"use client";

import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
import { useParams } from "next/navigation";
import { api } from "@/lib/api";
import type { TimeEntry } from "@/lib/types";
import { format } from "date-fns";
import { de } from "date-fns/locale";
import { Timer, Loader2, Plus, Trash2 } from "lucide-react";
import { useState } from "react";

function formatDuration(minutes: number): string {
  const h = Math.floor(minutes / 60);
  const m = minutes % 60;
  if (h === 0) return `${m}min`;
  if (m === 0) return `${h}h`;
  return `${h}h ${m}min`;
}

function formatAmount(minutes: number, rate?: number): string {
  if (!rate) return "-";
  return `${((minutes / 60) * rate).toFixed(2)} EUR`;
}

const ACTIVITIES = [
  { value: "", label: "Keine Kategorie" },
  { value: "research", label: "Recherche" },
  { value: "drafting", label: "Entwurf" },
  { value: "hearing", label: "Verhandlung" },
  { value: "call", label: "Telefonat" },
  { value: "review", label: "Prüfung" },
  { value: "travel", label: "Reise" },
  { value: "meeting", label: "Besprechung" },
];

export default function ZeiterfassungPage() {
  const { id } = useParams<{ id: string }>();
  const queryClient = useQueryClient();
  const [showForm, setShowForm] = useState(false);
  const [desc, setDesc] = useState("");
  const [hours, setHours] = useState("");
  const [minutes, setMinutes] = useState("");
  const [date, setDate] = useState(format(new Date(), "yyyy-MM-dd"));
  const [activity, setActivity] = useState("");
  const [billable, setBillable] = useState(true);

  const { data, isLoading } = useQuery({
    queryKey: ["case-time-entries", id],
    queryFn: () =>
      api.get<{ time_entries: TimeEntry[] }>(`/cases/${id}/time-entries`),
  });

  const createMutation = useMutation({
    mutationFn: (input: {
      description: string;
      duration_minutes: number;
      date: string;
      activity?: string;
      billable: boolean;
    }) => api.post<TimeEntry>(`/cases/${id}/time-entries`, input),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["case-time-entries", id] });
      setShowForm(false);
      setDesc("");
      setHours("");
      setMinutes("");
      setActivity("");
      setBillable(true);
    },
  });

  const deleteMutation = useMutation({
    mutationFn: (entryId: string) =>
      api.delete(`/time-entries/${entryId}`),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ["case-time-entries", id] });
    },
  });

  function handleSubmit(e: React.FormEvent) {
    e.preventDefault();
    const totalMinutes = (parseInt(hours || "0") * 60) + parseInt(minutes || "0");
    if (totalMinutes <= 0 || !desc.trim()) return;
    createMutation.mutate({
      description: desc.trim(),
      duration_minutes: totalMinutes,
      date,
      activity: activity || undefined,
      billable,
    });
  }

  if (isLoading) {
    return (
      <div className="flex items-center justify-center py-8">
        <Loader2 className="h-5 w-5 animate-spin text-neutral-400" />
      </div>
    );
  }

  const entries = data?.time_entries ?? [];
  const totalMinutes = entries.reduce((s, e) => s + e.duration_minutes, 0);
  const billableMinutes = entries
    .filter((e) => e.billable)
    .reduce((s, e) => s + e.duration_minutes, 0);

  return (
    <div className="space-y-4">
      {/* Summary bar */}
      <div className="flex flex-wrap items-center justify-between gap-3">
        <div className="flex gap-6 text-sm text-neutral-500">
          <span>
            Gesamt: <span className="font-medium text-neutral-900">{formatDuration(totalMinutes)}</span>
          </span>
          <span>
            Abrechenbar: <span className="font-medium text-neutral-900">{formatDuration(billableMinutes)}</span>
          </span>
        </div>
        <button
          onClick={() => setShowForm(!showForm)}
          className="inline-flex items-center gap-1.5 rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800"
        >
          <Plus className="h-3.5 w-3.5" />
          Eintrag
        </button>
      </div>

