import { useEffect, useState } from "react";
import { useTranslation } from "react-i18next";
import { api } from "../api";
import { useSettings } from "../settings";
import { useConfirm } from "../confirm";
import { useToast } from "../toast";
import Icon from "../components/Icon";
import IconChip from "../components/IconChip";
import Money from "../components/Money";
import Modal from "../components/Modal";
import IconPicker, { ACCOUNT_ICONS } from "../components/IconPicker";
import { centsToInput, formatDate, formatMoney, parseAmountToCents } from "../format";

const ACCOUNT_TYPES = ["girokonto", "sparkonto", "bargeld", "kreditkarte", "depot", "sonstiges"];
const TYPE_ICON = {
  girokonto: "landmark",
  sparkonto: "piggy-bank",
  bargeld: "wallet",
  kreditkarte: "credit-card",
  depot: "trending-up",
  sonstiges: "wallet",
};

function emptyForm() {
  return {
    name: "",
    type: "girokonto",
    currency: "EUR",
    icon: "landmark",
    color: "#3f51b5",
    opening_balance: "",
    opening_date: "",
    identifiers: [],
  };
}

// Globale Transfer-Schlagwörter: Text im Buchungstext -> Transfer. Das Zielkonto
// wird über die Erkennungs-Texte je Konto (Identifikator-Art „Text") erraten.
function TransferKeywords({ accounts }) {
  const { t } = useTranslation();
  const toast = useToast();
  const [words, setWords] = useState([]);
  const [input, setInput] = useState("");
  const [amount, setAmount] = useState("");
  const [target, setTarget] = useState("");
  const [busy, setBusy] = useState(false);
  // Was beim nachträglichen Anwenden übersprungen wurde, samt Grund.
  const [uebersprungen, setUebersprungen] = useState([]);
  const confirm = useConfirm();
  const accName = (id) => accounts.find((a) => a.id === id)?.name;

  // Regeln greifen beim Import. Alles, was vorher hereinkam – oder bevor es die
  // Regel gab –, liegt noch ohne Kategorie da; bei einer Bankanbindung dauernd.
  // Erst zeigen, dann tun: Ein Übertrag verschiebt Geld.
  async function nachtraeglichAnwenden() {
    setBusy(true);
    try {
      const vor = await api.applyRules(true);
      if (!vor.kategorien && !vor.uebertraege) {
        toast(t("categories.applyNothing"));
        setUebersprungen(vor.uebersprungen || []);
        return;
      }
      if (!(await confirm({
        title: t("categories.applyRules"),
        message: t("categories.applyPreview", {
          kategorien: vor.kategorien, uebertraege: vor.uebertraege,
        }),
        confirmLabel: t("categories.applyRules"),
      }))) return;
      const r = await api.applyRules(false);
      toast(t("categories.applyDone", {
        kategorien: r.kategorien, uebertraege: r.uebertraege,
      }));
      setUebersprungen(r.uebersprungen || []);
    } catch (err) {
      toast(err.message, "error");
    } finally {
      setBusy(false);
    }
  }


  async function laden() {
    try { setWords(await api.listTransferKeywords()); }
    catch (err) { toast(err.message, "error"); }
  }
  useEffect(() => { laden(); }, []);

  async function hinzufuegen() {
    const w = input.trim();
    if (!w) return;
    setBusy(true);
    try {
      const body = { word: w };
      const c = parseAmountToCents(amount);
      if (c) body.amount_cents = c;
      if (target) body.target_account_id = Number(target);
      await api.addTransferKeyword(body);
      setInput("");
      setAmount("");
      setTarget("");
      await laden();
    } catch (err) {
      toast(err.message, "error");
    } finally {
      setBusy(false);
    }
  }
  async function entfernen(id) {
    try { await api.deleteKeyword(id); setWords((ws) => ws.filter((x) => x.id !== id)); }
    catch (err) { toast(err.message, "error"); }
  }

