import { useEffect, useState, type CSSProperties } from "react";
import {
  api,
  type CurrentUser,
  type DnsProviderSummary,
  type DnsProviderType,
  type DnsRecord,
  type DnsRecordInput,
  type DnsZone,
} from "../api/client";
import DnsProviderForm from "../components/DnsProviderForm";
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";

const PROVIDER_LABELS: Record<DnsProviderType, string> = {
  cloudflare: "Cloudflare",
  loopia: "Loopia",
  pihole: "Pi-hole",
  azure: "Azure DNS",
  cpanel: "cPanel",
  technitium: "Technitium",
};

const emptyRecordForm: DnsRecordInput = { type: "A", name: "", content: "", ttl: 3600, priority: undefined, proxied: undefined };

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

export default function Dns({ user }: { user: CurrentUser }) {
  const isAdmin = user.role === "admin";
  const canEdit = user.role === "admin" || user.role === "operator";

  const [providers, setProviders] = useState<DnsProviderSummary[] | null>(null);
  const [managingProviders, setManagingProviders] = useState(false);
  const [selectedProviderId, setSelectedProviderId] = useState<number | null>(null);
  const [error, setError] = useState<string | null>(null);
  const [providerColors, setProviderColors] = useState<Record<string, string>>({});

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

  const [zones, setZones] = useState<DnsZone[] | null>(null);
  const [zonesError, setZonesError] = useState<string | null>(null);
  const [selectedZone, setSelectedZone] = useState<DnsZone | null>(null);

  const [records, setRecords] = useState<DnsRecord[] | null>(null);
  const [syncedAt, setSyncedAt] = useState<string | null>(null);
  const [syncing, setSyncing] = useState(false);

  const [recordForm, setRecordForm] = useState<DnsRecordInput | null>(null);
  const [editingRecordId, setEditingRecordId] = useState<string | null>(null);
  const [savingRecord, setSavingRecord] = useState(false);

  function loadProviders() {
    api.dns.providers
      .list()
      .then((res) => {
        setProviders(res.providers);
        if (!selectedProviderId && res.providers.length > 0) setSelectedProviderId(res.providers[0].id);
      })
      .catch((err) => setError(String(err)));
  }

  useEffect(loadProviders, []);

  function loadZones(providerId: number) {
    setZonesError(null);
    setZones(null);
    setSelectedZone(null);
    setRecords(null);
    api.dns.zones
      .list(providerId)
      .then((res) => setZones(res.zones))
      .catch((err) => setZonesError(err instanceof Error ? err.message : String(err)));
  }

  useEffect(() => {
    if (selectedProviderId && !managingProviders) loadZones(selectedProviderId);
  }, [selectedProviderId, managingProviders]);

  function loadRecords(providerId: number, zone: DnsZone) {
    api.dns.records
      .list(providerId, zone.id)
      .then((res) => {
        setRecords(res.records);
        setSyncedAt(res.syncedAt);
      })
      .catch((err) => setError(err instanceof Error ? err.message : String(err)));
  }

  function selectZone(zone: DnsZone) {
    setSelectedZone(zone);
    setRecordForm(null);
    setEditingRecordId(null);
    if (selectedProviderId) loadRecords(selectedProviderId, zone);
  }

  async function syncZone() {
    if (!selectedProviderId || !selectedZone) return;
    setSyncing(true);
    setError(null);
    try {
      const res = await api.dns.records.sync(selectedProviderId, selectedZone.id, selectedZone.name);
      setRecords(res.records);
      setSyncedAt(res.syncedAt);
      loadZones(selectedProviderId);
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    } finally {
      setSyncing(false);
    }
  }

  function startAddRecord() {
    setEditingRecordId(null);
    setRecordForm({ ...emptyRecordForm });
  }

  function startEditRecord(r: DnsRecord) {
    setEditingRecordId(r.id);
    setRecordForm({
      type: r.type,
      name: r.name,
      content: r.content,
      ttl: r.ttl ?? undefined,
      priority: r.priority ?? undefined,
      proxied: r.proxied ?? undefined,
    });
  }

  async function submitRecord(e: React.FormEvent) {
    e.preventDefault();
    if (!selectedProviderId || !selectedZone || !recordForm) return;
    setSavingRecord(true);
    setError(null);
    try {
      if (editingRecordId) {
        await api.dns.records.update(selectedProviderId, selectedZone.id, editingRecordId, recordForm);
      } else {
        await api.dns.records.create(selectedProviderId, selectedZone.id, recordForm);
      }
      setRecordForm(null);
      setEditingRecordId(null);
      loadRecords(selectedProviderId, selectedZone);
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    } finally {
      setSavingRecord(false);
    }
  }

