import { describe, test } from "node:test";
import assert from "node:assert/strict";
import { generateHeatmap } from "../src/reports/heatmap.js";
import type { PostAnalytics } from "../src/models/types.js";

function createPost(date: string, impressions: number, engagementRate: number): PostAnalytics {
  return {
    id: `post-${date}`,
    title: `Post on ${date}`,
    publishedDate: date,
    metrics: {
      impressions,
      reactions: 10,
      comments: 5,
      shares: 2,
      clicks: 3,
      engagementRate,
    },
    importedAt: "2026-04-01T00:00:00Z",
    exportSource: "test.csv",
  };
}

describe("generateHeatmap", () => {
  // Verified days: 2026-04-06=Mon, 07=Tue, 08=Wed, 09=Thu, 12=Sun, 13=Mon, 14=Tue, 15=Wed
  const posts: PostAnalytics[] = [
    createPost("2026-04-06", 1000, 3.0), // Monday
    createPost("2026-04-07", 2000, 4.0), // Tuesday
    createPost("2026-04-08", 1500, 3.5), // Wednesday
    createPost("2026-04-13", 3000, 5.0), // Monday
    createPost("2026-04-14", 2500, 4.5), // Tuesday
    createPost("2026-04-12", 800, 2.0),  // Sunday
  ];

  test("groups posts by day of week correctly", () => {
    const report = generateHeatmap(posts);
    const monday = report.byDayOfWeek.find(d => d.dayName === "Monday");
    const tuesday = report.byDayOfWeek.find(d => d.dayName === "Tuesday");
    const sunday = report.byDayOfWeek.find(d => d.dayName === "Sunday");

    assert.equal(monday?.postCount, 2);
    assert.equal(tuesday?.postCount, 2);
    assert.equal(sunday?.postCount, 1);
  });

  test("calculates correct averages per day", () => {
    const report = generateHeatmap(posts);
    const monday = report.byDayOfWeek.find(d => d.dayName === "Monday")!;
    const tuesday = report.byDayOfWeek.find(d => d.dayName === "Tuesday")!;

    assert.equal(monday.avgImpressions, 2000); // (1000+3000)/2
    assert.equal(tuesday.avgImpressions, 2250); // (2000+2500)/2
    assert.equal(monday.avgEngagementRate, 4.0); // (3.0+5.0)/2
  });

  test("handles days with no posts", () => {
    const report = generateHeatmap(posts);
    const friday = report.byDayOfWeek.find(d => d.dayName === "Friday")!;

    assert.equal(friday.postCount, 0);
    assert.equal(friday.avgImpressions, 0);
    assert.equal(friday.avgEngagementRate, 0);
  });

  test("returns 7 entries ordered Mon-Sun", () => {
    const report = generateHeatmap(posts);
    assert.equal(report.byDayOfWeek.length, 7);
    assert.equal(report.byDayOfWeek[0].dayName, "Monday");
    assert.equal(report.byDayOfWeek[6].dayName, "Sunday");
    assert.deepEqual(
      report.byDayOfWeek.map(d => d.dayIndex),
      [1, 2, 3, 4, 5, 6, 7]
    );
  });

  test("identifies best day for impressions", () => {
    const report = generateHeatmap(posts);
    assert.equal(report.bestDayImpressions, "Tuesday");
  });

  test("identifies best day for engagement", () => {
    const report = generateHeatmap(posts);
    assert.equal(report.bestDayEngagement, "Tuesday"); // (4.0+4.5)/2 = 4.25
  });

  test("sets correct postsAnalyzed count", () => {
    const report = generateHeatmap(posts);
    assert.equal(report.postsAnalyzed, 6);
  });

  test("handles empty post list", () => {
    const report = generateHeatmap([]);
    assert.equal(report.postsAnalyzed, 0);
    assert.equal(report.byDayOfWeek.length, 7);
    assert.equal(report.bestDayImpressions, "N/A");
    assert.equal(report.bestDayEngagement, "N/A");
    for (const day of report.byDayOfWeek) {
      assert.equal(day.postCount, 0);
    }
  });

  test("identifies best post per day", () => {
    const report = generateHeatmap(posts);
    const monday = report.byDayOfWeek.find(d => d.dayName === "Monday")!;
    assert.equal(monday.bestPost?.publishedDate, "2026-04-13"); // 3000 impressions
  });

  test("calculates correct date range", () => {
    const report = generateHeatmap(posts);
    assert.equal(report.dateRange.from, "2026-04-06");
    assert.equal(report.dateRange.to, "2026-04-14");
  });
});