/**
 * TASK-0126 — the frontend SSE parser must round-trip the page-generation
 * wire frames (tool started/done, terminal done{pageId,created}, cancelled,
 * error), skip keepalive lines, and survive frames split across chunk
 * boundaries. `parseSseFrames` is generic (it parses `data:` JSON), so the
 * generate frames are asserted by casting to `GenerateFrame`.
 *
 * @vitest-environment node (the config default is jsdom, not installed — every
 * web test opts into node explicitly).
 */
import { describe, it, expect } from "vitest";
import { parseSseFrames, type GenerateFrame } from "@/lib/ai";

const wire = (frames: GenerateFrame[]) =>
  frames.map((f) => `data: ${JSON.stringify(f)}\n\n`).join("");

const parse = (buf: string): GenerateFrame[] => parseSseFrames(buf).frames as GenerateFrame[];

describe("parseSseFrames — generate (TASK-0126) wire contract", () => {
  it("parses the tool started/done + terminal done{pageId,created} sequence", () => {
    const frames: GenerateFrame[] = [
      { type: "tool", name: "createPage", status: "started" },
      { type: "tool", name: "createPage", status: "done", ref: "pg_1" },
      { type: "tool", name: "insertBlocks", status: "started" },
      { type: "tool", name: "insertBlocks", status: "done" },
      { type: "tool", name: "createDatabase", status: "started" },
      { type: "tool", name: "createDatabase", status: "done", ref: "db_1" },
      {
        type: "done",
        pageId: "pg_1",
        created: { pages: ["pg_1"], blocks: 6, databases: ["db_1"], relations: 0 },
        tokensIn: 120,
        tokensOut: 40
      }
    ];
    const out = parse(wire(frames));
    expect(out).toEqual(frames);
  });

  it("parses a cancelled terminal frame", () => {
    const out = parse(`data: ${JSON.stringify({ type: "tool", name: "createPage", status: "started" })}\n\ndata: ${JSON.stringify({ type: "cancelled" })}\n\n`);
    expect(out).toEqual([
      { type: "tool", name: "createPage", status: "started" },
      { type: "cancelled" }
    ]);
  });

  it("parses an error frame with code + retryable", () => {
    const out = parse(`data: ${JSON.stringify({ type: "error", code: "generation_failed", message: "Step 2 failed.", retryable: true })}\n\n`);
    expect(out).toEqual([{ type: "error", code: "generation_failed", message: "Step 2 failed.", retryable: true }]);
  });

  it("skips `: keepalive` comment lines between tool frames", () => {
    const out = parse(
      ": keepalive\n\ndata: {\"type\":\"tool\",\"name\":\"createPage\",\"status\":\"started\"}\n\n: keepalive\n\ndata: {\"type\":\"tool\",\"name\":\"createPage\",\"status\":\"done\",\"ref\":\"p\"}\n\n"
    );
    expect(out).toEqual([
      { type: "tool", name: "createPage", status: "started" },
      { type: "tool", name: "createPage", status: "done", ref: "p" }
    ]);
  });

  it("keeps a partial trailing frame (the done payload split mid-JSON across chunks)", () => {
    const full = `data: ${JSON.stringify({
      type: "done",
      pageId: "pg_9",
      created: { pages: ["pg_9"], blocks: 1, databases: [], relations: 0 }
    })}\n\n`;
    const splitAt = 30; // mid-JSON
    const first = parseSseFrames(full.slice(0, splitAt));
    expect(first.frames).toEqual([]);
    const second = parseSseFrames(first.rest + full.slice(splitAt));
    expect(second.frames).toEqual([
      { type: "done", pageId: "pg_9", created: { pages: ["pg_9"], blocks: 1, databases: [], relations: 0 } }
    ]);
  });
});