import { FormEvent, useState } from "react";
import { useMutation, useQuery, useQueryClient } from "@tanstack/react-query";
import {
  api,
  assignGroupMember,
  assignGroupRole,
  removeGroupMember,
  removeGroupRole,
  type Group,
  type MqttClient,
  type Role,
} from "../api";

export function GroupsPage() {
  const queryClient = useQueryClient();
  const [name, setName] = useState("");
  const [error, setError] = useState<string | null>(null);

  const groups = useQuery({
    queryKey: ["groups"],
    queryFn: () => api.get<Group[]>("/mqtt/groups"),
  });

  // For the per-group assignment dropdowns.
  const roles = useQuery({
    queryKey: ["roles"],
    queryFn: () => api.get<Role[]>("/mqtt/roles"),
  });
  const clients = useQuery({
    queryKey: ["clients"],
    queryFn: () => api.get<MqttClient[]>("/mqtt/clients"),
  });

  const refresh = () => {
    queryClient.invalidateQueries({ queryKey: ["groups"] });
    queryClient.invalidateQueries({ queryKey: ["clients"] });
  };

  const create = useMutation({
    mutationFn: (groupname: string) => api.post("/mqtt/groups", { groupname }),
    onSuccess: () => {
      setName("");
      refresh();
    },
    onError: (e: Error) => setError(e.message),
  });

  const remove = useMutation({
    mutationFn: (groupname: string) => api.delete(`/mqtt/groups/${groupname}`),
    onSuccess: refresh,
    onError: (e: Error) => setError(e.message),
  });

  const addRole = useMutation({
    mutationFn: ({ groupname, rolename }: { groupname: string; rolename: string }) =>
      assignGroupRole(groupname, rolename),
    onSuccess: refresh,
    onError: (e: Error) => setError(e.message),
  });

  const dropRole = useMutation({
    mutationFn: ({ groupname, rolename }: { groupname: string; rolename: string }) =>
      removeGroupRole(groupname, rolename),
    onSuccess: refresh,
    onError: (e: Error) => setError(e.message),
  });

  const addMember = useMutation({
    mutationFn: ({ groupname, username }: { groupname: string; username: string }) =>
      assignGroupMember(groupname, username),
    onSuccess: refresh,
    onError: (e: Error) => setError(e.message),
  });

  const dropMember = useMutation({
    mutationFn: ({ groupname, username }: { groupname: string; username: string }) =>
      removeGroupMember(groupname, username),
    onSuccess: refresh,
    onError: (e: Error) => setError(e.message),
  });

  const submit = (e: FormEvent) => {
    e.preventDefault();
    if (name) create.mutate(name);
  };

  const roleNames = (roles.data ?? []).map((r) => r.rolename);
  const clientNames = (clients.data ?? []).map((c) => c.username);

  // Group membership lives on the client objects (c.groups), so derive
  // members from the clients query rather than the group list.
  const membersOf = (groupname: string) =>
    (clients.data ?? [])
      .filter((c) => c.groups.some((g) => g.groupname === groupname))
      .map((c) => ({ name: c.username }));

  return (
    <div>
      <h2>Groups</h2>
      <p>
        Assign roles to collections of clients (dynamic security groups). Each
        group manages its own roles and members.
      </p>
      {error && <div className="banner error">{error}</div>}

      <form className="stack" onSubmit={submit}>
        <label htmlFor="group-name">New group name</label>
        <input
          id="group-name"
          value={name}
          onChange={(e) => setName(e.target.value)}
          placeholder="e.g. sensors"
        />
        <p />
        <button className="primary" disabled={!name || create.isPending}>
          Create group
        </button>
      </form>

      <table style={{ marginTop: "1.5rem" }}>
        <thead>
          <tr>
            <th>Group</th>
            <th>Roles</th>
            <th>Members</th>
            <th>Add</th>
            <th></th>
          </tr>
        </thead>
        <tbody>
          {(groups.data ?? []).map((g) => {
            const groupRoles = (g.roles ?? []).map((r) => ({ name: r.rolename }));
            const members = membersOf(g.groupname);
            const freeRoles = roleNames.filter(
              (name) => !groupRoles.some((r) => r.name === name),
            );
            const freeMembers = clientNames.filter(
              (name) => !members.some((m) => m.name === name),
            );
            return (
              <tr key={g.groupname}>
                <td className="mono">{g.groupname}</td>
                <td>
                  {groupRoles.length === 0 ? (
                    "—"
                  ) : (
                    groupRoles.map((r) => (
                      <span
                        key={r.name}
                        className="mono"
                        style={{
                          display: "inline-block",
                          border: "1px solid #cbd2d9",
                          borderRadius: "10px",
                          padding: "0.05rem 0.4rem",
                          margin: "0.1rem",
                          fontSize: "0.8rem",
                        }}
                      >
                        {r.name}{" "}
                        <button
                          className="danger"
                          style={{ padding: "0 0.3rem", marginLeft: "0.15rem" }}
                          title={`Remove role ${r.name}`}
                          onClick={() =>
                            dropRole.mutate({ groupname: g.groupname, rolename: r.name })
                          }
                        >
                          ×
                        </button>
                      </span>
                    ))
                  )}
                </td>
                <td>
                  {members.length === 0 ? (
                    "—"
                  ) : (
                    members.map((m) => (
                      <span
                        key={m.name}
                        className="mono"
                        style={{
                          display: "inline-block",
                          border: "1px solid #cbd2d9",
                          borderRadius: "10px",
                          padding: "0.05rem 0.4rem",
                          margin: "0.1rem",
                          fontSize: "0.8rem",
                        }}
                      >
                        {m.name}{" "}
                        <button
                          className="danger"
                          style={{ padding: "0 0.3rem", marginLeft: "0.15rem" }}
                          title={`Remove member ${m.name}`}
                          onClick={() =>
                            dropMember.mutate({ groupname: g.groupname, username: m.name })
                          }
                        >
                          ×
                        </button>
                      </span>
                    ))
                  )}
                </td>
                <td>
                  {freeRoles.length > 0 ? (
                    <select
                      defaultValue=""
                      onChange={(e) => {
                        if (e.target.value)
                          addRole.mutate({ groupname: g.groupname, rolename: e.target.value });
                        e.target.value = "";
                      }}
                    >
                      <option value="">+ role…</option>
                      {freeRoles.map((name) => (
                        <option key={name} value={name}>
                          {name}
                        </option>
                      ))}
                    </select>
                  ) : null}{" "}
                  {freeMembers.length > 0 ? (
                    <select
                      defaultValue=""
                      onChange={(e) => {
                        if (e.target.value)
                          addMember.mutate({
                            groupname: g.groupname,
                            username: e.target.value,
                          });
                        e.target.value = "";
                      }}
                    >
                      <option value="">+ member…</option>
                      {freeMembers.map((name) => (
                        <option key={name} value={name}>
                          {name}
                        </option>
                      ))}
                    </select>
                  ) : null}
                </td>
                <td>
                  <button
                    className="danger"
                    onClick={() => {
                      if (confirm(`Delete group ${g.groupname}?`)) remove.mutate(g.groupname);
                    }}
                  >
                    Delete
                  </button>
                </td>
              </tr>
            );
          })}
        </tbody>
      </table>
    </div>
  );
}