"use client";

import React from "react";
import { useEffect, useState, useCallback } from "react";
import {
  fetchKpis, fetchRackBreakdown, fetchRoomPowerHistory, fetchUpsStatus, fetchCapacitySummary,
  fetchGeneratorStatus, fetchAtsStatus, fetchPowerRedundancy, fetchPhaseBreakdown,
  type KpiData, type RoomPowerBreakdown, type PowerHistoryBucket, type UpsAsset, type CapacitySummary,
  type GeneratorStatus, type AtsStatus, type PowerRedundancy, type RoomPhase,
} from "@/lib/api";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { Skeleton } from "@/components/ui/skeleton";
import { Tabs, TabsList, TabsTrigger } from "@/components/ui/tabs";
import {
  BarChart, Bar, XAxis, YAxis, CartesianGrid, Tooltip, ResponsiveContainer, ReferenceLine,
  AreaChart, Area, Cell,
} from "recharts";
import { Zap, Battery, AlertTriangle, CheckCircle2, Activity, Fuel, ArrowLeftRight, ShieldCheck, Server, Thermometer, Gauge } from "lucide-react";
import { UpsDetailSheet } from "@/components/dashboard/ups-detail-sheet";
import { cn } from "@/lib/utils";

const SITE_ID = "sg-01";

const ROOM_COLORS: Record<string, string> = {
  "hall-a": "oklch(0.62 0.17 212)",
  "hall-b": "oklch(0.7 0.15 162)",
};

const roomLabels: Record<string, string> = {
  "hall-a": "Hall A",
  "hall-b": "Hall B",
};

function formatTime(iso: string) {
  return new Date(iso).toLocaleTimeString([], { hour: "2-digit", minute: "2-digit" });
}

// ── Site capacity bar ─────────────────────────────────────────────────────────

function SiteCapacityBar({ usedKw, capacityKw }: { usedKw: number; capacityKw: number }) {
  const pct = capacityKw > 0 ? Math.min(100, (usedKw / capacityKw) * 100) : 0;
  const barColor =
    pct >= 85 ? "bg-destructive" :
    pct >= 70 ? "bg-amber-500"   :
    "bg-primary";
  const textColor =
    pct >= 85 ? "text-destructive" :
    pct >= 70 ? "text-amber-400"   :
    "text-green-400";

  return (
    <div className="rounded-xl border border-border bg-muted/10 px-5 py-4 space-y-3">
      <div className="flex items-center justify-between">
        <div className="flex items-center gap-2 text-sm font-medium">
          <Zap className="w-4 h-4 text-primary" />
          Site IT Load vs Rated Capacity
        </div>
        <span className={cn("text-xs font-semibold", textColor)}>
          {pct.toFixed(1)}% utilised
        </span>
      </div>
      <div className="h-3 rounded-full bg-muted overflow-hidden">
        <div
          className={cn("h-full rounded-full transition-all duration-700", barColor)}
          style={{ width: `${pct}%` }}
        />
      </div>
      <div className="flex justify-between text-xs text-muted-foreground">
        <span>
          <strong className="text-foreground">{usedKw.toFixed(1)} kW</strong> in use
        </span>
        <span>
          <strong className="text-foreground">{(capacityKw - usedKw).toFixed(1)} kW</strong> headroom
        </span>
        <span>
          <strong className="text-foreground">{capacityKw.toFixed(0)} kW</strong> rated
        </span>
      </div>
    </div>
  );
}

// ── KPI card ──────────────────────────────────────────────────────────────────

function KpiCard({ label, value, sub, icon: Icon, accent }: {
  label: string; value: string; sub?: string; icon: React.ElementType; accent?: boolean
}) {
  return (
    <Card>
      <CardContent className="p-4 flex items-center gap-3">
        <div className={cn("p-2 rounded-lg", accent ? "bg-primary/10" : "bg-muted")}>
          <Icon className={cn("w-4 h-4", accent ? "text-primary" : "text-muted-foreground")} />
        </div>
        <div>
          <p className="text-2xl font-bold">{value}</p>
          <p className="text-xs text-muted-foreground">{label}</p>
          {sub && <p className="text-[10px] text-muted-foreground">{sub}</p>}
        </div>
      </CardContent>
    </Card>
  );
}

