1 files changed, 100 insertions, 0 deletions
diff --git a/lib/event.model.ts b/lib/event.model.ts
new file mode 100644
index 0000000..a430674
--- /dev/null
+++ b/lib/event.model.ts
@@ -0,0 +1,100 @@
+import { model, Schema, Model } from 'mongoose';
+import cron from 'cron';
+import createEventSchema, { EventDocument } from './event.schema';
+import { LogDocument } from './log.schema';
+import LogModel from './log.model';
+
+interface Event<Context> extends EventDocument<Context> {
+  log(message: string): void;
+  start(): void;
+  complete(): void;
+  fail(error: Error): void;
+  computeNextRunAt(): Date;
+  getLogs(): Promise<LogDocument[]>;
+}
+
+export interface EventModel<Context> extends Model<Event<Context>> {
+  findNextEvents(): Event<Context>[];
+  findMissedEvents(): Event<Context>[];
+}
+
+const CronJob = cron.CronJob;
+
+const createEventModel = <Context>(name: string, contextSchema: Schema): EventModel<Context> => {
+  const schema = createEventSchema(contextSchema);
+
+  // Schema methods
+  schema.method('log', function(message: string) {
+    const timestamp = new Date().toLocaleString('en');
+    console.log(`[${timestamp}] ${this.name}: ${message}`);
+    return LogModel.create({ eventId: this._id, message });
+  });
+
+  schema.method('start', function() {
+    this.log('Event started')
+    this.lastRunAt = new Date();
+    this.status = 'running';
+    return this.save();
+  });
+
+  schema.method('complete', function() {
+    this.log('Event complete')
+    this.status = 'complete';
+    return this.save();
+  });
+
+  schema.method('fail', function(error: Error) {
+    this.log(error);
+    this.error = error;
+    this.status = 'failed';
+    return this.save();
+  });
+
+  schema.method('computeNextRunAt', function() {
+    const job = new CronJob(this.schedule);
+    const nextRunAt = job.nextDates();
+    return nextRunAt.toDate();
+  });
+
+  schema.method('getLogs', function() {
+    return LogModel.find({ eventId: this._id });
+  });
+
+  // Statics
+  schema.static('findMissedEvents', async function () {
+    return this.find({
+      nextRunAt: {
+        // TODO: skip single-fire events
+        $lt: new Date()
+      },
+    });
+  });
+
+  schema.static('findNextEvents', function(limit = 10) {
+    return this.find(
+      {
+        nextRunAt: {
+          $gt: new Date()
+        },
+      },
+      null,
+      {
+        sort: {
+          nextRunAt: 1
+        },
+        limit
+      }
+    )
+  });
+
+  // Hooks
+  schema.pre<Event<Context>>('save', async function() {
+    this.nextRunAt = this.computeNextRunAt();
+  });
+
+  return model<Event<Context>, EventModel<Context>>(name, schema);
+};
+
+
+export default createEventModel;
+