C4Context
    title System Context Diagram for MockShelf Library Management System

    Person(librarian, "Librarian", "Manages library resources and user accounts")
    Person(reader, "Library User", "Browses and borrows books")

    System(mockshelf, "MockShelf", "Library management system for book lending and tracking")

    Rel(librarian, mockshelf, "Manages")
    Rel(reader, mockshelf, "Uses")

C4Container
    title Container Diagram for MockShelf

    Person(reader, "Library User")
    Person(librarian, "Librarian")

    System_Boundary(mockshelf, "MockShelf") {
        Container(web_app, "Web Application", "Spring Boot, Thymeleaf, HTMX", "Provides user interfaces for book browsing, borrowing, and management")
        Container(auth_service, "Authentication Service", "Keycloak", "Handles user authentication and authorization")
        Container(book_service, "Book Service", "Spring Boot", "Manages book catalog and inventory")
        Container(loan_service, "Loan Service", "Spring Boot", "Manages book loans and returns")
        Container(notification_service, "Notification Service", "Spring Boot", "Handles email and SMS notifications")

        ContainerDb(postgres, "Database", "PostgreSQL", "Stores library data")
        ContainerDb(activemq, "Message Broker", "ActiveMQ", "Handles asynchronous messaging")
    }

    System_Ext(email_system, "Email System")
    System_Ext(isbn_lookup, "ISBN Lookup Service")

    Rel(reader, web_app, "Interacts with")
    Rel(librarian, web_app, "Manages")
    Rel(web_app, auth_service, "Authenticates")
    Rel(web_app, book_service, "Manages books")
    Rel(web_app, loan_service, "Manages loans")

    Rel(book_service, postgres, "Reads/Writes")
    Rel(loan_service, postgres, "Reads/Writes")
    Rel(notification_service, activemq, "Consumes/Publishes messages")
    Rel(notification_service, email_system, "Sends emails")
    Rel(book_service, isbn_lookup, "Looks up book details")

C4Component
    title Component Diagram for Book Service

    Container(book_service, "Book Service", "Spring Boot", "Manages book catalog and inventory")

    Component(book_controller, "Book Controller", "REST Controller", "Handles HTTP requests for book operations")
    Component(book_service_component, "Book Service", "Service Layer", "Business logic for book management")
    Component(book_repository, "Book Repository", "JPA Repository", "Handles database interactions")
    Component(isbn_lookup_service, "ISBN Lookup Service", "External Service Integration", "Fetches book details from external API")

    Rel(book_controller, book_service_component, "Uses")
    Rel(book_service_component, book_repository, "Persists")
    Rel(book_service_component, isbn_lookup_service, "Retrieves book details")

graph TD
    subgraph "External Services & Infrastructure"
        KC[" 🔐 Keycloak\nAuthentication & Authorization"]
        PG[" 🐘 PostgreSQL\nPersistent Data Storage"]
        AMQ[" 📬 ActiveMQ\nMessage Queuing"]
        MD[" 📧 MailDev\nEmail Testing"]
        WM[" 🌐 WireMock\nExternal API Simulation"]
        JR[" 🏃 JobRunr\nBackground Job Processing"]
        ISBN[" 📖 Open Library API\nISBN Book Lookup"]
    end

    subgraph "MockShelf Application"
        APP[" 🚀 Spring Boot App\nCore Application Logic"]
    end

    subgraph "Development & CI/CD"
        GH[" 🐙 GitHub\nSource Control"]
        DC[" 🐳 Docker Compose\nLocal Environment"]
        PC[" 🧪 Pre-commit\nCode Quality Checks"]
        MVN[" 🌟 Maven\nDependency Management"]
    end

    subgraph "Monitoring & Observability"
        ACT[" 🔍 Spring Actuator\nSystem Monitoring"]
        LOG[" 📊 SLF4J Logging\nApplication Logs"]
    end

    APP <-->|Authentication| KC
    APP <-->|Persistent Storage| PG
    APP <-->|Messaging| AMQ
    APP <-->|Job Processing| JR
    APP <-->|Book Lookup| ISBN

    DC <-->|Manages| KC
    DC <-->|Manages| PG
    DC <-->|Manages| AMQ
    DC <-->|Manages| MD
    DC <-->|Manages| WM

    GH <-->|CI/CD| APP
    MVN <-->|Dependency Management| APP

    APP <-->|Monitoring| ACT
    APP <-->|Logging| LOG