/** Sparziele mit Fortschritt und nötiger Monatsrate. */

import { type FormEvent, useState } from "react";

import { AlertTriangle, CheckCircle2, Pencil, PiggyBank, Plus, Trash2 } from "lucide-react";

import { AccountSelect } from "@/components/EntitySelects";
import { PageHeader } from "@/components/layout/AppLayout";
import { Button } from "@/components/ui/Button";
import { Badge, ConfirmDialog, EmptyState, Skeleton } from "@/components/ui/Feedback";
import { Field, Input } from "@/components/ui/Field";
import { Modal } from "@/components/ui/Modal";
import { MoneyInput } from "@/components/ui/MoneyInput";
import { useDeleteGoal, useSaveGoal, useSavingsGoals } from "@/hooks/useBudgets";
import { useGoalProgress } from "@/hooks/useReports";
import { formatDate, formatMoney, relativeDays } from "@/lib/format";
import type { SavingsGoal, SavingsGoalProgress } from "@/types/api";

export function GoalsPage() {
  const [bearbeiten, setBearbeiten] = useState<SavingsGoal | null | undefined>(undefined);
  const [loeschen, setLoeschen] = useState<SavingsGoal | null>(null);

  const { data: ziele = [], isLoading } = useSavingsGoals();
  const { data: fortschritt = [] } = useGoalProgress();
  const entfernen = useDeleteGoal();

  const nachId = new Map(fortschritt.map((eintrag) => [eintrag.goal_id, eintrag]));

  return (
    <>
      <PageHeader
        title="Sparziele"
        description="Fortschritt und die Rate, die bis zum Zieldatum nötig ist."
        actions={
          <Button variant="primary" onClick={() => setBearbeiten(null)}>
            <Plus aria-hidden className="h-4 w-4" />
            Sparziel
          </Button>
        }
      />

      {isLoading ? (
        <div className="grid gap-3 sm:grid-cols-2">
          {Array.from({ length: 2 }, (_, index) => (
            <Skeleton key={index} className="h-40" />
          ))}
        </div>
      ) : ziele.length === 0 ? (
        <EmptyState
          icon={PiggyBank}
          title="Noch keine Sparziele"
          description="Ob neues Fahrrad oder Rücklage fürs Auto – moneyfy rechnet aus, was du monatlich zurücklegen musst."
          action={
            <Button variant="primary" onClick={() => setBearbeiten(null)}>
              <Plus aria-hidden className="h-4 w-4" />
              Erstes Sparziel anlegen
            </Button>
          }
        />
      ) : (
        <ul className="grid gap-3 sm:grid-cols-2">
          {ziele.map((ziel) => (
            <GoalCard
              key={ziel.id}
              goal={ziel}
              progress={nachId.get(ziel.id)}
              onEdit={() => setBearbeiten(ziel)}
              onDelete={() => setLoeschen(ziel)}
            />
          ))}
        </ul>
      )}

      <GoalDialog
        goal={bearbeiten}
        open={bearbeiten !== undefined}
        onClose={() => setBearbeiten(undefined)}
      />

      <ConfirmDialog
        open={loeschen !== null}
        title="Sparziel löschen"
        description={`„${loeschen?.name}“ wird endgültig gelöscht.`}
        loading={entfernen.isPending}
        onCancel={() => setLoeschen(null)}
        onConfirm={() => {
          if (loeschen) entfernen.mutate(loeschen.id, { onSuccess: () => setLoeschen(null) });
        }}
      />
    </>
  );
}

function GoalCard({
  goal,
  progress,
  onEdit,
  onDelete,
}: {
  goal: SavingsGoal;
  progress: SavingsGoalProgress | undefined;
  onEdit: () => void;
  onDelete: () => void;
}) {
  const anteil = Math.min(progress?.ratio ?? 0, 1);
  const erreicht = anteil >= 1;

  return (
    <li className="card group p-4">
      <div className="flex items-start justify-between gap-2">
        <div className="min-w-0">
          <h3 className="truncate text-sm font-semibold text-ink">{goal.name}</h3>
          <p className="text-xs text-muted">
            {goal.target_date
              ? `Ziel bis ${formatDate(goal.target_date)} · ${relativeDays(goal.target_date)}`
              : "Ohne Zieldatum"}
          </p>
        </div>
        <div className="flex shrink-0 gap-1 opacity-0 transition group-hover:opacity-100 focus-within:opacity-100">
          <Button size="sm" variant="ghost" onClick={onEdit} aria-label={`${goal.name} bearbeiten`}>
            <Pencil aria-hidden className="h-3.5 w-3.5" />
          </Button>
          <Button size="sm" variant="ghost" onClick={onDelete} aria-label={`${goal.name} löschen`}>
            <Trash2 aria-hidden className="h-3.5 w-3.5" />
          </Button>
        </div>
      </div>

      <p className="mt-3 tabular text-2xl font-semibold text-ink">
        {formatMoney(goal.current_amount)}
        <span className="text-base font-normal text-faint"> / {formatMoney(goal.target_amount)}</span>
      </p>

