moveCursor returns whether it was able to or not

[vopamoi] / vopamoi.ts

// Typescript doesn't know about MAX_SAFE_INTEGER??  This was supposed to be
// fixed in typescript 2.0.1 in 2016, but is not working for me in typescript
// 4.2.4 in 2022.  :( https://github.com/microsoft/TypeScript/issues/9937
//const MAX_SAFE_INTEGER = Number.MAX_SAFE_INTEGER;
const MAX_SAFE_INTEGER = 9007199254740991;

// A sane split that splits N *times*, leaving the last chunk unsplit.
function splitN(str: string, delimiter: string, limit: number = MAX_SAFE_INTEGER): string[] {
  if (limit < 1) {
    return [str];
  }
  const at = str.indexOf(delimiter);
  return at === -1 ? [str] : [str.substring(0, at)].concat(splitN(str.substring(at + delimiter.length), delimiter, limit - 1));
}

const Model = {
  createTask: function (timestamp: string, description: string) {
    const task = document.createElement("div");
    task.appendChild(document.createTextNode(description));
    task.setAttribute("tabindex", "0");
    task.setAttribute("data-created", timestamp);
    return task;
  },

  addTask: function (timestamp: string, description: string) {
    document.body.appendChild(this.createTask(timestamp, description)).focus();
  },

  moveCursor: function (offset: number): boolean {
    var active = document.activeElement;
    if (offset === 1 && active) {
      active = active.nextElementSibling;
    }
    if (offset === -1 && active) {
      active = active.previousElementSibling;
    }
    if (active && active instanceof HTMLElement) {
      active.focus();
      return true;
    }
    return false;
  },
};

const Log = (function () {
  var next_log_index = 0;
  return {
    apply: function (entry: string) {
      const [timestamp, command, data] = splitN(entry, " ", 2);
      if (command == "Create") {
        Model.addTask(timestamp, data);
      }
    },

    record: function (entry: string) {
      window.localStorage.setItem(`${next_log_index++}`, entry);
    },

    recordAndApply: function (entry: string) {
      this.record(entry);
      this.apply(entry);
    },

    replay: function () {
      while (true) {
        const entry = window.localStorage.getItem(`${next_log_index}`);
        if (entry === null) {
          break;
        }
        this.apply(entry);
        next_log_index++;
      }
    },
  };
})();

const UI = {
  addTask: function (description: string) {
    Log.recordAndApply(`${Date.now()} Create ${description}`);
  },
};

function focusTaskNameInput(event: any) {
  document.getElementById("taskName")!.focus();
  event.preventDefault();
}

function handleKey(event: any) {
  if (event.target.tagName !== "INPUT") {
    if (event.key == "j") return Model.moveCursor(1);
    if (event.key == "k") return Model.moveCursor(-1);
    if (event.key == "c") return focusTaskNameInput(event);
  }
}

function browserCreateTask(form: any) {
  if (form.taskName.value) {
    UI.addTask(form.taskName.value);
  }
  form.taskName.value = "";
  return false;
}

function browserInit() {
  document.body.addEventListener("keydown", handleKey, { capture: false });
  Log.replay();
}