import React, { useEffect, useLayoutEffect, useRef, useState } from 'react';
import { Trans, useTranslation } from 'react-i18next';
import { useNavigate } from 'react-router-dom';
import { open as openUrl } from '@tauri-apps/plugin-shell';
import { AlertTriangle, CheckCircle2, Lock, LogOut, Pencil, Plus, Power, Server, Sparkles, Trash2, User, Wifi, WifiOff } from 'lucide-react';
import { useAuthStore } from '../../store/authStore';
import { useLibraryIndexStore } from '../../store/libraryIndexStore';
import { libraryDeleteServerData, librarySyncClearSession } from '../../api/library';
import { bootstrapIndexedServer } from '../../utils/library/librarySession';
import { useLibraryIndexSync } from '../../hooks/useLibraryIndexSync';
import ServerLibraryIndexControls from './ServerLibraryIndexControls';
import type { ServerProfile } from '../../store/authStoreTypes';
import { pingWithCredentials, scheduleInstantMixProbeForServer } from '../../api/subsonic';
import { useDragDrop } from '../../contexts/DragDropContext';
import { type ServerMagicPayload } from '../../utils/server/serverMagicString';
import { ensureConnectUrlResolved, invalidateReachableEndpointCache } from '../../utils/server/serverEndpoint';
import {
  verifySameServerEndpoints,
  type VerifySameServerResult,
} from '../../utils/server/serverFingerprint';
import {
  indexKeyRemapForUrlChange,
  runIndexKeyRemigration,
} from '../../utils/server/serverUrlRemigration';
import { useConfirmModalStore } from '../../store/confirmModalStore';
import { showToast } from '../../utils/ui/toast';
import { showAudiomuseNavidromeServerSetting } from '../../utils/server/subsonicServerIdentity';
import { serverListDisplayLabel } from '../../utils/server/serverDisplayName';
import { serverIndexKeyForProfile } from '../../utils/server/serverIndexKey';
import { switchActiveServer } from '../../utils/server/switchActiveServer';
import { AddServerForm } from './AddServerForm';
import { ServerGripHandle } from './ServerGripHandle';

const AUDIOMUSE_NV_PLUGIN_URL = 'https://github.com/NeptuneHub/AudioMuse-AI-NV-plugin';

type ServerDropTarget = { idx: number; before: boolean } | null;

export function ServersTab({
  initialInvite,
}: {
  initialInvite: ServerMagicPayload | null;
}) {
  const { t } = useTranslation();
  const navigate = useNavigate();
  const auth = useAuthStore();
  const psyDragState = useDragDrop();
  const librarySync = useLibraryIndexSync();

  const [connStatus, setConnStatus] = useState<Record<string, 'idle' | 'testing' | 'ok' | 'error'>>({});
  const [showAddForm, setShowAddForm] = useState<boolean>(initialInvite != null);
  const [editingServerId, setEditingServerId] = useState<string | null>(null);
  const [pastedServerInvite, setPastedServerInvite] = useState<ServerMagicPayload | null>(initialInvite);
  const [serverContainerEl, setServerContainerEl] = useState<HTMLDivElement | null>(null);
  const [serverDropTarget, setServerDropTarget] = useState<ServerDropTarget>(null);
  const serverDropTargetRef = useRef<ServerDropTarget>(null);
  const serversRef = useRef(auth.servers);
  serversRef.current = auth.servers;
  const addServerInviteAnchorRef = useRef<HTMLDivElement>(null);

  useLayoutEffect(() => {
    if (!showAddForm || !pastedServerInvite) return;
    addServerInviteAnchorRef.current?.scrollIntoView({ behavior: 'smooth', block: 'start' });
  }, [showAddForm, pastedServerInvite]);

  // Pick up later invites that arrive via the parent route handler while
  // ServersTab is already mounted (initial mount is handled via useState).
  useEffect(() => {
    if (initialInvite) {
      setPastedServerInvite(initialInvite);
      setShowAddForm(true);
    }
  }, [initialInvite]);

