"use client";

import Link from "next/link";
import { useRouter } from "next/navigation";
import { useState, useTransition } from "react";
import { Button } from "@/components/ui/button";
import { BottomSheet } from "@/components/ui/bottom-sheet";
import { Input } from "@/components/ui/input";
import type { TimeOffActionResult, TimeOffConflictItem } from "../actions/time-off";
import { createTimeOffAction, deleteTimeOffAction, updateTimeOffAction } from "../actions/time-off";
import type { TimeOffInput } from "@/services/staff/staff.service";

export interface EditableTimeOff {
  id: string;
  startDate: string;
  endDate: string;
  reason: string | null;
}

/** Same DI shape as AppointmentStatusActions' `actions` prop — the owner-on-behalf-of-staff editor injects its own Server Actions bound to a chosen staffId instead of forking this component. */
export interface TimeOffActionSet {
  create: (
    input: Pick<TimeOffInput, "startDate" | "endDate" | "reason">,
    acknowledgeConflicts?: boolean,
  ) => Promise<TimeOffActionResult>;
  update: (
    timeOffId: string,
    input: Pick<TimeOffInput, "startDate" | "endDate" | "reason">,
    acknowledgeConflicts?: boolean,
  ) => Promise<TimeOffActionResult>;
  remove: (timeOffId: string) => Promise<TimeOffActionResult>;
}

const DEFAULT_ACTIONS: TimeOffActionSet = {
  create: createTimeOffAction,
  update: updateTimeOffAction,
  remove: deleteTimeOffAction,
};

function todayIso(): string {
  return new Date().toISOString().slice(0, 10);
}

export function TimeOffFormSheet({
  open,
  onClose,
  existing,
  actions = DEFAULT_ACTIONS,
  appointmentHrefBase = "/staff/appointments",
}: {
  open: boolean;
  onClose: () => void;
  existing?: EditableTimeOff | null;
  actions?: TimeOffActionSet;
  appointmentHrefBase?: string;
}) {
  const router = useRouter();
  const [startDate, setStartDate] = useState(existing?.startDate ?? todayIso());
  const [endDate, setEndDate] = useState(existing?.endDate ?? existing?.startDate ?? todayIso());
  const [reason, setReason] = useState(existing?.reason ?? "");
  const [error, setError] = useState<string | null>(null);
  const [conflicts, setConflicts] = useState<TimeOffConflictItem[] | null>(null);
  const [isPending, startTransition] = useTransition();
  const [isDeleting, startDeleteTransition] = useTransition();

  const reset = () => {
    setStartDate(existing?.startDate ?? todayIso());
    setEndDate(existing?.endDate ?? existing?.startDate ?? todayIso());
    setReason(existing?.reason ?? "");
    setError(null);
    setConflicts(null);
  };

  const handleClose = () => {
    onClose();
    reset();
  };

  const submit = (acknowledgeConflicts: boolean) => {
    if (startDate > endDate) {
      setError("Start date must be on or before the end date.");
      return;
    }
    setError(null);
    startTransition(async () => {
      const input = { startDate, endDate, reason: reason.trim() || undefined };
      const result: TimeOffActionResult = existing
        ? await actions.update(existing.id, input, acknowledgeConflicts)
        : await actions.create(input, acknowledgeConflicts);
      if (!result.success) {
        setError(result.error ?? "Something went wrong.");
        setConflicts(result.conflicts ?? null);
        return;
      }
      handleClose();
      router.refresh();
    });
  };

  const handleDelete = () => {
    if (!existing) return;
    startDeleteTransition(async () => {
      const result = await actions.remove(existing.id);
      if (!result.success) {
        setError(result.error ?? "Couldn't remove this time off.");
        return;
      }
      handleClose();
      router.refresh();
    });
  };

  return (
    <BottomSheet open={open} onClose={handleClose} title={existing ? "Edit Time Off" : "New Time Off"}>
      <div className="space-y-4 pb-2">
        {conflicts && conflicts.length > 0 ? (
          <div className="space-y-3">
            <p role="alert" className="text-danger text-sm font-medium">
              This overlaps {conflicts.length} existing appointment
              {conflicts.length > 1 ? "s" : ""}. These won&apos;t be cancelled automatically —
              you&apos;ll need to reschedule or cancel them yourself.
            </p>
            <ul className="space-y-2">
              {conflicts.map((c) => (
                <li key={c.id} className="border-line rounded-lg border bg-white p-3 text-xs">
                  <Link href={`${appointmentHrefBase}/${c.id}`} className="font-bold underline">
                    {c.customerName}
                  </Link>
                  <p className="text-muted">{c.serviceNames}</p>
                </li>
              ))}
            </ul>
            <div className="flex gap-3">
              <Button variant="secondary" className="flex-1" onClick={handleClose}>
                Cancel
              </Button>
              <Button
                variant="destructive"
                className="flex-1"
                isLoading={isPending}
                onClick={() => submit(true)}
              >
                Save Anyway
              </Button>
            </div>
          </div>
        ) : (
          <>
            <div className="grid grid-cols-2 gap-4">
              <Input label="Start date" type="date" value={startDate} onChange={(e) => setStartDate(e.target.value)} />
              <Input label="End date" type="date" value={endDate} onChange={(e) => setEndDate(e.target.value)} />
            </div>
            <Input
              label="Reason (optional)"
              placeholder="e.g. Vacation"
              value={reason}
              onChange={(e) => setReason(e.target.value)}
            />
            {error && (
              <p role="alert" className="text-danger text-sm font-medium">
                {error}
              </p>
            )}
            <Button className="w-full" isLoading={isPending} onClick={() => submit(false)}>
              {existing ? "Save Changes" : "Add Time Off"}
            </Button>
            {existing && (
              <Button variant="ghost" className="w-full text-danger" isLoading={isDeleting} onClick={handleDelete}>
                Remove Time Off
              </Button>
            )}
          </>
        )}
      </div>
    </BottomSheet>
  );
}