---
title: '05 — Building Block View'
description: 'Explain the static structure: modules, components, services and their relationships.'
status: draft
---

<!-- markdownlint-disable-next-line MD025 -->

# 05 — Building Block View

## Architecture overview

This overview complements [architecture](README.md) with a high-level map of CalMiner's module layout and request flow.

Refer to the detailed architecture chapters in `docs/architecture/`:

- Module map & components: [Building Block View](05_building_block_view.md)
- Request flow & runtime interactions: [Runtime View](06_runtime_view.md)
- Simulation roadmap & strategy: [Solution Strategy](04_solution_strategy.md)

## System Components

### Backend

- **FastAPI application** (`main.py`): entry point that configures routers, middleware, and startup/shutdown events.
- **Routers** (`routes/`): modular route handlers for scenarios, parameters, costs, consumption, production, equipment, maintenance, simulations, and reporting. Each router defines RESTful endpoints, request/response schemas, and orchestrates service calls.
  - leveraging a shared dependency module (`routes/dependencies.get_db`) for SQLAlchemy session management.
- **Models** (`models/`): SQLAlchemy ORM models representing database tables and relationships, encapsulating domain entities like Scenario, CapEx, OpEx, Consumption, ProductionOutput, Equipment, Maintenance, and SimulationResult.
- **Services** (`services/`): business logic layer that processes data, performs calculations, and interacts with models. Key services include reporting calculations and Monte Carlo simulation scaffolding.
  - `services/settings.py`: manages application settings backed by the `application_setting` table, including CSS variable defaults, persistence, and environment-driven overrides that surface in both the API and UI.
- **Database** (`config/database.py`): sets up the SQLAlchemy engine and session management for PostgreSQL interactions.

### Frontend

- **Templates** (`templates/`): Jinja2 templates for server-rendered HTML views, extending a shared base layout with a persistent sidebar for navigation.
- **Static Assets** (`static/`): CSS and JavaScript files for styling and interactivity. Shared CSS variables in `static/css/main.css` define the color palette, while page-specific JS modules in `static/js/` handle dynamic behaviors.
- **Reusable partials** (`templates/partials/components.html`): macro library that standardises select inputs, feedback/empty states, and table wrappers so pages remain consistent while keeping DOM hooks stable for existing JavaScript modules.
  - `templates/settings.html`: Settings hub that renders theme controls and environment override tables using metadata provided by `routes/ui.py`.
  - `static/js/settings.js`: applies client-side validation, form submission, and live CSS updates for theme changes, respecting environment-managed variables returned by the API.

### Middleware & Utilities

- **Middleware** (`middleware/validation.py`): applies JSON validation before requests reach routers.
- **Testing** (`tests/unit/`): pytest suite covering route and service behavior, including UI rendering checks and negative-path router validation tests to ensure consistent HTTP error semantics. Playwright end-to-end coverage is planned for core smoke flows (dashboard load, scenario inputs, reporting) and will attach in CI once scaffolding is completed.

