import { Signal } from "@segment/analytics-signals-runtime";
import { logger } from "../../../lib/logger";
import { SignalBuffer } from "../../buffer";
import { SignalsMiddlewareContext, SignalsSubscriber } from "../../emitter";
import { SignalEventProcessor } from "../../processor/processor";
import {
  GlobalScopeSandbox,
  IframeSandboxSettings,
  NoopSandbox,
  SignalSandbox,
  WorkerSandbox,
  normalizeEdgeFunctionURL,
} from "../../processor/sandbox";

export class SignalsEventProcessorSubscriber implements SignalsSubscriber {
  processor!: SignalEventProcessor;
  buffer!: SignalBuffer;
  load(ctx: SignalsMiddlewareContext) {
    this.buffer = ctx.buffer;
    const sandboxSettings = ctx.unstableGlobalSettings.sandbox;
    const normalizedEdgeFunctionURL = normalizeEdgeFunctionURL(
      sandboxSettings.functionHost,
      sandboxSettings.edgeFnDownloadURL,
    );

    let sandbox: SignalSandbox;

    if (!normalizedEdgeFunctionURL) {
      console.warn(
        `No processSignal function found. Have you written a processSignal function on app.segment.com?`,
      );
      logger.debug("Initializing sandbox: noop");
      sandbox = new NoopSandbox();
    } else if (sandboxSettings.sandboxStrategy === "iframe") {
      logger.debug("Initializing sandbox: iframe");
      sandbox = new WorkerSandbox(
        new IframeSandboxSettings({
          edgeFnDownloadURL: normalizedEdgeFunctionURL,
        }),
      );
    } else {
      logger.debug("Initializing sandbox: global scope");
      sandbox = new GlobalScopeSandbox({
        edgeFnDownloadURL: normalizedEdgeFunctionURL,
      });
    }

    this.processor = new SignalEventProcessor(ctx.analyticsInstance, sandbox);
  }
  async process(signal: Signal) {
    return this.processor.process(signal, await this.buffer.getAll());
  }
}