import assert from "node:assert/strict";
import { readFileSync } from "node:fs";
import type { Range } from "../src/vocab/index.ts";

// tests/fixtures/rules/ 下的预期值由独立的 Python 脚本照 docs/方法.md 和约定表算出（脚本开头注释写了格式）。
// 这里只负责读文件和比较数字；把场景映射到 rules 的函数上，在各个 rules-fixtures-*.test.ts 里做。

export interface Scenario {
  name: string;
  section: string;
  params: Record<string, any>;
  input: Record<string, any>;
  expected: any;
  note: string;
}

export interface FixtureFile {
  generator: string;
  tolerance: Record<string, any>;
  models?: Record<string, { params: Record<string, any>; input: Record<string, any> }>;
  scenarios: Scenario[];
}

export function loadFixture(file: string): FixtureFile {
  return JSON.parse(readFileSync(new URL(`./fixtures/rules/${file}`, import.meta.url), "utf8")) as FixtureFile;
}

/** 按名字取场景，并登记"已覆盖"；每个测试文件最后核对 JSON 里的场景都被取过。 */
export function scenarioPicker(fixture: FixtureFile): {
  get: (name: string) => Scenario;
  unused: () => string[];
} {
  const used = new Set<string>();
  return {
    get(name) {
      const s = fixture.scenarios.find((x) => x.name === name);
      assert.ok(s, `JSON 里没有场景 ${name}`);
      used.add(name);
      return s;
    },
    unused: () => fixture.scenarios.map((s) => s.name).filter((n) => !used.has(n)),
  };
}

/** 绝对误差 tol 以内算相同。 */
export function close(actual: number, expected: number, tol: number, what: string): void {
  assert.ok(
    Number.isFinite(actual) && Math.abs(actual - expected) <= tol,
    `${what}：实现 ${actual}，预期 ${expected}，差 ${actual - expected}，容差 ${tol}`,
  );
}

/** 网格值：|差| ≤ 1e-12 + 1e-9·|值|（ablation.json tolerance.grid）。 */
export function closeGrid(actual: number, expected: number, what: string): void {
  close(actual, expected, 1e-12 + 1e-9 * Math.abs(expected), what);
}

export function closeArray(actual: readonly number[], expected: readonly number[], tol: number, what: string): void {
  assert.equal(actual.length, expected.length, `${what}：长度`);
  actual.forEach((a, i) => close(a, expected[i]!, tol, `${what}[${i}]`));
}

export function range(r: { q1: number; q5: number; q9: number }): Range {
  return { q1: r.q1, q5: r.q5, q9: r.q9 };
}