import { useEffect, useRef, useState } from "react";
import { useTranslation } from "react-i18next";
import {
  ApiError,
  armCapture,
  cancelCapture,
  createSubscription,
  deleteSubscription,
  fetchReaders,
  fetchSiteConfig,
  fetchSubscriptions,
  pollCapture,
  printSubscription,
  revokeSubscription,
  updateSubscription,
  type ReaderInfo,
  type Subscription,
  type SubscriptionCredential,
  type SubscriptionInput,
} from "./api.js";

// Subscription admin. Create/edit/revoke/delete subscriptions + their credentials
// (card/QR) and bound plates, and the recurring monthly price (e.g. 10,000 ALL). A
// subscription is mutable master data; every USE of it is a signed ledger event
// elsewhere. See wiki/entities/subscription.md.

const DEFAULT_CURRENCY = "ALL";

interface FormState {
  holderName: string;
  contact: string;
  priceMajor: string; // major units as typed (e.g. "10000"); "" = no price
  currency: string;
  carBound: boolean; // false = unbound (maxConcurrent null)
  maxConcurrent: string;
  validFrom: string;
  months: string; // months paid for; "" = none (use explicit validTo / open-ended)
  validTo: string;
  credentials: SubscriptionCredential[];
  platesText: string; // comma/space separated
}

/** Today (UTC date, yyyy-mm-dd) for a sensible default validFrom on new subs. */
function todayISODate(): string {
  return new Date().toISOString().slice(0, 10);
}

function emptyForm(defaultPriceMajor = "", currency = DEFAULT_CURRENCY): FormState {
  return {
    holderName: "",
    contact: "",
    priceMajor: defaultPriceMajor,
    currency,
    carBound: true,
    maxConcurrent: "1",
    validFrom: todayISODate(),
    months: "1",
    validTo: "",
    credentials: [{ kind: "qr", value: "" }],
    platesText: "",
  };
}
function formFrom(s: Subscription): FormState {
  return {
    holderName: s.holderName ?? "",
    contact: s.contact ?? "",
    priceMajor: s.priceMinor != null ? String(s.priceMinor / 100) : "",
    currency: s.currency ?? DEFAULT_CURRENCY,
    carBound: s.maxConcurrent != null,
    maxConcurrent: s.maxConcurrent != null ? String(s.maxConcurrent) : "1",
    validFrom: s.validFrom ?? "",
    months: "", // on edit, default to leaving the window as-is (explicit validTo below)
    validTo: s.validTo ?? "",
    credentials: s.credentials.length ? s.credentials : [{ kind: "qr", value: "" }],
    platesText: s.plates.join(", "),
  };
}

/** Add whole months to a yyyy-mm-dd (clamps day overflow), → yyyy-mm-dd. Mirrors the
 *  server's addMonths so the form can preview the coverage end. */
function addMonthsDate(date: string, months: number): string | null {
  const d = new Date(`${date}T00:00:00Z`);
  if (Number.isNaN(d.getTime())) return null;
  const day = d.getUTCDate();
  d.setUTCMonth(d.getUTCMonth() + months);
  if (d.getUTCDate() < day) d.setUTCDate(0);
  return d.toISOString().slice(0, 10);
}
const STATUS_KEY: Record<Subscription["status"], string> = {
  active: "subs.statusActive",
  suspended: "subs.statusSuspended",
  revoked: "subs.statusRevoked",
};

function toInput(f: FormState): SubscriptionInput {
  const major = Number(f.priceMajor);
  const priceSet = f.priceMajor.trim() !== "" && Number.isFinite(major) && major >= 0;
  const monthsNum = f.months.trim() === "" ? null : Math.max(1, Math.round(Number(f.months) || 0));
  return {
    holderName: f.holderName.trim() || null,
    contact: f.contact.trim() || null,
    priceMinor: priceSet ? Math.round(major * 100) : null,
    period: "monthly",
    currency: priceSet ? f.currency.trim() || DEFAULT_CURRENCY : null,
    maxConcurrent: f.carBound ? Math.max(1, Math.round(Number(f.maxConcurrent) || 1)) : null,
    validFrom: f.validFrom.trim() || null,
    // months (with validFrom) drives validTo server-side; else send the explicit end.
    months: monthsNum && f.validFrom.trim() ? monthsNum : null,
    validTo: f.validTo.trim() || null,
    // A QR credential with a blank value is sent as { kind:'qr' } (no value) so the
    // server auto-generates the code. RF (and pre-existing QR) keep their value.
    credentials: f.credentials
      .filter((c) => c.kind === "qr" || c.value.trim())
      .map((c) => (c.value.trim() ? { kind: c.kind, value: c.value.trim() } : { kind: c.kind })),
    plates: f.platesText.split(/[,\s]+/).map((s) => s.trim()).filter(Boolean),
  };
}

