/**
 * TASK-0123 — the diff's OLD-side extractor (`blockPlainText`) + the
 * word-level diff renderer's input contract (`wordDiff` from @factory/editor).
 *
 * The writing diff renders `wordDiff(oldText, newText)` for improve/rewrite/
 * translate (summarize shows the raw summary). These tests pin the pure
 * pieces: the extractor across the content model's shapes, and that the
 * shared diff util produces same/del/add segments that reconstruct BOTH sides
 * (so the UI can't silently drop or duplicate text).
 *
 * @vitest-environment node (no DOM).
 */
import { describe, it, expect } from "vitest";
import { blockPlainText } from "@/lib/ai";
import { wordDiff, reconstructOld, reconstructNew } from "@factory/editor";

describe("blockPlainText (the diff's OLD side)", () => {
  it("reads {text} (the canonical content model)", () => {
    expect(blockPlainText({ text: "Hello world" })).toBe("Hello world");
  });
  it("passes a raw string through (legacy/inline path)", () => {
    expect(blockPlainText("just a string")).toBe("just a string");
  });
  it("falls back to {title}", () => {
    expect(blockPlainText({ title: "Page title" })).toBe("Page title");
  });
  it("prefers {text} over {title}", () => {
    expect(blockPlainText({ text: "body", title: "head" })).toBe("body");
  });
  it("returns '' for null/undefined/non-object", () => {
    expect(blockPlainText(null)).toBe("");
    expect(blockPlainText(undefined)).toBe("");
    expect(blockPlainText(42)).toBe("");
    expect(blockPlainText({ text: 42 })).toBe("");
  });
});

describe("wordDiff (the diff renderer's input)", () => {
  it("marks unchanged text as `same`", () => {
    expect(wordDiff("hello world", "hello world")).toEqual([{ type: "same", text: "hello world" }]);
  });
  it("produces add/del segments that reconstruct BOTH sides", () => {
    const old = "the quick brown fox";
    const neu = "the slow brown fox";
    const segs = wordDiff(old, neu);
    // At least one del (quick) and one add (slow) — the visible diff.
    expect(segs.some((s) => s.type === "del")).toBe(true);
    expect(segs.some((s) => s.type === "add")).toBe(true);
    // The segments must reconstruct the original AND the proposed text, so
    // the UI can't drop or duplicate words.
    expect(reconstructOld(segs)).toBe(old);
    expect(reconstructNew(segs)).toBe(neu);
  });
  it("treats a full replacement as all-del + all-add", () => {
    const segs = wordDiff("alpha beta", "gamma delta");
    expect(reconstructOld(segs)).toBe("alpha beta");
    expect(reconstructNew(segs)).toBe("gamma delta");
    expect(segs.some((s) => s.type === "del")).toBe(true);
    expect(segs.some((s) => s.type === "add")).toBe(true);
  });
  it("returns [] for an empty old text", () => {
    expect(wordDiff("", "new")).toEqual([{ type: "add", text: "new" }]);
  });
});