import { useId, useMemo, useRef, useState } from "react";
import type { Project, ScheduledTask, ScheduledTaskInput, ScheduleKind } from "../../../lib/types";
import { addScheduledTask, updateScheduledTask } from "../../../lib/tauri-commands";
import { effectivePermissionMode, PERMISSION_MODES } from "../PermissionModeControl";
import Button from "../../ui/Button";
import Modal from "../../ui/Modal";
import SegmentedControl from "../../ui/SegmentedControl";
import { inputClass, monoInputClass } from "../../ui/Field";
import {
  atTimestampIsPast,
  CRON_PRESETS,
  DEFAULT_WORKING_DIR,
  describeCron,
  MAX_TASK_PROMPT_LEN,
  validateAtTimestamp,
  validateCronExpression,
  validateTaskName,
  validateTaskPrompt,
  validateWorkingDir,
} from "./taskValidation";

interface Props {
  project: Project;
  /** `null` creates a new task; a task edits it in place. */
  task: ScheduledTask | null;
  onClose: () => void;
  /** Called after the scheduler accepted the change, to refresh the list. */
  onSaved: () => void;
}

const DEFAULT_CRON = "0 9 * * *";

/** `YYYY-MM-DD HH:MM`, one hour from now, as the one-shot default. */
function defaultAtTimestamp(now = new Date()): string {
  const at = new Date(now.getTime() + 60 * 60 * 1000);
  at.setSeconds(0, 0);
  const pad = (n: number) => String(n).padStart(2, "0");
  return `${at.getFullYear()}-${pad(at.getMonth() + 1)}-${pad(at.getDate())} ${pad(
    at.getHours(),
  )}:${pad(at.getMinutes())}`;
}

/**
 * Create or edit a `triple-c-scheduler` task.
 *
 * Validation here mirrors the backend so mistakes surface before a round trip;
 * the backend re-checks everything regardless.
 */
export default function TaskEditorModal({ project, task, onClose, onSaved }: Props) {
  const formId = useId();
  const nameRef = useRef<HTMLInputElement>(null);

  const [name, setName] = useState(task?.name ?? "");
  const [prompt, setPrompt] = useState(task?.prompt ?? "");
  const [workingDir, setWorkingDir] = useState(task?.working_dir ?? DEFAULT_WORKING_DIR);
  const [kind, setKind] = useState<ScheduleKind>(
    task?.task_type === "once" ? "once" : "recurring",
  );
  const [cron, setCron] = useState(
    task && task.task_type !== "once" ? task.schedule : DEFAULT_CRON,
  );
  const [at, setAt] = useState(task?.at ?? defaultAtTimestamp());

  const [showAllErrors, setShowAllErrors] = useState(false);
  const [touched, setTouched] = useState<Record<string, boolean>>({});
  const [saving, setSaving] = useState(false);
  const [submitError, setSubmitError] = useState<string | null>(null);

  const errors = {
    name: validateTaskName(name),
    prompt: validateTaskPrompt(prompt),
    workingDir: validateWorkingDir(workingDir),
    schedule: kind === "recurring" ? validateCronExpression(cron) : validateAtTimestamp(at),
  };
  const hasErrors = Object.values(errors).some(Boolean);

  const show = (field: keyof typeof errors) =>
    (showAllErrors || touched[field]) && errors[field] ? errors[field] : null;

  const cronReading = useMemo(() => describeCron(cron), [cron]);
  const atIsPast = kind === "once" && atTimestampIsPast(at);

  const mode = effectivePermissionMode(project);
  const modeLabel = PERMISSION_MODES.find((m) => m.value === mode)?.label ?? mode;

  const handleSubmit = async (e: React.FormEvent) => {
    e.preventDefault();
    setShowAllErrors(true);
    setSubmitError(null);
    if (hasErrors) return;

    const input: ScheduledTaskInput = {
      name: name.trim(),
      prompt: prompt.trim(),
      scheduleKind: kind,
      schedule: kind === "recurring" ? cron.trim() : at.trim(),
      workingDir: workingDir.trim() || DEFAULT_WORKING_DIR,
    };

    setSaving(true);
    try {
      if (task) {
        await updateScheduledTask(project.id, task.id, input, task.enabled);
      } else {
        await addScheduledTask(project.id, input);
      }
      onSaved();
      onClose();
    } catch (err) {
      setSubmitError(String(err));
    } finally {
      setSaving(false);
    }
  };

  const errorText = (message: string | null) =>
    message ? (
      <p role="alert" className="mt-1 text-xs text-[var(--error)]">
        {message}
      </p>
    ) : null;

  return (
    <Modal
      title={task ? `Edit task — ${task.name}` : "New scheduled task"}
      onClose={onClose}
      widthClassName="w-[40rem]"
      initialFocusRef={nameRef}
      footer={
        <>
          <Button size="md" variant="ghost" onClick={onClose} disabled={saving}>
            Cancel
          </Button>
          <Button size="md" variant="primary" type="submit" form={formId} disabled={saving}>
            {saving ? "Saving…" : task ? "Save changes" : "Create task"}
          </Button>
        </>
      }
    >
      <form id={formId} onSubmit={handleSubmit} className="space-y-4">
        {/* Name */}
        <div>
          <label
            htmlFor={`${formId}-name`}
            className="block text-[13px] font-medium text-[var(--text-primary)] mb-1"
          >
            Name
          </label>
          <input
            id={`${formId}-name`}
            ref={nameRef}
            value={name}
            onChange={(e) => setName(e.target.value)}
            onBlur={() => setTouched((t) => ({ ...t, name: true }))}
            placeholder="nightly-tests"
            aria-invalid={show("name") ? true : undefined}
            className={inputClass}
          />
          {errorText(show("name"))}
        </div>

