import { readFileSync } from "node:fs";

// Case-sharded harnesses run in every job without Vitest file sharding.
export const effectFiles = ["tests/harness/effect.test.ts", "tests/harness/effect4.test.ts"];
export const corpusFiles = [
  "tests/harness/differential.test.ts",
  "tests/harness/llvm-differential.test.ts",
  "tests/harness/npm.test.ts",
  "tests/harness/server.test.ts",
  "tests/harness/test262.test.ts",
  "tests/harness/three.test.ts",
];
const coverageFile = "tests/harness/coverage.test.ts";
const cacheFile = "packages/compiler/src/backend/native-toolchain.test.ts";
// Expensive integration suites run in their own vitest process, serially
// beside the corpus, avoiding worker contention between large compilations.
export const isolatedFiles = [
  ["self-hosting serialization", "tests/harness/self-hosting-serialization.test.ts"],
  ["self-hosting", "tests/harness/self-hosting.test.ts"],
  ["self-hosting LLVM emitter", "tests/harness/self-hosting-llvm-emitter.test.ts"],
  ["fetch", "tests/harness/fetch.test.ts"],
  ["surface manifest", "tests/harness/surface-manifest.test.ts"],
];
// Suites that split their own tests across the shards (SCRIPTC_TEST_SHARD,
// skipUnownedTest in tests/harness/shard.ts): every shard runs its share in
// its own vitest process.
export const caseShardedSideFiles = [["npm static", "tests/harness/npm-static.test.ts"]];
export const fileExclusions = [
  ...corpusFiles,
  ...effectFiles,
  coverageFile,
  cacheFile,
  ...isolatedFiles.map(([, file]) => file),
  ...caseShardedSideFiles.map(([, file]) => file),
  "tests/harness/self-hosting-native-driver.test.ts",
];

// Milliseconds each side-queue file takes on a CI runner, per flavor, from the
// logs of green main runs (scripts/ci-test-costs.mjs refreshes it).
export const testCosts = JSON.parse(
  readFileSync(new URL("./ci-test-costs.json", import.meta.url), "utf8"),
);

// The shard (1-based) of each measured side-queue file and isolated suite:
// longest first to the shard with the least work so far, counting about a
// second per file for vitest to import it. Ties go to the highest shard, so the
// longest files start from the last shard while the cost-balanced corpus and
// three.js cases (tests/harness/shard.ts) place their longest from the first.
// An isolated suite without a measurement weighs as much as the median
// measured file. Files without a measurement are left to vitest's --shard,
// which splits them by count.
export function sideOwners(flavor, count) {
  const costs = testCosts[flavor];
  const known = Object.values(costs).sort((a, b) => a - b);
  const median = known.length === 0 ? 0 : known[Math.floor(known.length / 2)];
  const weight = (file) => (costs[file] ?? median) + 1000;
  const files = [...new Set([...Object.keys(costs), ...isolatedFiles.map(([, file]) => file)])];
  files.sort((a, b) => weight(b) - weight(a) || (a < b ? -1 : a > b ? 1 : 0));
  const loads = new Array(count).fill(0);
  const owners = new Map();
  for (const file of files) {
    let lightest = count - 1;
    for (let shard = count - 2; shard >= 0; shard--)
      if (loads[shard] < loads[lightest]) lightest = shard;
    loads[lightest] += weight(file);
    owners.set(file, lightest + 1);
  }
  return owners;
}

// Pull requests and pushes to main run the full suite on Linux. Their macOS
// lane runs the darwin suite, which keeps the darwin clang/libc/kqueue
// oracles: the Node differential corpus, plus every file whose assertions run
// only on darwin or take darwin-specific branches (including the Mach-O
// library localization arm and the arm64 runtime string oracle).
// The nightly schedule and manual runs with macos_full run the full suite on
// macOS.
export const darwinCorpusFiles = ["tests/harness/differential.test.ts"];
export const darwinFiles = [
  "packages/cli/test/bootstrap.test.ts",
  "packages/cli/test/native-link-info.test.ts",
  "packages/cli/test/native-output.test.ts",
  "packages/cli/test/runtime-pack.test.ts",
  "packages/compiler/test/debug-variables.test.ts",
  "packages/compiler/test/native-codegen-integration.test.ts",
  "packages/compiler/test/source-debugging.test.ts",
  "packages/runtime-darwin-arm64/test/archive.test.ts",
  "packages/runtime/test/string.test.ts",
  "tests/harness/ffi-callback-pool.test.ts",
  "tests/harness/ffi-catalog.test.ts",
  "tests/harness/ffi-frameworks.test.ts",
  "tests/harness/library-callbacks.test.ts",
  "tests/harness/library-dispatch.test.ts",
  "tests/harness/library-multi.test.ts",
  "tests/harness/native-object-example.test.ts",
  "tests/harness/runtime-tree-shaking.test.ts",
  "tests/harness/terminal-geometry.test.ts",
];