  async function removeRecord(r: DnsRecord) {
    if (!selectedProviderId || !selectedZone) return;
    if (!confirm(`Delete ${r.type} record "${r.name}"?`)) return;
    setError(null);
    try {
      await api.dns.records.remove(selectedProviderId, selectedZone.id, r.id);
      loadRecords(selectedProviderId, selectedZone);
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  }

  async function toggleProviderEnabled(p: DnsProviderSummary) {
    try {
      await api.dns.providers.update(p.id, { enabled: !p.enabled });
      loadProviders();
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  }

  async function removeProvider(p: DnsProviderSummary) {
    if (!confirm(`Delete provider "${p.name}"? This removes its cached zones and records too.`)) return;
    try {
      await api.dns.providers.remove(p.id);
      if (selectedProviderId === p.id) setSelectedProviderId(null);
      loadProviders();
    } catch (err) {
      setError(err instanceof Error ? err.message : String(err));
    }
  }

  const selectedProvider = providers?.find((p) => p.id === selectedProviderId) ?? null;

  const { sorted: sortedProviders, sortKey: providerSortKey, sortDir: providerSortDir, requestSort: requestProviderSort } = useSortable(
    providers,
  );
  const { sorted: sortedZones, sortKey: zoneSortKey, sortDir: zoneSortDir, requestSort: requestZoneSort } = useSortable(zones);
  const { sorted: sortedRecords, sortKey: recordSortKey, sortDir: recordSortDir, requestSort: requestRecordSort } = useSortable(records);
  const { pageItems: zonePageItems, page: zonePage, setPage: setZonePage, pageCount: zonePageCount, totalCount: zoneTotalCount } =
    usePagination(sortedZones);
  const {
    pageItems: recordPageItems,
    page: recordPage,
    setPage: setRecordPage,
    pageCount: recordPageCount,
    totalCount: recordTotalCount,
  } = usePagination(sortedRecords);

  function exportProvidersCsv() {
    if (!sortedProviders) return;
    downloadCsv(
      "dns-providers.csv",
      ["Name", "Provider", "Status"],
      sortedProviders.map((p) => [p.name, PROVIDER_LABELS[p.providerType], p.enabled ? "Enabled" : "Disabled"]),
    );
  }

  function exportZonesCsv() {
    if (!sortedZones) return;
    downloadCsv(
      "dns-zones.csv",
      ["Zone", "Records", "Synced"],
      sortedZones.map((z) => [z.name, z.recordCount, z.syncedAt ? formatDateTime(new Date(z.syncedAt)) : "never"]),
    );
  }

  function exportRecordsCsv() {
    if (!sortedRecords) return;
    downloadCsv(
      `dns-records${selectedZone ? `-${selectedZone.name}` : ""}.csv`,
      ["Type", "Name", "Content", "TTL"],
      sortedRecords.map((r) => [r.type, r.name, r.content, r.ttl ?? ""]),
    );
  }

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

      {managingProviders ? (
        <>
          <DnsProviderForm
            onCreated={() => {
              loadProviders();
            }}
            onCancel={() => setManagingProviders(false)}
          />
          <div className="card">
            <div className="card-header justify-content-end">
              <button
                className="btn btn-outline-secondary btn-sm"
                onClick={exportProvidersCsv}
                disabled={!providers || providers.length === 0}
              >
                Export CSV
              </button>
            </div>
            <div className="table-responsive">
              <table className="table table-vcenter card-table">
                <thead>
                  <tr>
                    <SortableTh<DnsProviderSummary>
                      label="Name"
                      sortKeyName="name"
                      activeKey={providerSortKey}
                      direction={providerSortDir}
                      onSort={requestProviderSort}
                    />
                    <SortableTh<DnsProviderSummary>
                      label="Provider"
                      sortKeyName="providerType"
                      activeKey={providerSortKey}
                      direction={providerSortDir}
                      onSort={requestProviderSort}
                    />
                    <SortableTh<DnsProviderSummary>
                      label="Status"
                      sortKeyName="enabled"
                      activeKey={providerSortKey}
                      direction={providerSortDir}
                      onSort={requestProviderSort}
                    />
                    <th className="w-1">Actions</th>
                  </tr>
                </thead>
                <tbody>
                  {sortedProviders?.map((p) => (
                    <tr key={p.id}>
                      <td>{p.name}</td>
                      <td>
                        <span className="badge" style={providerBadgeStyle(providerColors, p.providerType)}>
                          {PROVIDER_LABELS[p.providerType]}
                        </span>
                      </td>
                      <td>
                        <button
                          className={`badge ${p.enabled ? "bg-green-lt text-green" : "bg-secondary-lt text-secondary"} border-0`}
                          onClick={() => toggleProviderEnabled(p)}
                        >
                          {p.enabled ? "Enabled" : "Disabled"}
                        </button>
                      </td>
                      <td>
                        <button className="btn btn-sm btn-outline-danger" onClick={() => removeProvider(p)}>
                          Delete
                        </button>
                      </td>
                    </tr>
                  ))}
                  {sortedProviders?.length === 0 && (
                    <tr>
                      <td colSpan={4} className="text-secondary text-center">
                        No DNS providers configured yet.
                      </td>
                    </tr>
                  )}
                </tbody>
              </table>
            </div>
          </div>
        </>
      ) : (
        <>
          {providers?.length === 0 ? (
            <div className="card">
              <div className="card-body text-secondary">
                No DNS providers configured yet.
                {isAdmin && (
                  <>
                    {" "}
                    <button className="btn btn-link p-0 align-baseline" onClick={() => setManagingProviders(true)}>
                      Add one
                    </button>
                    .
                  </>
                )}
              </div>
            </div>
          ) : (
            <>
              <div className="mb-3" style={{ maxWidth: 320 }}>
                <select
                  className="form-select"
                  value={selectedProviderId ?? ""}
                  onChange={(e) => setSelectedProviderId(Number(e.target.value))}
                >
                  {providers?.map((p) => (
                    <option key={p.id} value={p.id} disabled={!p.enabled}>
                      {p.name} ({PROVIDER_LABELS[p.providerType]}){!p.enabled ? " — disabled" : ""}
                    </option>
                  ))}
                </select>
              </div>