  return (
    <div className="card" style={{ marginTop: "var(--sp-4)" }}>
      <h2>{t("transferRules.title")}</h2>
      <p className="muted small">{t("transferRules.hint")}</p>
      <div className="kw-add">
        <input value={input} placeholder={t("transferRules.wordPlaceholder")}
               onChange={(e) => setInput(e.target.value)}
               onKeyDown={(e) => { if (e.key === "Enter") { e.preventDefault(); hinzufuegen(); } }} />
        <input value={amount} inputMode="decimal" placeholder={t("categories.keywordAmount")}
               style={{ flex: "0 0 110px", minWidth: 0, marginTop: 0 }}
               onChange={(e) => setAmount(e.target.value)}
               onKeyDown={(e) => { if (e.key === "Enter") { e.preventDefault(); hinzufuegen(); } }} />
        <select value={target} onChange={(e) => setTarget(e.target.value)}
                style={{ flex: "0 0 160px", minWidth: 0, marginTop: 0 }}>
          <option value="">{t("transferRules.autoTarget")}</option>
          {accounts.map((a) => <option key={a.id} value={a.id}>{a.name}</option>)}
        </select>
        <button className="btn" onClick={hinzufuegen} disabled={busy || !input.trim()}>
          <Icon name="plus" size={15} />
        </button>
      </div>
      <div className="mail-actions" style={{ marginTop: "var(--sp-2)" }}>
        <button className="btn sm" disabled={busy} onClick={nachtraeglichAnwenden}>
          {t("categories.applyRules")}
        </button>
        <span className="muted small">{t("categories.applyRulesHint")}</span>
      </div>
      {uebersprungen.length > 0 && (
        <div className="alert warn" style={{ display: "block", marginTop: "var(--sp-2)" }}>
          <strong className="small">{t("categories.applySkipped")}</strong>
          <ul className="muted small" style={{ paddingLeft: "1.2em", margin: 0 }}>
            {uebersprungen.map((m, i) => (
              <li key={i} className="selectable">{m.datum} · {m.text} — {m.grund}</li>
            ))}
          </ul>
        </div>
      )}
      {words.length === 0 ? (
        <div className="muted small">{t("transferRules.empty")}</div>
      ) : (
        <div className="kw-chips">
          {words.map((w) => (
            <span className="kw-chip" key={w.id}>
              {w.word}
              {w.amount_cents ? <span className="kw-amount">= {centsToInput(w.amount_cents)}</span> : null}
              <span className="kw-amount">→ {w.target_account_id ? (accName(w.target_account_id) || "?") : t("transferRules.autoTarget")}</span>
              <button type="button" title={t("common.delete")} onClick={() => entfernen(w.id)}>
                <Icon name="close" size={13} />
              </button>
            </span>
          ))}
        </div>
      )}
    </div>
  );
}

export default function Accounts() {
  const { t } = useTranslation();
  const { baseCurrency } = useSettings();
  const confirm = useConfirm();
  const toast = useToast();

  const [accounts, setAccounts] = useState([]);
  const [editing, setEditing] = useState(null); // Account-Objekt oder null
  const [form, setForm] = useState(null); // Formularzustand oder null (geschlossen)
  const [busy, setBusy] = useState(false);

  async function saldoUebernehmen(a) {
    if (!(await confirm({
      title: t("accounts.adoptBankBalance"),
      message: t("accounts.adoptConfirm", {
        bank: formatMoney(a.bank_balance_cents, a.currency),
        diff: formatMoney(a.balance_cents - a.bank_balance_cents, a.currency),
      }),
      confirmLabel: t("accounts.adoptBankBalance"),
    }))) return;
    try {
      await api.adoptBankBalance(a.id);
      toast(t("accounts.adopted"));
      laden();
    } catch (e) {
      toast(e.message, "error");
    }
  }

  async function laden() {
    try {
      setAccounts(await api.listAccounts());
    } catch (err) {
      toast(err.message, "error");
    }
  }
  useEffect(() => { laden(); }, []);

  function openNew() {
    setEditing(null);
    setForm(emptyForm());
  }
  function openEdit(acc) {
    setEditing(acc);
    setForm({
      name: acc.name,
      type: acc.type,
      currency: acc.currency,
      icon: acc.icon,
      color: acc.color,
      opening_balance: centsToInput(acc.opening_balance_cents),
      opening_date: acc.opening_date || "",
      identifiers: acc.identifiers.map((i) => ({ kind: i.kind, value: i.value })),
    });
  }

  function setType(type) {
    // Icon mitziehen, solange der Nutzer das Standard-Icon des alten Typs hatte.
    setForm((f) => ({
      ...f,
      type,
      icon: f.icon === TYPE_ICON[f.type] ? TYPE_ICON[type] : f.icon,
    }));
  }

  async function speichern(e) {
    e.preventDefault();
    setBusy(true);
    const body = {
      name: form.name.trim(),
      type: form.type,
      currency: form.currency,
      icon: form.icon,
      color: form.color,
      opening_balance_cents: parseAmountToCents(form.opening_balance) ?? 0,
      opening_date: form.opening_date || null,
      identifiers: form.identifiers
        .filter((i) => i.value.trim())
        .map((i) => ({ kind: i.kind, value: i.value.trim() })),
    };
    try {
      if (editing) await api.updateAccount(editing.id, body);
      else await api.createAccount(body);
      setForm(null);
      toast(t("settings.saved"));
      laden();
    } catch (err) {
      toast(err.message, "error");
    } finally {
      setBusy(false);
    }
  }

