import amqplib, { type ChannelModel, type Channel, type ConsumeMessage } from "amqplib";
import type { Logger } from "pino";
import type { RabbitMqSecret } from "../secrets/VaultClient.js";
import type { CryptoTransferCompleted, CryptoTransferRequest } from "./messageSchema.js";
import { parseCryptoTransferRequest } from "./messageSchema.js";

export const REQUEST_QUEUE = "crypto.transfer.requested";
export const COMPLETED_QUEUE = "crypto.transfer.completed";

export type TransferRequestHandler = (
  message: CryptoTransferRequest,
  log: Logger
) => Promise<void>;

export interface AmqpClientOptions {
  secret: RabbitMqSecret;
  logger: Logger;
  onConnectionLost: () => void;
}

export class AmqpClient {
  private readonly logger: Logger;
  private readonly secret: RabbitMqSecret;
  private readonly onConnectionLost: () => void;
  private connection?: ChannelModel;
  private channel?: Channel;

  constructor(options: AmqpClientOptions) {
    this.secret = options.secret;
    this.logger = options.logger.child({ component: "amqp" });
    this.onConnectionLost = options.onConnectionLost;
  }

  async connect(): Promise<void> {
    this.connection = await amqplib.connect({
      protocol: "amqp",
      hostname: this.secret.host,
      port: this.secret.port,
      username: this.secret.user,
      password: this.secret.password,
      vhost: this.secret.vhost
    });

    this.connection.on("error", (error) => {
      this.logger.error({ err: error }, "amqp connection error");
    });
    this.connection.on("close", () => {
      this.logger.error("amqp connection closed");
      this.onConnectionLost();
    });

    this.channel = await this.connection.createChannel();
    await this.channel.prefetch(1);
    await this.channel.assertQueue(REQUEST_QUEUE, { durable: true });
    await this.channel.assertQueue(COMPLETED_QUEUE, { durable: true });

    this.logger.info(
      { host: this.secret.host, port: this.secret.port, vhost: this.secret.vhost },
      "amqp connected"
    );
  }

  async startConsumer(handler: TransferRequestHandler): Promise<void> {
    if (!this.channel) {
      throw new Error("AmqpClient not connected");
    }

    await this.channel.consume(REQUEST_QUEUE, (msg) => {
      if (!msg) {
        return;
      }
      void this.dispatch(msg, handler);
    });

    this.logger.info({ queue: REQUEST_QUEUE }, "amqp consumer started");
  }

  publishCompleted(payload: CryptoTransferCompleted): boolean {
    if (!this.channel) {
      throw new Error("AmqpClient not connected");
    }

    return this.channel.sendToQueue(
      COMPLETED_QUEUE,
      Buffer.from(JSON.stringify(payload)),
      { contentType: "application/json", persistent: true }
    );
  }

  async close(): Promise<void> {
    try {
      await this.channel?.close();
    } catch {
      /* ignore */
    }
    try {
      await this.connection?.close();
    } catch {
      /* ignore */
    }
  }

  private async dispatch(msg: ConsumeMessage, handler: TransferRequestHandler): Promise<void> {
    if (!this.channel) {
      return;
    }
    const channel = this.channel;

    let parsed: CryptoTransferRequest;
    try {
      const body = JSON.parse(msg.content.toString("utf8")) as unknown;
      parsed = parseCryptoTransferRequest(body);
    } catch (error) {
      this.logger.error(
        { err: error, raw: safeRaw(msg) },
        "rejected malformed message"
      );
      channel.ack(msg);
      return;
    }

    const log = this.logger.child({
      trace_id: parsed.trace_id,
      order_id: parsed.order_id,
      user_id: parsed.user_id,
      message_id: parsed.message_id
    });

    log.info({ event: "transfer.requested.received" }, "received from queue");

    try {
      await handler(parsed, log);
      channel.ack(msg);
    } catch (error) {
      log.error({ err: error }, "infrastructure error during message handling, requeue=false");
      channel.nack(msg, false, false);
    }
  }
}

function safeRaw(msg: ConsumeMessage): string {
  try {
    return msg.content.toString("utf8").slice(0, 512);
  } catch {
    return "<unreadable>";
  }
}