#!/usr/bin/env node
/**
 * Migrate ALL test files from node:test to vitest.
 *
 * Scans src/, packages/, web/, studio/, and scripts/.
 * Changes:
 * 1. Replace `from "node:test"` → `from 'vitest'` in all imports
 * 2. Files using mock.fn(): replace `mock.fn` → `vi.fn` and add `vi` to imports
 * 3. Files using mock.timers: migrate to vi fake timers API
 */

import { readFileSync, readdirSync, writeFileSync } from "node:fs";
import { join } from "node:path";

const ROOTS = [
  join(process.cwd(), "src"),
  join(process.cwd(), "packages"),
  join(process.cwd(), "web"),
  join(process.cwd(), "studio"),
  join(process.cwd(), "scripts"),
];

function collectTestFiles(dirs) {
  const results = [];
  for (const dir of dirs) {
    try {
      const entries = readdirSync(dir, { withFileTypes: true });
      for (const entry of entries) {
        const full = join(dir, entry.name);
        if (entry.isDirectory()) {
          results.push(...collectTestFiles([full]));
        } else if (
          (entry.name.endsWith(".test.ts") || entry.name.endsWith(".test.mjs")) &&
          !entry.name.endsWith(".d.ts")
        ) {
          results.push(full);
        }
      }
    } catch {
      // Directory may not exist
    }
  }
  return results;
}

function migrateImport(content, { hasMockFn, hasMockTimers }) {
  // Case 1: import test from "node:test"; (or single quotes, optional semicolon)
  content = content.replace(
    /^import test from ["']node:test["'];?$/gm,
    "import { test } from 'vitest';",
  );

  // Case 2: import { ... } from "node:test" (and variants with default import)
  content = content.replace(
    /import\s+(test,)?\s*\{\s*([^}]+)\}\s+from\s+["']node:test["'];?/g,
    (match, hasDefault, named) => {
      const namedList = named
        .split(",")
        .map((s) => s.trim())
        .filter((s) => s !== "mock" && s !== "");

      const extra = [];
      if (hasMockFn || hasMockTimers) {
        extra.push("vi");
      }

      const allNamed = [...extra, ...namedList.filter((s) => s !== "test")];
      const defaultImport = hasDefault ? "test, " : "";
      const namedStr = allNamed.join(", ");
      return `import { ${defaultImport}${namedStr} } from 'vitest';`;
    },
  );

  return content;
}

const files = collectTestFiles(ROOTS);
console.log(`Found ${files.length} test files`);

let updated = 0;
let errors = 0;

for (const file of files) {
  try {
    const content = readFileSync(file, "utf-8");
    if (!content.includes('from "node:test"') && !content.includes("from 'node:test'")) continue;

    const hasMockFn = content.includes("mock.fn");
    const hasMockTimers = content.includes("mock.timers");

    let newContent = migrateImport(content, { hasMockFn, hasMockTimers });

    // Migrate mock.fn → vi.fn
    if (hasMockFn) {
      newContent = newContent.replace(/\bmock\.fn\b/g, "vi.fn");
      newContent = newContent.replace(
        /ReturnType<typeof mock\.fn>/g,
        "ReturnType<typeof vi.fn>",
      );
    }

    // Migrate mock.timers → vi fake timers
    if (hasMockTimers) {
      newContent = newContent.replace(
        /\bmock\.timers\.enable\(\)/g,
        "vi.useFakeTimers()",
      );
      newContent = newContent.replace(
        /\bmock\.timers\.tick\(([^)]+)\)/g,
        "vi.advanceTimersByTime($1)",
      );
      newContent = newContent.replace(
        /\bmock\.timers\.reset\(\)/g,
        "vi.useRealTimers()",
      );
    }

    if (newContent !== content) {
      writeFileSync(file, newContent, "utf-8");
      updated++;
      const rel = file.replace(process.cwd() + "/", "");
      const tags = [];
      if (hasMockFn) tags.push("mock");
      if (hasMockTimers) tags.push("timers");
      const tagStr = tags.length ? ` (${tags.join(", ")})` : "";
      console.log(`  Migrated${tagStr}: ${rel}`);
    }
  } catch (err) {
    console.error(`Error: ${file}: ${err.message}`);
    errors++;
  }
}

console.log(`Updated ${updated} files, ${errors} errors`);