// ── UPS card ──────────────────────────────────────────────────────────────────

function UpsCard({ ups, onClick }: { ups: UpsAsset; onClick: () => void }) {
  const onBattery = ups.state === "battery";
  const overload  = ups.state === "overload";
  const abnormal  = onBattery || overload;
  const charge    = ups.charge_pct ?? 0;
  const runtime   = ups.runtime_min ?? null;

  return (
    <Card
      className={cn("border cursor-pointer hover:border-primary/40 transition-colors",
        overload  && "border-destructive/50",
        onBattery && !overload && "border-amber-500/40",
      )}
      onClick={onClick}
    >
      <CardHeader className="pb-2">
        <div className="flex items-center justify-between">
          <CardTitle className="text-sm font-semibold flex items-center gap-2">
            <Battery className="w-4 h-4 text-primary" />
            {ups.ups_id.toUpperCase()}
          </CardTitle>
          <span className={cn(
            "flex items-center gap-1.5 text-[10px] font-semibold px-2 py-0.5 rounded-full uppercase tracking-wide",
            overload  ? "bg-destructive/10 text-destructive" :
            onBattery ? "bg-amber-500/10 text-amber-400" :
            "bg-green-500/10 text-green-400"
          )}>
            {abnormal ? <AlertTriangle className="w-3 h-3" /> : <CheckCircle2 className="w-3 h-3" />}
            {overload ? "Overloaded" : onBattery ? "On Battery" : "Mains"}
          </span>
        </div>
      </CardHeader>
      <CardContent className="space-y-3">
        {/* Battery charge */}
        <div className="space-y-1">
          <div className="flex justify-between text-[11px] text-muted-foreground">
            <span>Battery charge</span>
            <span className="font-medium text-foreground">{ups.charge_pct !== null ? `${ups.charge_pct}%` : "—"}</span>
          </div>
          <div className="h-2 rounded-full bg-muted overflow-hidden">
            <div
              className={cn("h-full rounded-full transition-all duration-500",
                charge < 50 ? "bg-destructive" : charge < 80 ? "bg-amber-500" : "bg-green-500"
              )}
              style={{ width: `${charge}%` }}
            />
          </div>
        </div>

        <div className="grid grid-cols-3 gap-3 text-xs">
          <div>
            <p className="text-muted-foreground">Load</p>
            <p className={cn("font-semibold",
              (ups.load_pct ?? 0) >= 95 ? "text-destructive" :
              (ups.load_pct ?? 0) >= 85 ? "text-amber-400" : "",
            )}>
              {ups.load_pct !== null ? `${ups.load_pct}%` : "—"}
            </p>
          </div>
          <div>
            <p className="text-muted-foreground">Runtime</p>
            <p className={cn(
              "font-semibold",
              runtime !== null && runtime < 5  ? "text-destructive" :
              runtime !== null && runtime < 15 ? "text-amber-400" : ""
            )}>
              {runtime !== null ? `${Math.round(runtime)} min` : "—"}
            </p>
          </div>
          <div>
            <p className="text-muted-foreground">Voltage</p>
            <p className={cn("font-semibold",
              ups.voltage_v !== null && (ups.voltage_v < 210 || ups.voltage_v > 250) ? "text-amber-400" : "",
            )}>
              {ups.voltage_v !== null ? `${ups.voltage_v} V` : "—"}
            </p>
          </div>
        </div>

        {/* Runtime bar */}
        {runtime !== null && (
          <div className="space-y-1">
            <div className="flex justify-between text-[10px] text-muted-foreground">
              <span>Est. runtime remaining</span>
              <span className={cn(
                "font-medium",
                runtime < 5  ? "text-destructive" :
                runtime < 15 ? "text-amber-400"   : "text-green-400"
              )}>
                {runtime < 5 ? "Critical" : runtime < 15 ? "Low" : "OK"}
              </span>
            </div>
            <div className="h-2 rounded-full bg-muted overflow-hidden">
              <div
                className={cn("h-full rounded-full transition-all duration-500",
                  runtime < 5  ? "bg-destructive" :
                  runtime < 15 ? "bg-amber-500"   : "bg-green-500"
                )}
                style={{ width: `${Math.min(100, (runtime / 120) * 100)}%` }}
              />
            </div>
          </div>
        )}

        <p className="text-[10px] text-muted-foreground/50 text-right">Click for details</p>
      </CardContent>
    </Card>
  );
}

// ── Rack bar chart ────────────────────────────────────────────────────────────

function RackPowerChart({ rooms }: { rooms: RoomPowerBreakdown[] }) {
  const [activeRoom, setActiveRoom] = useState(rooms[0]?.room_id ?? "");
  const room = rooms.find((r) => r.room_id === activeRoom);

  if (!room) return null;

  const maxKw = Math.max(...room.racks.map((r) => r.power_kw ?? 0), 1);

