//  File:    composite.test.ts
//  Path:    packages/scoring/src/composite.test.ts
//  Project: AI Risk Index — airiskindex.io
//  Author:  Simon-Pierre Boucher
//  Contact: contact@spboucher.ai
//  Copyright © 2026 Simon-Pierre Boucher. All rights reserved.
//
//  Description: Snapshot tests against the published methodology worked example.

import { readFileSync } from "node:fs";
import { describe, expect, it } from "vitest";
import { HIGH_EXPOSURE_THRESHOLD, scoreOccupation } from "./index";

// Published worked example — METHODOLOGY.md §5-6. Changing it requires an INDEX_VERSION bump.
const example = JSON.parse(
  readFileSync(new URL("../../../docs/methodology/examples/example-analyst.json", import.meta.url), "utf8"),
);

const BAND_KEYS = ["substitution", "exposure", "augmentation"] as const;

describe("published methodology example (example-analyst.json)", () => {
  const result = scoreOccupation(example.tasks);

  it("matches the expected task scores", () => {
    expect(result.tasks).toHaveLength(example.expected.taskScores.length);
    for (const [index, expected] of example.expected.taskScores.entries()) {
      const actual = result.tasks[index];
      expect(actual.taskId).toBe(expected.taskId);
      for (const key of BAND_KEYS) {
        expect(actual[key].low).toBeCloseTo(expected[key].low, 3);
        expect(actual[key].score).toBeCloseTo(expected[key].score, 3);
        expect(actual[key].high).toBeCloseTo(expected[key].high, 3);
      }
    }
  });

  it("matches the expected occupation scores", () => {
    for (const key of BAND_KEYS) {
      expect(result[key].low).toBeCloseTo(example.expected.occupation[key].low, 3);
      expect(result[key].score).toBeCloseTo(example.expected.occupation[key].score, 3);
      expect(result[key].high).toBeCloseTo(example.expected.occupation[key].high, 3);
    }
  });

  it("reports the highly exposed task share", () => {
    expect(HIGH_EXPOSURE_THRESHOLD).toBe(70);
    expect(result.highlyExposedTaskShare).toBeCloseTo(
      example.expected.occupation.highlyExposedTaskShare,
      3,
    );
  });
});

describe("scoreOccupation input handling", () => {
  it("rejects an empty task list", () => {
    expect(() => scoreOccupation([])).toThrow(RangeError);
  });

  it("fills missing importance with the occupation mean", () => {
    const [t1, t2, t3] = example.tasks;
    const withMissing = [t1, { ...t2, importance: undefined }, t3];
    const result = scoreOccupation(withMissing);
    // t2 gets mean(4, 1) = 2.5 → weights 4/7.5, 2.5/7.5, 1/7.5
    const expected =
      (4 / 7.5) * 71.25 + (2.5 / 7.5) * 27.5 + (1 / 7.5) * 86.25;
    expect(result.substitution.score).toBeCloseTo(expected, 3);
  });

  it("rejects out-of-range ratings", () => {
    const bad = JSON.parse(JSON.stringify(example.tasks[0]));
    bad.ratings.automatability.mid = 6;
    expect(() => scoreOccupation([bad])).toThrow(RangeError);
  });

  it("rejects inverted bands (low > high)", () => {
    const bad = JSON.parse(JSON.stringify(example.tasks[0]));
    bad.ratings.feasibility = { low: 4, mid: 3, high: 2 };
    expect(() => scoreOccupation([bad])).toThrow(RangeError);
  });
});