### Component Diagram

# System Architecture — Mermaid Diagram

```mermaid
graph LR
  %% Direction
  %% LR = left-to-right for a wide architecture view

  %% === Clients ===
  U["User (Browser)"]

  %% === Frontend ===
  subgraph FE[Frontend]
    TPL["Jinja2 Templates\n(templates/)\n• base layout + sidebar"]
    PARTS["Reusable Partials\n(templates/partials/components.html)\n• inputs • empty states • table wrappers"]
    STATIC["Static Assets\n(static/)\n• CSS: static/css/main.css (palette via CSS vars)\n• JS: static/js/*.js (page modules)"]
    SETPAGE["Settings View\n(templates/settings.html)"]
    SETJS["Settings Logic\n(static/js/settings.js)\n• validation • submit • live CSS updates"]
  end

  %% === Backend ===
  subgraph BE[Backend FastAPI]
    MAIN["FastAPI App\n(main.py)\n• routers • middleware • startup/shutdown"]

    subgraph ROUTES[Routers]
      R_SCN["scenarios"]
      R_PAR["parameters"]
      R_CST["costs"]
      R_CONS["consumption"]
      R_PROD["production"]
      R_EQP["equipment"]
      R_MNT["maintenance"]
      R_SIM["simulations"]
      R_REP["reporting"]
      R_UI["ui.py (metadata for UI)"]
      DEP["dependencies.get_db\n(shared SQLAlchemy session)"]
    end

    subgraph SRV[Services]
      S_BLL["Business Logic Layer\n• orchestrates models + calc"]
      S_REP["Reporting Calculations"]
      S_SIM["Monte Carlo\n(simulation scaffolding)"]
      S_SET["Settings Manager\n(services/settings.py)\n• defaults via CSS vars\n• persistence in DB\n• env overrides\n• surfaces to API & UI"]
    end

    subgraph MOD[Models]
      M_SCN["Scenario"]
      M_CAP["CapEx"]
      M_OPEX["OpEx"]
      M_CONS["Consumption"]
      M_PROD["ProductionOutput"]
      M_EQP["Equipment"]
      M_MNT["Maintenance"]
      M_SIMR["SimulationResult"]
    end

    subgraph DB[Database Layer]
      CFG["config/database.py\n(SQLAlchemy engine & sessions)"]
      PG[("PostgreSQL")]
      APPSET["application_setting table"]
    end
  end

  %% === Middleware & Utilities ===
  subgraph MW[Middleware & Utilities]
    VAL["JSON Validation Middleware\n(middleware/validation.py)"]
  end

  subgraph TEST[Testing]
    UNIT["pytest unit tests\n(tests/unit/)\n• routes • services • UI rendering\n• negative-path validation"]
    E2E["Playwright E2E (planned)\n• dashboard • scenario inputs • reporting\n• attach in CI"]
  end

  %% ===================== Edges / Flows =====================
  %% User to Frontend/Backend
  U -->|HTTP GET| MAIN
  U --> TPL
  TPL -->|server-rendered HTML| U
  STATIC --> U
  PARTS --> TPL
  SETPAGE --> U
  SETJS --> U

  %% Frontend to Routers (AJAX/form submits)
  SETJS -->|fetch/POST| R_UI
  TPL -->|form submit / fetch| ROUTES

  %% FastAPI app wiring and middleware
  VAL --> MAIN
  MAIN --> ROUTES

  %% Routers to Services
  ROUTES -->|calls| SRV
  R_REP -->|calc| S_REP
  R_SIM -->|run| S_SIM
  R_UI -->|read/write settings meta| S_SET

  %% Services to Models & DB
  SRV --> MOD
  MOD --> CFG
  CFG --> PG

  %% Settings manager persistence path
  S_SET -->|persist/read| APPSET
  APPSET --- PG

  %% Shared DB session dependency
  DEP -. provides .-> ROUTES
  DEP -. session .-> SRV

  %% Model entities mapping
  S_BLL --> M_SCN & M_CAP & M_OPEX & M_CONS & M_PROD & M_EQP & M_MNT & M_SIMR

  %% Testing coverage
  UNIT --> ROUTES
  UNIT --> SRV
  UNIT --> TPL
  UNIT --> VAL
  E2E --> U
  E2E --> MAIN

  %% Legend
  classDef store fill:#fff,stroke:#555,stroke-width:1px;
  class PG store;
```

---

**Notes**

- Arrows represent primary data/command flow. Dashed arrows denote shared dependencies (injected SQLAlchemy session).
- The settings pipeline shows how environment overrides and DB-backed defaults propagate to both API and UI.

```

```

## Module Map (code)

- `scenario.py`: central scenario entity with relationships to cost, consumption, production, equipment, maintenance, and simulation results.
- `capex.py`, `opex.py`: financial expenditures tied to scenarios.
- `consumption.py`, `production_output.py`: operational data tables.
- `equipment.py`, `maintenance.py`: asset management models.
- `simulation_result.py`: stores Monte Carlo iteration outputs.
- `application_setting.py`: persists editable application configuration, currently focused on theme variables but designed to store future settings categories.

## Service Layer

- `reporting.py`: computes aggregates (count, min/max, mean, median, percentiles, standard deviation, variance, tail-risk metrics) from simulation results.
- `simulation.py`: scaffolds Monte Carlo simulation logic (currently in-memory; persistence planned).
- `currency.py`: handles currency normalization for cost tables.
- `utils.py`: shared helper functions (e.g., statistical calculations).
- `validation.py`: JSON schema validation middleware.
- `database.py`: SQLAlchemy engine and session setup.
- `dependencies.py`: FastAPI dependency injection for DB sessions.