  // Clear drop target when drag ends
  useEffect(() => {
    if (!psyDragState.isDragging) {
      serverDropTargetRef.current = null;
      setServerDropTarget(null);
    }
  }, [psyDragState.isDragging]);

  // psy-drop listener for server reorder
  useEffect(() => {
    if (!serverContainerEl) return;
    const onPsyDrop = (e: Event) => {
      const detail = (e as CustomEvent).detail;
      if (!detail?.data) return;
      let parsed: { type?: string; index?: number };
      try { parsed = JSON.parse(detail.data as string); } catch { return; }
      if (parsed.type !== 'server_reorder' || parsed.index == null) return;

      const fromIdx = parsed.index;
      const target = serverDropTargetRef.current;
      serverDropTargetRef.current = null; setServerDropTarget(null);
      if (!target) return;

      const insertBefore = target.before ? target.idx : target.idx + 1;
      if (insertBefore === fromIdx || insertBefore === fromIdx + 1) return;

      const next = [...serversRef.current];
      const [moved] = next.splice(fromIdx, 1);
      next.splice(insertBefore > fromIdx ? insertBefore - 1 : insertBefore, 0, moved);
      auth.setServers(next);
    };
    serverContainerEl.addEventListener('psy-drop', onPsyDrop);
    return () => serverContainerEl.removeEventListener('psy-drop', onPsyDrop);
  }, [serverContainerEl, auth]);

  const handleServerDragMove = (e: React.MouseEvent) => {
    if (!psyDragState.isDragging || !serverContainerEl) return;
    const rows = serverContainerEl.querySelectorAll<HTMLElement>('[data-server-idx]');
    let target: ServerDropTarget = null;
    for (const row of rows) {
      const rect = row.getBoundingClientRect();
      const idx = Number(row.dataset.serverIdx);
      if (e.clientY < rect.top + rect.height / 2) { target = { idx, before: true }; break; }
      target = { idx, before: false };
    }
    serverDropTargetRef.current = target;
    setServerDropTarget(target);
  };

  const testConnection = async (server: ServerProfile) => {
    setConnStatus(s => ({ ...s, [server.id]: 'testing' }));
    try {
      // Dual-address: probe through the connect layer so the test reflects
      // whichever endpoint the app would actually use right now (LAN at home,
      // public elsewhere). probe.baseUrl also feeds the AudioMuse probe so
      // that one hits the same endpoint.
      const probe = await ensureConnectUrlResolved(server);
      if (probe.ok) {
        const identity = {
          type: probe.ping.type,
          serverVersion: probe.ping.serverVersion,
          openSubsonic: probe.ping.openSubsonic,
        };
        auth.setSubsonicServerIdentity(server.id, identity);
        scheduleInstantMixProbeForServer(server.id, probe.baseUrl, server.username, server.password, identity);
      }
      setConnStatus(s => ({ ...s, [server.id]: probe.ok ? 'ok' : 'error' }));
    } catch {
      setConnStatus(s => ({ ...s, [server.id]: 'error' }));
    }
  };

  const switchToServer = async (server: ServerProfile) => {
    setConnStatus(s => ({ ...s, [server.id]: 'testing' }));
    const ok = await switchActiveServer(server);
    if (ok) {
      setConnStatus(s => ({ ...s, [server.id]: 'ok' }));
      // Auf der Servers-Seite bleiben, damit der User seinen Switch hier
      // sofort visuell bestaetigt sieht (gruener Check, aktiv-Badge).
    } else {
      setConnStatus(s => ({ ...s, [server.id]: 'error' }));
    }
  };

  const deleteServer = async (server: ServerProfile) => {
    if (!confirm(t('settings.confirmDeleteServer', { name: serverListDisplayLabel(server, auth.servers) }))) {
      return;
    }
    // §5.6: when a local library index exists for this server, let the
    // user keep the cached rows (offline use) or delete them. OK =
    // delete the cache, Cancel = keep it.
    const hadIndex = useLibraryIndexStore.getState().isIndexEnabled(server.id);
    const purgeLibrary = hadIndex && confirm(t('settings.confirmDeleteServerLibrary'));

    auth.removeServer(server.id);
    try {
      await librarySyncClearSession(server.id);
      if (purgeLibrary) {
        await libraryDeleteServerData(server.id);
      }
    } catch {
      /* best-effort — server already removed from the store */
    }
  };

  const closeAddServerForm = () => {
    setShowAddForm(false);
    setPastedServerInvite(null);
  };

