"use client";

import { useRouter } from "next/navigation";
import { useState } from "react";
import { adjustKarenzReturn, recordKarenzReturn, startKarenz } from "@/actions/employees";
import { Button } from "@/components/ui/Button";
import { SelectField, TextField, TextareaField } from "@/components/ui/Field";
import { SegmentedControl } from "@/components/ui/SegmentedControl";
import { SlideOver } from "@/components/ui/SlideOver";
import { useToast } from "@/components/ui/Toast";
import { fmtDate } from "@/lib/format";
import type { Database } from "@/lib/supabase/types";

type EmployeeRow = Database["public"]["Tables"]["employees"]["Row"];
type Mode = "adjust" | "return";
type EmploymentMode = "unverändert" | "Vollzeit" | "Teilzeit";

export function KarenzPanel({ open, onClose, employee }: { open: boolean; onClose: () => void; employee: EmployeeRow }) {
  const { showToast } = useToast();
  const router = useRouter();
  const isOnKarenz = employee.status === "Karenz";
  const [mode, setMode] = useState<Mode>("adjust");
  const [pending, setPending] = useState(false);

  const [karenzStart, setKarenzStart] = useState("");
  const [plannedReturn, setPlannedReturn] = useState("");
  const [startNote, setStartNote] = useState("");

  const [newReturnDate, setNewReturnDate] = useState(employee.karenz_return_date ?? "");
  const [adjustNote, setAdjustNote] = useState("");

  const [returnDate, setReturnDate] = useState("");
  const [employmentMode, setEmploymentMode] = useState<EmploymentMode>("unverändert");
  const [weeklyHours, setWeeklyHours] = useState("20");

  const diffDays =
    isOnKarenz && employee.karenz_return_date && newReturnDate
      ? Math.round((new Date(newReturnDate).getTime() - new Date(employee.karenz_return_date).getTime()) / 86400000)
      : 0;

  async function handleStart() {
    if (!karenzStart || !plannedReturn) {
      showToast("Bitte beide Daten angeben.", "error");
      return;
    }
    setPending(true);
    const result = await startKarenz({ employee_id: employee.id, karenz_start_date: karenzStart, planned_return_date: plannedReturn, note: startNote });
    setPending(false);
    if (result.success) {
      showToast("Karenz erfasst.");
      router.refresh();
      onClose();
    } else {
      showToast(result.error ?? "Fehler.", "error");
    }
  }

  async function handleAdjust() {
    if (!newReturnDate || newReturnDate === employee.karenz_return_date) {
      showToast("Bitte ein neues Rückkehrdatum angeben.", "error");
      return;
    }
    if (new Date(newReturnDate) <= new Date()) {
      showToast("Rückkehrdatum muss in der Zukunft liegen.", "error");
      return;
    }
    setPending(true);
    const result = await adjustKarenzReturn({ employee_id: employee.id, new_return_date: newReturnDate, note: adjustNote });
    setPending(false);
    if (result.success) {
      showToast("Rückkehrdatum angepasst.");
      router.refresh();
      onClose();
    } else {
      showToast(result.error ?? "Fehler.", "error");
    }
  }

  async function handleReturn() {
    if (!returnDate) {
      showToast("Bitte Rückkehrdatum angeben.", "error");
      return;
    }
    if (employmentMode === "Teilzeit" && (Number(weeklyHours) <= 0 || Number(weeklyHours) >= 38.5)) {
      showToast("Wochenstunden müssen zwischen 0 und 38,5 liegen.", "error");
      return;
    }
    setPending(true);
    const result = await recordKarenzReturn({
      employee_id: employee.id,
      return_date: returnDate,
      employment_mode: employmentMode,
      weekly_hours: employmentMode === "Teilzeit" ? Number(weeklyHours) : undefined,
    });
    setPending(false);
    if (result.success) {
      showToast("Wiedereintritt erfasst.");
      router.refresh();
      onClose();
    } else {
      showToast(result.error ?? "Fehler.", "error");
    }
  }

  return (
    <SlideOver
      open={open}
      onClose={onClose}
      title={isOnKarenz ? "Karenz verwalten" : "Karenz"}
      subtitle={`${employee.first_name} ${employee.last_name} · ${employee.job_title}`}
      footer={
        <>
          <Button variant="ghost" onClick={onClose}>
            Abbrechen
          </Button>
          {/* Karenz keeps the warning tone it uses everywhere else. */}
          {!isOnKarenz && (
            <Button onClick={handleStart} pending={pending} className="!bg-warning-text text-white hover:brightness-110">
              Karenz erfassen
            </Button>
          )}
          {isOnKarenz && mode === "adjust" && (
            <Button onClick={handleAdjust} pending={pending} className="!bg-warning-text text-white hover:brightness-110">
              Speichern
            </Button>
          )}
          {isOnKarenz && mode === "return" && (
            <Button onClick={handleReturn} pending={pending} className="!bg-warning-text text-white hover:brightness-110">
              Wiedereintritt erfassen
            </Button>
          )}
        </>
      }
    >
      {!isOnKarenz && (
        <div className="flex flex-col gap-4">
          <TextField label="Karenzbeginn" required type="date" value={karenzStart} onChange={setKarenzStart} />
          <TextField label="Geplante Rückkehr" required type="date" value={plannedReturn} onChange={setPlannedReturn} />
          <TextareaField label="Anmerkung" rows={3} value={startNote} onChange={setStartNote} />
        </div>
      )}

      {isOnKarenz && (
        <div className="flex flex-col gap-4">
          <SegmentedControl<Mode>
            value={mode}
            onChange={setMode}
            options={[
              { value: "adjust", label: "Rückkehr anpassen" },
              { value: "return", label: "Wiedereintritt erfassen" },
            ]}
          />

          {mode === "adjust" && (
            <>
              <p className="text-sm text-ink-muted">Aktuelles Rückkehrdatum: {fmtDate(employee.karenz_return_date)}</p>
              <TextField label="Neues Rückkehrdatum" required type="date" value={newReturnDate} onChange={setNewReturnDate} />
              {diffDays !== 0 && (
                <div className={`rounded px-3 py-2 text-sm ${diffDays > 0 ? "bg-warning-bg text-warning-text" : "bg-success-bg text-success-text"}`}>
                  {diffDays > 0 ? `Verlängerung um ${diffDays} Tage` : `Verkürzung um ${Math.abs(diffDays)} Tage`}
                </div>
              )}
              <TextareaField label="Grund/Anmerkung" rows={3} value={adjustNote} onChange={setAdjustNote} />
            </>
          )}

          {mode === "return" && (
            <>
              <TextField label="Rückkehrdatum" required type="date" value={returnDate} onChange={setReturnDate} />
              <SelectField
                label="Beschäftigungsausmaß"
                value={employmentMode}
                onChange={(v) => setEmploymentMode(v as EmploymentMode)}
                options={[
                  { value: "unverändert", label: "unverändert" },
                  { value: "Vollzeit", label: "Vollzeit (38,5h)" },
                  { value: "Teilzeit", label: "Teilzeit-Elternteilzeit" },
                ]}
              />
              {employmentMode === "Teilzeit" && (
                <TextField
                  label="Wochenstunden"
                  required
                  type="number"
                  step="0.5"
                  max="38"
                  value={weeklyHours}
                  onChange={setWeeklyHours}
                  hint="Muss unter 38,5 liegen."
                />
              )}
            </>
          )}
        </div>
      )}
    </SlideOver>
  );
}