abstract application-to-database interface

database/common.ts

@@ -0,0 +1,9 @@
+export interface Entity<T, ID> {
+  construct: (data: T) => T;
+  create: (data: T) => Promise<T>;
+  createMany: (data: T[]) => Promise<T[]>;
+  findAll: () => Promise<T[]>;
+  findById: (id: ID) => Promise<T | undefined>;
+  update: (id: ID, data: Partial<T>) => Promise<void>;
+  delete: (id: ID) => Promise<void>;
+}

database/lowdb.ts

@@ -1,6 +1,8 @@
 import { Low } from "lowdb";
 import { JSONFile } from "lowdb/node";
 import type { CommittedMessage } from "../types";
+import type { Entity } from "./common";
+import { nanoid } from "nanoid";
 
 export type Conversation = {
   id: string;
@@ -51,3 +53,209 @@ export const db = new Low<DB>(new JSONFile("db.json"), {
 await db.read();
 /** Write the database to the file, in case it didn't exist before. */
 await db.write();
+
+const conversations: Entity<Conversation, string> & {
+  fetchMessages: (conversationId: string) => Promise<Array<CommittedMessage>>;
+} = {
+  construct: (conversation: Conversation) => conversation,
+  create: async (conversation: Conversation) => {
+    conversation.id = conversation.id ?? nanoid();
+    await db.data.conversations.push(conversation);
+    await db.write();
+    return conversation;
+  },
+  createMany: async (conversations: Array<Conversation>) => {
+    await db.data.conversations.push(...conversations);
+    await db.write();
+    return conversations;
+  },
+  findAll: async () => {
+    return db.data.conversations;
+  },
+  findById: async (id) => {
+    return db.data.conversations.find((c) => c.id === id);
+  },
+  update: async (id, data: Partial<Conversation>) => {
+    const conversationIndex = db.data.conversations.findIndex(
+      (c) => c.id === id
+    );
+    if (conversationIndex === -1) throw new Error("Conversation not found");
+    db.data.conversations[conversationIndex] = {
+      ...db.data.conversations[conversationIndex],
+      ...data,
+    };
+    await db.write();
+  },
+  delete: async (id) => {
+    db.data.conversations.splice(
+      db.data.conversations.findIndex((c) => c.id === id),
+      1
+    );
+    const deletedMessageIds = db.data.messages
+      .filter((m) => m.conversationId === id)
+      .map((m) => m.id);
+    db.data.messages = db.data.messages.filter((m) => m.conversationId !== id);
+    const deletedFactIds = db.data.facts
+      .filter((fact) => deletedMessageIds.includes(fact.sourceMessageId))
+      .map((fact) => fact.id);
+    db.data.facts = db.data.facts.filter(
+      (fact) => !deletedFactIds.includes(fact.id)
+    );
+    db.data.factTriggers = db.data.factTriggers.filter(
+      (factTrigger) => !deletedFactIds.includes(factTrigger.sourceFactId)
+    );
+    await db.write();
+  },
+  fetchMessages: async (conversationId) => {
+    const rows = await db.data.messages.filter(
+      (m) => m.conversationId === conversationId
+    );
+    return rows as Array<CommittedMessage>;
+  },
+};
+
+const factTriggers: Entity<FactTrigger, string> & {
+  findByFactId: (factId: string) => Promise<Array<FactTrigger>>;
+} = {
+  construct: (factTrigger: FactTrigger) => factTrigger,
+  create: async (factTrigger: FactTrigger) => {
+    factTrigger.id = factTrigger.id ?? nanoid();
+    await db.data.factTriggers.push(factTrigger);
+    await db.write();
+    return factTrigger;
+  },
+  createMany: async (factTriggers: Array<FactTrigger>) => {
+    await db.data.factTriggers.push(...factTriggers);
+    await db.write();
+    return factTriggers;
+  },
+  findAll: async () => {
+    return db.data.factTriggers;
+  },
+  findById: async (id) => {
+    return db.data.factTriggers.find((factTrigger) => factTrigger.id === id);
+  },
+  update: async (id, data: Partial<FactTrigger>) => {