  /**
   * Surface a dual-address verify failure as a toast (mismatch /
   * insufficient / unreachable). Returns true when the result is `ok` and
   * the caller should proceed; false when the user must fix something
   * before save.
   */
  const announceVerifyResult = (result: VerifySameServerResult): boolean => {
    if (result.ok) return true;
    if (result.reason === 'unreachable') {
      showToast(
        t('settings.dualAddressUnreachable', { host: result.unreachableHost ?? '' }),
        6000,
        'error',
      );
    } else if (result.reason === 'mismatch') {
      showToast(t('settings.dualAddressMismatch'), 6000, 'error');
    } else {
      showToast(t('settings.dualAddressInsufficient'), 6000, 'error');
    }
    return false;
  };

  const handleAddServer = async (data: Omit<ServerProfile, 'id'>) => {
    setShowAddForm(false);
    setPastedServerInvite(null);
    const tempId = '_new';
    setConnStatus(s => ({ ...s, [tempId]: 'testing' }));
    try {
      // Dual-address: confirm both addresses point at the same server
      // before persisting anything. Single-address adds skip verify and go
      // straight to the legacy ping (which is also the connect-test).
      if (data.alternateUrl) {
        const verify = await verifySameServerEndpoints(
          { url: data.url, alternateUrl: data.alternateUrl },
          data.username,
          data.password,
        );
        if (!announceVerifyResult(verify)) {
          setConnStatus(s => ({ ...s, [tempId]: 'error' }));
          return;
        }
      }
      const ping = await pingWithCredentials(data.url, data.username, data.password);
      if (ping.ok) {
        const id = auth.addServer(data);
        const identity = {
          type: ping.type,
          serverVersion: ping.serverVersion,
          openSubsonic: ping.openSubsonic,
        };
        auth.setSubsonicServerIdentity(id, identity);
        scheduleInstantMixProbeForServer(id, data.url, data.username, data.password, identity);
        setConnStatus(s => ({ ...s, [id]: 'ok' }));
        const added = useAuthStore.getState().servers.find(s => s.id === id);
        if (added) void bootstrapIndexedServer(added);
      } else {
        setConnStatus(s => ({ ...s, [tempId]: 'error' }));
      }
    } catch {
      setConnStatus(s => ({ ...s, [tempId]: 'error' }));
    }
  };

  // Edit normally saves unconditionally — ping result becomes a post-save
  // status indicator (analog zum existing Test-Button) rather than blocking
  // the save. Lets users update a profile even when the server is currently
  // unreachable.
  //
  // **Dual-address exception:** when the edit introduces or changes the
  // second address (or changes the primary url while a second address is
  // already saved), verify both addresses are the same server *before*
  // persisting. A mismatch here would silently bind library / cover / queue
  // data to two unrelated boxes — the spec blocks save in v1.
  const handleEditServer = async (id: string, data: Omit<ServerProfile, 'id'>) => {
    const previous = auth.servers.find(s => s.id === id);

    // URL-change remigration — runs BEFORE everything else when the edit
    // changes the derived index key. User confirms first; on failure the
    // edit is aborted with a stage-specific toast. Spec §8.
    const remap = previous ? indexKeyRemapForUrlChange(previous, data) : null;
    if (remap) {
      const confirmed = await useConfirmModalStore.getState().request({
        title: t('settings.urlRemigrationTitle'),
        message: t('settings.urlRemigrationMessage', {
          oldKey: remap.oldKey,
          newKey: remap.newKey,
        }),
        confirmLabel: t('settings.urlRemigrationConfirm'),
        cancelLabel: t('common.cancel'),
        danger: true,
      });
      if (!confirmed) return;
      setConnStatus(s => ({ ...s, [id]: 'testing' }));
      const result = await runIndexKeyRemigration(remap);
      if (!result.ok) {
        const failureKey =
          result.failure.stage === 'inspect'
            ? 'settings.urlRemigrationFailureInspect'
            : result.failure.stage === 'run'
            ? 'settings.urlRemigrationFailureRun'
            : 'settings.urlRemigrationFailureCoverRename';
        showToast(t(failureKey), 8000, 'error');
        setConnStatus(s => ({ ...s, [id]: 'error' }));
        return;
      }
    }

