gem-spaas · AndySmet · May 23, 2026
diff --git a/.dockerignore b/.dockerignore
@@ -0,0 +1,9 @@
+**/.git
+**/.vs
+**/.vscode
+**/bin
+**/obj
+**/TestResults
+**/*.user
+**/*.suo
+README.md
diff --git a/.editorconfig b/.editorconfig
@@ -0,0 +1,18 @@
+root = true
+
+[*]
+charset = utf-8
+end_of_line = lf
+insert_final_newline = true
+trim_trailing_whitespace = true
+indent_style = space
+indent_size = 4
+
+[*.{json,yml,yaml}]
+indent_size = 2
+
+[*.cs]
+dotnet_style_qualification_for_field = false:suggestion
+dotnet_style_qualification_for_property = false:suggestion
+dotnet_style_qualification_for_method = false:suggestion
+dotnet_style_qualification_for_event = false:suggestion
diff --git a/.gitignore b/.gitignore
@@ -0,0 +1,11 @@
+[Bb]in/
+[Oo]bj/
+.vs/
+.vscode/
+.idea/
+*.user
+*.suo
+*.swp
+*.cache
+TestResults/
+coverage/
diff --git a/Directory.Build.props b/Directory.Build.props
@@ -0,0 +1,8 @@
+<Project>
+  <PropertyGroup>
+    <TreatWarningsAsErrors>false</TreatWarningsAsErrors>
+    <Nullable>enable</Nullable>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+</Project>
diff --git a/Dockerfile b/Dockerfile
@@ -0,0 +1,29 @@
+# syntax=docker/dockerfile:1
+
+FROM mcr.microsoft.com/dotnet/sdk:9.0 AS build
+WORKDIR /src
+
+COPY PowerplantProductionPlan.sln ./
+COPY Directory.Build.props ./
+COPY global.json ./
+COPY src/Powerplant.Api/Powerplant.Api.csproj src/Powerplant.Api/
+COPY tests/Powerplant.Api.Tests/Powerplant.Api.Tests.csproj tests/Powerplant.Api.Tests/
+
+RUN dotnet restore PowerplantProductionPlan.sln
+
+COPY . .
+RUN dotnet publish src/Powerplant.Api/Powerplant.Api.csproj \
+    --configuration Release \
+    --output /app/publish \
+    /p:UseAppHost=false
+
+FROM mcr.microsoft.com/dotnet/aspnet:9.0 AS runtime
+WORKDIR /app
+
+ENV ASPNETCORE_URLS=http://+:8888 \
+    DOTNET_RUNNING_IN_CONTAINER=true
+
+EXPOSE 8888
+
+COPY --from=build /app/publish .
+ENTRYPOINT ["dotnet", "Powerplant.Api.dll"]
diff --git a/PowerplantProductionPlan.sln b/PowerplantProductionPlan.sln
@@ -0,0 +1,30 @@
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio Version 18
+VisualStudioVersion = 18.6.11819.183
+MinimumVisualStudioVersion = 10.0.40219.1
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Powerplant.Api", "src\Powerplant.Api\Powerplant.Api.csproj", "{916AB86E-B84F-4A61-A719-82C889D357CF}"
+EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Powerplant.Api.Tests", "tests\Powerplant.Api.Tests\Powerplant.Api.Tests.csproj", "{C58E130D-DB33-4932-ABCA-59BD77995162}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+		Debug|Any CPU = Debug|Any CPU
+		Release|Any CPU = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{916AB86E-B84F-4A61-A719-82C889D357CF}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{916AB86E-B84F-4A61-A719-82C889D357CF}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{916AB86E-B84F-4A61-A719-82C889D357CF}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{916AB86E-B84F-4A61-A719-82C889D357CF}.Release|Any CPU.Build.0 = Release|Any CPU
+		{C58E130D-DB33-4932-ABCA-59BD77995162}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C58E130D-DB33-4932-ABCA-59BD77995162}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C58E130D-DB33-4932-ABCA-59BD77995162}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{C58E130D-DB33-4932-ABCA-59BD77995162}.Release|Any CPU.Build.0 = Release|Any CPU
+	EndGlobalSection
+	GlobalSection(SolutionProperties) = preSolution
+		HideSolutionNode = FALSE
+	EndGlobalSection
+	GlobalSection(ExtensibilityGlobals) = postSolution
+		SolutionGuid = {61019972-2ADA-4956-AFF8-501E3C16F430}
+	EndGlobalSection
+EndGlobal
diff --git a/README.md b/README.md
@@ -1,4 +1,62 @@
-# powerplant-coding-challenge
+# Powerplant Coding Challenge
+
+REST API for calculating a powerplant production plan.