function priceLabel(s: Subscription, t: (k: string) => string): string {
  if (s.priceMinor == null) return t("subs.noPrice");
  return `${(s.priceMinor / 100).toLocaleString()} ${s.currency ?? ""} / ${t("subs.perMonth")}`.trim();
}

export function SubscriptionManager() {
  const { t } = useTranslation();
  const [subs, setSubs] = useState<Subscription[] | null>(null);
  const [defaultPriceMajor, setDefaultPriceMajor] = useState("");
  const [editing, setEditing] = useState<string | "new" | null>(null);
  const [form, setForm] = useState<FormState>(() => emptyForm());
  const [msg, setMsg] = useState<{ kind: "ok" | "err"; text: string } | null>(null);
  // Credential capture ("Read card"): which credential index is being captured, the
  // reader picker list, and a live status line. null = no capture in progress.
  const [capture, setCapture] = useState<{ credIndex: number; phase: "pick" | "waiting"; status?: string } | null>(null);
  const [readers, setReaders] = useState<ReaderInfo[]>([]);
  const pollRef = useRef<ReturnType<typeof setInterval> | null>(null);

  function reload() {
    fetchSubscriptions()
      .then((r) => setSubs(r.subscriptions))
      .catch((e) => setMsg({ kind: "err", text: (e as Error).message }));
  }
  useEffect(() => {
    reload();
    // Pull the site default monthly price to pre-fill new subscriptions.
    fetchSiteConfig()
      .then((c) => {
        if (c.subscriptionMonthlyPriceMinor != null) setDefaultPriceMajor(String(c.subscriptionMonthlyPriceMinor / 100));
      })
      .catch(() => {
        /* non-fatal — the form just won't pre-fill */
      });
  }, []);

  function startNew() {
    setForm(emptyForm(defaultPriceMajor));
    setEditing("new");
    setMsg(null);
  }
  function startEdit(s: Subscription) {
    setForm(formFrom(s));
    setEditing(s.id);
    setMsg(null);
  }

  async function save() {
    setMsg(null);
    try {
      if (editing === "new") {
        const created = await createSubscription(toInput(form));
        setEditing(null);
        reload();
        // Reflect the auto-print outcome: printed OK, or saved-but-print-failed (the
        // operator can use "Print code" to retry).
        if (created.printed) {
          setMsg({ kind: "ok", text: t("subs.savedPrinted") });
        } else if (created.printError) {
          setMsg({ kind: "err", text: t("subs.savedPrintFailed", { error: created.printError }) });
        } else {
          setMsg({ kind: "ok", text: t("subs.saved") });
        }
        return;
      }
      if (editing) await updateSubscription(editing, toInput(form));
      setEditing(null);
      reload();
      setMsg({ kind: "ok", text: t("subs.saved") });
    } catch (e) {
      const problems = e instanceof ApiError ? (e as ApiError & { problems?: string[] }).problems : undefined;
      setMsg({ kind: "err", text: problems?.length ? `${(e as Error).message}: ${problems.join("; ")}` : (e as Error).message });
    }
  }
  async function doPrint(s: Subscription) {
    setMsg(null);
    try {
      const r = await printSubscription(s.id);
      setMsg({ kind: "ok", text: t("subs.printedOn", { printer: r.printedBy }) });
    } catch (e) {
      setMsg({ kind: "err", text: (e as Error).message });
    }
  }
  async function doRevoke(s: Subscription) {
    if (!confirm(t("subs.confirmRevoke", { name: s.holderName ?? s.id }))) return;
    await revokeSubscription(s.id).catch((e) => setMsg({ kind: "err", text: (e as Error).message }));
    reload();
  }
  async function doDelete(s: Subscription) {
    if (!confirm(t("subs.confirmDelete", { name: s.holderName ?? s.id }))) return;
    await deleteSubscription(s.id).catch((e) => setMsg({ kind: "err", text: (e as Error).message }));
    reload();
  }