  // Reihenfolge per Pfeil: die Liste stand sonst in der Anlegereihenfolge.
  // Optimistisch umsortieren, damit die Liste nicht bei jedem Klick springt.
  async function verschiebe(index, richtung) {
    const ziel = index + richtung;
    if (ziel < 0 || ziel >= accounts.length) return;
    const neu = [...accounts];
    [neu[index], neu[ziel]] = [neu[ziel], neu[index]];
    setAccounts(neu);
    try {
      await api.setAccountOrder(neu.map((a) => a.id));
    } catch (e) {
      toast(e.message, "error");
      laden();
    }
  }

  async function loeschen(acc) {
    if (!(await confirm({ title: t("common.delete"), message: t("accounts.deleteConfirm"), danger: true, confirmLabel: t("common.delete") }))) return;
    try {
      await api.deleteAccount(acc.id);
      laden();
    } catch (err) {
      toast(err.message, "error");
    }
  }

  const total = accounts.reduce((s, a) => s + a.balance_base_cents, 0);

  return (
    <div>
      <div className="page-head">
        <h1>{t("accounts.title")}</h1>
        <button className="btn primary" onClick={openNew}>
          <Icon name="plus" size={16} /> {t("accounts.new")}
        </button>
      </div>

      {accounts.length === 0 ? (
        <div className="card"><div className="empty-state">{t("accounts.empty")}</div></div>
      ) : (
        <div className="card">
          <div className="account-total">
            <span className="muted">{t("accounts.total")}</span>
            <strong>{formatMoney(total, baseCurrency)}</strong>
          </div>
          <div className="account-list">
            {accounts.map((a, i) => (
              <div className="account-row" key={a.id}>
                <IconChip name={a.icon} color={a.color} />
                <div className="named-text grow">
                  <div><strong>{a.name}</strong></div>
                  <div className="named-sub">
                    {t(`accountTypes.${a.type}`)} · {a.currency}
                    {/* „1 Nr." sagte niemandem, was gemeint ist: die Kennungen, an denen
                        Certain eine Auszugszeile diesem Konto zuordnet. */}
                    {a.identifiers.length > 0
                      && ` · ${t("accounts.identShort", { count: a.identifiers.length })}`}
                  </div>
                  {/* Bei angebundenen Konten der Saldo, den die Bank fuehrt.
                      Er ersetzt die eigene Rechnung nicht, er prueft sie: Eine
                      Abweichung heisst, dass eine Buchung fehlt oder doppelt
                      ist – sonst faellt das erst beim Vergleich von Hand auf. */}
                  {a.bank_balance_cents != null && (
                    <div className="named-sub">
                      {a.bank_balance_cents === a.balance_cents ? (
                        <span className="saldo-ok">
                          {t("accounts.bankBalanceMatches")}
                          {a.bank_balance_at ? ` · ${formatDate(a.bank_balance_at)}` : ""}
                        </span>
                      ) : (
                        <span className="saldo-abweichung">
                          {t("accounts.bankBalanceDiffers", {
                            bank: formatMoney(a.bank_balance_cents, a.currency),
                            diff: formatMoney(a.balance_cents - a.bank_balance_cents,
                                              a.currency),
                          })}{" "}
                          {/* Die Bank kennt den wahren Stand. Uebernehmen legt
                              die Differenz in den Anfangsbestand – Buchungen
                              werden nicht angefasst. */}
                          <button type="button" className="btn sm"
                                  onClick={() => saldoUebernehmen(a)}>
                            {t("accounts.adoptBankBalance")}
                          </button>
                        </span>
                      )}
                    </div>
                  )}
                </div>
                <Money cents={a.balance_cents} currency={a.currency}
                       baseCents={a.balance_base_cents} baseCurrency={baseCurrency} />
                <div className="row-actions">
                  <button className="btn sm ghost" title={t("accounts.moveUp")}
                          disabled={i === 0} onClick={() => verschiebe(i, -1)}>
                    <Icon name="chevron-up" size={15} />
                  </button>
                  <button className="btn sm ghost" title={t("accounts.moveDown")}
                          disabled={i === accounts.length - 1} onClick={() => verschiebe(i, 1)}>
                    <Icon name="chevron-down" size={15} />
                  </button>
                  <button className="btn sm ghost" title={t("common.edit")} onClick={() => openEdit(a)}>
                    <Icon name="edit" size={15} />
                  </button>
                  <button className="btn sm danger" title={t("common.delete")} onClick={() => loeschen(a)}>
                    <Icon name="trash" size={15} />
                  </button>
                </div>
              </div>
            ))}
          </div>
        </div>
      )}

