import { describe, expect, test } from "bun:test";
import {
  type AiMapStreamEvent,
  createAiMapEventBuffer,
  parseAiMapEvent,
  serializeAiMapEvent,
} from "./ndjson";

describe("parseAiMapEvent", () => {
  test("accepts each well-formed event and trims mapping fields", () => {
    expect(parseAiMapEvent({ type: "meta", prompt: "p" })).toEqual({
      type: "meta",
      prompt: "p",
    });
    expect(parseAiMapEvent({ type: "reasoning", text: "thinking" })).toEqual({
      type: "reasoning",
      text: "thinking",
    });
    expect(
      parseAiMapEvent({ type: "mapping", id: "r1", group: "  Scribe  " }),
    ).toEqual({ type: "mapping", id: "r1", group: "Scribe" });
    expect(parseAiMapEvent({ type: "done" })).toEqual({ type: "done" });
  });

  test("rejects malformed events", () => {
    expect(parseAiMapEvent(null)).toBeNull();
    expect(parseAiMapEvent({ type: "reasoning", text: "" })).toBeNull();
    expect(
      parseAiMapEvent({ type: "mapping", id: "r1", group: "  " }),
    ).toBeNull();
    expect(parseAiMapEvent({ type: "mapping", id: "", group: "x" })).toBeNull();
    expect(parseAiMapEvent({ type: "unknown" })).toBeNull();
  });

  test("error defaults its message", () => {
    expect(parseAiMapEvent({ type: "error" })).toEqual({
      type: "error",
      message: "AI mapping failed",
    });
  });
});

describe("createAiMapEventBuffer", () => {
  test("emits complete lines and holds a partial line across chunks", () => {
    const buf = createAiMapEventBuffer();
    const events: AiMapStreamEvent[] = [];

    // A meta line split across two chunks, then a full reasoning line.
    events.push(...buf.push('{"type":"meta","prompt":"P'));
    expect(events).toHaveLength(0); // partial — nothing yet
    events.push(
      ...buf.push('"}\n{"type":"reasoning","text":"a"}\n{"type":"mapp'),
    );
    expect(events).toEqual([
      { type: "meta", prompt: "P" },
      { type: "reasoning", text: "a" },
    ]);

    events.length = 0;
    events.push(...buf.push('ing","id":"r1","group":"G"}\n'));
    expect(events).toEqual([{ type: "mapping", id: "r1", group: "G" }]);
  });

  test("flush emits a final newline-less line and skips junk", () => {
    const buf = createAiMapEventBuffer();
    expect(buf.push("not json\n")).toEqual([]); // malformed line skipped
    expect(buf.push('{"type":"done"}')).toEqual([]); // no newline yet
    expect(buf.flush()).toEqual([{ type: "done" }]);
  });

  test("round-trips serializeAiMapEvent through the buffer", () => {
    const buf = createAiMapEventBuffer();
    const wire =
      serializeAiMapEvent({ type: "meta", prompt: "hi" }) +
      serializeAiMapEvent({ type: "mapping", id: "a", group: "B" }) +
      serializeAiMapEvent({ type: "done" });
    expect(buf.push(wire)).toEqual([
      { type: "meta", prompt: "hi" },
      { type: "mapping", id: "a", group: "B" },
      { type: "done" },
    ]);
  });
});