+
+## Start the API
+
+The API listens on port `8888` when started with Docker.
+
+Swagger UI is available at:
+
+```text
+http://localhost:8888/swagger
+```
+
+The production-plan endpoint is:
+
+```text
+POST http://localhost:8888/productionplan
+```
+
+## Using Docker
+
+Run these commands from the repository root, where the `Dockerfile` is located:
+
+```bash
+docker build -t powerplant-coding-challenge .
+docker run --rm -p 8888:8888 --name powerplant-coding-challenge powerplant-coding-challenge
+```
+
+The container may log something like:
+
+```text
+Now listening on: http://[::]:8888
+```
+
+That is normal. It means the API is listening inside the container on port `8888`.
+From your host machine, open:
+
+```text
+http://localhost:8888/swagger
+```
+
+## Without Docker
+
+1. Open the solution in Visual Studio or JetBrains Rider.
+2. Build the solution.
+3. Select the API project as the startup project:
+
+```text
+powerplant-coding-challenge/src/Powerplant.Api/Powerplant.Api.csproj
+```
+
+4. Run the project.
+
+## Requirements
+
+- .NET 9 SDK, when running without Docker
+- Docker Desktop, when running with Docker
+
 
 
 ## Welcome !

diff --git a/global.json b/global.json
@@ -0,0 +1,6 @@
+{
+  "sdk": {
+    "version": "9.0.100",
+    "rollForward": "latestFeature"
+  }
+}
diff --git a/src/Powerplant.Api/Application/Abstractions/IProductionPlanService.cs b/src/Powerplant.Api/Application/Abstractions/IProductionPlanService.cs
@@ -0,0 +1,13 @@
+using Powerplant.Api.Domain;
+using Powerplant.Api.Generated;
+
+namespace Powerplant.Api.Application.Abstractions
+{
+    public interface IProductionPlanService
+    {
+        IReadOnlyCollection<ProductionPlanEntry> Calculate(
+            decimal Load,
+            FuelPrices fuelPrices,
+            List<PowerPlant> powerPlants);
+    }
+}
diff --git a/src/Powerplant.Api/Application/Services/ProductionPlanService.cs b/src/Powerplant.Api/Application/Services/ProductionPlanService.cs
@@ -0,0 +1,38 @@
+using Powerplant.Api.Application.Abstractions;
+using Powerplant.Api.Domain;
+using Powerplant.Api.Generated;
+
+namespace Powerplant.Api.Application.Services
+{
+    public class ProductionPlanService : IProductionPlanService
+    {
+        public IReadOnlyCollection<ProductionPlanEntry> Calculate(
+            decimal Load,
+            FuelPrices fuelPrices,
+            List<PowerPlant> powerPlants)
+        {
+
+            var result = new List<ProductionPlanEntry>();
+            var remainingLoad = Load;
+
+            var sortedPowerPlants = powerPlants
+                .OrderBy(p => p.CostPerMWh(fuelPrices))
+                .ToList();
+
+            foreach (PowerPlant powerPlant in sortedPowerPlants)
+            {
+                var possibleLoad = powerPlant.GetPossibleLoad(remainingLoad, fuelPrices);
+                result.Add(new ProductionPlanEntry
+                {
+                    Name = powerPlant.Name,
+                    Power = possibleLoad
+                });
+                remainingLoad -= possibleLoad;
+
+            }
+            return result;
+
+        }
+
+    }
+}
diff --git a/src/Powerplant.Api/Contracts/openapi.yaml b/src/Powerplant.Api/Contracts/openapi.yaml
@@ -0,0 +1,158 @@
+openapi: 3.0.3
+info:
+  title: Powerplant Production Plan API
+  version: 1.0.0
+  description: API for the powerplant production-plan.