    const dualAddressChanged =
      data.alternateUrl != null &&
      data.alternateUrl !== '' &&
      (data.alternateUrl !== previous?.alternateUrl ||
        data.url !== previous?.url ||
        data.username !== previous?.username ||
        data.password !== previous?.password);

    if (dualAddressChanged) {
      setConnStatus(s => ({ ...s, [id]: 'testing' }));
      const verify = await verifySameServerEndpoints(
        { url: data.url, alternateUrl: data.alternateUrl },
        data.username,
        data.password,
      );
      if (!announceVerifyResult(verify)) {
        setConnStatus(s => ({ ...s, [id]: 'error' }));
        return;
      }
    }

    setEditingServerId(null);
    auth.updateServer(id, data);
    // Profile edited → any cached sticky connect URL for this id may now be
    // stale (credentials may have changed, alternate may have been added).
    invalidateReachableEndpointCache(id);
    setConnStatus(s => ({ ...s, [id]: 'testing' }));
    try {
      const ping = await pingWithCredentials(data.url, data.username, data.password);
      if (ping.ok) {
        const identity = {
          type: ping.type,
          serverVersion: ping.serverVersion,
          openSubsonic: ping.openSubsonic,
        };
        auth.setSubsonicServerIdentity(id, identity);
        scheduleInstantMixProbeForServer(id, data.url, data.username, data.password, identity);
      }
      setConnStatus(s => ({ ...s, [id]: ping.ok ? 'ok' : 'error' }));
    } catch {
      setConnStatus(s => ({ ...s, [id]: 'error' }));
    }
  };

  const handleLogout = () => {
    auth.logout();
    navigate('/login');
  };

  return (
    <>
      <section className="settings-section">
        <div className="settings-section-header">
          <Server size={18} />
          <h2>{t('settings.servers')}</h2>
        </div>
        <div style={{ fontSize: 12, color: 'var(--text-muted)', marginBottom: '0.75rem' }}>
          {t('settings.serverCompatible')}
        </div>

