import { useCallback, useEffect, useState, type CSSProperties } from "react";
import { Link, useSearchParams } from "react-router-dom";
import { api, type CurrentUser, type ServerRecord } from "../api/client";
import CopyButton from "../components/CopyButton";
import { formatDateTime } from "../utils/date";
import { useSortable } from "../hooks/useSortable";
import SortableTh from "../components/SortableTh";
import { usePagination } from "../hooks/usePagination";
import Pagination from "../components/Pagination";
import { downloadCsv } from "../utils/csv";
import { TagBadges } from "../components/ServerTags";
import { AGENT_RUN_HINT, agentOsOf, installCommand, uninstallCommand, type AgentOs } from "../utils/agentCommands";
import { tagBadge, useTagColors } from "../utils/tags";
import { confirmDialog } from "../utils/dialogs";

function typeBadgeStyle(colors: Record<string, string>, type: string): CSSProperties {
  const color = colors[type];
  if (!color) return {};
  return { backgroundColor: `${color}22`, color, border: `1px solid ${color}55` };
}


export default function Servers({ user }: { user: CurrentUser }) {
  const isAdmin = user.role === "admin";

  const [servers, setServers] = useState<ServerRecord[]>([]);
  const [error, setError] = useState<string | null>(null);
  const [managingServers, setManagingServers] = useState(false);
  const [integrationColors, setIntegrationColors] = useState<Record<string, string>>({});
  // The active tag filter lives in the URL, so a tag chip on a server's page can link straight to "everything with this tag".
  const [searchParams, setSearchParams] = useSearchParams();
  const selectedTags = searchParams.getAll("tag");
  const tagColors = useTagColors();

  useEffect(() => {
    api.settings.integrationColors().then((res) => setIntegrationColors(res.integrationColors)).catch(() => {});
  }, []);

  const [serverName, setServerName] = useState("");
  const [serverHostname, setServerHostname] = useState("");
  const [serverDescription, setServerDescription] = useState("");
  const [serverOs, setServerOs] = useState<AgentOs>("linux");
  const [newToken, setNewToken] = useState<{ server: ServerRecord; token: string } | null>(null);
  const [uninstallFor, setUninstallFor] = useState<ServerRecord | null>(null);
  const [insecureAgent, setInsecureAgent] = useState(false);

  const loadServers = useCallback(() => {
    return api.servers
      .list()
      .then((res) => setServers(res.servers))
      .catch((err) => setError(String(err)));
  }, []);

  useEffect(() => {
    loadServers();
  }, [loadServers]);

  async function createServer(e: React.FormEvent) {
    e.preventDefault();
    setError(null);
    try {
      const result = await api.servers.create({
        name: serverName,
        hostname: serverHostname || undefined,
        description: serverDescription || undefined,
        osType: serverOs,
      });
      setNewToken(result);
      setServerName("");
      setServerHostname("");
      setServerDescription("");
      await loadServers();
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  }

  async function rotateToken(id: number) {
    try {
      const result = await api.servers.rotateToken(id);
      setNewToken(result);
      await loadServers();
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  }

  async function deleteServer(id: number) {
    if (!(await confirmDialog({ title: "Remove server", message: "Remove this server and all its tracked tasks?", confirmLabel: "Remove", danger: true }))) return;
    try {
      await api.servers.remove(id);
      await loadServers();
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  }

  const { sorted: sortedServers, sortKey, sortDir, requestSort } = useSortable(servers);
  const { pageItems: serverPageItems, page: serverPage, setPage: setServerPage, pageCount: serverPageCount, totalCount: serverTotalCount } =
    usePagination(sortedServers);

  const tagCounts = new Map<string, number>();
  for (const s of servers) for (const t of s.tags) tagCounts.set(t, (tagCounts.get(t) ?? 0) + 1);
  // A tag from the URL that no server has (any more) stays listed, so it can still be switched off.
  for (const t of selectedTags) if (!tagCounts.has(t)) tagCounts.set(t, 0);
  const allTags = [...tagCounts.keys()].sort((a, b) => a.localeCompare(b, "sv"));
  const visibleServers = servers.filter((s) => selectedTags.every((t) => s.tags.includes(t)));

  function toggleTag(tag: string) {
    const next = selectedTags.includes(tag) ? selectedTags.filter((t) => t !== tag) : [...selectedTags, tag];
    setSearchParams(next.length > 0 ? { tag: next } : {}, { replace: true });
  }

  function exportCsv() {
    if (!sortedServers) return;
    downloadCsv(
      "servers.csv",
      ["Name", "Hostname", "Tags", "Token prefix", "Last seen"],
      sortedServers.map((s) => [
        s.name,
        s.hostname ?? "",
        s.tags.join(" "),
        s.apiTokenPrefix,
        s.lastSeenAt ? formatDateTime(new Date(s.lastSeenAt)) : "never",
      ]),
    );
  }

  return (
    <>
      <div className="d-flex align-items-center mb-3">
        <h2 className="page-title mb-0">Servers</h2>
        {isAdmin && (
          <button className="btn btn-outline-secondary ms-auto" onClick={() => setManagingServers((v) => !v)}>
            {managingServers ? "Back to servers" : "Manage servers"}
          </button>
        )}
      </div>
      {error && <div className="alert alert-danger">{error}</div>}

