Add restore function

index.html

@@ -21,8 +21,9 @@
                 </div>
                 <div class="btn-group">
                     <button class="btn btn-secondary" type="button" @click="save" :disabled="!launched">Save</button>
-                    <button class="btn btn-success" type="button" @click="restore" :disabled="launched">Restore</button>
+                    <label for="restore-input" class="btn btn-success" :class="{disabled: launched}">Restore</label>
                 </div>
+                <input id="restore-input" type="file" @input="restore" style="display: none;"></button>
             </div>
         </div>
         <div class="row" v-show="state_cities != null">
@@ -156,7 +157,35 @@
                 downloadAnchorNode.click();
                 downloadAnchorNode.remove();
             },
-            async restore() {
+            async restore(event) {
+                this.launched = true;
+
+                // Sure would be nice if the API were just designed this way!
+                const read_file = async (file) => new Promise((resolve) => {
+                        const fileReader = new FileReader();
+                        fileReader.onload = (e) => resolve(fileReader.result);
+                        fileReader.readAsText(file);
+                });
+
+                const save_data = await read_file(event.target.files[0]);
+                const save = JSON.parse(save_data, (k, v) => k == 'time' ? new Date(v) : v);
+                this.state_cities = save.cities;
+                this.simplified_cities = this.state_cities.map(city => simplify(city.name));
+                this.state_name = save.state;
+                this.message = `Restored game from ${save.time.toLocaleString()} with ${save.cities.filter(c => c.guessed).length }/${ save.cities.length} cities guessed`;
+
+                // The rest of this function is duplicated from launch(), above
+                const shapes_response = await this.shapes_request;
+                const shapes_data = await shapes_response.json();
+                const shape = shapes_data.features.find(f => f.properties.NAME.toLowerCase() == this.state_name.toLowerCase());
+                if (shape.geometry.type == "MultiPolygon") {
+                    this.state_shape = shape.geometry.coordinates.map(a => a.flat());
+                } else { // Polygon
+                    this.state_shape = shape.geometry.coordinates;
+                }
+                this.state_mercator_adjusted_bounds = find_bounds(this.state_shape.flat().map(mercator));
+
+                this.draw();
             },
             guess() {
                 const rank = this.simplified_cities.indexOf(simplify(this.city_guess))