  function setCred(i: number, patch: Partial<SubscriptionCredential>) {
    setForm((f) => ({ ...f, credentials: f.credentials.map((c, j) => (j === i ? { ...c, ...patch } : c)) }));
  }

  function clearPoll() {
    if (pollRef.current) {
      clearInterval(pollRef.current);
      pollRef.current = null;
    }
  }
  // Stop a capture in progress (cancel on the server + clear local state).
  function stopCapture() {
    clearPoll();
    void cancelCapture().catch(() => {});
    setCapture(null);
  }
  // "Read card" on credential i → load readers + show the picker.
  async function startCapture(i: number) {
    setMsg(null);
    try {
      const r = await fetchReaders();
      setReaders(r.readers);
      setCapture({ credIndex: i, phase: "pick" });
    } catch (e) {
      setMsg({ kind: "err", text: (e as Error).message });
    }
  }
  // Operator picked a reader → arm it and poll until captured / expired.
  async function pickReader(deviceId: string) {
    const cap = capture;
    if (!cap) return;
    try {
      await armCapture(deviceId);
      setCapture({ ...cap, phase: "waiting", status: t("subs.captureWaiting") });
      clearPoll();
      pollRef.current = setInterval(async () => {
        try {
          const st = await pollCapture();
          if (st.status === "captured") {
            clearPoll();
            setCred(cap.credIndex, { value: st.value });
            void cancelCapture().catch(() => {}); // clear the server-side result
            setCapture(null);
            setMsg({ kind: "ok", text: t("subs.captured", { value: st.value }) });
          } else if (st.status === "expired" || st.status === "idle") {
            clearPoll();
            setCapture({ ...cap, phase: "waiting", status: t("subs.captureTimeout") });
          }
        } catch {
          /* transient poll error — keep polling */
        }
      }, 700);
    } catch (e) {
      setMsg({ kind: "err", text: (e as Error).message });
      setCapture(null);
    }
  }
  // Stop polling if the form closes or the component unmounts.
  useEffect(() => clearPoll, []);

  // Live coverage preview: when months + validFrom are set, show the end date and
  // (if priced) the N×monthly total the operator should collect.
  const monthsN = form.months.trim() === "" ? 0 : Math.max(0, Math.round(Number(form.months) || 0));
  const coverageEnd = monthsN >= 1 && form.validFrom.trim() ? addMonthsDate(form.validFrom.trim(), monthsN) : null;
  const priceMajorN = form.priceMajor.trim() === "" ? null : Number(form.priceMajor);
  const totalDue =
    coverageEnd && priceMajorN != null && Number.isFinite(priceMajorN)
      ? `${(priceMajorN * monthsN).toLocaleString()} ${form.currency.trim() || DEFAULT_CURRENCY}`
      : null;
  const coverageHint = coverageEnd
    ? t("subs.coverageHint", { end: coverageEnd }) + (totalDue ? ` · ${t("subs.totalDue", { total: totalDue })}` : "")
    : null;

  if (!subs) return null;

