export async function runBrowserOpfsMirrorSections(context, simulator) {
  const {
    expectEvent,
    expectIncludes,
    expectOpfsDirectoryStat,
    expectMissingWasmPath,
    expectText,
    expectWasmFilesMissing,
    near,
    readOpfsText,
    runSection,
    withSmokeSimulator,
  } = context;

  await runSection("opfs wasm mirror persist file", async () => {
    const wasmPath = simulator.fs.opfs.resolvePath("programs/browser-smoke.ngc");
    const wasmDecoded = new TextDecoder().decode(simulator.fs.module.FS.readFile(wasmPath));
    expectText(wasmDecoded, "G21 G90\nG0 X1\n", "OPFS file was not mirrored into the WASM filesystem");
    const persistedPath = simulator.fs.opfs.resolvePath("programs/browser-persisted.ngc");
    simulator.fs.module.FS.writeFile(persistedPath, new TextEncoder().encode("G21 G90\nG0 X2\n"));
    const persisted = new TextDecoder().decode(await simulator.fs.opfs.persistFile("programs/browser-persisted.ngc"));
    expectText(persisted, "G21 G90\nG0 X2\n", "WASM filesystem file was not persisted into OPFS");
    const persistedDecoded = new TextDecoder().decode(
      await simulator.fs.opfs.readFile("programs/browser-persisted.ngc"),
    );
    expectText(persistedDecoded, "G21 G90\nG0 X2\n",
      "persisted WASM filesystem file was not readable from OPFS");
  });

  await runSection("opfs persisted wasm mirror parse in new instance", async () => {
    await withSmokeSimulator(async (restoredMirrorSimulator) => {
      // LinuxCNC source basis: rs274ngc_pre.cc read_text() reads
      // program blocks after the OPFS file is mirrored into the WASM FS.
      const persistedProgram = new TextDecoder().decode(
        await restoredMirrorSimulator.fs.opfs.readFile("programs/browser-persisted.ngc"),
      );
      expectText(persistedProgram, "G21 G90\nG0 X2\n",
        "persisted WASM mirror file was not restored from OPFS in a new instance");
      const persistedEvents = await restoredMirrorSimulator.parseFile(
        "programs/browser-persisted.ngc",
        "linuxcnc",
        { backend: "linuxcnc-rs274" },
      );
      expectEvent(persistedEvents, (event) => event.type === "rapid" && near(event.end.x, 2),
        "persisted WASM mirror file was not parsed through LinuxCNC in a new instance");
    });
  });

  await runSection("opfs copy and move mirror files", async () => {
    // LinuxCNC source basis: rs274ngc_pre.cc save_parameters()
    // links the current parameter file to filename + ".bak", then
    // writes filename + ".new" and renames it over the parameter file.
    await simulator.fs.opfs.writeFile("parameters/move-main.var", "5161\t1.000000\n");
    const copiedParameterBackup = new TextDecoder().decode(
      await simulator.fs.opfs.copyFile("parameters/move-main.var", "parameters/move-main.var.bak"),
    );
    expectText(copiedParameterBackup, "5161\t1.000000\n",
      "OPFS copyFile did not return the copied file contents");
    const copiedParameterBackupFile = new TextDecoder().decode(
      await simulator.fs.opfs.readFile("parameters/move-main.var.bak"),
    );
    expectText(copiedParameterBackupFile, "5161\t1.000000\n",
      "OPFS copyFile did not create the backup file");
    const copiedParameterBackupWasmPath = simulator.fs.opfs.resolvePath("parameters/move-main.var.bak");
    const copiedParameterBackupWasm = new TextDecoder().decode(
      simulator.fs.module.FS.readFile(copiedParameterBackupWasmPath),
    );
    expectText(copiedParameterBackupWasm, "5161\t1.000000\n",
      "OPFS copyFile did not update the WASM mirror destination");
    await simulator.fs.opfs.writeFile("parameters/move-main.var.new", "5161\t2.000000\n");
    await simulator.fs.opfs.moveFile("parameters/move-main.var.new", "parameters/move-main.var");
    const movedParameterFile = new TextDecoder().decode(
      await simulator.fs.opfs.readFile("parameters/move-main.var"),
    );
    expectText(movedParameterFile, "5161\t2.000000\n",
      "OPFS moveFile did not replace the destination file");
    if (await simulator.fs.opfs.exists("parameters/move-main.var.new")) {
      throw new Error("OPFS moveFile left the source file behind");
    }
    const movedParameterWasmPath = simulator.fs.opfs.resolvePath("parameters/move-main.var");
    const movedParameterWasm = new TextDecoder().decode(
      simulator.fs.module.FS.readFile(movedParameterWasmPath),
    );
    expectText(movedParameterWasm, "5161\t2.000000\n",
      "OPFS moveFile did not update the WASM mirror destination");
    const movedTemporaryWasmPath = simulator.fs.opfs.resolvePath("parameters/move-main.var.new");
    expectMissingWasmPath(
      () => simulator.fs.module.FS.stat(movedTemporaryWasmPath),
      "OPFS moveFile left the WASM mirror source behind",
    );
    await withSmokeSimulator(async (restoredMoveSimulator) => {
      const restoredMovedParameterFile = await readOpfsText(restoredMoveSimulator, "parameters/move-main.var");
      expectText(restoredMovedParameterFile, "5161\t2.000000\n",
        "OPFS moveFile destination was not persisted for a new WASM instance");
      if (await restoredMoveSimulator.fs.opfs.exists("parameters/move-main.var.new")) {
        throw new Error("OPFS moveFile source was still persisted for a new WASM instance");
      }
      const restoredMovedParameterWasmPath = restoredMoveSimulator.fs.opfs.resolvePath("parameters/move-main.var");
      const restoredMovedParameterWasm = new TextDecoder().decode(
        restoredMoveSimulator.fs.module.FS.readFile(restoredMovedParameterWasmPath),
      );
      expectText(restoredMovedParameterWasm, "5161\t2.000000\n",
        "OPFS moveFile destination was not mirrored for a new WASM instance");
      const restoredMovedTemporaryWasmPath = restoredMoveSimulator.fs.opfs.resolvePath("parameters/move-main.var.new");
      expectMissingWasmPath(
        () => restoredMoveSimulator.fs.module.FS.stat(restoredMovedTemporaryWasmPath),
        "OPFS moveFile source was mirrored for a new WASM instance",
      );
    });

