import { useEffect, useState } from "react";
import { useTranslation } from "react-i18next";
import { useRouteContext } from "@tanstack/react-router";
import {
  fetchMe,
  fetchOccupancy,
  fetchSiteConfig,
  fetchValidationPrograms,
  saveSiteConfig,
  saveValidationProgram,
  type Occupancy,
  type SiteConfig,
  type ValidationProgramView,
} from "./api.js";
import { STATIONS, ValidationStationsPanel, defaultProgram, stationLabelKey, type StationId } from "./ValidationSetup.js";
import { MODULES, type ModuleId } from "@parking/shared";
import type { RouterContext } from "./router.js";

// Live occupancy + capacity + park metadata. Occupancy is shown to everyone (it's a
// fold over the signed ledger); capacity and the metadata fields are admin-editable.
// The FULL gate (refuse transient entry at capacity) is enforced server-side in the
// entry flow. Metadata (name, NIUS, address, contact) feeds the ticket header.
// See wiki/concepts/capacity-occupancy.md and wiki/concepts/site-metadata.md.

// The optional text fields, in display order. `labelKey`/`phKey` are i18n keys
// (resolved at render); only `address` is multiline.
const META_FIELDS: ReadonlyArray<{ key: keyof SiteConfig; labelKey: string; phKey?: string; multiline?: boolean }> = [
  { key: "parkName", labelKey: "site.fieldParkName", phKey: "site.fieldParkNamePh" },
  { key: "operatorName", labelKey: "site.fieldOperator", phKey: "site.fieldOperatorPh" },
  { key: "nius", labelKey: "site.fieldNius", phKey: "site.fieldNiusPh" },
  { key: "address", labelKey: "site.fieldAddress", multiline: true },
  { key: "phone", labelKey: "site.fieldPhone" },
  { key: "email", labelKey: "site.fieldEmail" },
];

export function SiteSettings({ canEdit }: { canEdit: boolean }) {
  const { t } = useTranslation();
  const [occ, setOcc] = useState<Occupancy | null>(null);
  const [capInput, setCapInput] = useState("");
  const [meta, setMeta] = useState<Record<string, string>>({});
  const [exitVoucherDefault, setExitVoucherDefault] = useState(false);
  const [reserveSubs, setReserveSubs] = useState(false);
  const [anprEntry, setAnprEntry] = useState(true);
  const [msg, setMsg] = useState<string | null>(null);
  // Merchant-validation programs (bar / lavazh). The checkboxes below toggle a
  // station's `active` (persisted at once — each flip signs a config_change); the
  // right-column panel edits the enabled stations. See validation-discounts.md.
  const [programs, setPrograms] = useState<ValidationProgramView[]>([]);
  // Venue modules: what this site is entitled to (vendor-set), what the admin has
  // activated, and the effective set. Toggling persists at once (the server signs a
  // config_change per module that flips and validates dependencies). See
  // wiki/decisions/venue-modules.md.
  const [mods, setMods] = useState<{ entitled: ModuleId[]; activated: ModuleId[]; effective: ModuleId[] } | null>(null);
  const [modMsg, setModMsg] = useState<string | null>(null);
  const moduleOn = (id: ModuleId) => mods?.effective.includes(id) ?? false;
  // The header nav gates module entries on the SESSION's module set (/api/auth/me),
  // so a flip here must refresh the session too or the nav stays stale until reload
  // (App re-validates the router whenever `user` changes).
  const { setUser } = useRouteContext({ strict: false }) as RouterContext;

  function reload() {
    fetchOccupancy().then(setOcc).catch(() => {});
  }
  /** The validation programs are a module route — only ask for them while the
   *  module is effective (the server 403s otherwise, which would land in app_logs
   *  as a failed request every time an admin opens this page). */
  function loadPrograms(effective: ModuleId[]) {
    if (!canEdit || !effective.includes("validation")) {
      setPrograms([]);
      return;
    }
    fetchValidationPrograms()
      .then((r) => setPrograms(r.programs))
      .catch(() => {});
  }
  useEffect(() => {
    reload();
    fetchSiteConfig()
      .then((c) => {
        setCapInput(c.capacity == null ? "" : String(c.capacity));
        setExitVoucherDefault(c.exitVoucherDefault);
        setReserveSubs(c.reserveSubscriberSpots);
        setAnprEntry(c.anprEntryEnabled);
        setMods({ entitled: c.modulesEntitled, activated: c.modulesActivated, effective: c.modules });
        loadPrograms(c.modules);
        const m: Record<string, string> = {};
        for (const { key } of META_FIELDS) m[key] = c[key] == null ? "" : String(c[key]);
        setMeta(m);
      })
      .catch(() => {});
  }, [canEdit]);