  return (
    <section style={{ marginTop: "2rem" }}>
      <h2>{t("subs.title")}</h2>
      <ul style={{ listStyle: "none", padding: 0 }}>
        {subs.map((s) => (
          <li key={s.id} style={{ display: "flex", gap: "0.5rem", alignItems: "center", padding: "0.4rem 0", borderBottom: "1px solid #eee" }}>
            <strong>{s.holderName ?? t("subs.unnamed")}</strong>
            <span style={{ color: s.status === "active" ? "#16a34a" : "#b45309" }}>{t(STATUS_KEY[s.status])}</span>
            <span style={{ color: "#0a7", fontVariantNumeric: "tabular-nums" }}>{priceLabel(s, t)}</span>
            <span style={{ color: "#666" }}>
              {s.maxConcurrent == null ? t("subs.unbound") : t("subs.car", { count: s.maxConcurrent })} ·{" "}
              {s.credentials.length} {t("subs.cred")} · {t("subs.plates", { count: s.plates.length })}
            </span>
            <span style={{ flex: 1 }} />
            {/* Print code — only when the subscription has a QR credential to encode. */}
            {s.credentials.some((c) => c.kind === "qr") && (
              <button type="button" onClick={() => doPrint(s)}>{t("subs.printCode")}</button>
            )}
            <button type="button" onClick={() => startEdit(s)}>{t("subs.edit")}</button>
            {s.status !== "revoked" && <button type="button" onClick={() => doRevoke(s)}>{t("subs.revoke")}</button>}
            <button type="button" onClick={() => doDelete(s)}>{t("subs.delete")}</button>
          </li>
        ))}
        {subs.length === 0 && <li style={{ color: "#777" }}>{t("subs.noneYet")}</li>}
      </ul>

      {editing == null ? (
        <button type="button" onClick={startNew}>{t("subs.add")}</button>
      ) : (
        <div style={{ border: "1px solid #ddd", padding: "1rem", marginTop: "0.5rem", maxWidth: 460 }}>
          <h3 style={{ marginTop: 0 }}>{editing === "new" ? t("subs.new") : t("subs.editTitle")}</h3>
          <div style={{ display: "grid", gridTemplateColumns: "max-content 1fr", gap: "0.4rem 0.75rem", alignItems: "center" }}>
            <label>{t("subs.holderName")}</label>
            <input value={form.holderName} onChange={(e) => setForm((f) => ({ ...f, holderName: e.target.value }))} />
            <label>{t("subs.contact")}</label>
            <input value={form.contact} onChange={(e) => setForm((f) => ({ ...f, contact: e.target.value }))} />
            <label>{t("subs.monthlyPrice")}</label>
            <span style={{ display: "flex", gap: "0.4rem", alignItems: "center" }}>
              <input
                value={form.priceMajor}
                onChange={(e) => setForm((f) => ({ ...f, priceMajor: e.target.value }))}
                inputMode="decimal"
                placeholder={t("subs.pricePlaceholder")}
                style={{ width: 110 }}
              />
              <input value={form.currency} onChange={(e) => setForm((f) => ({ ...f, currency: e.target.value }))} style={{ width: 60 }} />
              <span style={{ color: "#888" }}>/ {t("subs.perMonth")}</span>
            </span>
            <label>{t("subs.carLimit")}</label>
            <span>
              <label style={{ marginRight: "0.5rem" }}>
                <input type="checkbox" checked={form.carBound} onChange={(e) => setForm((f) => ({ ...f, carBound: e.target.checked }))} /> {t("subs.limitCarsInAtOnce")}
              </label>
              {form.carBound && (
                <input value={form.maxConcurrent} onChange={(e) => setForm((f) => ({ ...f, maxConcurrent: e.target.value }))} style={{ width: 50 }} />
              )}
            </span>
            <label>{t("subs.validFrom")}</label>
            <input type="date" value={form.validFrom} onChange={(e) => setForm((f) => ({ ...f, validFrom: e.target.value }))} />
            <label>{t("subs.months")}</label>
            <span style={{ display: "flex", gap: "0.4rem", alignItems: "center", flexWrap: "wrap" }}>
              <input
                value={form.months}
                onChange={(e) => setForm((f) => ({ ...f, months: e.target.value }))}
                inputMode="numeric"
                placeholder="1"
                style={{ width: 50 }}
              />
              <span style={{ color: "#888" }}>{t("subs.monthsHint")}</span>
              {/* Live preview of the coverage end + the N×price total. */}
              {coverageHint && <span style={{ color: "#0a7" }}>{coverageHint}</span>}
            </span>
            <label>{t("subs.validToOverride")}</label>
            <input type="date" value={form.validTo} onChange={(e) => setForm((f) => ({ ...f, validTo: e.target.value }))} />
            <label>{t("subs.boundPlates")}</label>
            <input value={form.platesText} onChange={(e) => setForm((f) => ({ ...f, platesText: e.target.value }))} placeholder={t("subs.commaSeparatedOptional")} />
          </div>

