added swagger ui and implemented save, get, and stats api.

SampleApplication/Controllers/ShapeController.cs

@@ -2,6 +2,7 @@
 using Microsoft.AspNetCore.Mvc;
 using Microsoft.EntityFrameworkCore;
 using SampleApplication.Entities;
+using System.Threading.Tasks;
 
 namespace SampleApplication.Controllers
 {
@@ -29,7 +30,7 @@ namespace SampleApplication.Controllers
 
         [HttpPost]
 
-        public IActionResult AddShapes(List<ShapeInput> shapes)
+        public async Task<IActionResult> AddShapes([FromBody] List<ShapeInput> shapes)
 
         {
 
@@ -40,12 +41,19 @@ namespace SampleApplication.Controllers
             // - Ignore duplicate IDs
 
             // - Save via EF Core
+
+            if (!shapes.Any())
+            {
+                throw new ArgumentNullException();
+            }
             
             this._calculator.AddShapes(shapes);
 
-            this._db.Shapes.AddRange(shapes);
+           this._db.Shapes.AddRange(shapes);
 
-            return Ok(shapes);
+            await this._db.SaveChangesAsync();
+
+            return Ok();
         }
 
         [HttpGet("{id}")]
@@ -58,19 +66,33 @@ namespace SampleApplication.Controllers
 
             var shape = await this._db.Shapes.Where(s => s.Id == id).FirstOrDefaultAsync();
 
+            if(shape is null)
+            {
+                return NotFound();
+            }
+
             return Ok(shape);
         }
 
         [HttpGet("stats")]
 
-        public IActionResult Stats()
-
+        public async Task<IActionResult> Stats()
         {
 
             // TODO:
 
-            throw new NotImplementedException();
+            var shapes = await this._db.Shapes.ToListAsync();
 
+            if (!shapes.Any())
+            {
+                return NoContent();
+            }
+
+            this._calculator.AddShapes(shapes);
+
+            var stats = this._calculator.GetStatistics();
+
+            return Ok(new {stats.TotalShapes, stats.TotalArea, stats.MaxPerimeterId});
         }
 
     }