adds frontend history

frontend/src/graph/line.ts

@@ -2,3 +2,40 @@ export interface Point {
     x: number;
     y: number;
 }
+
+export class PointLine {
+    data: Point[];
+
+    constructor() {
+        this.data = [];
+    }
+
+    find_index(x: number) {
+        if (this.data.length == 0) {
+            return 0;
+        }
+
+        // left should be too early to insert
+        // right should be too late to insert
+        let left = 0;
+        let size = this.data.length;
+
+        while (size > 1) {
+            const half = Math.floor(size / 2);
+            const mid = left + half;
+
+            const is_less = this.data[mid].x < x;
+            if (is_less) {
+                left = mid;
+            }
+            size -= half;
+        }
+
+        return left + (this.data[left].x < x ? 1 : 0);
+    }
+
+    insert(point: Point) {
+        const index = this.find_index(point.x);
+        this.data.splice(index, 0, point);
+    }
+}