import { Data, Effect, Schema } from "effect";

class SentryTunnelError extends Data.TaggedError("SentryTunnelError")<{
  readonly cause?: unknown;
}> {}

const SentryEnvelopeHeader = Schema.Struct({
  dsn: Schema.optional(Schema.String),
});

const decodeSentryEnvelopeHeader = Schema.decodeUnknownEffect(
  Schema.fromJsonString(SentryEnvelopeHeader),
);

const badSentryEnvelopeResponse = () => new Response("bad envelope", { status: 400 });

export const handleSentryTunnelRequest = (request: Request, configuredDsn: string) =>
  Effect.gen(function* () {
    const envelope = yield* Effect.tryPromise({
      try: () => request.text(),
      catch: (cause) => new SentryTunnelError({ cause }),
    });
    const firstLine = envelope.slice(0, envelope.indexOf("\n"));
    const header = yield* decodeSentryEnvelopeHeader(firstLine).pipe(
      Effect.mapError((cause) => new SentryTunnelError({ cause })),
    );
    const dsn = header.dsn;
    if (!dsn) return new Response("missing dsn", { status: 400 });

    const envelopeDsn = yield* Effect.try({
      try: () => new URL(dsn),
      catch: (cause) => new SentryTunnelError({ cause }),
    });
    const ourDsn = yield* Effect.try({
      try: () => new URL(configuredDsn),
      catch: (cause) => new SentryTunnelError({ cause }),
    });
    if (envelopeDsn.host !== ourDsn.host || envelopeDsn.pathname !== ourDsn.pathname) {
      return new Response("dsn mismatch", { status: 400 });
    }

    const projectId = envelopeDsn.pathname.replace(/^\//, "");
    const ingestUrl = `https://${envelopeDsn.host}/api/${projectId}/envelope/`;
    return yield* Effect.tryPromise({
      try: () =>
        fetch(ingestUrl, {
          method: "POST",
          body: envelope,
          headers: { "Content-Type": "application/x-sentry-envelope" },
        }),
      catch: (cause) => new SentryTunnelError({ cause }),
    });
  }).pipe(Effect.catch(() => Effect.succeed(badSentryEnvelopeResponse())));