/*
<MODULE_CONTRACT>
<purpose>
Unit tests for feed covering buildRssFeed; buildJsonFeed. It also guards the documented public contract and regression-sensitive edge cases.
</purpose>
<non-goals>
  <item>Not a contract source of truth — the module under test owns the authoritative behavior; fixtures are minimal scaffolding only.</item>
</non-goals>
</MODULE_CONTRACT>
<CHANGE_SUMMARY>
  <item>RFC-1311: Compass header sweep — declares the feed suite's contract for test-file scaffold coverage.</item>
</CHANGE_SUMMARY>
*/

import { describe, expect, it } from "vitest";
import { buildJsonFeed, buildRssFeed } from "../feed.ts";

const channel = {
  title: "Test Feed",
  url: "https://example.com",
  description: "A test feed",
  language: "de",
  selfUrl: "https://example.com/feed.xml",
};

const items = [
  {
    title: "Item 1",
    url: "https://example.com/1",
    summary: "Summary 1",
    publishedAt: "2024-01-01",
  },
  {
    title: "Item 2",
    url: "https://example.com/2",
    summary: "Summary 2",
    publishedAt: "2024-06-01",
  },
];

describe("buildRssFeed", () => {
  it("produces valid RSS XML", () => {
    const result = buildRssFeed(channel, items);
    expect(result).toContain('<?xml version="1.0"');
    expect(result).toContain('<rss version="2.0"');
    expect(result).toContain("<channel>");
    expect(result).toContain("<title>Test Feed</title>");
    expect(result).toContain("<language>de</language>");
  });

  it("sorts items by publishedAt descending", () => {
    const result = buildRssFeed(channel, items);
    const item1Idx = result.indexOf("Item 1");
    const item2Idx = result.indexOf("Item 2");
    expect(item2Idx).toBeLessThan(item1Idx);
  });

  it("escapes XML special characters", () => {
    const result = buildRssFeed(channel, [
      { title: "A & B <C>", url: "https://example.com/x", summary: "S", publishedAt: "2024-01-01" },
    ]);
    expect(result).toContain("A &amp; B &lt;C&gt;");
  });

  it("includes atom self link", () => {
    const result = buildRssFeed(channel, items);
    expect(result).toContain('href="https://example.com/feed.xml"');
    expect(result).toContain('rel="self"');
  });

  it("derives lastBuildDate from latest item", () => {
    const result = buildRssFeed(channel, items);
    expect(result).toContain("<lastBuildDate>");
  });

  it("omits lastBuildDate for empty feed", () => {
    const result = buildRssFeed(channel, []);
    expect(result).not.toContain("<lastBuildDate>");
  });
});

describe("buildJsonFeed", () => {
  it("produces JSON Feed v1.1", () => {
    const result = buildJsonFeed({
      title: "Test Feed",
      home_page_url: "https://example.com",
      feed_url: "https://example.com/feed.json",
      description: "A test feed",
      language: "de",
      items,
    });
    const parsed = JSON.parse(result);
    expect(parsed.version).toBe("https://jsonfeed.org/version/1.1");
    expect(parsed.title).toBe("Test Feed");
    expect(parsed.items).toHaveLength(2);
  });

  it("sorts items by publishedAt descending", () => {
    const result = buildJsonFeed({
      title: "Test",
      home_page_url: "https://example.com",
      feed_url: "https://example.com/feed.json",
      description: "",
      language: "de",
      items,
    });
    const parsed = JSON.parse(result);
    expect(parsed.items[0].title).toBe("Item 2");
    expect(parsed.items[1].title).toBe("Item 1");
  });

  it("includes date_modified when updatedAt provided", () => {
    const result = buildJsonFeed({
      title: "Test",
      home_page_url: "https://example.com",
      feed_url: "https://example.com/feed.json",
      description: "",
      language: "de",
      items: [
        {
          title: "T",
          url: "https://example.com/1",
          summary: "S",
          publishedAt: "2024-01-01",
          updatedAt: "2024-06-01",
        },
      ],
    });
    const parsed = JSON.parse(result);
    expect(parsed.items[0].date_modified).toBe("2024-06-01");
  });

  it("omits items array for empty feed", () => {
    const result = buildJsonFeed({
      title: "Test",
      home_page_url: "https://example.com",
      feed_url: "https://example.com/feed.json",
      description: "",
      language: "de",
      items: [],
    });
    const parsed = JSON.parse(result);
    expect(parsed.items).toBeUndefined();
  });
});