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;
  title: string;
  userId: string;
};

export type Fact = {
  id: string;
  userId: string;
  sourceMessageId: string;
  content: string;
  createdAt: string;
};

export type FactTrigger = {
  id: string;
  sourceFactId: string;
  content: string;
  priorityMultiplier: number;
  priorityMultiplierReason: string;
  scopeConversationId: string;
  createdAt: string;
};

type DB = {
  conversations: Array<Conversation>;
  messages: Array</*{
    id: string;
    conversationId: string;
    content: string;
    role: "user" | "assistant" | "system" | "data";
    index: number;
    createdAt: string;
    runningSummary?: string;
  }*/ CommittedMessage>;
  facts: Array<Fact>;
  factTriggers: Array<FactTrigger>;
};

export const db = new Low<DB>(new JSONFile("db.json"), {
  conversations: [],
  messages: [],
  facts: [],
  factTriggers: [],
});
/** Initialize the database. Sets `db.data` to the default state if the file doesn't exist. */
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,
};