      {managingServers ? (
        <>
          <div className="card mb-3">
            <div className="card-header">
              <h3 className="card-title">Add a server</h3>
            </div>
            <form onSubmit={createServer}>
              <div className="card-body row g-3">
                <div className="col-md-3">
                  <label className="form-label">Server name</label>
                  <input
                    className="form-control"
                    required
                    placeholder="e.g. nas01"
                    value={serverName}
                    onChange={(e) => setServerName(e.target.value)}
                  />
                </div>
                <div className="col-md-2">
                  <label className="form-label">Operating system</label>
                  <select className="form-select" value={serverOs} onChange={(e) => setServerOs(e.target.value as AgentOs)}>
                    <option value="linux">Linux</option>
                    <option value="windows">Windows</option>
                  </select>
                </div>
                <div className="col-md-3">
                  <label className="form-label">Hostname</label>
                  <input
                    className="form-control"
                    placeholder="optional"
                    value={serverHostname}
                    onChange={(e) => setServerHostname(e.target.value)}
                  />
                </div>
                <div className="col-md-4">
                  <label className="form-label">Description</label>
                  <input
                    className="form-control"
                    placeholder="optional"
                    value={serverDescription}
                    onChange={(e) => setServerDescription(e.target.value)}
                  />
                </div>
              </div>
              <div className="card-footer">
                <button type="submit" className="btn btn-primary">
                  Add server
                </button>
              </div>
            </form>
          </div>

          {newToken && (
            <div className="card mb-3">
              <div className="card-header">
                <h3 className="card-title">Agent token for {newToken.server.name}</h3>
              </div>
              <div className="card-body">
                <p className="text-secondary">This token is only shown once — copy it now.</p>
                <div className="input-group mb-3">
                  <code className="form-control">{newToken.token}</code>
                  <CopyButton text={newToken.token} />
                </div>
                <label className="form-check mb-2">
                  <input
                    type="checkbox"
                    className="form-check-input"
                    checked={insecureAgent}
                    onChange={(e) => setInsecureAgent(e.target.checked)}
                  />
                  <span className="form-check-label">
                    This Homelab Manager instance uses a self-signed certificate (skip TLS verification on the agent)
                  </span>
                </label>
                <p className="text-secondary">{AGENT_RUN_HINT[agentOsOf(newToken.server.osType)].install}</p>
                <div className="input-group">
                  <pre className="form-control text-wrap mb-0">
                    {installCommand(agentOsOf(newToken.server.osType), window.location.origin, newToken.token, insecureAgent)}
                  </pre>
                  <CopyButton text={installCommand(agentOsOf(newToken.server.osType), window.location.origin, newToken.token, insecureAgent)} />
                </div>
                {agentOsOf(newToken.server.osType) === "windows" && insecureAgent && (
                  <div className="text-secondary small mt-2">
                    This form is for Windows PowerShell 5.1, the one built into Windows. In PowerShell 7 the download step needs{" "}
                    <code>-SkipCertificateCheck</code> instead.
                  </div>
                )}
              </div>
              <div className="card-footer">
                <button className="btn" onClick={() => setNewToken(null)}>
                  Dismiss
                </button>
              </div>
            </div>
          )}

          {uninstallFor && (
            <div className="card mb-3">
              <div className="card-header">
                <h3 className="card-title">Uninstall agent from {uninstallFor.name}</h3>
              </div>
              <div className="card-body">
                <p className="text-secondary">{AGENT_RUN_HINT[agentOsOf(uninstallFor.osType)].uninstall}</p>
                <div className="input-group">
                  <pre className="form-control text-wrap mb-0">
                    {uninstallCommand(agentOsOf(uninstallFor.osType), window.location.origin, insecureAgent)}
                  </pre>
                  <CopyButton text={uninstallCommand(agentOsOf(uninstallFor.osType), window.location.origin, insecureAgent)} />
                </div>
              </div>
              <div className="card-footer">
                <button className="btn" onClick={() => setUninstallFor(null)}>
                  Dismiss
                </button>
              </div>
            </div>
          )}