              <div className="row g-3">
                <div className="col-md-5">
                  <div className="card">
                    <div className="card-header">
                      <h3 className="card-title">Zones</h3>
                      <div className="card-actions">
                        <button
                          className="btn btn-sm btn-outline-secondary"
                          onClick={exportZonesCsv}
                          disabled={!sortedZones || sortedZones.length === 0}
                        >
                          Export CSV
                        </button>
                      </div>
                    </div>
                    {zonesError && <div className="alert alert-danger m-3 mb-0">{zonesError}</div>}
                    <div className="table-responsive">
                      <table className="table table-vcenter card-table">
                        <thead>
                          <tr>
                            <SortableTh<DnsZone> label="Zone" sortKeyName="name" activeKey={zoneSortKey} direction={zoneSortDir} onSort={requestZoneSort} />
                            <SortableTh<DnsZone>
                              label="Records"
                              sortKeyName="recordCount"
                              activeKey={zoneSortKey}
                              direction={zoneSortDir}
                              onSort={requestZoneSort}
                            />
                            <SortableTh<DnsZone>
                              label="Synced"
                              sortKeyName="syncedAt"
                              activeKey={zoneSortKey}
                              direction={zoneSortDir}
                              onSort={requestZoneSort}
                            />
                          </tr>
                        </thead>
                        <tbody>
                          {zonePageItems?.map((z) => (
                            <tr
                              key={z.id}
                              role="button"
                              className={selectedZone?.id === z.id ? "table-active" : ""}
                              onClick={() => selectZone(z)}
                            >
                              <td>{z.name}</td>
                              <td>{z.recordCount}</td>
                              <td className="text-secondary">
                                {z.syncedAt ? formatDateTime(new Date(z.syncedAt)) : "never"}
                              </td>
                            </tr>
                          ))}
                          {sortedZones && sortedZones.length === 0 && (
                            <tr>
                              <td colSpan={3} className="text-secondary text-center">
                                No zones found for this provider.
                              </td>
                            </tr>
                          )}
                        </tbody>
                      </table>
                    </div>
                    <Pagination page={zonePage} pageCount={zonePageCount} totalCount={zoneTotalCount} onPageChange={setZonePage} />
                  </div>
                </div>

                <div className="col-md-7">
                  {selectedZone ? (
                    <div className="card">
                      <div className="card-header">
                        <h3 className="card-title">{selectedZone.name}</h3>
                        <div className="card-actions">
                          <button
                            className="btn btn-sm btn-outline-secondary me-2"
                            onClick={exportRecordsCsv}
                            disabled={!sortedRecords || sortedRecords.length === 0}
                          >
                            Export CSV
                          </button>
                          {canEdit && (
                            <button className="btn btn-sm btn-outline-secondary me-2" onClick={syncZone} disabled={syncing}>
                              {syncing ? "Syncing…" : "Sync now"}
                            </button>
                          )}
                          {canEdit && !recordForm && (
                            <button className="btn btn-sm btn-primary" onClick={startAddRecord}>
                              Add record
                            </button>
                          )}
                        </div>
                      </div>

