"use client";

import { useCallback, useEffect, useState } from "react";
import { userApi, type UserDto, type UserRole } from "../../../frontend/utils/auth-api";
import { useAuth } from "../../../frontend/components/AuthProvider";
import { USER_ROLES, USER_ROLE_LABEL } from "../../../shared/constants/user-roles";

const zeitpunkt = new Intl.DateTimeFormat("de-DE", {
  dateStyle: "short",
  timeStyle: "short",
});

export default function BenutzerPage() {
  const { user: currentUser } = useAuth();
  const [users, setUsers] = useState<UserDto[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [busyUserId, setBusyUserId] = useState<string | null>(null);
  const [resetPasswordFor, setResetPasswordFor] = useState<UserDto | null>(null);

  const load = useCallback(async () => {
    setLoading(true);
    try {
      const rows = await userApi.list();
      setUsers(rows);
      setError(null);
    } catch (err) {
      setError(err instanceof Error ? err.message : "Benutzer konnten nicht geladen werden.");
    } finally {
      setLoading(false);
    }
  }, []);

  useEffect(() => {
    void load();
  }, [load]);

  async function withBusy(userId: string, action: () => Promise<void>) {
    setBusyUserId(userId);
    setError(null);
    try {
      await action();
    } catch (err) {
      setError(err instanceof Error ? err.message : "Aktion fehlgeschlagen.");
    } finally {
      setBusyUserId(null);
    }
  }

  async function changeRole(item: UserDto, role: UserRole) {
    await withBusy(item.id, async () => {
      const updated = await userApi.update(item.id, { role });
      setUsers((list) => list.map((row) => (row.id === updated.id ? updated : row)));
    });
  }

  async function toggleActive(item: UserDto) {
    await withBusy(item.id, async () => {
      const updated = await userApi.update(item.id, { active: !item.active });
      setUsers((list) => list.map((row) => (row.id === updated.id ? updated : row)));
    });
  }

  return (
    <div className="card" style={{ padding: "1.5rem" }}>
      <div className="page-header" style={{ marginTop: 0 }}>
        <h2 className="h5" style={{ margin: 0 }}>
          Benutzer
        </h2>
      </div>
      <p className="text-body-secondary" style={{ marginBottom: "1rem" }}>
        Es gibt kein Self-Signup: Jeder Zugang wird hier bewusst von einem
        Administrator angelegt. Das Startpasswort wird direkt eingetragen; die
        Person muss es beim ersten Anmelden durch ein eigenes ersetzen.
      </p>

      <NeuerBenutzerFormular
        onCreated={(created) => {
          setUsers((list) => [...list, created]);
        }}
      />

      {error && <p className="text-danger">{error}</p>}
      {loading && <p>Lädt…</p>}

      {!loading && users.length > 0 && (
        <table className="table" style={{ marginTop: "1.5rem" }}>
          <thead>
            <tr>
              <th>Name</th>
              <th>Anmeldename</th>
              <th>Rolle</th>
              <th>Aktiv</th>
              <th>Status</th>
              <th>Angelegt</th>
              <th>Aktionen</th>
            </tr>
          </thead>
          <tbody>
            {users.map((item) => {
              const isSelf = item.id === currentUser?.id;
              const busy = busyUserId === item.id;
              return (
                <tr key={item.id}>
                  <td>{item.name}</td>
                  <td>{item.username}</td>
                  <td>
                    <select
                      className="form-select form-select-sm"
                      value={item.role}
                      disabled={busy || isSelf}
                      title={isSelf ? "Der eigene Zugang kann hier nicht geändert werden." : undefined}
                      onChange={(event) => void changeRole(item, event.target.value as UserRole)}
                    >
                      {USER_ROLES.map((role) => (
                        <option key={role} value={role}>
                          {USER_ROLE_LABEL[role]}
                        </option>
                      ))}
                    </select>
                  </td>
                  <td>
                    <input
                      type="checkbox"
                      checked={item.active}
                      disabled={busy || isSelf}
                      title={isSelf ? "Der eigene Zugang kann hier nicht geändert werden." : undefined}
                      onChange={() => void toggleActive(item)}
                    />
                  </td>
                  <td>{item.mustChangePassword ? "Muss Passwort setzen" : "In Ordnung"}</td>
                  <td>{zeitpunkt.format(new Date(item.createdAt))}</td>
                  <td>
                    <button
                      type="button"
                      className="btn btn-outline-primary btn-sm"
                      disabled={busy}
                      onClick={() => setResetPasswordFor(item)}
                    >
                      Passwort zurücksetzen
                    </button>
                  </td>
                </tr>
              );
            })}
          </tbody>
        </table>
      )}