  return (
    <Card>
      <CardHeader className="pb-2">
        <div className="flex items-center justify-between">
          <CardTitle className="text-sm font-semibold">Per-Rack Power (kW)</CardTitle>
          <Tabs value={activeRoom} onValueChange={setActiveRoom}>
            <TabsList className="h-7">
              {rooms.map((r) => (
                <TabsTrigger key={r.room_id} value={r.room_id} className="text-xs px-2 py-0.5">
                  {roomLabels[r.room_id] ?? r.room_id}
                </TabsTrigger>
              ))}
            </TabsList>
          </Tabs>
        </div>
      </CardHeader>
      <CardContent>
        <div className="flex items-center gap-3 mb-3 text-[10px] text-muted-foreground">
          {[
            { color: "oklch(0.62 0.17 212)", label: "Normal" },
            { color: "oklch(0.68 0.14 162)", label: "Moderate" },
            { color: "oklch(0.65 0.20 45)",  label: "High (≥7.5 kW)" },
            { color: "oklch(0.55 0.22 25)",  label: "Critical (≥9.5 kW)" },
          ].map(({ color, label }) => (
            <span key={label} className="flex items-center gap-1">
              <span className="w-3 h-2 rounded-sm inline-block" style={{ backgroundColor: color }} />
              {label}
            </span>
          ))}
        </div>
        <ResponsiveContainer width="100%" height={220}>
          <BarChart data={room.racks} margin={{ top: 4, right: 4, left: -20, bottom: 0 }}>
            <CartesianGrid strokeDasharray="3 3" stroke="oklch(1 0 0 / 8%)" />
            <XAxis
              dataKey="rack_id"
              tick={{ fontSize: 9, fill: "oklch(0.65 0.04 257)" }}
              tickLine={false}
              axisLine={false}
              tickFormatter={(v) => v.replace("rack-", "")}
            />
            <YAxis
              tick={{ fontSize: 10, fill: "oklch(0.65 0.04 257)" }}
              tickLine={false}
              axisLine={false}
              domain={[0, Math.ceil(maxKw * 1.2)]}
            />
            <Tooltip
              contentStyle={{ backgroundColor: "oklch(0.16 0.04 265)", border: "1px solid oklch(1 0 0 / 9%)", borderRadius: "6px", fontSize: "12px" }}
              formatter={(v) => [`${v} kW`, "Power"]}
              labelFormatter={(l) => l}
            />
            <ReferenceLine y={7.5} stroke="oklch(0.72 0.18 84)" strokeDasharray="4 4" strokeWidth={1}
              label={{ value: "Warn 7.5kW", fontSize: 9, fill: "oklch(0.72 0.18 84)", position: "insideTopRight" }} />
            <ReferenceLine y={9.5} stroke="oklch(0.55 0.22 25)" strokeDasharray="4 4" strokeWidth={1}
              label={{ value: "Crit 9.5kW", fontSize: 9, fill: "oklch(0.55 0.22 25)", position: "insideTopRight" }} />
            <Bar dataKey="power_kw" radius={[3, 3, 0, 0]} maxBarSize={32}>
              {room.racks.map((r) => (
                <Cell
                  key={r.rack_id}
                  fill={
                    (r.power_kw ?? 0) >= 9.5 ? "oklch(0.55 0.22 25)"  :
                    (r.power_kw ?? 0) >= 7.5 ? "oklch(0.65 0.20 45)"  :
                    (r.power_kw ?? 0) >= 4.0 ? "oklch(0.68 0.14 162)" :
                    ROOM_COLORS[room.room_id] ?? "oklch(0.62 0.17 212)"
                  }
                />
              ))}
            </Bar>
          </BarChart>
        </ResponsiveContainer>
      </CardContent>
    </Card>
  );
}

// ── Room power history chart ──────────────────────────────────────────────────

function RoomPowerHistoryChart({ data }: { data: PowerHistoryBucket[] }) {
  type Row = { time: string; [room: string]: string | number };
  const bucketMap = new Map<string, Row>();
  for (const row of data) {
    const time = formatTime(row.bucket);
    if (!bucketMap.has(time)) bucketMap.set(time, { time });
    bucketMap.get(time)![row.room_id] = row.total_kw;
  }
  const chartData = Array.from(bucketMap.values());
  const roomIds = [...new Set(data.map((d) => d.room_id))].sort();