                      {recordForm && (
                        <form onSubmit={submitRecord}>
                          <div className="card-body row g-2">
                            <div className="col-2">
                              <label className="form-label">Type</label>
                              <input
                                className="form-control"
                                required
                                list="dns-record-types"
                                value={recordForm.type}
                                onChange={(e) => setRecordForm({ ...recordForm, type: e.target.value.toUpperCase() })}
                              />
                              <datalist id="dns-record-types">
                                {["A", "AAAA", "CNAME", "MX", "TXT", "NS", "PTR"].map((t) => (
                                  <option key={t} value={t} />
                                ))}
                              </datalist>
                            </div>
                            <div className="col-3">
                              <label className="form-label">Name</label>
                              <input
                                className="form-control"
                                required
                                value={recordForm.name}
                                onChange={(e) => setRecordForm({ ...recordForm, name: e.target.value })}
                              />
                            </div>
                            <div className="col-3">
                              <label className="form-label">Content</label>
                              <input
                                className="form-control"
                                required
                                value={recordForm.content}
                                onChange={(e) => setRecordForm({ ...recordForm, content: e.target.value })}
                              />
                            </div>
                            <div className="col-2">
                              <label className="form-label">TTL</label>
                              <input
                                type="number"
                                className="form-control"
                                value={recordForm.ttl ?? ""}
                                onChange={(e) => setRecordForm({ ...recordForm, ttl: Number(e.target.value) || undefined })}
                              />
                            </div>
                            <div className="col-2">
                              <label className="form-label">Priority</label>
                              <input
                                type="number"
                                className="form-control"
                                value={recordForm.priority ?? ""}
                                onChange={(e) =>
                                  setRecordForm({ ...recordForm, priority: e.target.value === "" ? undefined : Number(e.target.value) })
                                }
                              />
                            </div>
                            {selectedProvider?.providerType === "cloudflare" && (
                              <div className="col-12">
                                <label className="form-check">
                                  <input
                                    type="checkbox"
                                    className="form-check-input"
                                    checked={Boolean(recordForm.proxied)}
                                    onChange={(e) => setRecordForm({ ...recordForm, proxied: e.target.checked })}
                                  />
                                  <span className="form-check-label">Proxied through Cloudflare</span>
                                </label>
                              </div>
                            )}
                          </div>
                          <div className="card-footer d-flex gap-2">
                            <button type="submit" className="btn btn-primary" disabled={savingRecord}>
                              {editingRecordId ? "Save changes" : "Add record"}
                            </button>
                            <button type="button" className="btn" onClick={() => setRecordForm(null)}>
                              Cancel
                            </button>
                          </div>
                        </form>
                      )}

                      <div className="table-responsive">
                        <table className="table table-vcenter card-table">
                          <thead>
                            <tr>
                              <SortableTh<DnsRecord> label="Type" sortKeyName="type" activeKey={recordSortKey} direction={recordSortDir} onSort={requestRecordSort} />
                              <SortableTh<DnsRecord> label="Name" sortKeyName="name" activeKey={recordSortKey} direction={recordSortDir} onSort={requestRecordSort} />
                              <SortableTh<DnsRecord>
                                label="Content"
                                sortKeyName="content"
                                activeKey={recordSortKey}
                                direction={recordSortDir}
                                onSort={requestRecordSort}
                              />
                              <SortableTh<DnsRecord> label="TTL" sortKeyName="ttl" activeKey={recordSortKey} direction={recordSortDir} onSort={requestRecordSort} />
                              {canEdit && <th className="w-1">Actions</th>}
                            </tr>
                          </thead>
                          <tbody>
                            {recordPageItems?.map((r) => (
                              <tr key={r.id}>
                                <td>
                                  <span className="badge bg-blue-lt">{r.type}</span>
                                </td>
                                <td>{r.name}</td>
                                <td className="text-secondary">{r.content}</td>
                                <td>{r.ttl ?? "—"}</td>
                                {canEdit && (
                                  <td>
                                    <div className="btn-list flex-nowrap">
                                      <button className="btn btn-sm" onClick={() => startEditRecord(r)}>
                                        Edit
                                      </button>
                                      <button className="btn btn-sm btn-outline-danger" onClick={() => removeRecord(r)}>
                                        Delete
                                      </button>
                                    </div>
                                  </td>
                                )}
                              </tr>
                            ))}
                            {sortedRecords?.length === 0 && (
                              <tr>
                                <td colSpan={canEdit ? 5 : 4} className="text-secondary text-center">
                                  No cached records.{" "}
                                  {syncedAt === null ? "Sync this zone to fetch them." : ""}
                                </td>
                              </tr>
                            )}
                          </tbody>
                        </table>
                      </div>
                      <Pagination page={recordPage} pageCount={recordPageCount} totalCount={recordTotalCount} onPageChange={setRecordPage} />
                    </div>
                  ) : (
                    <div className="card">
                      <div className="card-body text-secondary">Select a zone to view its records.</div>
                    </div>
                  )}
                </div>
              </div>
            </>
          )}
        </>
      )}
    </>
  );
}