2 files changed, 122 insertions, 0 deletions
diff --git a/lib/model.ts b/lib/model.ts
new file mode 100644
index 0000000..77fede0
--- /dev/null
+++ b/lib/model.ts
@@ -0,0 +1,87 @@
+import { model, Schema, Model } from 'mongoose';
+import createEventSchema, { EventDocument } from './schema';
+import cron from 'cron';
+
+interface Event<Context> extends EventDocument<Context> {
+  log(message: string): void;
+  start(): void;
+  complete(): void;
+  fail(): void;
+  computeNextRunAt(): Date;
+}
+
+const CronJob = cron.CronJob;
+
+const createEventModel = <Context extends Schema>(name: string, contextSchema: Context) => {
+  const schema = createEventSchema(contextSchema);
+
+  // Schema methods
+  schema.method('log', function(message: string) {
+    // TODO: Actually create logs
+    console.log(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();
+  });
+
+  // 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>>(name, schema);
+};
+
+
+export default createEventModel;
+
diff --git a/lib/schema.ts b/lib/schema.ts
new file mode 100644
index 0000000..4e5dd69
--- /dev/null
+++ b/lib/schema.ts
@@ -0,0 +1,35 @@
+import { Schema, Document } from 'mongoose';
+
+export interface EventDocument<Context> extends Document {
+  name: string;
+  schedule: string;
+  status: 'notStarted' | 'running' | 'complete' | 'failed';
+  error?: string;
+  context: Context;
+  nextRunAt: Date;
+  lastRunAt: Date;
+}
+
+const createEventSchema = (contextSchema: Schema) => new Schema({
+  name: {
+    type: String,
+    required: true,
+    unique: true
+  },
+  schedule: {
+    type: String,
+    required: true
+  },
+  status: {
+    type: String,
+    default: 'notStarted'
+  },
+  error: String,
+  context: contextSchema,
+  nextRunAt: Date,
+  lastRunAt: Date
+}, { timestamps: true });
+
+
+export default createEventSchema;
+