  return (
    <Card>
      <CardHeader className="pb-2">
        <div className="flex items-center justify-between">
          <CardTitle className="text-sm font-semibold">Power by Room</CardTitle>
          <div className="flex items-center gap-3 text-xs text-muted-foreground">
            {roomIds.map((id) => (
              <span key={id} className="flex items-center gap-1">
                <span className="w-3 h-0.5 inline-block" style={{ backgroundColor: ROOM_COLORS[id] }} />
                {roomLabels[id] ?? id}
              </span>
            ))}
          </div>
        </div>
      </CardHeader>
      <CardContent>
        {chartData.length === 0 ? (
          <div className="h-[200px] flex items-center justify-center text-sm text-muted-foreground">
            Waiting for data...
          </div>
        ) : (
          <ResponsiveContainer width="100%" height={200}>
            <AreaChart data={chartData} margin={{ top: 4, right: 4, left: -20, bottom: 0 }}>
              <defs>
                {roomIds.map((id) => (
                  <linearGradient key={id} id={`grad-${id}`} x1="0" y1="0" x2="0" y2="1">
                    <stop offset="5%"  stopColor={ROOM_COLORS[id]} stopOpacity={0.3} />
                    <stop offset="95%" stopColor={ROOM_COLORS[id]} stopOpacity={0} />
                  </linearGradient>
                ))}
              </defs>
              <CartesianGrid strokeDasharray="3 3" stroke="oklch(1 0 0 / 8%)" />
              <XAxis dataKey="time" tick={{ fontSize: 10, fill: "oklch(0.65 0.04 257)" }} tickLine={false} axisLine={false} />
              <YAxis tick={{ fontSize: 10, fill: "oklch(0.65 0.04 257)" }} tickLine={false} axisLine={false} />
              <Tooltip
                contentStyle={{ backgroundColor: "oklch(0.16 0.04 265)", border: "1px solid oklch(1 0 0 / 9%)", borderRadius: "6px", fontSize: "12px" }}
                formatter={(v, name) => [`${v} kW`, roomLabels[String(name)] ?? String(name)]}
              />
              {roomIds.map((id) => (
                <Area key={id} type="monotone" dataKey={id} stroke={ROOM_COLORS[id]} fill={`url(#grad-${id})`} strokeWidth={2} dot={false} />
              ))}
            </AreaChart>
          </ResponsiveContainer>
        )}
      </CardContent>
    </Card>
  );
}

// ── Generator card ────────────────────────────────────────────────

function GeneratorCard({ gen }: { gen: GeneratorStatus }) {
  const faulted  = gen.state === "fault";
  const running  = gen.state === "running" || gen.state === "test";
  const fuel     = gen.fuel_pct ?? 0;
  const stateLabel = { standby: "Standby", running: "Running", test: "Test Run", fault: "FAULT", unknown: "Unknown" }[gen.state] ?? gen.state;

  return (
    <Card className={cn("border", faulted && "border-destructive/50")}>
      <CardHeader className="pb-2">
        <div className="flex items-center justify-between">
          <CardTitle className="text-sm font-semibold flex items-center gap-2">
            <Fuel className="w-4 h-4 text-primary" />
            {gen.gen_id.toUpperCase()}
          </CardTitle>
          <span className={cn("text-[10px] font-semibold px-2 py-0.5 rounded-full uppercase tracking-wide",
            faulted ? "bg-destructive/10 text-destructive" :
            running ? "bg-amber-500/10 text-amber-400" :
            "bg-green-500/10 text-green-400",
          )}>
            {faulted ? <AlertTriangle className="w-3 h-3 inline mr-0.5" /> : <CheckCircle2 className="w-3 h-3 inline mr-0.5" />}
            {stateLabel}
          </span>
        </div>
      </CardHeader>
      <CardContent className="space-y-3">
        <div className="space-y-1">
          <div className="flex justify-between text-[11px] text-muted-foreground">
            <span>Fuel level</span>
            <span className={cn("font-medium", fuel < 10 ? "text-destructive" : fuel < 25 ? "text-amber-400" : "text-foreground")}>
              {gen.fuel_pct != null ? `${gen.fuel_pct.toFixed(1)}%` : "—"}
              {gen.fuel_litres != null ? ` (${gen.fuel_litres.toFixed(0)} L)` : ""}
            </span>
          </div>
          <div className="h-2 rounded-full bg-muted overflow-hidden">
            <div className={cn("h-full rounded-full transition-all duration-500",
              fuel < 10 ? "bg-destructive" : fuel < 25 ? "bg-amber-500" : "bg-green-500"
            )} style={{ width: `${fuel}%` }} />
          </div>
        </div>
        <div className="grid grid-cols-2 gap-3 text-xs">
          <div><p className="text-muted-foreground">Load</p>
            <p className={cn("font-semibold",
              (gen.load_pct ?? 0) >= 95 ? "text-destructive" :
              (gen.load_pct ?? 0) >= 85 ? "text-amber-400" : ""
            )}>
              {gen.load_kw != null ? `${gen.load_kw} kW (${gen.load_pct}%)` : "—"}
            </p>
          </div>
          <div><p className="text-muted-foreground">Run hours</p>
            <p className="font-semibold">{gen.run_hours != null ? `${gen.run_hours.toFixed(0)} h` : "—"}</p></div>
          <div><p className="text-muted-foreground">Output voltage</p>
            <p className="font-semibold">{gen.voltage_v != null && gen.voltage_v > 0 ? `${gen.voltage_v} V` : "—"}</p></div>
          <div><p className="text-muted-foreground">Frequency</p>
            <p className="font-semibold">{gen.frequency_hz != null && gen.frequency_hz > 0 ? `${gen.frequency_hz} Hz` : "—"}</p></div>
          <div><p className="text-muted-foreground flex items-center gap-1">
            <Thermometer className="w-3 h-3" />Coolant
          </p>
            <p className={cn("font-semibold",
              (gen.coolant_temp_c ?? 0) >= 105 ? "text-destructive" :
              (gen.coolant_temp_c ?? 0) >= 95  ? "text-amber-400" : ""
            )}>
              {gen.coolant_temp_c != null ? `${gen.coolant_temp_c}°C` : "—"}
            </p>
          </div>
          <div><p className="text-muted-foreground flex items-center gap-1">
            <Thermometer className="w-3 h-3" />Exhaust
          </p>
            <p className="font-semibold">{gen.exhaust_temp_c != null && gen.exhaust_temp_c > 0 ? `${gen.exhaust_temp_c}°C` : "—"}</p>
          </div>
          <div><p className="text-muted-foreground flex items-center gap-1">
            <Gauge className="w-3 h-3" />Oil pressure
          </p>
            <p className={cn("font-semibold",
              gen.oil_pressure_bar !== null && gen.oil_pressure_bar < 2 ? "text-destructive" : ""
            )}>
              {gen.oil_pressure_bar != null && gen.oil_pressure_bar > 0 ? `${gen.oil_pressure_bar} bar` : "—"}
            </p>
          </div>
          <div><p className="text-muted-foreground">Battery</p>
            <p className="font-semibold">{gen.battery_v != null ? `${gen.battery_v} V` : "—"}</p></div>
        </div>
      </CardContent>
    </Card>
  );
}

