"use client";

import { useEffect, useState, useCallback } from "react";
import {
  Sheet, SheetContent, SheetHeader, SheetTitle,
} from "@/components/ui/sheet";
import { Tabs, TabsList, TabsTrigger, TabsContent } from "@/components/ui/tabs";
import {
  LineChart, Line, XAxis, YAxis, CartesianGrid, Tooltip as RechartTooltip,
  ResponsiveContainer, ReferenceLine,
} from "recharts";
import { Battery, Zap, Activity, AlertTriangle, CheckCircle2, TrendingDown } from "lucide-react";
import { cn } from "@/lib/utils";
import { fetchUpsHistory, type UpsAsset, type UpsHistoryPoint } from "@/lib/api";

const SITE_ID = "sg-01";

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

function StatRow({ label, value, color }: { label: string; value: string; color?: string }) {
  return (
    <div className="flex items-center justify-between py-2 border-b border-border/20 last:border-0">
      <span className="text-sm text-muted-foreground">{label}</span>
      <span className={cn("text-sm font-semibold tabular-nums", color)}>{value}</span>
    </div>
  );
}

function GaugeBar({
  label, value, max, unit, warnAt, critAt, reverse = false,
}: {
  label: string; value: number | null; max: number; unit: string;
  warnAt?: number; critAt?: number; reverse?: boolean;
}) {
  const v = value ?? 0;
  const pct = Math.min(100, (v / max) * 100);
  const isWarn = warnAt !== undefined && (reverse ? v < warnAt : v >= warnAt);
  const isCrit = critAt !== undefined && (reverse ? v < critAt : v >= critAt);
  const barColor = isCrit ? "bg-destructive" : isWarn ? "bg-amber-500" : "bg-green-500";
  const textColor = isCrit ? "text-destructive" : isWarn ? "text-amber-400" : "";

  return (
    <div className="space-y-1.5">
      <div className="flex justify-between text-xs">
        <span className="text-muted-foreground">{label}</span>
        <span className={cn("font-semibold", textColor)}>
          {value !== null ? `${value}${unit}` : "—"}
        </span>
      </div>
      <div className="h-2 rounded-full bg-muted overflow-hidden">
        <div className={cn("h-full rounded-full transition-all duration-500", barColor)}
          style={{ width: `${pct}%` }} />
      </div>
    </div>
  );
}

function MiniChart({
  data, dataKey, color, refLines = [], unit, domain,
}: {
  data: UpsHistoryPoint[]; dataKey: keyof UpsHistoryPoint; color: string;
  refLines?: { y: number; color: string; label: string }[];
  unit?: string; domain?: [number, number];
}) {
  if (data.length === 0) {
    return (
      <div className="h-36 flex items-center justify-center text-xs text-muted-foreground">
        Waiting for data...
      </div>
    );
  }
  return (
    <ResponsiveContainer width="100%" height={144}>
      <LineChart data={data} margin={{ top: 4, right: 8, left: -20, bottom: 0 }}>
        <CartesianGrid strokeDasharray="3 3" stroke="oklch(1 0 0 / 8%)" />
        <XAxis dataKey="bucket" tickFormatter={fmt}
          tick={{ fontSize: 9, fill: "oklch(0.65 0.04 257)" }} tickLine={false} axisLine={false} />
        <YAxis domain={domain} tick={{ fontSize: 9, fill: "oklch(0.65 0.04 257)" }}
          tickLine={false} axisLine={false} />
        <RechartTooltip
          contentStyle={{ backgroundColor: "oklch(0.16 0.04 265)", border: "1px solid oklch(1 0 0 / 9%)", borderRadius: "6px", fontSize: "11px" }}
          formatter={(v) => [`${v}${unit ?? ""}`, String(dataKey)]}
          labelFormatter={(l) => fmt(String(l))}
        />
        {refLines.map((r) => (
          <ReferenceLine key={r.y} y={r.y} stroke={r.color} strokeDasharray="4 4" strokeWidth={1}
            label={{ value: r.label, fontSize: 8, fill: r.color, position: "insideTopRight" }} />
        ))}
        <Line type="monotone" dataKey={dataKey as string} stroke={color}
          dot={false} strokeWidth={2} connectNulls />
      </LineChart>
    </ResponsiveContainer>
  );
}

