import { For, Show, createEffect, createMemo, createSignal, onCleanup, onMount, createResource } from 'solid-js';
import { useSearchParams } from '@solidjs/router';
import {
  BarChart3,
  Building2,
  CircleDashed,
  Coins,
  EllipsisVertical,
  Eye,
  EyeOff,
  GripVertical,
  LineChart,
  RotateCcw,
  Search,
  Settings2,
  TrendingUp,
  Users,
} from 'lucide-solid';
import {
  ADMIN_DASHBOARD_WIDGETS,
  type DashboardWidgetDefinition,
  type DashboardWidgetSize,
} from '~/lib/admin/dashboard';
import type { RuntimeDashboardLayout } from '~/lib/runtime/types';
import { loadAdminDashboardLayout, saveAdminDashboardLayout } from '~/lib/runtime/storage';

const API = '/api/gateway';

async function fetchMetrics() {
  const accessToken = typeof sessionStorage !== 'undefined'
    ? (sessionStorage.getItem('nxtgauge_admin_access_token') || '').trim()
    : '';
  const res = await fetch(`${API}/api/admin/dashboard/metrics`, {
    headers: {
      Accept: 'application/json',
      ...(accessToken ? { Authorization: `Bearer ${accessToken}` } : {}),
    },
    credentials: 'include',
  });
  if (!res.ok) throw new Error('Failed to load metrics');
  return res.json();
}

type WidgetStateKind = 'live' | 'empty' | 'pending';
type WidgetType = 'summary' | 'analytics';
type SortMode = 'layout' | 'name' | 'status';
type FilterMode = 'all' | WidgetType;
type GridLayoutMode = '3x4' | '3x3';

type WidgetMeta = {
  state: WidgetStateKind;
  type: WidgetType;
  statusLabel: string;
  subtitle: string;
  emptyMessage?: string;
  pendingMessage?: string;
};

const WIDGET_DEFINITION_MAP = Object.fromEntries(
  ADMIN_DASHBOARD_WIDGETS.map((definition) => [definition.widgetKey, definition])
);

const DEFAULT_LAYOUT: RuntimeDashboardLayout = {
  order: ADMIN_DASHBOARD_WIDGETS.slice()
    .sort((a, b) => a.order - b.order)
    .map((definition) => definition.widgetKey),
  visibility: Object.fromEntries(ADMIN_DASHBOARD_WIDGETS.map((definition) => [definition.widgetKey, definition.defaultVisible])),
  size: Object.fromEntries(ADMIN_DASHBOARD_WIDGETS.map((definition) => [definition.widgetKey, definition.defaultSize])),
};

const WIDGET_META: Record<string, WidgetMeta> = {
  kpi_total_users: {
    state: 'empty',
    type: 'summary',
    statusLabel: 'No Data',
    subtitle: 'Powered by USER_MANAGEMENT',
    emptyMessage: 'No user data available yet',
  },
  kpi_active_companies: {
    state: 'empty',
    type: 'summary',
    statusLabel: 'No Data',
    subtitle: 'Powered by COMPANY_MANAGEMENT',
    emptyMessage: 'No company data available yet',
  },
  kpi_open_leads: {
    state: 'empty',
    type: 'summary',
    statusLabel: 'No Data',
    subtitle: 'Powered by REQUIREMENTS_MANAGEMENT',
    emptyMessage: 'No lead data available yet',
  },
  kpi_credits_purchased: {
    state: 'empty',
    type: 'summary',
    statusLabel: 'No Data',
    subtitle: 'Powered by CREDIT_MANAGEMENT',
    emptyMessage: 'No credit activity available yet',
  },
  chart_leads_trend: {
    state: 'pending',
    type: 'analytics',
    statusLabel: 'Module Pending',
    subtitle: 'Monthly leads performance overview • Powered by REPORTS',
    pendingMessage: 'This widget will connect to live reporting data once the Reports module is completed',
  },
  chart_revenue_overview: {
    state: 'pending',
    type: 'analytics',
    statusLabel: 'Module Pending',
    subtitle: 'Monthly revenue vs expenses comparison • Powered by REVENUE_LEDGER',
    pendingMessage: 'This widget will connect to ledger-based analytics once the Revenue Ledger module is completed',
  },
};