+servers:
+  - url: /
+paths:
+  /productionplan:
+    post:
+      operationId: calculateProductionPlan
+      tags:
+        - ProductionPlan
+      requestBody:
+        required: true
+        content:
+          application/json:
+            schema:
+              $ref: '#/components/schemas/ProductionPlanRequest'
+      responses:
+        '200':
+          description: Production plan
+          content:
+            application/json:
+              schema:
+                type: array
+                items:
+                  $ref: '#/components/schemas/ProductionPlanResponseItem'
+        '400':
+          description: Invalid request payload.
+          content:
+            application/problem+json:
+              schema:
+                $ref: '#/components/schemas/ProblemDetails'
+        '422':
+          description: The request is syntactically valid but no feasible plan can satisfy the load.
+          content:
+            application/problem+json:
+              schema:
+                $ref: '#/components/schemas/ProblemDetails'
+        '500':
+          description: Unexpected server error.
+          content:
+            application/problem+json:
+              schema:
+                $ref: '#/components/schemas/ProblemDetails'
+        '501':
+          description: Production-plan algorithm is not implemented yet in this scaffold.
+          content:
+            application/problem+json:
+              schema:
+                $ref: '#/components/schemas/ProblemDetails'
+components:
+  schemas:
+    ProductionPlanRequest:
+      type: object
+      required:
+        - load
+        - fuels
+        - powerplants
+      properties:
+        load:
+          type: number
+          format: decimal
+          example: 480
+        fuels:
+          $ref: '#/components/schemas/Fuels'
+        powerplants:
+          type: array
+          items:
+            $ref: '#/components/schemas/PowerPlantDto'
+
+    Fuels:
+      type: object
+      required:
+        - gas(euro/MWh)
+        - kerosine(euro/MWh)
+        - co2(euro/ton)
+        - wind(%)
+      additionalProperties:
+        type: number
+        format: decimal
+      example:
+        gas(euro/MWh): 13.4
+        kerosine(euro/MWh): 50.8
+        co2(euro/ton): 20
+        wind(%): 60
+
+    PowerPlantDto:
+      type: object
+      required:
+        - name
+        - type
+        - efficiency
+        - pmin
+        - pmax
+      properties:
+        name:
+          type: string
+          example: gasfiredbig1
+        type:
+          type: string
+          enum:
+            - gasfired
+            - turbojet
+            - windturbine
+          example: gasfired
+        efficiency:
+          type: number
+          format: decimal
+          example: 0.53
+        pmin:
+          type: number
+          format: decimal
+          example: 100
+        pmax:
+          type: number
+          format: decimal
+          example: 460
+
+    ProductionPlanResponseItem:
+      type: object
+      required:
+        - name
+        - p
+      properties:
+        name:
+          type: string
+          example: windpark1
+        p:
+          type: number
+          format: decimal
+          example: 90.0
+    ProblemDetails:
+      type: object
+      properties:
+        type:
+          type: string
+          nullable: true
+        title:
+          type: string
+          nullable: true
+          example: Bad Request
+        status:
+          type: integer
+          format: int32
+          nullable: true
+          example: 400
+        detail:
+          type: string
+          nullable: true
+          example: The request payload is invalid.
+        instance:
+          type: string
+          nullable: true
+          example: /productionplan
+      additionalProperties: true
+