IO-2836 Charts Route

Signed-off-by: Allan Carr <allan.carr@thinkimex.com>

server/render/canvas-handler.js

@@ -0,0 +1,92 @@
+const { createCanvas } = require("canvas");
+const Chart = require("chart.js/auto");
+
+const { backgroundColors, borderColors } = require("./canvas-colors");
+const { isObject, defaultsDeep, isNumber } = require("lodash");
+
+exports.canvastest = function (req, res) {
+  console.log("Incoming test request.", req);
+  res.status(200).send("OK");
+};
+
+exports.canvas = function (req, res) {
+  const { w, h, values, keys, override } = req.body;
+  console.log("Incoming Canvas Request:", w, h, values, keys, override);
+
+  // Gate required values
+  if (!values || !keys) {
+    res.status(400).send("Missing required data");
+    return;
+  }
+
+  // Override must be an object if it exists
+  if (override && !isObject(override)) {
+    res.status(400).send("Override must be an object");
+    return;
+  }
+
+  // Set the default Width and Height
+  let [width, height] = [500, 275];
+
+  // Allow for custom width and height
+  if (isNumber(w)) {
+    width = w;
+  }
+  if (isNumber(h)) {
+    height = h;
+  }
+
+  const configuration = {
+    type: "doughnut",
+    data: {
+      labels: keys,
+      datasets: [
+        {
+          data: values,
+          backgroundColor: backgroundColors,
+          borderColor: borderColors,
+          borderWidth: 1
+        }
+      ]
+    },
+    options: {
+      devicePixelRatio: 4,
+      responsive: false,
+      maintainAspectRatio: true,
+      circumference: 180,
+      rotation: -90,
+      plugins: {
+        legend: {
+          labels: {
+            boxWidth: 20,
+            font: {
+              family: "'Montserrat'",
+              size: 10,
+              style: "normal",
+              weight: "normal"
+            }
+          },
+          position: "left"
+        }
+      }
+    }
+  };
+
+  // If we have a valid override object, merge it with the default configuration object.
+  // This allows for you to override the default configuration with a custom one.
+  const defaults = () => {
+    if (!override || !isObject(override)) {
+      return configuration;
+    }
+    return defaultsDeep(override, configuration);
+  };
+
+  res.status(200).send(
+    (() => {
+      const canvas = createCanvas(width, height);
+      const ctx = canvas.getContext("2d");
+      new Chart(ctx, defaults());
+      return canvas.toDataURL();
+    })()
+  );
+};