import { describe, expect, it } from "@suaveplan/testing/runner";
import { SSE_BUN_CODES, SseBunError } from "../error-codes/error-codes.js";
import {
    encodeComment,
    encodeSseEvent,
    encodeStreamPrologue,
} from "./sse-stream.js";

const dec = (bytes: Uint8Array): string => new TextDecoder().decode(bytes);

describe("stream.encodeSseEvent", () => {
    it("emits id, event, data lines for a basic event", () => {
        const out = dec(
            encodeSseEvent(
                { id: "1", event: "ping", data: "hello" },
                { maxEventBytes: 1024 }
            )
        );
        expect(out).toBe("id: 1\nevent: ping\ndata: hello\n\n");
    }, 5000);

    it("omits event line when undefined and includes retry when supplied", () => {
        const out = dec(
            encodeSseEvent(
                { id: "2", data: "x", retry: 5000 },
                { maxEventBytes: 1024 }
            )
        );
        expect(out).toBe("id: 2\nretry: 5000\ndata: x\n\n");
    }, 5000);

    it("splits multi-line data into one data: line per chunk", () => {
        const out = dec(
            encodeSseEvent(
                { id: "3", data: "a\nb\nc" },
                { maxEventBytes: 1024 }
            )
        );
        expect(out).toBe("id: 3\ndata: a\ndata: b\ndata: c\n\n");
    }, 5000);

    it("throws EVENT_TOO_LARGE when encoded bytes exceed cap", () => {
        try {
            encodeSseEvent(
                { id: "4", data: "x".repeat(1000) },
                { maxEventBytes: 100 }
            );
            expect.fail("expected throw");
        } catch (err) {
            expect(err).toBeInstanceOf(SseBunError);
            expect((err as SseBunError).code).toBe(
                SSE_BUN_CODES.EVENT_TOO_LARGE
            );
        }
    }, 5000);
});

describe("stream.encodeStreamPrologue", () => {
    it("emits retry directive then blank line", () => {
        expect(dec(encodeStreamPrologue(3000))).toBe("retry: 3000\n\n");
    }, 5000);
});

describe("stream.encodeComment", () => {
    it("emits a colon-prefixed comment terminated by a blank line", () => {
        expect(dec(encodeComment("keepalive"))).toBe(":keepalive\n\n");
    }, 5000);
});