+    const factTriggerIndex = db.data.factTriggers.findIndex(
+      (factTrigger) => factTrigger.id === id
+    );
+    if (factTriggerIndex === -1) throw new Error("Fact trigger not found");
+    db.data.factTriggers[factTriggerIndex] = {
+      ...db.data.factTriggers[factTriggerIndex],
+      ...data,
+    };
+    await db.write();
+  },
+  delete: async (id) => {
+    const deletedFactTriggerIndex = db.data.factTriggers.findIndex(
+      (factTrigger) => factTrigger.id === id
+    );
+    if (deletedFactTriggerIndex === -1)
+      throw new Error("Fact trigger not found");
+    db.data.factTriggers.splice(deletedFactTriggerIndex, 1);
+    await db.write();
+  },
+  findByFactId: async (factId: string) => {
+    return db.data.factTriggers.filter(
+      (factTrigger) => factTrigger.sourceFactId === factId
+    );
+  },
+};
+
+const facts: Entity<Fact, string> & {
+  findByConversationId: (conversationId: string) => Promise<Array<Fact>>;
+} = {
+  construct: (fact: Fact) => fact,
+  create: async (fact: Fact) => {
+    fact.id = fact.id ?? nanoid();
+    await db.data.facts.push(fact);
+    await db.write();
+    return fact;
+  },
+  createMany: async (facts: Array<Fact>) => {
+    await db.data.facts.push(...facts);
+    await db.write();
+    return facts;
+  },
+  findAll: async () => {
+    return db.data.facts;
+  },
+  findById: async (id) => {
+    return db.data.facts.find((fact) => fact.id === id);
+  },
+  update: async (id, data: Partial<Fact>) => {
+    const factIndex = db.data.facts.findIndex((fact) => fact.id === id);
+    if (factIndex === -1) throw new Error("Fact not found");
+    db.data.facts[factIndex] = {
+      ...db.data.facts[factIndex],
+      ...data,
+    };
+    await db.write();
+  },
+  delete: async (id) => {
+    const deletedFactId = db.data.facts.findIndex((fact) => fact.id === id);
+    if (deletedFactId === -1) throw new Error("Fact not found");
+    db.data.facts.splice(deletedFactId, 1);
+    await db.write();
+  },
+  findByConversationId: async (conversationId) => {
+    const conversationMessageIds = db.data.messages
+      .filter((m) => m.conversationId === conversationId)
+      .map((m) => m.id);
+    const rows = await db.data.facts.filter((f) =>
+      conversationMessageIds.includes(f.sourceMessageId)
+    );
+    return rows as Array<Fact>;
+  },
+};
+
+const messages: Entity<CommittedMessage, string> & {
+  findByConversationId: (
+    conversationId: string
+  ) => Promise<Array<CommittedMessage>>;
+} = {
+  construct: (message: CommittedMessage) => message,
+  create: async (message: CommittedMessage) => {
+    message.id = message.id ?? nanoid();
+    await db.data.messages.push(message);
+    await db.write();
+    return message;
+  },
+  createMany: async (messages: Array<CommittedMessage>) => {
+    await db.data.messages.push(...messages);
+    await db.write();
+    return messages;
+  },
+  findAll: async () => {
+    return db.data.messages;
+  },
+  findById: async (id) => {
+    return db.data.messages.find((m) => m.id === id);
+  },
+  update: async (id, data: Partial<CommittedMessage>) => {
+    const messageIndex = db.data.messages.findIndex((m) => m.id === id);
+    if (messageIndex === -1) throw new Error("Message not found");
+    db.data.messages[messageIndex] = {
+      ...db.data.messages[messageIndex],
+      ...data,
+    };
+    await db.write();
+  },
+  delete: async (id) => {
+    db.data.messages.splice(
+      db.data.messages.findIndex((m) => m.id === id),
+      1
+    );
+    await db.write();
+  },
+  findByConversationId: async (conversationId) => {
+    return db.data.messages.filter((m) => m.conversationId === conversationId);
+  },
+};
+
+export const _db = {
+  conversations,
+  factTriggers,
+  facts,
+  messages,
+};