          <div className="card">
            <div className="card-header justify-content-end">
              <button className="btn btn-outline-secondary btn-sm" onClick={exportCsv} disabled={servers.length === 0}>
                Export CSV
              </button>
            </div>
            <div className="table-responsive">
              <table className="table table-vcenter card-table">
                <thead>
                  <tr>
                    <SortableTh<ServerRecord> label="Name" sortKeyName="name" activeKey={sortKey} direction={sortDir} onSort={requestSort} />
                    <SortableTh<ServerRecord>
                      label="Hostname"
                      sortKeyName="hostname"
                      activeKey={sortKey}
                      direction={sortDir}
                      onSort={requestSort}
                    />
                    <th>Tags</th>
                    <th>Token</th>
                    <SortableTh<ServerRecord>
                      label="Last seen"
                      sortKeyName="lastSeenAt"
                      activeKey={sortKey}
                      direction={sortDir}
                      onSort={requestSort}
                    />
                    <th className="w-1">Actions</th>
                  </tr>
                </thead>
                <tbody>
                  {serverPageItems?.map((s) => (
                    <tr key={s.id}>
                      <td>
                        <Link to={`/servers/${s.id}`}>{s.name}</Link>
                      </td>
                      <td>{s.hostname ?? "—"}</td>
                      <td>
                        <div className="d-flex flex-wrap gap-1">
                          <TagBadges tags={s.tags} />
                        </div>
                      </td>
                      <td className="text-secondary">{s.apiTokenPrefix}…</td>
                      <td>{s.lastSeenAt ? formatDateTime(new Date(s.lastSeenAt)) : "never"}</td>
                      <td>
                        <div className="btn-list flex-nowrap">
                          <button className="btn btn-sm" onClick={() => rotateToken(s.id)}>
                            Rotate token
                          </button>
                          <button className="btn btn-sm" onClick={() => setUninstallFor(s)}>
                            Uninstall
                          </button>
                          <button className="btn btn-sm btn-outline-danger" onClick={() => deleteServer(s.id)}>
                            Delete
                          </button>
                        </div>
                      </td>
                    </tr>
                  ))}
                  {sortedServers?.length === 0 && (
                    <tr>
                      <td colSpan={6} className="text-secondary text-center">
                        No servers registered yet.
                      </td>
                    </tr>
                  )}
                </tbody>
              </table>
            </div>
            <Pagination page={serverPage} pageCount={serverPageCount} totalCount={serverTotalCount} onPageChange={setServerPage} />
          </div>
        </>
      ) : servers.length === 0 ? (
        <div className="card">
          <div className="card-body text-secondary">
            No servers registered yet.
            {isAdmin && (
              <>
                {" "}
                <button className="btn btn-link p-0 align-baseline" onClick={() => setManagingServers(true)}>
                  Add one
                </button>
                .
              </>
            )}
          </div>
        </div>
      ) : (
        <>
          {allTags.length > 0 && (
            <div className="d-flex flex-wrap align-items-center gap-1 mb-3">
              <span className="text-secondary small me-1">Tags</span>
              {allTags.map((tag) => {
                const active = selectedTags.includes(tag);
                const look = tagBadge(tag, tagColors);
                return (
                  <button
                    key={tag}
                    type="button"
                    className={active ? "badge border-0 bg-primary text-white" : `${look.className} border-0`}
                    style={active ? undefined : look.style}
                    aria-pressed={active}
                    onClick={() => toggleTag(tag)}
                  >
                    {tag} <span className="opacity-75">· {tagCounts.get(tag)}</span>
                  </button>
                );
              })}
              {selectedTags.length > 0 && (
                <button type="button" className="btn btn-link btn-sm p-0 ms-1" onClick={() => setSearchParams({}, { replace: true })}>
                  Clear
                </button>
              )}
            </div>
          )}
          {visibleServers.length === 0 && (
            <div className="card">
              <div className="card-body text-secondary">No server has {selectedTags.length > 1 ? "all of those tags" : "that tag"}.</div>
            </div>
          )}
        <div className="row row-cards">
          {visibleServers.map((s) => (
            <div className="col-sm-6 col-lg-3" key={s.id}>
              <Link to={`/servers/${s.id}`} className="card card-sm text-reset text-decoration-none">
                <div className="card-body">
                  <div className="d-flex align-items-center">
                    <div className="flex-fill">
                      <div className="font-weight-medium">{s.name}</div>
                      <div className="text-secondary small">{s.hostname ?? "no hostname reported"}</div>
                    </div>
                    {s.proxmoxIntegrationId ? (
                      <span className="badge" style={typeBadgeStyle(integrationColors, "proxmox")}>
                        Proxmox
                      </span>
                    ) : s.lastSeenAt ? (
                      <span className="badge bg-green-lt text-green">Agent</span>
                    ) : (
                      <span className="badge bg-secondary-lt text-secondary">No data</span>
                    )}
                  </div>
                  {s.tags.length > 0 && (
                    <div className="d-flex flex-wrap gap-1 mt-2">
                      <TagBadges tags={s.tags} />
                    </div>
                  )}
                  <div className="text-secondary small mt-2">
                    {s.lastSeenAt ? `Last seen ${formatDateTime(new Date(s.lastSeenAt))}` : "Never reported"}
                  </div>
                </div>
              </Link>
            </div>
          ))}
        </div>
        </>
      )}
    </>
  );
}