import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
import { createDebugLogger } from "./log";

describe("createDebugLogger", () => {
  beforeEach(() => {
    vi.spyOn(console, "debug").mockImplementation(() => {});
  });

  afterEach(() => {
    vi.restoreAllMocks();
  });

  it("returns a function", () => {
    expect(typeof createDebugLogger("test")).toBe("function");
  });

  it("prefixes output with [namespace]", () => {
    const log = createDebugLogger("my-ns");
    log("hello");
    expect(console.debug).toHaveBeenCalledWith("[my-ns] hello");
  });

  it("logs plain strings as-is", () => {
    const log = createDebugLogger("ns");
    log("simple message");
    expect(console.debug).toHaveBeenCalledWith("[ns] simple message");
  });

  it("flattens plain objects to key=value pairs", () => {
    const log = createDebugLogger("ns");
    log("msg", { a: 1, b: "hello world" });
    expect(console.debug).toHaveBeenCalledWith('[ns] msg a=1 b="hello world"');
  });

  it("quotes values containing spaces", () => {
    const log = createDebugLogger("ns");
    log({ key: "value with space" });
    expect(console.debug).toHaveBeenCalledWith('[ns] key="value with space"');
  });

  it("leaves bare values unquoted", () => {
    const log = createDebugLogger("ns");
    log({ key: "simple_value" });
    expect(console.debug).toHaveBeenCalledWith("[ns] key=simple_value");
  });

  it("formats null and undefined", () => {
    const log = createDebugLogger("ns");
    log({ a: null, b: undefined });
    expect(console.debug).toHaveBeenCalledWith("[ns] a=null b=undefined");
  });

  it("formats numbers and booleans", () => {
    const log = createDebugLogger("ns");
    log({ count: 42, flag: true });
    expect(console.debug).toHaveBeenCalledWith("[ns] count=42 flag=true");
  });

  it("formats Error objects with name and message", () => {
    const log = createDebugLogger("ns");
    log({ err: new Error("boom") });
    expect(console.debug).toHaveBeenCalledWith('[ns] err={"name":"Error","message":"boom"}');
  });

  it("serializes nested objects as JSON", () => {
    const log = createDebugLogger("ns");
    log({ nested: { x: 1 } });
    expect(console.debug).toHaveBeenCalledWith('[ns] nested={"x":1}');
  });

  it("mixes strings and objects in a single call", () => {
    const log = createDebugLogger("ns");
    log("prefix", { a: 1 }, "suffix");
    expect(console.debug).toHaveBeenCalledWith("[ns] prefix a=1 suffix");
  });
});