// ── ATS card ──────────────────────────────────────────────────────

function AtsCard({ ats }: { ats: AtsStatus }) {
  const onGenerator = ats.active_feed === "generator";
  const transferring = ats.state === "transferring";
  const feedLabel: Record<string, string> = {
    "utility-a": "Utility A", "utility-b": "Utility B", "generator": "Generator",
  };

  return (
    <Card className={cn("border", onGenerator && "border-amber-500/40")}>
      <CardHeader className="pb-2">
        <div className="flex items-center justify-between">
          <CardTitle className="text-sm font-semibold flex items-center gap-2">
            <ArrowLeftRight className="w-4 h-4 text-primary" />
            {ats.ats_id.toUpperCase()}
          </CardTitle>
          <span className={cn("text-[10px] font-semibold px-2 py-0.5 rounded-full uppercase tracking-wide",
            transferring ? "bg-amber-500/10 text-amber-400 animate-pulse" :
            onGenerator  ? "bg-amber-500/10 text-amber-400" :
            "bg-green-500/10 text-green-400",
          )}>
            {transferring ? "Transferring" : onGenerator ? "Generator feed" : "Stable"}
          </span>
        </div>
      </CardHeader>
      <CardContent className="space-y-3">
        <div className="text-center rounded-lg bg-muted/20 py-3">
          <p className="text-[10px] text-muted-foreground uppercase tracking-wide mb-1">Active Feed</p>
          <p className={cn("text-xl font-bold", onGenerator ? "text-amber-400" : "text-green-400")}>
            {feedLabel[ats.active_feed] ?? ats.active_feed}
          </p>
        </div>
        <div className="grid grid-cols-3 gap-2 text-[11px]">
          {[
            { label: "Utility A", v: ats.utility_a_v, active: ats.active_feed === "utility-a" },
            { label: "Utility B", v: ats.utility_b_v, active: ats.active_feed === "utility-b" },
            { label: "Generator", v: ats.generator_v, active: ats.active_feed === "generator" },
          ].map(({ label, v, active }) => (
            <div key={label} className={cn("rounded-md px-2 py-1.5 text-center",
              active ? "bg-primary/10 border border-primary/20" : "bg-muted/20",
            )}>
              <p className="text-muted-foreground">{label}</p>
              <p className={cn("font-semibold", active ? "text-foreground" : "text-muted-foreground")}>
                {v != null && v > 0 ? `${v.toFixed(0)} V` : "—"}
              </p>
            </div>
          ))}
        </div>
        <div className="flex justify-between text-[11px] text-muted-foreground border-t border-border/30 pt-2">
          <span>Transfers: <strong className="text-foreground">{ats.transfer_count}</strong></span>
          {ats.last_transfer_ms != null && (
            <span>Last xfer: <strong className="text-foreground">{ats.last_transfer_ms} ms</strong></span>
          )}
        </div>
      </CardContent>
    </Card>
  );
}

// ── Redundancy banner ─────────────────────────────────────────────

function RedundancyBanner({ r }: { r: PowerRedundancy }) {
  const color =
    r.level === "2N" ? "border-green-500/30 bg-green-500/5 text-green-400" :
    r.level === "N+1" ? "border-amber-500/30 bg-amber-500/5 text-amber-400" :
    "border-destructive/30 bg-destructive/5 text-destructive";

  return (
    <div className={cn("flex items-center justify-between rounded-xl border px-5 py-3", color)}>
      <div className="flex items-center gap-3">
        <ShieldCheck className="w-5 h-5 shrink-0" />
        <div>
          <p className="text-sm font-bold">Power Redundancy: {r.level}</p>
          <p className="text-xs opacity-70">{r.notes}</p>
        </div>
      </div>
      <div className="text-right text-xs opacity-80 space-y-0.5">
        <p>UPS online: {r.ups_online}/{r.ups_total}</p>
        <p>Generator: {r.generator_ok ? "available" : "unavailable"}</p>
        <p>Feed: {r.ats_active_feed ?? "—"}</p>
      </div>
    </div>
  );
}