      <TransferKeywords accounts={accounts} />

      {form && (
        <Modal
          title={editing ? t("accounts.edit") : t("accounts.new")}
          onClose={() => setForm(null)}
          footer={
            <>
              <button className="btn" onClick={() => setForm(null)}>{t("common.cancel")}</button>
              <button className="btn primary" form="account-form" type="submit" disabled={busy}>
                {t("common.save")}
              </button>
            </>
          }
        >
          <form id="account-form" onSubmit={speichern}>
            <label>
              <span>{t("accounts.name")}</span>
              {/* eslint-disable-next-line jsx-a11y/no-autofocus */}
              <input autoFocus value={form.name} onChange={(e) => setForm({ ...form, name: e.target.value })} required />
            </label>
            <div className="row">
              <label className="grow">
                <span>{t("accounts.type")}</span>
                <select value={form.type} onChange={(e) => setType(e.target.value)}>
                  {ACCOUNT_TYPES.map((tp) => (
                    <option key={tp} value={tp}>{t(`accountTypes.${tp}`)}</option>
                  ))}
                </select>
              </label>
              <label style={{ minWidth: 120 }}>
                <span>{t("accounts.currency")}</span>
                <select value={form.currency} onChange={(e) => setForm({ ...form, currency: e.target.value })}>
                  <option value="EUR">EUR</option>
                  <option value="CHF">CHF</option>
                </select>
              </label>
            </div>
            <div className="row">
              <label className="grow">
                <span>{t("accounts.openingBalance")} ({form.currency})</span>
                <input inputMode="decimal" value={form.opening_balance}
                       onChange={(e) => setForm({ ...form, opening_balance: e.target.value })} placeholder="0,00" />
              </label>
              <label style={{ minWidth: 150 }}>
                <span>{t("accounts.openingDate")}</span>
                <input type="date" value={form.opening_date}
                       onChange={(e) => setForm({ ...form, opening_date: e.target.value })} />
              </label>
            </div>
            <p className="muted small">{t("accounts.openingDateHint")}</p>
            <label>
              <span>{t("accounts.icon")}</span>
              <IconPicker icons={ACCOUNT_ICONS} value={form.icon} color={form.color}
                          onChange={(name) => setForm({ ...form, icon: name })} />
            </label>
            <label>
              <span>{t("accounts.color")}</span>
              <div className="color-row">
                <input type="color" value={form.color} onChange={(e) => setForm({ ...form, color: e.target.value })} />
                <IconChip name={form.icon} color={form.color} />
              </div>
            </label>

            <label style={{ marginBottom: 6 }}><span>{t("accounts.identifiers")}</span></label>
            {form.identifiers.map((ident, idx) => (
              <div className="row" key={idx} style={{ marginBottom: 6 }}>
                <select style={{ flex: "0 0 150px", width: "auto" }} value={ident.kind}
                        onChange={(e) => {
                          const next = [...form.identifiers];
                          next[idx] = { ...ident, kind: e.target.value };
                          setForm({ ...form, identifiers: next });
                        }}>
                  <option value="iban">IBAN</option>
                  <option value="account_no">{t("identifierKinds.account_no")}</option>
                  <option value="card_no">{t("identifierKinds.card_no")}</option>
                  <option value="text">{t("identifierKinds.text")}</option>
                </select>
                <input className="grow" style={{ minWidth: 0 }} value={ident.value}
                       placeholder={ident.kind === "text" ? t("accounts.textIdentPlaceholder") : "DE.. / Nr."}
                       onChange={(e) => {
                         const next = [...form.identifiers];
                         next[idx] = { ...ident, value: e.target.value };
                         setForm({ ...form, identifiers: next });
                       }} />
                <button type="button" className="btn sm ghost"
                        onClick={() => setForm({ ...form, identifiers: form.identifiers.filter((_, i) => i !== idx) })}>
                  <Icon name="trash" size={15} />
                </button>
              </div>
            ))}
            {form.identifiers.some((i) => i.kind === "text" && i.value.trim().length > 0
                                          && i.value.trim().length < 6) && (
              <p className="muted small">{t("accounts.shortIdentWarning")}</p>
            )}
            <button type="button" className="btn sm"
                    onClick={() => setForm({ ...form, identifiers: [...form.identifiers, { kind: "iban", value: "" }] })}>
              <Icon name="plus" size={15} /> {t("accounts.addIdentifier")}
            </button>
          </form>
        </Modal>
      )}
    </div>
  );
}