  /** Flip a merchant station's checkbox: persist `active` at once (a signed
   *  config_change server-side), creating the well-known row with comp defaults on
   *  the first enable. Config details are edited in the right-column panel. */
  async function toggleStation(id: StationId, active: boolean) {
    const existing = programs.find((p) => p.id === id);
    const body = existing
      ? { ...existing, active }
      : { ...defaultProgram(id, t(stationLabelKey(id))), active };
    try {
      const saved = await saveValidationProgram(id, body);
      setPrograms((ps) => [...ps.filter((p) => p.id !== id), saved]);
    } catch (e) {
      setMsg((e as Error).message);
    }
  }

  /** Flip a module: send the full desired activation set; the server decides
   *  (required always on, must be entitled, dependencies) and echoes the result. */
  async function toggleModule(id: ModuleId, on: boolean) {
    if (!mods) return;
    setModMsg(null);
    const next = on ? [...new Set([...mods.activated, id])] : mods.activated.filter((m) => m !== id);
    try {
      const c = await saveSiteConfig({ modules: next });
      setMods({ entitled: c.modulesEntitled, activated: c.modulesActivated, effective: c.modules });
      loadPrograms(c.modules);
      const me = await fetchMe();
      if (me) setUser(me);
    } catch (e) {
      setModMsg((e as Error).message);
    }
  }

  async function save() {
    setMsg(null);
    const raw = capInput.trim();
    const patch: Partial<SiteConfig> = {
      capacity: raw === "" ? null : Math.round(Number(raw)),
      exitVoucherDefault,
      reserveSubscriberSpots: reserveSubs,
      anprEntryEnabled: anprEntry,
    };
    // Send each metadata field; "" → null is applied server-side.
    for (const { key } of META_FIELDS) (patch as Record<string, string | null>)[key] = meta[key] ?? "";
    try {
      await saveSiteConfig(patch);
      reload();
      setMsg(t("site.saved"));
    } catch (e) {
      setMsg((e as Error).message);
    }
  }