// ── Phase imbalance table ──────────────────────────────────────────

function PhaseImbalanceTable({ rooms }: { rooms: RoomPhase[] }) {
  const allRacks = rooms.flatMap(r => r.racks).filter(r => (r.imbalance_pct ?? 0) > 5);
  if (allRacks.length === 0) return null;

  return (
    <Card>
      <CardHeader className="pb-2">
        <CardTitle className="text-sm font-semibold flex items-center gap-2">
          <AlertTriangle className="w-4 h-4 text-amber-400" />
          Phase Imbalance — {allRacks.length} rack{allRacks.length !== 1 ? "s" : ""} flagged
        </CardTitle>
      </CardHeader>
      <CardContent>
        <div className="overflow-x-auto">
          <table className="w-full text-xs">
            <thead>
              <tr className="text-muted-foreground border-b border-border/30">
                <th className="text-left py-1.5 pr-3 font-medium">Rack</th>
                <th className="text-right py-1.5 pr-3 font-medium">Phase A kW</th>
                <th className="text-right py-1.5 pr-3 font-medium">Phase B kW</th>
                <th className="text-right py-1.5 pr-3 font-medium">Phase C kW</th>
                <th className="text-right py-1.5 font-medium">Imbalance</th>
              </tr>
            </thead>
            <tbody>
              {allRacks.map(rack => {
                const imb = rack.imbalance_pct ?? 0;
                const crit = imb >= 15;
                return (
                  <tr key={rack.rack_id} className="border-b border-border/10">
                    <td className="py-1.5 pr-3 font-medium">{rack.rack_id}</td>
                    <td className="text-right pr-3 tabular-nums">{rack.phase_a_kw?.toFixed(2) ?? "—"}</td>
                    <td className="text-right pr-3 tabular-nums">{rack.phase_b_kw?.toFixed(2) ?? "—"}</td>
                    <td className="text-right pr-3 tabular-nums">{rack.phase_c_kw?.toFixed(2) ?? "—"}</td>
                    <td className={cn("text-right tabular-nums font-semibold", crit ? "text-destructive" : "text-amber-400")}>
                      {imb.toFixed(1)}%
                    </td>
                  </tr>
                );
              })}
            </tbody>
          </table>
        </div>
      </CardContent>
    </Card>
  );
}

// ── Page ──────────────────────────────────────────────────────────────────────

export default function PowerPage() {
  const [kpis, setKpis]             = useState<KpiData | null>(null);
  const [racks, setRacks]           = useState<RoomPowerBreakdown[]>([]);
  const [history, setHistory]       = useState<PowerHistoryBucket[]>([]);
  const [ups, setUps]               = useState<UpsAsset[]>([]);
  const [capacity, setCapacity]     = useState<CapacitySummary | null>(null);
  const [generators, setGenerators] = useState<GeneratorStatus[]>([]);
  const [atsUnits, setAtsUnits]     = useState<AtsStatus[]>([]);
  const [redundancy, setRedundancy] = useState<PowerRedundancy | null>(null);
  const [phases, setPhases]         = useState<RoomPhase[]>([]);
  const [historyHours, setHistoryHours] = useState(6);
  const [loading, setLoading]       = useState(true);
  const [phaseExpanded, setPhaseExpanded] = useState(false);
  const [selectedUps, setSelectedUps] = useState<typeof ups[0] | null>(null);

  const loadHistory = useCallback(async () => {
    try {
      const h = await fetchRoomPowerHistory(SITE_ID, historyHours);
      setHistory(h);
    } catch { /* keep stale */ }
  }, [historyHours]);

  const load = useCallback(async () => {
    try {
      const [k, r, h, u, cap, g, a, red, ph] = await Promise.all([
        fetchKpis(SITE_ID),
        fetchRackBreakdown(SITE_ID),
        fetchRoomPowerHistory(SITE_ID, historyHours),
        fetchUpsStatus(SITE_ID),
        fetchCapacitySummary(SITE_ID),
        fetchGeneratorStatus(SITE_ID).catch(() => []),
        fetchAtsStatus(SITE_ID).catch(() => []),
        fetchPowerRedundancy(SITE_ID).catch(() => null),
        fetchPhaseBreakdown(SITE_ID).catch(() => []),
      ]);
      setKpis(k);
      setRacks(r);
      setHistory(h);
      setUps(u);
      setCapacity(cap);
      setGenerators(g);
      setAtsUnits(a);
      setRedundancy(red);
      setPhases(ph);
    } catch {
      // keep stale data
    } finally {
      setLoading(false);
    }
  }, [historyHours]);

