import cronstrue from "cronstrue";
import { CronExpressionParser } from "cron-parser";
import type { TaskRecord } from "../api/client";

function describeSchedule(task: TaskRecord): string {
  if (!task.scheduleExpression) return "—";
  if (task.scheduleType === "cron") {
    try {
      return cronstrue.toString(task.scheduleExpression, { verbose: false });
    } catch {
      return task.scheduleExpression;
    }
  }
  return task.scheduleExpression;
}

interface NextRun {
  date: Date;
  /** true when computed client-side from the cron expression rather than reported by the agent */
  estimated: boolean;
}

function computeNextRun(task: TaskRecord): NextRun | null {
  if (task.nextRunAt) {
    return { date: new Date(task.nextRunAt), estimated: false };
  }
  if (task.scheduleType !== "cron" || !task.scheduleExpression || task.isStale || !task.enabled) {
    return null;
  }
  try {
    const date = CronExpressionParser.parse(task.scheduleExpression).next().toDate();
    return { date, estimated: true };
  } catch {
    return null;
  }
}

interface Props {
  tasks: TaskRecord[];
  onEdit?: (task: TaskRecord) => void;
  onDelete?: (task: TaskRecord) => void;
}

export default function TaskTable({ tasks, onEdit, onDelete }: Props) {
  return (
    <table className="task-table">
      <thead>
        <tr>
          <th>Name</th>
          <th>Command</th>
          <th>Schedule</th>
          <th>Next run</th>
          <th>Status</th>
          <th></th>
        </tr>
      </thead>
      <tbody>
        {tasks.map((task) => {
          const nextRun = computeNextRun(task);
          return (
            <tr key={task.id} className={task.isStale ? "stale" : undefined}>
              <td>{task.name}</td>
              <td className="mono">{task.command ?? "—"}</td>
              <td>
                <div className="schedule-human">{describeSchedule(task)}</div>
                {task.scheduleExpression && (
                  <span className="mono schedule-raw">{task.scheduleExpression}</span>
                )}
              </td>
              <td>
                {nextRun ? (
                  <span
                    title={
                      nextRun.estimated
                        ? "Estimated from the cron expression in your browser's timezone — the server may run in a different timezone"
                        : undefined
                    }
                  >
                    {nextRun.estimated ? "~" : ""}
                    {nextRun.date.toLocaleString()}
                  </span>
                ) : (
                  "—"
                )}
              </td>
              <td>
                {task.isStale ? (
                  <span className="badge badge-stale">Missing</span>
                ) : task.enabled ? (
                  <span className="badge badge-ok">Enabled</span>
                ) : (
                  <span className="badge badge-disabled">Disabled</span>
                )}
                {task.origin === "manual" && <span className="badge badge-manual">Manual</span>}
              </td>
              <td className="actions">
                {task.origin === "manual" && (
                  <>
                    <button className="btn btn-small" onClick={() => onEdit?.(task)}>
                      Edit
                    </button>
                    <button className="btn btn-small btn-danger" onClick={() => onDelete?.(task)}>
                      Delete
                    </button>
                  </>
                )}
              </td>
            </tr>
          );
        })}
      </tbody>
    </table>
  );
}