function sanitizeLayout(layout: RuntimeDashboardLayout | null | undefined): RuntimeDashboardLayout {
  const knownKeys = new Set(ADMIN_DASHBOARD_WIDGETS.map((definition) => definition.widgetKey));
  const fallbackOrder = DEFAULT_LAYOUT.order;
  const incomingOrder = Array.isArray(layout?.order) ? layout!.order : [];

  const seen = new Set<string>();
  const normalizedOrder: string[] = [];

  for (const key of incomingOrder) {
    const normalizedKey = String(key || '');
    if (!knownKeys.has(normalizedKey) || seen.has(normalizedKey)) continue;
    seen.add(normalizedKey);
    normalizedOrder.push(normalizedKey);
  }

  for (const key of fallbackOrder) {
    if (!seen.has(key)) normalizedOrder.push(key);
  }

  const visibility: Record<string, boolean> = {};
  const size: Record<string, DashboardWidgetSize> = {};

  for (const definition of ADMIN_DASHBOARD_WIDGETS) {
    const key = definition.widgetKey;
    visibility[key] = typeof layout?.visibility?.[key] === 'boolean'
      ? Boolean(layout?.visibility?.[key])
      : definition.defaultVisible;

    const rawSize = String(layout?.size?.[key] || '').toUpperCase();
    size[key] = rawSize === 'S' || rawSize === 'M' || rawSize === 'L'
      ? (rawSize as DashboardWidgetSize)
      : definition.defaultSize;
  }

  return {
    order: normalizedOrder,
    visibility,
    size,
  };
}

function reorderKeys(order: string[], draggedKey: string, targetKey: string): string[] {
  if (draggedKey === targetKey) return order;
  const next = order.slice();
  const fromIndex = next.indexOf(draggedKey);
  const toIndex = next.indexOf(targetKey);
  if (fromIndex === -1 || toIndex === -1) return order;
  next.splice(fromIndex, 1);
  next.splice(toIndex, 0, draggedKey);
  return next;
}

function iconForWidget(widgetKey: string) {
  const cls = 'text-[#FA5014]';
  if (widgetKey.includes('users')) return <Users size={22} class={cls} />;
  if (widgetKey.includes('companies')) return <Building2 size={22} class={cls} />;
  if (widgetKey.includes('leads')) return <TrendingUp size={22} class={cls} />;
  if (widgetKey.includes('credits')) return <Coins size={22} class={cls} />;
  if (widgetKey.includes('revenue')) return <BarChart3 size={22} class={cls} />;
  return <LineChart size={22} class={cls} />;
}

function badgeClass(state: WidgetStateKind): string {
  if (state === 'live') return 'border-[#FDBA8C] bg-[#FFF1EB] text-[#FA5014]';
  if (state === 'pending') return 'border-[#D1D5DB] bg-[#F3F4F6] text-[#6B7280]';
  return 'border-[#E5E7EB] bg-white text-[#6B7280]';
}

function widgetSpan(mode: GridLayoutMode): string {
  return mode === '3x3' ? 'xl:col-span-4' : 'xl:col-span-3';
}

function EmptyPreview() {
  return (
    <div class="flex h-full flex-col items-center justify-center">
      <CircleDashed size={22} class="text-[#FA5014]" />
      <div class="mt-3 text-2xl font-bold leading-none text-[#9CA3AF]">--</div>
    </div>
  );
}

function PendingPreview() {
  return (
    <div class="flex h-full flex-col items-center justify-center gap-3">
      <LineChart size={22} class="text-[#FA5014]" />
      <div class="w-full max-w-[130px] space-y-2">
        <div class="h-2 rounded bg-[#E5E7EB]" />
        <div class="h-2 w-5/6 rounded bg-[#E5E7EB]" />
        <div class="h-2 w-4/6 rounded bg-[#E5E7EB]" />
      </div>
    </div>
  );
}