    await simulator.fs.opfs.writeFile("parameters/mirror-conflict-source.var", "5161\t3.000000\n");
    const copyConflictPath = simulator.fs.opfs.resolvePath("parameters/mirror-conflict-copy.var");
    simulator.fs.module.FS.mkdir(copyConflictPath);
    await simulator.fs.opfs.copyFile("parameters/mirror-conflict-source.var", "parameters/mirror-conflict-copy.var");
    const copyConflictMode = simulator.fs.module.FS.stat(copyConflictPath).mode;
    if (!simulator.fs.module.FS.isFile(copyConflictMode)) {
      throw new Error("OPFS copyFile did not replace a WASM mirror directory with a file");
    }
    expectText(
      new TextDecoder().decode(simulator.fs.module.FS.readFile(copyConflictPath)),
      "5161\t3.000000\n",
      "OPFS copyFile did not write copied contents over a WASM mirror directory",
    );

    await simulator.fs.opfs.writeFile("parameters/mirror-conflict-move.var.new", "5161\t4.000000\n");
    const moveConflictPath = simulator.fs.opfs.resolvePath("parameters/mirror-conflict-move.var");
    simulator.fs.module.FS.mkdir(moveConflictPath);
    await simulator.fs.opfs.moveFile("parameters/mirror-conflict-move.var.new", "parameters/mirror-conflict-move.var");
    const moveConflictMode = simulator.fs.module.FS.stat(moveConflictPath).mode;
    if (!simulator.fs.module.FS.isFile(moveConflictMode)) {
      throw new Error("OPFS moveFile did not replace a WASM mirror directory with a file");
    }
    expectText(
      new TextDecoder().decode(simulator.fs.module.FS.readFile(moveConflictPath)),
      "5161\t4.000000\n",
      "OPFS moveFile did not write moved contents over a WASM mirror directory",
    );
  });

  await runSection("opfs write truncates wasm mirror", async () => {
    await simulator.fs.opfs.writeFile("programs/truncate.ngc", "G21 G90\nG0 X12345\nM30\n");
    await simulator.fs.opfs.writeFile("programs/truncate.ngc", "G21\n");
    const truncatedProgram = new TextDecoder().decode(await simulator.fs.opfs.readFile("programs/truncate.ngc"));
    expectText(truncatedProgram, "G21\n", "OPFS writeFile did not truncate stale program bytes");
    const truncatedWasmPath = simulator.fs.opfs.resolvePath("programs/truncate.ngc");
    const truncatedWasmProgram = new TextDecoder().decode(simulator.fs.module.FS.readFile(truncatedWasmPath));
    expectText(truncatedWasmProgram, "G21\n", "OPFS writeFile did not truncate the WASM mirror");
  });

  await runSection("opfs parameter backup bridge failure is non-fatal", async () => {
    // LinuxCNC source basis: rs274ngc_pre.cc save_parameters()
    // reports link(filename, filename + ".bak") failure with perror()
    // but still renames filename + ".new" over the parameter file.
    simulator.fs.module.FS.writeFile("rs274ngc.var", "5161\t12.000000\n");
    simulator.fs.module.FS.writeFile("rs274ngc.var.bak", "5161\t11.000000\n");
    const backupBridgeDirectory = simulator.fs.opfs.resolvePath("parameters/backup-bridge-directory.var.bak");
    simulator.fs.module.FS.mkdir(backupBridgeDirectory);
    await simulator.fs.opfs.persistDirectory("parameters/backup-bridge-directory.var.bak");
    await simulator.fs.opfs.persistParameterFile("parameters/backup-bridge-directory.var");
    expectIncludes(
      await readOpfsText(simulator, "parameters/backup-bridge-directory.var"),
      "5161\t12.000000",
      "LinuxCNC parameter bridge did not persist the main file when backup link failed",
    );
    await expectOpfsDirectoryStat(
      simulator,
      "parameters/backup-bridge-directory.var.bak",
      "LinuxCNC parameter backup bridge removed an existing OPFS backup directory",
    );
    expectWasmFilesMissing(simulator.fs.module.FS, ["rs274ngc.var", "rs274ngc.var.new", "rs274ngc.var.bak"], (parameterPath) => `LinuxCNC parameter scratch file remained outside OPFS after non-fatal backup bridge failure: ${parameterPath}`);
  });
}