|No| Error
    LicenseOK -->|Yes| Inspect[🔍 Inspect vehicle exterior]
    Inspect --> TakePhotos[📸 Take damage photos]
    TakePhotos --> CreateDamageReport[📝 Create damage report]
    CreateDamageReport --> RecordMileage[⛽ Record mileage & fuel]
    RecordMileage --> SignContract[✍️ Customer signs agreement]
    SignContract --> CollectDeposit[💳 Collect security deposit]
    CollectDeposit --> DepositOK{✓ Deposit authorized?}
    DepositOK -->|No| Error
    DepositOK -->|Yes| ActivateRental[🚀 Create rental transaction]
    ActivateRental --> UpdateStatus[📊 Update reservation to ACTIVE]
    UpdateStatus --> HandKeys[🔑 Hand over keys]
    HandKeys --> SendNotif[📧 Send checkout confirmation]
    SendNotif --> End([✅ Vehicle checked out])

    style Start fill:#FFF3E0,stroke:#E65100,stroke-width:3px
    style End fill:#C8E6C9,stroke:#2E7D32,stroke-width:3px
    style Error fill:#FFCDD2,stroke:#C62828,stroke-width:3px

    style GetRes fill:#FFE0B2,stroke:#EF6C00,stroke-width:2px
    style CheckLicense fill:#FFE0B2,stroke:#EF6C00,stroke-width:2px
    style Inspect fill:#FFCC80,stroke:#F57C00,stroke-width:2px
    style TakePhotos fill:#FFCC80,stroke:#F57C00,stroke-width:2px
    style CreateDamageReport fill:#FFCC80,stroke:#F57C00,stroke-width:2px
    style RecordMileage fill:#FFB74D,stroke:#FB8C00,stroke-width:2px
    style SignContract fill:#FFB74D,stroke:#FB8C00,stroke-width:2px

    style CollectDeposit fill:#FFE082,stroke:#F9A825,stroke-width:2px
    style ActivateRental fill:#AED581,stroke:#689F38