function LivePreview(props: { value?: string; trend?: string; trendUp?: boolean }) {
  return (
    <div class="flex h-full flex-col items-center justify-center">
      <p class="text-[26px] font-bold leading-none text-[#111827]">{props.value || '0'}</p>
      <p class="mt-2 inline-flex items-center gap-1 text-xs font-semibold text-[#FA5014]">
        {props.trendUp ? '↗' : '↘'} {props.trend || '0%'}
      </p>
    </div>
  );
}

export default function AdminHomePage() {
  const [searchParams] = useSearchParams();
  const [layout, setLayout] = createSignal<RuntimeDashboardLayout>(sanitizeLayout(DEFAULT_LAYOUT));
  const [settingsOpen, setSettingsOpen] = createSignal(false);
  const [isHydrating, setIsHydrating] = createSignal(true);
  const [isAutoSaving, setIsAutoSaving] = createSignal(false);
  const [autoSaveNotice, setAutoSaveNotice] = createSignal('');
  const [lastSavedSnapshot, setLastSavedSnapshot] = createSignal('');
  const [draggingKey, setDraggingKey] = createSignal<string | null>(null);
  const [openMenuId, setOpenMenuId] = createSignal<string | null>(null);

  const [search, setSearch] = createSignal('');
  const [filterMode, setFilterMode] = createSignal<FilterMode>('all');
  const [sortMode, setSortMode] = createSignal<SortMode>('layout');
  const [gridLayout, setGridLayout] = createSignal<GridLayoutMode>('3x4');

  const [metrics] = createResource(fetchMetrics);

  const getWidgetState = (key: string) => {
    if (key.startsWith('kpi_')) {
      const idMap: Record<string, string> = {
        kpi_total_users: 'users',
        kpi_active_companies: 'companies',
        kpi_open_leads: 'leads',
        kpi_credits_purchased: 'credits',
      };
      if (metrics.loading) return { state: 'pending', statusLabel: 'Loading...' };
      const m = metrics()?.kpis?.find((k: any) => k.id === idMap[key]);
      if (m) return { state: 'live', statusLabel: 'Live Data', data: m };
      return { state: 'empty', statusLabel: 'No Data' };
    }
    const meta = WIDGET_META[key];
    return { state: meta?.state || 'empty', statusLabel: meta?.statusLabel || 'No Data' };
  };

  const orderedWidgets = createMemo(() => {
    const current = layout();
    const rows = current.order
      .map((key) => WIDGET_DEFINITION_MAP[key])
      .filter((definition): definition is DashboardWidgetDefinition => Boolean(definition))
      .filter((definition) => current.visibility[definition.widgetKey] !== false)
      .filter((definition) => {
        const query = search().trim().toLowerCase();
        if (!query) return true;
        const meta = WIDGET_META[definition.widgetKey];
        return definition.title.toLowerCase().includes(query)
          || definition.moduleKey.toLowerCase().includes(query)
          || (meta?.subtitle || '').toLowerCase().includes(query);
      })
      .filter((definition) => {
        const mode = filterMode();
        if (mode === 'all') return true;
        return (WIDGET_META[definition.widgetKey]?.type || 'summary') === mode;
      });

    const mode = sortMode();
    if (mode === 'layout') return rows;

    const next = rows.slice();
    next.sort((a, b) => {
      if (mode === 'name') return a.title.localeCompare(b.title);
      const rank = (key: string) => {
        const info = getWidgetState(key);
        if (info.state === 'live') return 1;
        if (info.state === 'empty') return 2;
        return 3;
      };
      return rank(a.widgetKey) - rank(b.widgetKey);
    });

    return next;
  });

  onMount(async () => {
    try {
      const persistedLayout = await loadAdminDashboardLayout();
      const normalized = sanitizeLayout(persistedLayout || DEFAULT_LAYOUT);
      setLayout(normalized);
      setLastSavedSnapshot(JSON.stringify(normalized));
    } finally {
      setIsHydrating(false);
    }
  });

