import { describe, expect, it } from "vitest";
import { MCP_HTTP_ACCEPT, mcpHttpRequestHeaders, parseMcpHttpResponseBody } from "../services/mcp-http.js";

describe("mcpHttpRequestHeaders", () => {
  it("advertises both JSON and SSE on every request", () => {
    expect(mcpHttpRequestHeaders()).toMatchObject({
      "content-type": "application/json",
      accept: "application/json, text/event-stream",
    });
    expect(MCP_HTTP_ACCEPT).toBe("application/json, text/event-stream");
  });

  it("preserves caller-supplied headers while keeping the required Accept value", () => {
    expect(mcpHttpRequestHeaders({ Authorization: "Bearer x", accept: "application/json" })).toMatchObject({
      accept: "application/json, text/event-stream",
      Authorization: "Bearer x",
    });
  });
});

describe("parseMcpHttpResponseBody", () => {
  it("parses a plain application/json body", () => {
    const payload = { jsonrpc: "2.0", id: "1", result: { tools: [] } };
    expect(parseMcpHttpResponseBody(JSON.stringify(payload), "application/json")).toEqual(payload);
  });

  it("parses an SSE-framed body, extracting the JSON-RPC message", () => {
    const payload = { jsonrpc: "2.0", id: "1", result: { tools: [{ name: "kv_get" }] } };
    const body = `event: message\ndata: ${JSON.stringify(payload)}\n\n`;
    expect(parseMcpHttpResponseBody(body, "text/event-stream; charset=utf-8")).toEqual(payload);
  });

  it("skips non-JSON-RPC SSE events and returns the response message", () => {
    const ping = "event: ping\ndata: {\"type\":\"ping\"}";
    const message = { jsonrpc: "2.0", id: "1", result: { ok: true } };
    const body = `${ping}\n\nevent: message\ndata: ${JSON.stringify(message)}\n\n`;
    expect(parseMcpHttpResponseBody(body, "text/event-stream")).toEqual(message);
  });

  it("handles multi-line SSE data fields", () => {
    const payload = { jsonrpc: "2.0", id: "1", result: { note: "line" } };
    const json = JSON.stringify(payload, null, 2);
    const body = `data: ${json.split("\n").join("\ndata: ")}\n\n`;
    expect(parseMcpHttpResponseBody(body, "text/event-stream")).toEqual(payload);
  });

  it("throws when an SSE stream carries no data events", () => {
    expect(() => parseMcpHttpResponseBody("event: ping\n\n", "text/event-stream")).toThrow();
  });
});