        {/* Prompt */}
        <div>
          <label
            htmlFor={`${formId}-prompt`}
            className="block text-[13px] font-medium text-[var(--text-primary)]"
          >
            Prompt
          </label>
          <p className="mt-0.5 mb-1 text-xs text-[var(--text-secondary)] leading-snug">
            What Claude Code is asked to do on each run.
          </p>
          <textarea
            id={`${formId}-prompt`}
            value={prompt}
            onChange={(e) => setPrompt(e.target.value)}
            onBlur={() => setTouched((t) => ({ ...t, prompt: true }))}
            rows={4}
            maxLength={MAX_TASK_PROMPT_LEN}
            placeholder="Run the test suite and summarise any failures."
            aria-invalid={show("prompt") ? true : undefined}
            className={`${inputClass} resize-y`}
          />
          {errorText(show("prompt"))}
        </div>

        {/* Schedule */}
        <div>
          <span className="block text-[13px] font-medium text-[var(--text-primary)] mb-1">
            Schedule
          </span>
          <SegmentedControl
            label="Schedule kind"
            segments={[
              { value: "recurring", label: "Recurring" },
              { value: "once", label: "Once" },
            ]}
            value={kind}
            onChange={(v) => {
              setKind(v);
              setSubmitError(null);
            }}
          />

          {kind === "recurring" ? (
            <div className="mt-2 space-y-2">
              <div className="flex flex-wrap gap-1">
                {CRON_PRESETS.map((preset) => (
                  <Button
                    key={preset.expression}
                    onClick={() => {
                      setCron(preset.expression);
                      setTouched((t) => ({ ...t, schedule: true }));
                    }}
                  >
                    {preset.label}
                  </Button>
                ))}
              </div>
              <input
                id={`${formId}-cron`}
                value={cron}
                onChange={(e) => setCron(e.target.value)}
                onBlur={() => setTouched((t) => ({ ...t, schedule: true }))}
                placeholder="0 9 * * 1-5"
                aria-label="Cron expression"
                aria-describedby={`${formId}-cron-reading`}
                aria-invalid={show("schedule") ? true : undefined}
                className={monoInputClass}
              />
              <p
                id={`${formId}-cron-reading`}
                aria-live="polite"
                className="text-xs text-[var(--text-secondary)]"
              >
                <span className="font-mono">minute hour day-of-month month day-of-week</span> ·{" "}
                {cronReading ? (
                  <span className="text-[var(--text-primary)]">{cronReading}</span>
                ) : (
                  <span>not a valid schedule yet</span>
                )}
              </p>
              {errorText(show("schedule"))}
            </div>
          ) : (
            <div className="mt-2 space-y-1">
              <input
                id={`${formId}-at`}
                value={at}
                onChange={(e) => setAt(e.target.value)}
                onBlur={() => setTouched((t) => ({ ...t, schedule: true }))}
                placeholder="2026-12-25 09:05"
                aria-label="Run at (YYYY-MM-DD HH:MM)"
                aria-invalid={show("schedule") ? true : undefined}
                className={monoInputClass}
              />
              <p className="text-xs text-[var(--text-secondary)]">
                Container local time, as <code className="font-mono">YYYY-MM-DD HH:MM</code>. The
                task removes itself after it runs.
              </p>
              {atIsPast && (
                <p className="text-xs text-[var(--warning)]">
                  That time has already passed. A one-shot task is stored as a cron entry without a
                  year, so it would next fire on that date next year.
                </p>
              )}
              {errorText(show("schedule"))}
            </div>
          )}
        </div>

        {/* Working directory */}
        <div>
          <label
            htmlFor={`${formId}-wd`}
            className="block text-[13px] font-medium text-[var(--text-primary)]"
          >
            Working directory
          </label>
          <p className="mt-0.5 mb-1 text-xs text-[var(--text-secondary)] leading-snug">
            Absolute path inside the container. Project folders are mounted under{" "}
            <code className="font-mono">/workspace</code>.
          </p>
          <input
            id={`${formId}-wd`}
            value={workingDir}
            onChange={(e) => setWorkingDir(e.target.value)}
            onBlur={() => setTouched((t) => ({ ...t, workingDir: true }))}
            placeholder={DEFAULT_WORKING_DIR}
            aria-invalid={show("workingDir") ? true : undefined}
            className={monoInputClass}
          />
          {errorText(show("workingDir"))}
        </div>

        {/* How a scheduled run actually behaves. */}
        <div className="rounded-[var(--radius-control)] border border-[var(--border-color)] bg-[var(--bg-secondary)] px-3 py-2 space-y-1">
          <p className="text-xs text-[var(--text-secondary)]">
            Scheduled runs are <strong className="text-[var(--text-primary)]">headless</strong> —
            the container executes <code className="font-mono">claude -p "…"</code> with no
            terminal attached, using this project&rsquo;s permission mode (
            <strong className="text-[var(--text-primary)]">{modeLabel}</strong>).
          </p>
          {mode !== "bypass" && (
            <p className="text-xs text-[var(--warning)]">
              A headless run cannot answer a permission prompt. In {modeLabel} mode the task may
              stall and produce an empty log; set the mode to Bypass in the Config tab for
              unattended runs.
            </p>
          )}
        </div>

        {task && (
          <p className="text-xs text-[var(--text-secondary)]">
            The scheduler has no edit command, so saving re-creates this task under a new id and
            removes <code className="font-mono">{task.id}</code>. Its previous run logs stay under
            the old id.
          </p>
        )}

        {submitError && (
          <p role="alert" className="text-xs text-[var(--error)] whitespace-pre-wrap break-words">
            {submitError}
          </p>
        )}
      </form>
    </Modal>
  );
}