  createEffect(() => {
    if (isHydrating()) return;
    const nextLayout = layout();
    const nextSnapshot = JSON.stringify(nextLayout);
    if (nextSnapshot === lastSavedSnapshot()) return;

    setIsAutoSaving(true);
    setAutoSaveNotice('');

    const timer = setTimeout(async () => {
      const ok = await saveAdminDashboardLayout(nextLayout);
      setIsAutoSaving(false);
      if (ok) {
        setLastSavedSnapshot(nextSnapshot);
        setAutoSaveNotice('Layout saved automatically.');
      } else {
        setAutoSaveNotice('Auto-save failed. Please try again.');
      }
    }, 450);

    onCleanup(() => clearTimeout(timer));
  });

  const setWidgetVisibility = (widgetKey: string, visible: boolean) => {
    setLayout((current) => ({
      ...current,
      visibility: {
        ...current.visibility,
        [widgetKey]: visible,
      },
    }));
  };

  const resetLayout = () => {
    const normalized = sanitizeLayout(DEFAULT_LAYOUT);
    setLayout(normalized);
    setAutoSaveNotice('Layout reset to default.');
  };

  const handleDragStart = (event: DragEvent, widgetKey: string) => {
    event.dataTransfer?.setData('text/plain', widgetKey);
    if (event.dataTransfer) event.dataTransfer.effectAllowed = 'move';
    setDraggingKey(widgetKey);
  };

  const handleDrop = (event: DragEvent, targetKey: string) => {
    event.preventDefault();
    const dragged = event.dataTransfer?.getData('text/plain') || draggingKey();
    if (!dragged) return;

    setLayout((current) => ({
      ...current,
      order: reorderKeys(current.order, dragged, targetKey),
    }));
    setDraggingKey(null);
  };

  return (
      <div class="w-full">
        <Show when={Boolean(searchParams.denied)}>
          <div class="rounded-2xl border border-[#E5E7EB] bg-white shadow-sm" style="margin-bottom: 18px">
            <p class="notice">You don’t have access to {String(searchParams.denied || '').replace(/_/g, ' ')}.</p>
          </div>
        </Show>
        <div class="rounded-2xl border border-[#E5E7EB] bg-white px-6 py-5 shadow-sm md:px-8" style="margin-bottom: 28px">
          <div class="flex flex-col gap-3 sm:flex-row sm:items-center sm:justify-between">
            <div>
              <h1 class="text-[22px] font-bold leading-tight text-[#111827]">Dashboard Overview</h1>
              <p class="mt-0.5 text-[13px] text-[#6B7280]">Manage widget layout, visibility, sizing, and dashboard presentation</p>
            </div>

            <div class="flex shrink-0">
              <button
                type="button"
                class="inline-flex h-9 items-center gap-1.5 whitespace-nowrap rounded-xl bg-[#0D0D2A] px-5 text-[13px] font-semibold leading-none text-white shadow-sm"
                onClick={() => {
                  const next = !settingsOpen();
                  setSettingsOpen(next);
                  if (!next) setOpenMenuId(null);
                }}
              >
                <Settings2 size={14} class="text-[#FA5014]" />
                {settingsOpen() ? 'Close Settings' : 'Customize Widgets'}
              </button>
            </div>
          </div>
        </div>

        <Show when={settingsOpen()}>
          <div class="rounded-2xl border border-[#E5E7EB] bg-white p-6 shadow-sm md:p-7">
            {/* Settings header */}
            <div class="flex flex-wrap items-start justify-between gap-4">
              <div>
                <h2 class="text-[15px] font-semibold text-[#111827]">Widget Settings</h2>
                <p class="mt-1 text-[13px] text-[#6B7280]">Choose visible widgets and select a grid layout.</p>
              </div>
              <button
                type="button"
                class="inline-flex h-9 items-center gap-1.5 rounded-lg border border-[#E5E7EB] bg-white px-3 text-xs font-semibold text-[#111827] shadow-sm"
                onClick={resetLayout}
              >
                <RotateCcw size={13} class="text-[#FA5014]" />
                Reset Layout
              </button>
            </div>