      <div
        className="mt-2 h-2 overflow-hidden rounded-full bg-raised"
        role="meter"
        aria-valuenow={Math.round(anteil * 100)}
        aria-valuemin={0}
        aria-valuemax={100}
        aria-label={`${goal.name}: ${Math.round(anteil * 100)} Prozent erreicht`}
      >
        <div
          className="h-full rounded-full transition-all"
          style={{ width: `${anteil * 100}%`, backgroundColor: goal.color }}
        />
      </div>

      <div className="mt-2 flex flex-wrap items-center justify-between gap-2 text-xs">
        <span className="text-muted">{Math.round(anteil * 100)} % erreicht</span>
        {erreicht ? (
          <Badge tone="positive">
            <CheckCircle2 aria-hidden className="h-3 w-3" />
            Ziel erreicht
          </Badge>
        ) : (
          progress?.required_monthly && (
            <span className="text-muted">
              {formatMoney(progress.required_monthly)} pro Monat nötig
              {progress.months_left !== null && ` (${progress.months_left} Monate)`}
            </span>
          )
        )}
      </div>

      {progress?.is_on_track === false && (
        <p className="mt-2 flex items-center gap-1.5 rounded-lg bg-warning/10 px-2 py-1.5 text-xs text-warning">
          <AlertTriangle aria-hidden className="h-3.5 w-3.5 shrink-0" />
          Die geplante Rate von {formatMoney(goal.monthly_contribution)} reicht nicht bis zum
          Zieldatum.
        </p>
      )}
    </li>
  );
}

function GoalDialog({
  goal,
  open,
  onClose,
}: {
  goal: SavingsGoal | null | undefined;
  open: boolean;
  onClose: () => void;
}) {
  const speichern = useSaveGoal();
  const [name, setName] = useState("");
  const [ziel, setZiel] = useState("");
  const [stand, setStand] = useState("0.00");
  const [zieldatum, setZieldatum] = useState("");
  const [rate, setRate] = useState("");
  const [konto, setKonto] = useState<number | null>(null);
  const [farbe, setFarbe] = useState("#10b981");
  const [initialisiert, setInitialisiert] = useState<number | null | undefined>(undefined);

  if (open && initialisiert !== (goal?.id ?? null)) {
    setName(goal?.name ?? "");
    setZiel(goal?.target_amount ?? "");
    setStand(goal?.current_amount ?? "0.00");
    setZieldatum(goal?.target_date ?? "");
    setRate(goal?.monthly_contribution ?? "");
    setKonto(goal?.account_id ?? null);
    setFarbe(goal?.color ?? "#10b981");
    setInitialisiert(goal?.id ?? null);
  }

  function absenden(ereignis: FormEvent) {
    ereignis.preventDefault();
    if (!name.trim() || !ziel) return;

    speichern.mutate(
      {
        id: goal?.id,
        daten: {
          name: name.trim(),
          target_amount: ziel,
          current_amount: stand || "0.00",
          target_date: zieldatum || null,
          monthly_contribution: rate || null,
          account_id: konto,
          color: farbe,
        },
      },
      {
        onSuccess: () => {
          setInitialisiert(undefined);
          onClose();
        },
      },
    );
  }

  return (
    <Modal
      open={open}
      onClose={onClose}
      title={goal ? "Sparziel bearbeiten" : "Neues Sparziel"}
      footer={
        <>
          <Button onClick={onClose}>Abbrechen</Button>
          <Button
            variant="primary"
            onClick={absenden}
            loading={speichern.isPending}
            disabled={!name.trim() || !ziel}
          >
            Speichern
          </Button>
        </>
      }
    >
      <form onSubmit={absenden} className="grid gap-3 sm:grid-cols-2">
        <Field label="Name" required className="sm:col-span-2">
          {(id) => (
            <Input
              id={id}
              value={name}
              required
              autoFocus
              placeholder="Neues Fahrrad"
              onChange={(ereignis) => setName(ereignis.target.value)}
            />
          )}
        </Field>

        <Field label="Zielbetrag" required>
          {(id) => <MoneyInput id={id} value={ziel} onValueChange={setZiel} />}
        </Field>

        <Field label="Bereits gespart">
          {(id) => <MoneyInput id={id} value={stand} onValueChange={setStand} />}
        </Field>

        <Field label="Zieldatum" hint="Ohne Datum wird keine Rate berechnet.">
          {(id) => (
            <Input
              id={id}
              type="date"
              value={zieldatum}
              onChange={(ereignis) => setZieldatum(ereignis.target.value)}
            />
          )}
        </Field>

        <Field label="Geplante Monatsrate" hint="moneyfy prüft, ob sie ausreicht.">
          {(id) => <MoneyInput id={id} value={rate} onValueChange={setRate} />}
        </Field>

        <Field label="Konto">
          {(id) => <AccountSelect id={id} value={konto} onChange={setKonto} />}
        </Field>

        <Field label="Farbe">
          {(id) => (
            <Input
              id={id}
              type="color"
              value={farbe}
              className="h-10 p-1"
              onChange={(ereignis) => setFarbe(ereignis.target.value)}
            />
          )}
        </Field>
      </form>
    </Modal>
  );
}