          <h4 style={{ marginBottom: "0.25rem" }}>{t("subs.credentials")}</h4>
          {form.credentials.map((c, i) => (
            <div key={i} style={{ display: "flex", gap: "0.4rem", marginBottom: "0.3rem" }}>
              {/* Operator chooses the credential type: QR (auto-generated) or RFID
                  (read off a card via "Read card"). */}
              <select value={c.kind} onChange={(e) => setCred(i, { kind: e.target.value as "rf" | "qr" })}>
                <option value="qr">{t("subs.qr")}</option>
                <option value="rf">{t("subs.rfCardTag")}</option>
              </select>
              {c.kind === "qr" ? (
                // QR codes are server-generated. Blank → "will be generated"; an
                // existing code is shown read-only (it can be printed; never typed).
                c.value.trim() ? (
                  <input value={c.value} readOnly style={{ flex: 1, fontFamily: "ui-monospace, monospace", background: "#f6f6f6" }} />
                ) : (
                  <span style={{ flex: 1, color: "#888", fontStyle: "italic", alignSelf: "center" }}>{t("subs.qrAutoGen")}</span>
                )
              ) : (
                // RFID: the value is read off a physical card (or typed). "Read card"
                // arms a chosen reader and fills the captured value.
                <input value={c.value} onChange={(e) => setCred(i, { value: e.target.value })} placeholder={t("subs.rfPlaceholder")} style={{ flex: 1, fontFamily: "ui-monospace, monospace" }} />
              )}
              {c.kind === "rf" && (
                <button type="button" onClick={() => startCapture(i)} disabled={capture != null}>{t("subs.readCard")}</button>
              )}
              <button type="button" onClick={() => setForm((f) => ({ ...f, credentials: f.credentials.filter((_, j) => j !== i) }))}>×</button>
            </div>
          ))}
          <button type="button" onClick={() => setForm((f) => ({ ...f, credentials: [...f.credentials, { kind: "qr", value: "" }] }))}>{t("subs.addCredential")}</button>

          {/* Capture panel: pick a reader, present the card; the captured value fills
              the credential. The OTHER reader keeps serving the live flow. */}
          {capture && (
            <div style={{ marginTop: "0.5rem", padding: "0.6rem 0.75rem", border: "1px solid #0a7", borderRadius: 6, background: "#f0fbf6" }}>
              {capture.phase === "pick" ? (
                <>
                  <div style={{ marginBottom: "0.35rem" }}>{t("subs.captureChooseReader")}</div>
                  <div style={{ display: "flex", gap: "0.4rem", flexWrap: "wrap" }}>
                    {readers.length === 0 && <span style={{ color: "#a00" }}>{t("subs.captureNoReaders")}</span>}
                    {readers.map((r) => (
                      <button key={r.id} type="button" onClick={() => pickReader(r.id)}>
                        {t(`devices.role.${r.direction}`)} ({r.driverId})
                      </button>
                    ))}
                    <button type="button" onClick={stopCapture}>{t("subs.cancel")}</button>
                  </div>
                </>
              ) : (
                <div style={{ display: "flex", gap: "0.6rem", alignItems: "center" }}>
                  <span>{capture.status ?? t("subs.captureWaiting")}</span>
                  <button type="button" onClick={stopCapture}>{t("subs.cancel")}</button>
                </div>
              )}
            </div>
          )}

          <p style={{ color: "#777", fontSize: "0.85em", margin: "0.5rem 0 0" }}>
            {t("subs.needCredentialOrPlate")}
          </p>

          <div style={{ marginTop: "1rem", display: "flex", gap: "0.5rem" }}>
            <button type="button" onClick={save}>{t("subs.save")}</button>
            <button type="button" onClick={() => setEditing(null)}>{t("subs.cancel")}</button>
          </div>
        </div>
      )}
      {msg && <p style={{ color: msg.kind === "ok" ? "#16a34a" : "crimson" }}>{msg.text}</p>}
    </section>
  );
}