        {auth.servers.length === 0 && !showAddForm ? (
          <div className="settings-card" style={{ color: 'var(--text-muted)', fontSize: 14 }}>
            {t('settings.noServers')}
          </div>
        ) : (
          <div
            ref={setServerContainerEl}
            onMouseMove={handleServerDragMove}
            style={{ display: 'flex', flexDirection: 'column', gap: '0.75rem' }}
          >
            {auth.servers.map((srv, srvIdx) => {
              if (editingServerId === srv.id) {
                return (
                  <AddServerForm
                    key={srv.id}
                    editingServer={srv}
                    onSave={(data) => handleEditServer(srv.id, data)}
                    onCancel={() => setEditingServerId(null)}
                  />
                );
              }
              const isActive = srv.id === auth.activeServerId;
              const status = connStatus[srv.id];
              const isBefore = psyDragState.isDragging && serverDropTarget?.idx === srvIdx && serverDropTarget.before;
              const isAfter  = psyDragState.isDragging && serverDropTarget?.idx === srvIdx && !serverDropTarget.before;
              return (
                <div
                  key={srv.id}
                  data-server-idx={srvIdx}
                  className="settings-card"
                  style={{
                    border: isActive ? '1px solid var(--accent)' : undefined,
                    background: isActive ? 'color-mix(in srgb, var(--accent) 10%, var(--bg-card))' : undefined,
                    borderTop:    isBefore ? '2px solid var(--accent)' : undefined,
                    borderBottom: isAfter  ? '2px solid var(--accent)' : undefined,
                  }}
                >
                  <div style={{ display: 'flex', alignItems: 'stretch', gap: '0.75rem' }}>
                    <ServerGripHandle idx={srvIdx} label={serverListDisplayLabel(srv, auth.servers)} />
                    <div style={{ flex: 1, display: 'flex', alignItems: 'flex-start', justifyContent: 'space-between', gap: '1rem', flexWrap: 'wrap' }}>
                    <div style={{ minWidth: 0 }}>
                      <div style={{ display: 'flex', alignItems: 'center', gap: '0.5rem', marginBottom: '2px' }}>
                        <span style={{ fontWeight: 600 }}>{serverListDisplayLabel(srv, auth.servers)}</span>
                        {isActive && (
                          <span style={{ fontSize: 11, background: 'var(--accent)', color: 'var(--ctp-crust)', padding: '1px 6px', borderRadius: 'var(--radius-sm)', fontWeight: 600 }}>
                            {t('settings.serverActive')}
                          </span>
                        )}
                      </div>
                      <div style={{ fontSize: 12, color: 'var(--text-muted)', display: 'flex', alignItems: 'center', gap: 4, overflow: 'hidden' }}>
                        {srv.url.startsWith('https://') && (
                          <Lock size={11} style={{ color: 'var(--positive)', flexShrink: 0 }} />
                        )}
                        <span style={{ overflow: 'hidden', textOverflow: 'ellipsis', whiteSpace: 'nowrap' }}>
                          {srv.url.replace(/^https?:\/\//, '')}
                        </span>
                      </div>
                      <div style={{ fontSize: 12, color: 'var(--text-muted)', display: 'flex', alignItems: 'center', gap: 4, marginTop: 1 }}>
                        <User size={11} />
                        {srv.username}
                      </div>
                    </div>
                    <div style={{ display: 'flex', gap: '6px', flexShrink: 0, alignItems: 'center', marginLeft: 'auto' }}>
                      {status === 'ok' && <CheckCircle2 size={16} style={{ color: 'var(--positive)' }} />}
                      {status === 'error' && <WifiOff size={16} style={{ color: 'var(--danger)' }} />}
                      {status === 'testing' && <div className="spinner" style={{ width: 16, height: 16 }} />}
                      <button
                        className="btn btn-surface"
                        style={{ fontSize: 12, padding: '4px 10px' }}
                        onClick={() => testConnection(srv)}
                        disabled={status === 'testing'}
                        data-tooltip={t('settings.testBtn')}
                        aria-label={t('settings.testBtn')}
                      >
                        <Wifi size={13} />
                        <span className="server-card-btn-label">{t('settings.testBtn')}</span>
                      </button>
                      {!isActive && (
                        <button
                          className="btn btn-primary"
                          style={{ fontSize: 12, padding: '4px 10px' }}
                          onClick={() => switchToServer(srv)}
                          disabled={status === 'testing'}
                          id={`settings-use-server-${srv.id}`}
                          data-tooltip={t('settings.useServer')}
                          aria-label={t('settings.useServer')}
                        >
                          <Power size={13} />
                          <span className="server-card-btn-label">{t('settings.useServer')}</span>
                        </button>
                      )}
                      <button
                        className="btn btn-ghost"
                        style={{ padding: '4px 8px' }}
                        onClick={() => {
                          setShowAddForm(false);
                          setPastedServerInvite(null);
                          setEditingServerId(srv.id);
                        }}