            {/* Filter controls */}
            <div class="mt-5 flex flex-wrap gap-3">
              <div class="relative min-w-[200px] flex-1">
                <Search size={14} class="pointer-events-none absolute left-3 top-1/2 -translate-y-1/2 text-[#FA5014]" style="z-index:1" />
                <input
                  value={search()}
                  onInput={(event) => setSearch(event.currentTarget.value)}
                  placeholder="Search widgets"
                  class="h-10 w-full rounded-lg border border-[#E5E7EB] bg-white pl-10 pr-3 text-sm text-[#111827] outline-none focus:border-[#FA5014]"
                />
              </div>

              <select
                class="h-10 rounded-lg border border-[#E5E7EB] bg-white px-3 text-sm text-[#111827]"
                value={filterMode()}
                onChange={(event) => setFilterMode(event.currentTarget.value as FilterMode)}
              >
                <option value="all">All Widgets</option>
                <option value="summary">Summary Only</option>
                <option value="analytics">Analytical Only</option>
              </select>

              <select
                class="h-10 rounded-lg border border-[#E5E7EB] bg-white px-3 text-sm text-[#111827]"
                value={sortMode()}
                onChange={(event) => setSortMode(event.currentTarget.value as SortMode)}
              >
                <option value="layout">Layout Order</option>
                <option value="name">Name</option>
                <option value="status">Status</option>
              </select>

              <select
                class="h-10 rounded-lg border border-[#E5E7EB] bg-white px-3 text-sm text-[#111827]"
                value={gridLayout()}
                onChange={(event) => setGridLayout(event.currentTarget.value as GridLayoutMode)}
              >
                <option value="3x4">Grid 3 × 4</option>
                <option value="3x3">Grid 3 × 3</option>
              </select>
            </div>

            {/* Widget list */}
            <div class="mt-5 grid gap-3 md:grid-cols-2">
              <For each={ADMIN_DASHBOARD_WIDGETS}>
                {(definition) => {
                  const visible = () => layout().visibility[definition.widgetKey] !== false;
                  const meta = WIDGET_META[definition.widgetKey];
                  const stateInfo = getWidgetState(definition.widgetKey);
                  const state = stateInfo.state;

                  return (
                    <div class="flex items-center justify-between gap-4 rounded-xl border border-[#E5E7EB] bg-[#F9FAFB] px-4 py-4">
                      <div class="flex items-center gap-3 min-w-0">
                        <div class="shrink-0 text-[#FA5014]">
                          {iconForWidget(definition.widgetKey)}
                        </div>
                        <div class="min-w-0">
                          <p class="text-sm font-semibold text-[#111827]">{definition.title}</p>
                          <p class="mt-0.5 text-[11px] font-medium uppercase tracking-wide text-[#9CA3AF]">{definition.moduleKey}</p>
                        </div>
                      </div>
                      <div class="flex shrink-0 items-center gap-2">
                        <span class={`hidden rounded-full border px-2 py-0.5 text-[10px] font-semibold sm:inline-flex ${badgeClass(state as WidgetStateKind)}`}>
                          {stateInfo.statusLabel}
                        </span>
                        <button
                          type="button"
                          class={`inline-flex h-8 items-center gap-1.5 rounded-md border px-3 text-xs font-semibold ${
                            visible()
                              ? 'border-[#FDBA8C] bg-[#FFF1EB] text-[#FA5014]'
                              : 'border-[#E5E7EB] bg-white text-[#6B7280]'
                          }`}
                          onClick={() => setWidgetVisibility(definition.widgetKey, !visible())}
                        >
                          {visible() ? <Eye size={12} /> : <EyeOff size={12} />}
                          {visible() ? 'Visible' : 'Hidden'}
                        </button>
                      </div>
                    </div>
                  );
                }}
              </For>
            </div>

