"use client";

import { useState } from "react";
import { useRouter } from "next/navigation";
import { useTranslations } from "next-intl";
import { CircleCheck, LoaderCircle, Pause, Play, TriangleAlert, Truck, Wrench, Handshake } from "lucide-react";
import type { WorkOrderStatus } from "@/lib/work-orders/status";
import { errorKey, isSuccess, newClientId, submitOp } from "@/lib/field/client-ops";
import { currentPosition } from "@/lib/field/image";
import { btnPrimary, btnSecondary, noticeError, noticeWarn } from "./ui";

type SessionState = "en_route" | "running" | "paused" | null;
type ActionKey = "accept" | "travel" | "start" | "pause" | "resume" | "complete";

const WORKING: WorkOrderStatus[] = ["in_progress", "paused", "waiting_material", "daily_report_created"];

/** One primary action per state (Brandbook §12.1): Annehmen → Losfahren → Arbeit starten → Pause/Weiter → Abschließen. */
export function resolveActions(status: WorkOrderStatus, mySession: SessionState): { primary: ActionKey | null; secondary: ActionKey | null } {
  if (status === "assigned") return { primary: "accept", secondary: null };
  if (status === "accepted") return { primary: "travel", secondary: "start" };
  if (status === "en_route") return { primary: "start", secondary: null };
  if (WORKING.includes(status)) {
    if (mySession === "running") return { primary: "complete", secondary: "pause" };
    if (mySession === "paused") return { primary: "resume", secondary: "complete" };
    return { primary: "start", secondary: status === "in_progress" ? "complete" : null };
  }
  return { primary: null, secondary: null };
}

const ICONS = { accept: Handshake, travel: Truck, start: Wrench, pause: Pause, resume: Play, complete: CircleCheck } as const;

async function sessionStartPayload(workOrderId: string, mode: "travel" | "work") {
  const pos = await currentPosition(3000);
  return {
    workOrderId,
    mode,
    clientId: newClientId(),
    at: new Date().toISOString(),
    offline: typeof navigator !== "undefined" ? !navigator.onLine : false,
    deviceInfo: typeof navigator !== "undefined" ? navigator.userAgent.slice(0, 200) : undefined,
    ...(pos ?? {}),
  };
}

export function PrimaryAction({
  workOrderId,
  status,
  version,
  mySession,
  blockers,
}: {
  workOrderId: string;
  status: WorkOrderStatus;
  version: number;
  mySession: SessionState;
  /** translated completion blockers (without the user's own session, which is ended on completion) */
  blockers: string[];
}) {
  const t = useTranslations("field");
  const router = useRouter();
  const [busy, setBusy] = useState<ActionKey | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [confirm, setConfirm] = useState(false);
  const { primary, secondary } = resolveActions(status, mySession);

  async function run(action: ActionKey) {
    if (action === "complete" && !confirm) {
      setConfirm(true);
      return;
    }
    setBusy(action);
    setError(null);
    const at = new Date().toISOString();
    let result;
    switch (action) {
      case "accept":
        result = await submitOp({ opType: "work_order.transition", baseVersion: version, payload: { workOrderId, to: "accepted" } });
        break;
      case "travel":
        result = await submitOp({ opType: "session.start", payload: await sessionStartPayload(workOrderId, "travel") });
        break;
      case "start":
        result = await submitOp({ opType: "session.start", payload: await sessionStartPayload(workOrderId, "work") });
        break;
      case "pause":
        result = await submitOp({ opType: "session.pause", payload: { workOrderId, at } });
        break;
      case "resume":
        result = await submitOp({ opType: "session.resume", payload: { workOrderId, at } });
        break;
      case "complete": {
        let base = version;
        if (mySession) {
          const ended = await submitOp({ opType: "session.end", payload: { workOrderId, at } });
          if (!isSuccess(ended)) {
            result = ended;
            break;
          }
          base = ended.entityVersion ?? version;
        }
        result = await submitOp({ opType: "work_order.transition", baseVersion: base, payload: { workOrderId, to: "technically_completed" } });
        break;
      }
    }
    setBusy(null);
    setConfirm(false);
    if (!isSuccess(result)) setError(t(`errors.${errorKey(result)}`));
    router.refresh();
  }

  if (!primary) {
    return <p className="text-[15px] text-muted-foreground">{["technically_completed", "signature_pending"].includes(status) ? t("action.reportNext") : t("action.nothing")}</p>;
  }

  const completeBlocked = blockers.length > 0;
  const renderButton = (action: ActionKey, variant: "primary" | "secondary") => {
    const Icon = busy === action ? LoaderCircle : ICONS[action];
    const disabled = busy !== null || (action === "complete" && completeBlocked);
    return (
      <button type="button" onClick={() => run(action)} disabled={disabled} className={variant === "primary" ? btnPrimary : btnSecondary}>
        <Icon className={busy === action ? "size-5 animate-spin" : "size-5"} aria-hidden />
        {busy === action ? t("action.saving") : action === "complete" && confirm ? t("action.confirmComplete") : t(`action.${action}`)}
      </button>
    );
  };

  return (
    <div className="space-y-2.5">
      {renderButton(primary, "primary")}
      {secondary && renderButton(secondary, "secondary")}
      {confirm && (
        <div className={noticeWarn}>
          <TriangleAlert className="mt-0.5 size-4.5 shrink-0" aria-hidden />
          <span>
            {t("action.confirmHint")}{" "}
            <button type="button" className="ml-1 font-semibold underline" onClick={() => setConfirm(false)}>
              {t("photos.discard")}
            </button>
          </span>
        </div>
      )}
      {completeBlocked && (primary === "complete" || secondary === "complete") && (
        <div className={noticeWarn} role="note">
          <TriangleAlert className="mt-0.5 size-4.5 shrink-0 text-[var(--warn)]" aria-hidden />
          <div>
            <p className="font-semibold">{t("action.blocked")}</p>
            <ul className="mt-1 list-disc pl-4">
              {blockers.map((b) => (
                <li key={b}>{b}</li>
              ))}
            </ul>
          </div>
        </div>
      )}
      {error && (
        <p className={noticeError} role="alert">
          <TriangleAlert className="mt-0.5 size-4.5 shrink-0" aria-hidden />
          {error}
        </p>
      )}
    </div>
  );
}