                        data-tooltip={t('settings.editServer')}
                        id={`settings-edit-server-${srv.id}`}
                      >
                        <Pencil size={14} />
                      </button>
                      <button
                        className="btn btn-ghost"
                        style={{ color: 'var(--danger)', padding: '4px 8px' }}
                        onClick={() => void deleteServer(srv)}
                        data-tooltip={t('settings.deleteServer')}
                        id={`settings-delete-server-${srv.id}`}
                      >
                        <Trash2 size={14} />
                      </button>
                    </div>
                  </div>
                  </div>
                  <ServerLibraryIndexControls
                    status={librarySync.statusByServer[serverIndexKeyForProfile(srv)] ?? null}
                    connection={librarySync.connectionByServer[serverIndexKeyForProfile(srv)] ?? 'unknown'}
                    progressLabel={librarySync.progressByServer[serverIndexKeyForProfile(srv)] ?? null}
                    busy={librarySync.busyServerId === serverIndexKeyForProfile(srv)}
                    actionsDisabled={librarySync.globalBusy && librarySync.busyServerId !== serverIndexKeyForProfile(srv)}
                    onFullSync={() => void librarySync.runServerAction(serverIndexKeyForProfile(srv), 'full')}
                    onDeltaSync={() => void librarySync.runServerAction(serverIndexKeyForProfile(srv), 'delta')}
                    onVerify={() => void librarySync.runServerAction(serverIndexKeyForProfile(srv), 'verify')}
                    onCancel={() => void librarySync.handleCancel()}
                  />
                  {showAudiomuseNavidromeServerSetting(
                    auth.subsonicServerIdentityByServer[srv.id],
                    auth.instantMixProbeByServer[srv.id],
                  ) && (
                    <div
                      className="settings-toggle-row"
                      style={{ marginTop: '0.75rem', paddingTop: '0.75rem', borderTop: '1px solid color-mix(in srgb, var(--text-muted) 18%, transparent)' }}
                    >
                      <div style={{ display: 'flex', alignItems: 'flex-start', gap: '0.5rem', minWidth: 0 }}>
                        <Sparkles size={16} style={{ color: 'var(--accent)', flexShrink: 0, marginTop: 2 }} />
                        <div>
                          <div style={{ fontWeight: 500, display: 'flex', alignItems: 'center', gap: 8, flexWrap: 'wrap' }}>
                            {t('settings.audiomuseTitle')}
                            {!!auth.audiomuseNavidromeByServer[srv.id] && auth.audiomuseNavidromeIssueByServer[srv.id] && (
                              <AlertTriangle
                                size={16}
                                style={{ color: 'var(--color-warning, #f59e0b)', flexShrink: 0 }}
                                data-tooltip={t('settings.audiomuseIssueHint')}
                                aria-label={t('settings.audiomuseIssueHint')}
                              />
                            )}
                          </div>
                          <div style={{ fontSize: 12, color: 'var(--text-muted)', lineHeight: 1.45 }}>
                            <Trans
                              i18nKey="settings.audiomuseDesc"
                              components={{
                                pluginLink: (
                                  <a
                                    href={AUDIOMUSE_NV_PLUGIN_URL}
                                    onClick={e => {
                                      e.preventDefault();
                                      void openUrl(AUDIOMUSE_NV_PLUGIN_URL);
                                    }}
                                    style={{ color: 'var(--accent)', textDecoration: 'underline' }}
                                  />
                                ),
                              }}
                            />
                          </div>
                        </div>
                      </div>
                      <label className="toggle-switch" aria-label={t('settings.audiomuseTitle')}>
                        <input
                          type="checkbox"
                          checked={!!auth.audiomuseNavidromeByServer[srv.id]}
                          onChange={e => auth.setAudiomuseNavidromeEnabled(srv.id, e.target.checked)}
                        />
                        <span className="toggle-track" />
                      </label>
                    </div>
                  )}
                </div>
              );
            })}
          </div>
        )}

        <div
          ref={addServerInviteAnchorRef}
          id="settings-add-server-anchor"
          style={{ scrollMarginTop: '12px' }}
        >
          {showAddForm ? (
            <AddServerForm
              initialInvite={pastedServerInvite}
              onSave={handleAddServer}
              onCancel={closeAddServerForm}
            />
          ) : (
            <button
              className="btn btn-surface"
              style={{ marginTop: '0.75rem' }}
              onClick={() => {
                setPastedServerInvite(null);
                setShowAddForm(true);
              }}
              id="settings-add-server-btn"
            >
              <Plus size={16} /> {t('settings.addServer')}
            </button>
          )}
        </div>
      </section>

      <section className="settings-section">
        <button className="btn btn-danger" onClick={handleLogout} id="settings-logout-btn">
          <LogOut size={16} /> {t('settings.logout')}
        </button>
      </section>
    </>
  );
}