// ── Overview Tab ──────────────────────────────────────────────────────────────

function OverviewTab({ ups }: { ups: UpsAsset }) {
  const onBattery = ups.state === "battery";
  const overload  = ups.state === "overload";
  const charge    = ups.charge_pct ?? 0;
  const runtime   = ups.runtime_min ?? null;
  const load      = ups.load_pct ?? null;

  return (
    <div className="space-y-5">
      {/* State hero */}
      <div className={cn(
        "rounded-xl border px-5 py-4 flex items-center gap-4",
        overload  ? "border-destructive/40 bg-destructive/5" :
        onBattery ? "border-amber-500/40 bg-amber-500/5" :
        "border-green-500/30 bg-green-500/5",
      )}>
        <Battery className={cn("w-8 h-8",
          overload ? "text-destructive" : onBattery ? "text-amber-400" : "text-green-400"
        )} />
        <div>
          <p className={cn("text-xl font-bold",
            overload ? "text-destructive" : onBattery ? "text-amber-400" : "text-green-400"
          )}>
            {overload ? "Overloaded" : onBattery ? "On Battery" : "Mains Power"}
          </p>
          <p className="text-xs text-muted-foreground mt-0.5">
            {overload
              ? "Critical — load exceeds safe capacity"
              : onBattery
              ? "Mains power lost — running on battery"
              : "Grid power normal — charging battery"}
          </p>
        </div>
      </div>

      {/* Gauges */}
      <div className="space-y-4">
        <GaugeBar label="Battery charge" value={ups.charge_pct} max={100} unit="%" warnAt={80} critAt={50} reverse />
        <GaugeBar label="Load"           value={load}           max={100} unit="%" warnAt={85} critAt={95} />
      </div>

      {/* Runtime + voltage row */}
      <div className="grid grid-cols-2 gap-4">
        <div className="rounded-lg bg-muted/20 px-4 py-3 text-center">
          <p className="text-[10px] text-muted-foreground uppercase tracking-wide mb-1">Est. Runtime</p>
          <p className={cn("text-2xl font-bold tabular-nums",
            runtime !== null && runtime < 5  ? "text-destructive" :
            runtime !== null && runtime < 15 ? "text-amber-400"   : "text-green-400",
          )}>
            {runtime !== null ? `${Math.round(runtime)}` : "—"}
          </p>
          <p className="text-[10px] text-muted-foreground">minutes</p>
        </div>
        <div className="rounded-lg bg-muted/20 px-4 py-3 text-center">
          <p className="text-[10px] text-muted-foreground uppercase tracking-wide mb-1">Input Voltage</p>
          <p className={cn("text-2xl font-bold tabular-nums",
            ups.voltage_v !== null && (ups.voltage_v < 210 || ups.voltage_v > 250) ? "text-amber-400" : "",
          )}>
            {ups.voltage_v !== null ? `${ups.voltage_v}` : "—"}
          </p>
          <p className="text-[10px] text-muted-foreground">V AC</p>
        </div>
      </div>

      {/* Quick stats */}
      <div className="space-y-0">
        <StatRow label="Unit ID"         value={ups.ups_id.toUpperCase()} />
        <StatRow
          label="Battery charge"
          value={charge < 50 ? `${charge.toFixed(1)}% — Low` : `${charge.toFixed(1)}%`}
          color={charge < 50 ? "text-destructive" : charge < 80 ? "text-amber-400" : "text-green-400"}
        />
        <StatRow
          label="Runtime remaining"
          value={runtime !== null ? `${Math.round(runtime)} min` : "—"}
          color={runtime !== null && runtime < 5 ? "text-destructive" : runtime !== null && runtime < 15 ? "text-amber-400" : ""}
        />
        <StatRow
          label="Load"
          value={load !== null ? `${load.toFixed(1)}%` : "—"}
          color={load !== null && load >= 95 ? "text-destructive" : load !== null && load >= 85 ? "text-amber-400" : ""}
        />
        <StatRow
          label="Input voltage"
          value={ups.voltage_v !== null ? `${ups.voltage_v} V` : "—"}
          color={ups.voltage_v !== null && (ups.voltage_v < 210 || ups.voltage_v > 250) ? "text-amber-400" : ""}
        />
      </div>
    </div>
  );
}