      {!loading && users.length === 0 && <p>Noch keine Benutzer angelegt.</p>}

      {resetPasswordFor && (
        <PasswortZuruecksetzenDialog
          item={resetPasswordFor}
          onClose={() => setResetPasswordFor(null)}
          onDone={(updated) => {
            setUsers((list) => list.map((row) => (row.id === updated.id ? updated : row)));
            setResetPasswordFor(null);
          }}
        />
      )}
    </div>
  );
}

function NeuerBenutzerFormular({ onCreated }: { onCreated: (created: UserDto) => void }) {
  const [username, setUsername] = useState("");
  const [name, setName] = useState("");
  const [role, setRole] = useState<UserRole>("user");
  const [initialPassword, setInitialPassword] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [submitting, setSubmitting] = useState(false);

  async function handleSubmit(event: React.FormEvent) {
    event.preventDefault();
    setSubmitting(true);
    setError(null);
    try {
      const created = await userApi.create({ username, name, role, initialPassword });
      onCreated(created);
      setUsername("");
      setName("");
      setRole("user");
      setInitialPassword("");
    } catch (err) {
      setError(err instanceof Error ? err.message : "Benutzer konnte nicht angelegt werden.");
    } finally {
      setSubmitting(false);
    }
  }

  return (
    <form
      onSubmit={handleSubmit}
      className="row g-2 align-items-end"
      style={{ borderBottom: "1px solid rgba(0,0,0,0.1)", paddingBottom: "1rem" }}
    >
      <div className="col-sm-3">
        <label className="form-label" htmlFor="new-user-username">
          Anmeldename
        </label>
        <input
          id="new-user-username"
          className="form-control form-control-sm"
          value={username}
          onChange={(event) => setUsername(event.target.value)}
          required
        />
      </div>
      <div className="col-sm-3">
        <label className="form-label" htmlFor="new-user-name">
          Name
        </label>
        <input
          id="new-user-name"
          className="form-control form-control-sm"
          value={name}
          onChange={(event) => setName(event.target.value)}
          required
        />
      </div>
      <div className="col-sm-2">
        <label className="form-label" htmlFor="new-user-role">
          Rolle
        </label>
        <select
          id="new-user-role"
          className="form-select form-select-sm"
          value={role}
          onChange={(event) => setRole(event.target.value as UserRole)}
        >
          {USER_ROLES.map((r) => (
            <option key={r} value={r}>
              {USER_ROLE_LABEL[r]}
            </option>
          ))}
        </select>
      </div>
      <div className="col-sm-3">
        <label className="form-label" htmlFor="new-user-password">
          Startpasswort
        </label>
        <input
          id="new-user-password"
          type="text"
          className="form-control form-control-sm"
          value={initialPassword}
          onChange={(event) => setInitialPassword(event.target.value)}
          minLength={8}
          required
        />
      </div>
      <div className="col-sm-1">
        <button type="submit" className="btn btn-primary btn-sm w-100" disabled={submitting}>
          {submitting ? "…" : "Anlegen"}
        </button>
      </div>
      {error && (
        <div className="col-12">
          <p className="text-danger mb-0">{error}</p>
        </div>
      )}
    </form>
  );
}

function PasswortZuruecksetzenDialog({
  item,
  onClose,
  onDone,
}: {
  item: UserDto;
  onClose: () => void;
  onDone: (updated: UserDto) => void;
}) {
  const [newPassword, setNewPassword] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [submitting, setSubmitting] = useState(false);

  async function handleSubmit(event: React.FormEvent) {
    event.preventDefault();
    setSubmitting(true);
    setError(null);
    try {
      const updated = await userApi.resetPassword(item.id, newPassword);
      onDone(updated);
    } catch (err) {
      setError(err instanceof Error ? err.message : "Passwort konnte nicht zurückgesetzt werden.");
    } finally {
      setSubmitting(false);
    }
  }

  return (
    <div className="modal-backdrop-inline">
      <form className="card" style={{ maxWidth: 360, padding: "1.5rem" }} onSubmit={handleSubmit}>
        <h3 className="h6">Passwort zurücksetzen für {item.name}</h3>
        <div className="mb-3">
          <label className="form-label" htmlFor="reset-password">
            Neues Startpasswort
          </label>
          <input
            id="reset-password"
            type="text"
            className="form-control"
            value={newPassword}
            onChange={(event) => setNewPassword(event.target.value)}
            minLength={8}
            autoFocus
            required
          />
        </div>
        {error && <p className="text-danger">{error}</p>}
        <div className="d-flex gap-2">
          <button type="submit" className="btn btn-primary" disabled={submitting}>
            {submitting ? "Speichert…" : "Zurücksetzen"}
          </button>
          <button type="button" className="btn btn-outline-secondary" onClick={onClose}>
            Abbrechen
          </button>
        </div>
      </form>
    </div>
  );
}