  useEffect(() => {
    load();
    const id = setInterval(load, 30_000);
    return () => clearInterval(id);
  }, [load]);

  useEffect(() => { loadHistory(); }, [historyHours, loadHistory]);

  const totalKw      = kpis?.total_power_kw ?? 0;
  const hallAKw      = racks.find((r) => r.room_id === "hall-a")?.racks.reduce((s, r) => s + (r.power_kw ?? 0), 0) ?? 0;
  const hallBKw      = racks.find((r) => r.room_id === "hall-b")?.racks.reduce((s, r) => s + (r.power_kw ?? 0), 0) ?? 0;
  const siteCapacity = capacity ? capacity.rooms.reduce((s, r) => s + r.power.capacity_kw, 0) : 0;

  // Phase summary data
  const allPhaseRacks = phases.flatMap(r => r.racks);
  const phaseViolations = allPhaseRacks.filter(r => (r.imbalance_pct ?? 0) > 5);

  return (
    <div className="p-6 space-y-6">
      <div>
        <h1 className="text-xl font-semibold">Power Management</h1>
        <p className="text-sm text-muted-foreground">Singapore DC01 — refreshes every 30s</p>
      </div>

      {/* Internal anchor sub-nav */}
      <div className="sticky top-14 z-20 -mx-6 px-6 py-2 bg-background/95 backdrop-blur-sm border-b border-border/30">
        <nav className="flex gap-1">
          {[
            { label: "Overview", href: "#power-overview" },
            { label: "UPS",      href: "#power-ups" },
            { label: "Generator", href: "#power-generator" },
            { label: "Transfer Switch", href: "#power-ats" },
            { label: "Phase Analysis", href: "#power-phase" },
          ].map(({ label, href }) => (
            <a key={href} href={href} className="px-3 py-1 rounded-md text-xs font-medium text-muted-foreground hover:text-foreground hover:bg-muted transition-colors">
              {label}
            </a>
          ))}
        </nav>
      </div>

      {/* Site capacity bar */}
      <div id="power-overview">
        {!loading && siteCapacity > 0 && (
          <SiteCapacityBar usedKw={totalKw} capacityKw={siteCapacity} />
        )}
      </div>

      {/* KPIs */}
      {loading ? (
        <div className="grid grid-cols-2 sm:grid-cols-4 gap-4">
          {Array.from({ length: 4 }).map((_, i) => <Skeleton key={i} className="h-20" />)}
        </div>
      ) : (
        <div className="grid grid-cols-2 sm:grid-cols-4 gap-4">
          <KpiCard label="Total Site Load" value={`${totalKw} kW`}            icon={Zap}      accent />
          <KpiCard label="PUE"             value={kpis?.pue.toFixed(2) ?? "—"} icon={Activity} sub="Target: < 1.4" />
          <KpiCard label="Hall A"          value={`${hallAKw.toFixed(1)} kW`}  icon={Zap} />
          <KpiCard label="Hall B"          value={`${hallBKw.toFixed(1)} kW`}  icon={Zap} />
        </div>
      )}

      {/* Power path diagram */}
      {!loading && redundancy && (
        <div className="rounded-xl border border-border bg-muted/10 px-5 py-3">
          <p className="text-[10px] text-muted-foreground uppercase tracking-wider font-semibold mb-3">Power Path</p>
          <div className="flex items-center gap-2 flex-wrap">
            {[
              { label: "Grid",     icon: Zap,            ok: redundancy.ats_active_feed !== "generator" },
              { label: "ATS",      icon: ArrowLeftRight, ok: true },
              { label: "UPS",      icon: Battery,        ok: redundancy.ups_online > 0 },
              { label: "Racks",    icon: Server,         ok: true },
            ].map(({ label, icon: Icon, ok }, i, arr) => (
              <React.Fragment key={label}>
                <div className={cn(
                  "flex items-center gap-2 rounded-lg px-3 py-2 border text-xs font-medium",
                  ok ? "border-green-500/30 bg-green-500/5 text-green-400" : "border-amber-500/30 bg-amber-500/5 text-amber-400"
                )}>
                  <Icon className="w-3.5 h-3.5" />
                  {label}
                </div>
                {i < arr.length - 1 && (
                  <div className="h-px flex-1 min-w-4 border-t border-dashed border-muted-foreground/30" />
                )}
              </React.Fragment>
            ))}
            {redundancy.ats_active_feed === "generator" && (
              <span className="ml-auto text-[10px] text-amber-400 font-medium flex items-center gap-1">
                <AlertTriangle className="w-3 h-3" /> Running on generator
              </span>
            )}
          </div>
        </div>
      )}