export function ciTestPlan({ shard, flavor, workers = 4, suite = "full" }) {
  const match = /^([1-9]\d*)\/([1-9]\d*)$/.exec(shard);
  if (
    !match ||
    !Number.isSafeInteger(Number(match[1])) ||
    !Number.isSafeInteger(Number(match[2])) ||
    Number(match[1]) > Number(match[2])
  )
    throw new Error("invalid CI shard");
  if (flavor !== "plain" && flavor !== "san") throw new Error("invalid CI flavor");
  if (!Number.isInteger(workers) || workers < 1) throw new Error("invalid CI worker budget");
  if (suite !== "full" && suite !== "darwin") throw new Error("invalid CI suite");
  const index = Number(match[1]),
    count = Number(match[2]);
  const sideWorkers = workers === 1 ? 0 : 1;
  const env = { SCRIPTC_TEST_SHARD: shard, SCRIPTC_SAN: flavor === "san" ? "1" : "" };
  if (suite === "darwin") {
    // vitest runs one file's cases in sequence, so the shard's corpus cases
    // run as two halves in separate processes: case shards 2i-1 and 2i of
    // 2n. The second half follows the darwin contracts in the side queue.
    const half = (part) => ({
      name: `case-sharded differential corpus ${part}/2`,
      args: ["test", ...darwinCorpusFiles],
      env: {
        ...env,
        SCRIPTC_TEST_SHARD: `${2 * index - 2 + part}/${2 * count}`,
        SCRIPTC_TEST_WORKERS: "1",
      },
    });
    return {
      sideWorkers,
      corpus: half(1),
      side: [
        {
          name: "darwin contracts",
          args: ["test", "--passWithNoTests", "--shard=" + shard, ...darwinFiles],
          env: { ...env, SCRIPTC_TEST_WORKERS: "1" },
        },
        half(2),
      ],
    };
  }
  const owners = sideOwners(flavor, count);
  const isolated = new Set(isolatedFiles.map(([, file]) => file));
  const balanced = [...owners]
    .filter(([file, owner]) => owner === index && !isolated.has(file))
    .map(([file]) => file)
    .sort();
  const side = [
    {
      name: "file-sharded tests",
      args: [
        "test",
        "--passWithNoTests",
        "--shard=" + shard,
        ...[...new Set([...fileExclusions, ...owners.keys()])].map((file) => "--exclude=" + file),
      ],
      env: { ...env, SCRIPTC_TEST_WORKERS: "1" },
    },
  ];
  if (balanced.length > 0)
    side.push({
      name: "cost-balanced tests",
      args: ["test", "--passWithNoTests", ...balanced],
      env: { ...env, SCRIPTC_TEST_WORKERS: "1" },
    });
  for (const [name, file] of isolatedFiles) {
    if (owners.get(file) === index)
      side.push({ name, args: ["test", file], env: { ...env, SCRIPTC_TEST_WORKERS: "1" } });
  }
  for (const [name, file] of caseShardedSideFiles)
    side.push({ name, args: ["test", file], env: { ...env, SCRIPTC_TEST_WORKERS: "1" } });
  // Frontend coverage and cache invalidation do not consume sanitizer state.
  if (flavor === "plain") {
    side.push({
      name: "native-cache correctness",
      args: ["test", cacheFile],
      env: {
        ...env,
        SCRIPTC_TEST_WORKERS: "1",
        SCRIPTC_CACHE_TEST_SHARD: shard,
        SCRIPTC_TEST_STABLE_TOOLCHAIN: "0",
      },
    });
    side.push({
      name: "coverage sweep",
      args: ["test", coverageFile],
      env: { ...env, SCRIPTC_TEST_WORKERS: "1" },
    });
  }
  return {
    sideWorkers,
    corpus: {
      name: "case-sharded corpus",
      args: ["test", ...corpusFiles],
      env: {
        ...env,
        SCRIPTC_TEST_WORKERS: String(workers - sideWorkers),
        SCRIPTC_LLVM_TEST_MODE: "dev",
      },
    },
    side,
  };
}