/**
 * Fixture-driven migration tests.
 *
 * Each fixture directory under `fixtures/` contains:
 *   - input.yml             (GitHub Actions workflow)
 *   - expected.gitlab-ci.yml (expected GitLab CI output)
 *   - expected-report.json  (expected diagnostic + provenance shape)
 *
 * The test asserts canonical-YAML equality on the output and shape
 * equality on the report. Adding a new fixture requires no manifest
 * edit — just drop the three files into a new directory.
 */

import { describe, test, expect } from "vitest";
import { readFileSync, readdirSync, statSync } from "node:fs";
import { join } from "node:path";
import { parseYAML } from "@intentius/chant/yaml";
import { transform } from "./index";

const FIXTURE_ROOT = join(__dirname, "fixtures");

interface Fixture { name: string; dir: string }

function* walkFixtures(root: string, prefix = ""): Generator<Fixture> {
  for (const entry of readdirSync(root)) {
    const p = join(root, entry);
    if (!statSync(p).isDirectory()) continue;
    const name = prefix ? `${prefix}/${entry}` : entry;
    const files = readdirSync(p);
    if (files.includes("input.yml") && files.includes("expected.gitlab-ci.yml")) {
      yield { name, dir: p };
    } else {
      yield* walkFixtures(p, name);
    }
  }
}

function canonicalYaml(text: string): unknown {
  // Strip leading comments so the "Generated by chant migrate from ..."
  // banner doesn't have to match byte-for-byte when sourceFile differs.
  const stripped = text.replace(/^#[^\n]*\n+/g, "");
  if (!stripped.trim()) return {};
  return parseYAML(stripped);
}

interface ReportShape {
  totals: { error: number; warning: number; info: number };
  ruleIds: string[];
  needsReview: Array<{ line: number; ruleId: string }>;
  provenance: { literalRewrites: number; actionMappings: Array<{ action: string; tier: number | undefined }> };
}

function reportShape(diagnostics: Array<Record<string, unknown>>, provenance: Array<Record<string, unknown>>): ReportShape {
  const totals = { error: 0, warning: 0, info: 0 };
  for (const d of diagnostics) {
    const sev = d.severity as string;
    if (sev in totals) totals[sev as "error" | "warning" | "info"]++;
  }
  const ruleIds = Array.from(new Set(diagnostics.map((d) => d.ruleId as string))).sort();
  const needsReview = diagnostics
    .filter((d) => d.severity === "warning" || d.severity === "error")
    .map((d) => ({ line: d.line as number, ruleId: d.ruleId as string }));
  const literalRewrites = provenance.filter((p) => p.category === "literal" || p.category === "rewrite").length;
  const actionMappings = provenance
    .filter((p) => p.category === "action-map")
    .map((p) => ({ action: p.actionRef as string, tier: p.mappingTier as number | undefined }));
  return { totals, ruleIds, needsReview, provenance: { literalRewrites, actionMappings } };
}

describe("github → gitlab fixtures", () => {
  for (const f of walkFixtures(FIXTURE_ROOT)) {
    test(f.name, async () => {
      const input = readFileSync(join(f.dir, "input.yml"), "utf-8");
      const expectedYaml = readFileSync(join(f.dir, "expected.gitlab-ci.yml"), "utf-8");
      const expectedReport: ReportShape = JSON.parse(
        readFileSync(join(f.dir, "expected-report.json"), "utf-8"),
      );

      const result = await transform(input, { sourceFile: "input.yml" });

      // Canonical YAML compare (parse + re-stringify absorbs whitespace/key order)
      expect(canonicalYaml(result.output)).toEqual(canonicalYaml(expectedYaml));

      // Shape compare
      const actualShape = reportShape(
        result.diagnostics as unknown as Array<Record<string, unknown>>,
        result.provenance as unknown as Array<Record<string, unknown>>,
      );
      expect(actualShape).toEqual(expectedReport);
    });
  }
});