      {/* Charts */}
      <div className="flex items-center justify-between">
        <p className="text-xs text-muted-foreground font-medium uppercase tracking-wider">Power History</p>
        <select
          value={historyHours}
          onChange={(e) => setHistoryHours(Number(e.target.value))}
          className="text-xs bg-muted border border-border rounded px-2 py-1 text-foreground"
        >
          {[1, 3, 6, 12, 24].map((h) => (
            <option key={h} value={h}>{h}h</option>
          ))}
        </select>
      </div>
      <div className="space-y-4">
        {loading ? (
          <>
            <Skeleton className="h-64" />
            <Skeleton className="h-64" />
          </>
        ) : (
          <>
            {racks.length > 0 && <RackPowerChart rooms={racks} />}
            <RoomPowerHistoryChart data={history} />
          </>
        )}
      </div>

      {/* Redundancy banner */}
      {!loading && redundancy && <RedundancyBanner r={redundancy} />}

      {/* UPS */}
      <div id="power-ups">
        <h2 className="text-xs font-semibold uppercase tracking-widest text-muted-foreground mb-3">UPS Units</h2>
        {loading ? (
          <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
            <Skeleton className="h-48" />
            <Skeleton className="h-48" />
          </div>
        ) : (
          <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
            {ups.map((u) => (
              <UpsCard key={u.ups_id} ups={u} onClick={() => setSelectedUps(u)} />
            ))}
          </div>
        )}
      </div>

      {/* Generator */}
      {(loading || generators.length > 0) && (
        <div id="power-generator">
          <h2 className="text-xs font-semibold uppercase tracking-widest text-muted-foreground mb-3">Generators</h2>
          {loading ? (
            <div className="grid grid-cols-1 sm:grid-cols-2 gap-4"><Skeleton className="h-48" /></div>
          ) : (
            <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
              {generators.map((g) => <GeneratorCard key={g.gen_id} gen={g} />)}
            </div>
          )}
        </div>
      )}

      {/* ATS */}
      {(loading || atsUnits.length > 0) && (
        <div id="power-ats">
          <h2 className="text-xs font-semibold uppercase tracking-widest text-muted-foreground mb-3">Transfer Switches</h2>
          {loading ? (
            <div className="grid grid-cols-1 sm:grid-cols-2 gap-4"><Skeleton className="h-40" /></div>
          ) : (
            <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
              {atsUnits.map((a) => <AtsCard key={a.ats_id} ats={a} />)}
            </div>
          )}
        </div>
      )}

      {/* UPS detail sheet */}
      <UpsDetailSheet ups={selectedUps} onClose={() => setSelectedUps(null)} />

      {/* Phase analysis — always visible summary */}
      <div id="power-phase">
        {!loading && phases.length > 0 && (
          <div className="space-y-3">
            <div className="flex items-center justify-between">
              <h2 className="text-xs font-semibold uppercase tracking-widest text-muted-foreground">Phase Analysis</h2>
              {phaseViolations.length === 0 ? (
                <span className="flex items-center gap-1.5 text-[10px] font-semibold px-2 py-0.5 rounded-full bg-green-500/10 text-green-400">
                  <CheckCircle2 className="w-3 h-3" /> Phase balance OK
                </span>
              ) : (
                <button
                  onClick={() => setPhaseExpanded(!phaseExpanded)}
                  className="flex items-center gap-1.5 text-[10px] font-semibold px-2 py-0.5 rounded-full bg-amber-500/10 text-amber-400 hover:bg-amber-500/20 transition-colors"
                >
                  <AlertTriangle className="w-3 h-3" />
                  {phaseViolations.length} rack{phaseViolations.length !== 1 ? "s" : ""} flagged
                  {phaseExpanded ? " — Hide details" : " — Show details"}
                </button>
              )}
            </div>

            {/* Phase summary row */}
            <div className="grid grid-cols-3 gap-3">
              {(["Phase A", "Phase B", "Phase C"] as const).map((phase, idx) => {
                const phaseKey = (["phase_a_kw", "phase_b_kw", "phase_c_kw"] as const)[idx];
                const total = allPhaseRacks.reduce((s, r) => s + (r[phaseKey] ?? 0), 0);
                return (
                  <div key={phase} className="rounded-lg bg-muted/20 px-4 py-3 text-center">
                    <p className="text-[10px] text-muted-foreground uppercase tracking-wide mb-1">{phase}</p>
                    <p className="text-lg font-bold tabular-nums">{total.toFixed(1)} kW</p>
                  </div>
                );
              })}
            </div>

            {/* Expanded violation table */}
            {phaseExpanded && phaseViolations.length > 0 && (
              <PhaseImbalanceTable rooms={phases} />
            )}
          </div>
        )}
      </div>
    </div>
  );
}