      {/* Quick add form */}
      {showForm && (
        <form
          onSubmit={handleSubmit}
          className="rounded-md border border-neutral-200 bg-neutral-50 p-4 space-y-3"
        >
          <div>
            <label className="block text-xs font-medium text-neutral-600 mb-1">
              Beschreibung
            </label>
            <input
              type="text"
              value={desc}
              onChange={(e) => setDesc(e.target.value)}
              placeholder="Was wurde getan?"
              className="w-full rounded-md border border-neutral-300 px-3 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
              required
            />
          </div>
          <div className="flex flex-wrap gap-3">
            <div className="flex-1 min-w-[120px]">
              <label className="block text-xs font-medium text-neutral-600 mb-1">
                Dauer
              </label>
              <div className="flex gap-2">
                <div className="flex items-center gap-1">
                  <input
                    type="number"
                    min="0"
                    value={hours}
                    onChange={(e) => setHours(e.target.value)}
                    placeholder="0"
                    className="w-16 rounded-md border border-neutral-300 px-2 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
                  />
                  <span className="text-xs text-neutral-500">h</span>
                </div>
                <div className="flex items-center gap-1">
                  <input
                    type="number"
                    min="0"
                    max="59"
                    value={minutes}
                    onChange={(e) => setMinutes(e.target.value)}
                    placeholder="0"
                    className="w-16 rounded-md border border-neutral-300 px-2 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
                  />
                  <span className="text-xs text-neutral-500">min</span>
                </div>
              </div>
            </div>
            <div className="flex-1 min-w-[120px]">
              <label className="block text-xs font-medium text-neutral-600 mb-1">
                Datum
              </label>
              <input
                type="date"
                value={date}
                onChange={(e) => setDate(e.target.value)}
                className="w-full rounded-md border border-neutral-300 px-3 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
              />
            </div>
            <div className="flex-1 min-w-[120px]">
              <label className="block text-xs font-medium text-neutral-600 mb-1">
                Kategorie
              </label>
              <select
                value={activity}
                onChange={(e) => setActivity(e.target.value)}
                className="w-full rounded-md border border-neutral-300 px-3 py-1.5 text-sm focus:border-neutral-500 focus:outline-none"
              >
                {ACTIVITIES.map((a) => (
                  <option key={a.value} value={a.value}>
                    {a.label}
                  </option>
                ))}
              </select>
            </div>
          </div>
          <div className="flex items-center justify-between">
            <label className="flex items-center gap-2 text-sm text-neutral-600">
              <input
                type="checkbox"
                checked={billable}
                onChange={(e) => setBillable(e.target.checked)}
                className="rounded border-neutral-300"
              />
              Abrechenbar
            </label>
            <div className="flex gap-2">
              <button
                type="button"
                onClick={() => setShowForm(false)}
                className="rounded-md px-3 py-1.5 text-sm text-neutral-600 transition-colors hover:bg-neutral-100"
              >
                Abbrechen
              </button>
              <button
                type="submit"
                disabled={createMutation.isPending}
                className="rounded-md bg-neutral-900 px-3 py-1.5 text-sm font-medium text-white transition-colors hover:bg-neutral-800 disabled:opacity-50"
              >
                {createMutation.isPending ? "Speichern..." : "Speichern"}
              </button>
            </div>
          </div>
          {createMutation.isError && (
            <p className="text-sm text-red-600">Fehler beim Speichern.</p>
          )}
        </form>
      )}

      {/* Entries list */}
      {entries.length === 0 ? (
        <div className="flex flex-col items-center py-8 text-center">
          <div className="rounded-xl bg-neutral-100 p-3">
            <Timer className="h-5 w-5 text-neutral-400" />
          </div>
          <p className="mt-2 text-sm text-neutral-500">
            Keine Zeiteintraege vorhanden.
          </p>
        </div>
      ) : (
        <div className="space-y-2">
          {entries.map((entry) => (
            <div
              key={entry.id}
              className="flex items-center justify-between rounded-md border border-neutral-200 bg-white px-4 py-3"
            >
              <div className="min-w-0 flex-1">
                <div className="flex items-center gap-2">
                  <p className="text-sm font-medium text-neutral-900 truncate">
                    {entry.description}
                  </p>
                  {entry.activity && (
                    <span className="shrink-0 rounded-full bg-neutral-100 px-2 py-0.5 text-xs text-neutral-500">
                      {ACTIVITIES.find((a) => a.value === entry.activity)?.label ?? entry.activity}
                    </span>
                  )}
                  {!entry.billable && (
                    <span className="shrink-0 rounded-full bg-neutral-100 px-2 py-0.5 text-xs text-neutral-400">
                      nicht abrechenbar
                    </span>
                  )}
                  {entry.billed && (
                    <span className="shrink-0 rounded-full bg-emerald-50 px-2 py-0.5 text-xs text-emerald-700">
                      abgerechnet
                    </span>
                  )}
                </div>
                <div className="mt-0.5 flex gap-4 text-xs text-neutral-500">
                  <span>
                    {format(new Date(entry.date), "d. MMM yyyy", { locale: de })}
                  </span>
                  {entry.hourly_rate && (
                    <span>{formatAmount(entry.duration_minutes, entry.hourly_rate)}</span>
                  )}
                </div>
              </div>
              <div className="flex items-center gap-3 ml-4">
                <span className="text-sm font-medium text-neutral-900 whitespace-nowrap">
                  {formatDuration(entry.duration_minutes)}
                </span>
                {!entry.billed && (
                  <button
                    onClick={() => deleteMutation.mutate(entry.id)}
                    className="rounded-md p-1 text-neutral-400 transition-colors hover:bg-red-50 hover:text-red-600"
                    title="Loeschen"
                  >
                    <Trash2 className="h-3.5 w-3.5" />
                  </button>
                )}
              </div>
            </div>
          ))}
        </div>
      )}
    </div>
  );
}