            <Show when={isAutoSaving() || autoSaveNotice()}>
              <p class="mt-4 text-xs text-[#6B7280]">{isAutoSaving() ? 'Saving layout...' : autoSaveNotice()}</p>
            </Show>
          </div>
        </Show>

        <div class="grid grid-cols-1 gap-5 xl:grid-cols-12" style="margin-top: 28px">
            <For each={orderedWidgets()}>
              {(definition) => {
                const meta = WIDGET_META[definition.widgetKey];
                const stateInfo = getWidgetState(definition.widgetKey);
                const state = stateInfo.state;
                const isOpenMenu = () => openMenuId() === definition.widgetKey;

                return (
                  <section
                    draggable={settingsOpen()}
                    onDragStart={(event) => handleDragStart(event, definition.widgetKey)}
                    onDragOver={(event) => event.preventDefault()}
                    onDrop={(event) => handleDrop(event, definition.widgetKey)}
                    onDragEnd={() => setDraggingKey(null)}
                    class={`relative aspect-square min-h-[235px] rounded-2xl border border-[#E5E7EB] bg-white p-5 shadow-sm md:min-h-[260px] md:p-6 ${widgetSpan(gridLayout())} ${
                      state === 'pending' ? 'opacity-95' : ''
                    } ${draggingKey() === definition.widgetKey ? 'opacity-60' : ''}`}
                  >
                    <Show when={settingsOpen()}>
                      <>
                        <button
                          type="button"
                          class="absolute left-3 top-3 inline-flex h-8 w-8 items-center justify-center rounded-md border border-[#E5E7EB] bg-white cursor-grab text-[#FA5014]"
                          aria-label="Drag to reorder"
                        >
                          <GripVertical size={14} class="text-[#FA5014]" />
                        </button>
                        <div class="absolute right-3 top-3">
                          <button
                            type="button"
                            class="inline-flex h-8 w-8 items-center justify-center rounded-md border border-[#E5E7EB] bg-white text-[#FA5014]"
                            onClick={() => setOpenMenuId(isOpenMenu() ? null : definition.widgetKey)}
                          >
                            <EllipsisVertical size={14} class="text-[#FA5014]" />
                          </button>

                          <Show when={isOpenMenu()}>
                            <div class="absolute right-0 top-10 z-20 w-40 rounded-lg border border-[#E5E7EB] bg-white p-1 shadow-md">
                              {['Edit Widget', 'Duplicate Widget', 'Hide Widget', 'Remove Widget'].map((item) => (
                                <button
                                  type="button"
                                  class="block w-full rounded-md px-2 py-2 text-left text-xs font-medium text-[#111827] hover:bg-[#F9FAFB]"
                                  onClick={() => setOpenMenuId(null)}
                                >
                                  {item}
                                </button>
                              ))}
                            </div>
                          </Show>
                        </div>
                      </>
                    </Show>

                    <div class="flex h-full flex-col items-center justify-center px-4">
                      <div class="mb-3 text-[#FA5014]">
                        {iconForWidget(definition.widgetKey)}
                      </div>
                      <h3 class="text-center text-[15px] font-semibold text-[#111827]">{definition.title}</h3>
                      <div class="mt-4 h-[116px] w-full max-w-[210px] rounded-xl border border-[#E5E7EB] bg-[#F9FAFB] p-4">
                        <Show when={state === 'live'}>
                          <LivePreview value={stateInfo.data?.value} trend={stateInfo.data?.trend} trendUp={stateInfo.data?.trendUp} />
                        </Show>
                        <Show when={state === 'empty'}>
                          <EmptyPreview />
                        </Show>
                        <Show when={state === 'pending'}>
                          <PendingPreview />
                        </Show>
                      </div>
                      <span class={`mt-4 inline-flex rounded-full border px-2 py-1 text-[11px] font-semibold ${badgeClass(state as WidgetStateKind)}`}>
                        {stateInfo.statusLabel}
                      </span>
                    </div>
                  </section>
                );
              }}
            </For>
        </div>
      </div>
  );
}