  return (
    <div className="mt-6 flex flex-wrap items-start gap-6">
    <section className="card w-full max-w-md p-4">
      <div className="flex flex-wrap items-center gap-1.5 text-[0.8125rem]">
        <strong className="uppercase tracking-wider text-term-muted">{t("site.occupancy")}</strong>
        {occ == null ? (
          <span className="text-term-muted">…</span>
        ) : (
          <>
            <span className="text-h5 font-semibold tabular-nums text-term-text">{occ.count}</span>
            <span className="tabular-nums text-term-muted">
              {occ.capacity != null ? `/ ${occ.capacity}` : t("site.noCapacitySet")}
            </span>
            {occ.capacity != null && (
              <span className="tabular-nums text-term-muted">· {occ.free} {t("site.free")}</span>
            )}
            {occ.full && <span className="font-semibold text-term-red">{t("site.full")}</span>}
            <button type="button" className="btn btn-ghost btn-sm" onClick={reload}>↻</button>
          </>
        )}
      </div>
      {canEdit && (
        <div className="mt-4 grid gap-3">
          <div className="field">
            <span className="label">{t("site.capacityLabel")}</span>
            <input className="input w-32" value={capInput} onChange={(e) => setCapInput(e.target.value)} placeholder={t("site.capacityPlaceholder")} />
          </div>
          <label className="flex items-center gap-2 text-[0.75rem] text-term-text">
            <input
              type="checkbox"
              className="accent-term-amber"
              checked={exitVoucherDefault}
              onChange={(e) => setExitVoucherDefault(e.target.checked)}
            />
            {t("site.printExitDefault")}
            <span className="hint">{t("site.printExitHint")}</span>
          </label>
          <label className="flex items-start gap-2 text-[0.75rem] text-term-text">
            <input
              type="checkbox"
              className="mt-0.5 accent-term-amber"
              checked={reserveSubs}
              onChange={(e) => setReserveSubs(e.target.checked)}
            />
            <span>
              {t("site.reserveSubs")}
              <span className="hint block">{t("site.reserveSubsHint")}</span>
            </span>
          </label>
          <label className="flex items-start gap-2 text-[0.75rem] text-term-text">
            <input
              type="checkbox"
              className="mt-0.5 accent-term-amber"
              checked={anprEntry}
              onChange={(e) => setAnprEntry(e.target.checked)}
            />
            <span>
              {t("site.anprEntry")}
              <span className="hint block">{t("site.anprEntryHint")}</span>
            </span>
          </label>
          <div className="border-t border-term-border pt-3 text-[0.6875rem] uppercase tracking-wider text-term-muted">
            {t("modules.sectionTitle")}
          </div>
          <span className="hint -mt-2">{t("modules.sectionHint")}</span>
          <div className="grid gap-1.5">
            {MODULES.filter((m) => mods?.entitled.includes(m.id)).map((m) => (
              <label key={m.id} className="flex items-start gap-2 text-[0.75rem] text-term-text">
                <input
                  type="checkbox"
                  className="mt-0.5 accent-term-amber"
                  checked={moduleOn(m.id)}
                  disabled={m.required || !mods}
                  onChange={(e) => toggleModule(m.id, e.target.checked)}
                />
                <span>
                  {t(`modules.name.${m.id}`)}
                  {m.required && <span className="hint block">{t("modules.required")}</span>}
                  {m.dependsOn.length > 0 && (
                    <span className="hint block">
                      {t("modules.requires", { deps: m.dependsOn.map((d) => t(`modules.name.${d}`)).join(", ") })}
                    </span>
                  )}
                </span>
              </label>
            ))}
            {modMsg && <span className="text-[0.75rem] text-term-red">{modMsg}</span>}
          </div>
          {moduleOn("validation") && (
            <>
              <div className="border-t border-term-border pt-3 text-[0.6875rem] uppercase tracking-wider text-term-muted">
                {t("val.sectionTitle")}
              </div>
              <span className="hint -mt-2">{t("val.sectionHint")}</span>
              <div className="flex gap-6">
                {STATIONS.map((id) => (
                  <label key={id} className="flex items-center gap-2 text-[0.75rem] text-term-text">
                    <input
                      type="checkbox"
                      className="accent-term-amber"
                      checked={programs.find((p) => p.id === id)?.active ?? false}
                      onChange={(e) => toggleStation(id, e.target.checked)}
                    />
                    {t(stationLabelKey(id))}
                  </label>
                ))}
              </div>
            </>
          )}
          <div className="border-t border-term-border pt-3 text-[0.6875rem] uppercase tracking-wider text-term-muted">
            {t("site.parkDetails")}
          </div>
          {META_FIELDS.map(({ key, labelKey, phKey, multiline }) => (
            <div key={key} className="field">
              <span className="label">{t(labelKey)}</span>
              {multiline ? (
                <textarea
                  className="textarea"
                  value={meta[key] ?? ""}
                  onChange={(e) => setMeta((m) => ({ ...m, [key]: e.target.value }))}
                  rows={2}
                  placeholder={phKey ? t(phKey) : undefined}
                />
              ) : (
                <input
                  className="input"
                  value={meta[key] ?? ""}
                  onChange={(e) => setMeta((m) => ({ ...m, [key]: e.target.value }))}
                  placeholder={phKey ? t(phKey) : undefined}
                />
              )}
            </div>
          ))}
          <div className="flex items-center gap-3">
            <button type="button" className="btn btn-primary btn-sm" onClick={save}>{t("site.save")}</button>
            {msg && <span className="text-[0.75rem] text-term-muted">{msg}</span>}
          </div>
        </div>
      )}
    </section>
    {canEdit && moduleOn("validation") && (
      <ValidationStationsPanel
        programs={programs}
        onSaved={(p) => setPrograms((ps) => [...ps.filter((x) => x.id !== p.id), p])}
      />
    )}
    </div>
  );
}