// // from /my/site/homepage/www/rdf/streamed-graph.js

// import { eachJsonLdQuad } from "./json_ld_quads";
// import { N3Store } from "n3";
// import { Store } from "n3";

// export class StreamedGraphClient {
//   // holds a n3 Store, which is synced to a server-side
//   // store that sends patches over SSE

//   onStatus: (msg: string) => void;
//   onGraphChanged: () => void;
//   store: N3Store;
//   _deletedCount: number = 0;
//   events!: EventSource;
//   constructor(
//     eventsUrl: string,
//     onGraphChanged: () => void,
//     onStatus: (status: string) => void,
//     prefixes: Array<Record<string, string>>,
//     staticGraphUrls: Array<string>
//   ) {
//     console.log("new StreamedGraph", eventsUrl);
//     this.onStatus = onStatus;
//     this.onGraphChanged = onGraphChanged;
//     this.onStatus("startup...");

//     this.store = new Store();

//     //     //             Object.keys(prefixes).forEach((prefix) => {
//     //     //                 this.store.setPrefix(prefix, prefixes[prefix]);
//     //     //             });

//     this.connect(eventsUrl);
//     this.reconnectOnWake();

//     //     staticGraphUrls.forEach((url) => {
//     //         fetch(url).then((response) => response.text())
//     //             .then((body) => {
//     //                 // parse with n3, add to output
//     //             });
//     //     });
//   }

//   _vacuum() {
//     // workaround for the growing _ids map
//     this.store = new Store(this.store.getQuads(null, null, null, null));
//   }

//   reconnectOnWake() {
//     // it's not this, which fires on every mouse-in on a browser window, and doesn't seem to work for screen-turned-back-on
//     //window.addEventListener('focus', function() { this.connect(eventsUrl); }.bind(this));
//   }

//   connect(eventsUrl: string) {
//     // need to exit here if this obj has been replaced

//     this.onStatus("start connect...");
//     this.close();
//     if (this.events && this.events.readyState != EventSource.CLOSED) {
//       this.onStatus("zombie");
//       throw new Error("zombie eventsource");
//     }

//     this.events = new EventSource(eventsUrl);

//     this.events.addEventListener("error", ev => {
//       // todo: this is piling up tons of retries and eventually multiple connections
//       // this.testEventUrl(eventsUrl);
//       this.onStatus("connection lost- retrying");
//       setTimeout(() => {
//         requestAnimationFrame(() => {
//           this.connect(eventsUrl);
//         });
//       }, 3000);
//     });

//     this.events.addEventListener("fullGraph", async ev => {
//       this.onStatus("sync- full graph update");
//       await this.replaceFullGraph((ev as MessageEvent).data);
//       this.onStatus(`synced ${this.store.size}`);
//       this.onGraphChanged();
//     });

//     this.events.addEventListener("patch", async ev => {
//       this.onStatus("sync- updating");
//       await this.patchGraph((ev as MessageEvent).data);
//       this.onStatus(`synced ${this.store.size}`);
//       this.onGraphChanged();
//     });
//     this.onStatus("connecting...");
//   }

//   // these need some locks
//   async replaceFullGraph(jsonLdText: string) {
//     this.store = new Store();
//     await eachJsonLdQuad(
//       JSON.parse(jsonLdText),
//       this.store.addQuad.bind(this.store)
//     );
//   }

//   async patchGraph(patchJson: string) {
//     var patch = JSON.parse(patchJson).patch;

//     await eachJsonLdQuad(patch.deletes, quad => {
//       this.store.removeQuad(quad);
//       this._deletedCount++;
//     });
//     await eachJsonLdQuad(patch.adds, this.store.addQuad.bind(this.store));

//     if (this._deletedCount > 100) {
//       this._vacuum();
//       this._deletedCount = 0;
//     }
//   }

//   close() {
//     if (this.events) {
//       this.events.close();
//     }
//   }

//   async testEventUrl(eventsUrl: string): Promise<void> {
//     return new Promise<void>((resolve, reject) => {
//       this.onStatus("testing connection");
//       fetch(eventsUrl, {
//         method: "HEAD",
//         credentials: "include"
//       })
//         .then(value => {
//           if (value.status == 403) {
//             reject();
//             return;
//           }
//           resolve();
//         })
//         .catch(err => {
//           reject();
//         });
//     });
//   }
// }