// ── Battery Tab ───────────────────────────────────────────────────────────────

function BatteryTab({ history }: { history: UpsHistoryPoint[] }) {
  const charge = history.map((d) => ({ ...d, bucket: d.bucket }));
  const runtime = history.map((d) => ({ ...d, bucket: d.bucket }));

  return (
    <div className="space-y-6">
      <div>
        <p className="text-xs font-semibold text-muted-foreground uppercase tracking-wider mb-2">
          Battery Charge (%)
        </p>
        <MiniChart
          data={charge}
          dataKey="charge_pct"
          color="oklch(0.65 0.16 145)"
          unit="%"
          domain={[0, 100]}
          refLines={[
            { y: 80, color: "oklch(0.72 0.18 84)", label: "Warn 80%" },
            { y: 50, color: "oklch(0.55 0.22 25)", label: "Crit 50%" },
          ]}
        />
      </div>
      <div>
        <p className="text-xs font-semibold text-muted-foreground uppercase tracking-wider mb-2">
          Estimated Runtime (min)
        </p>
        <MiniChart
          data={runtime}
          dataKey="runtime_min"
          color="oklch(0.62 0.17 212)"
          unit=" min"
          refLines={[
            { y: 15, color: "oklch(0.72 0.18 84)", label: "Warn 15m" },
            { y: 5,  color: "oklch(0.55 0.22 25)", label: "Crit 5m" },
          ]}
        />
      </div>
    </div>
  );
}

// ── Load Tab ──────────────────────────────────────────────────────────────────

function LoadTab({ history }: { history: UpsHistoryPoint[] }) {
  return (
    <div className="space-y-6">
      <div>
        <p className="text-xs font-semibold text-muted-foreground uppercase tracking-wider mb-2">
          Load (%)
        </p>
        <MiniChart
          data={history}
          dataKey="load_pct"
          color="oklch(0.7 0.15 50)"
          unit="%"
          domain={[0, 100]}
          refLines={[
            { y: 85, color: "oklch(0.72 0.18 84)", label: "Warn 85%" },
            { y: 95, color: "oklch(0.55 0.22 25)", label: "Crit 95%" },
          ]}
        />
      </div>
      <div>
        <p className="text-xs font-semibold text-muted-foreground uppercase tracking-wider mb-2">
          Input Voltage (V)
        </p>
        <MiniChart
          data={history}
          dataKey="voltage_v"
          color="oklch(0.62 0.17 280)"
          unit=" V"
          refLines={[
            { y: 210, color: "oklch(0.55 0.22 25)", label: "Low 210V" },
            { y: 250, color: "oklch(0.55 0.22 25)", label: "High 250V" },
          ]}
        />
      </div>
    </div>
  );
}

// ── Sheet ─────────────────────────────────────────────────────────────────────

interface Props {
  ups: UpsAsset | null;
  onClose: () => void;
}

export function UpsDetailSheet({ ups, onClose }: Props) {
  const [history, setHistory] = useState<UpsHistoryPoint[]>([]);
  const [hours, setHours]     = useState(6);

  const loadHistory = useCallback(async () => {
    if (!ups) return;
    try {
      const h = await fetchUpsHistory(SITE_ID, ups.ups_id, hours);
      setHistory(h);
    } catch { /* keep stale */ }
  }, [ups, hours]);

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

  if (!ups) return null;

  const overload  = ups.state === "overload";
  const onBattery = ups.state === "battery";

  return (
    <Sheet open={!!ups} onOpenChange={(open) => { if (!open) onClose(); }}>
      <SheetContent side="right" className="w-full sm:max-w-lg overflow-y-auto">
        <SheetHeader className="pb-4 border-b border-border/30">
          <div className="flex items-center justify-between">
            <SheetTitle className="flex items-center gap-2">
              <Battery className="w-5 h-5 text-primary" />
              {ups.ups_id.toUpperCase()}
            </SheetTitle>
            <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",
            )}>
              {overload || onBattery
                ? <AlertTriangle className="w-3 h-3" />
                : <CheckCircle2 className="w-3 h-3" />}
              {overload ? "Overloaded" : onBattery ? "On Battery" : "Mains"}
            </span>
          </div>
        </SheetHeader>

        <div className="pt-4">
          <Tabs defaultValue="overview">
            <div className="flex items-center justify-between mb-4 gap-3">
              <TabsList className="h-8">
                <TabsTrigger value="overview"  className="text-xs px-3">Overview</TabsTrigger>
                <TabsTrigger value="battery"   className="text-xs px-3">Battery</TabsTrigger>
                <TabsTrigger value="load"      className="text-xs px-3">Load & Voltage</TabsTrigger>
              </TabsList>
              <select
                value={hours}
                onChange={(e) => setHours(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>

            <TabsContent value="overview" className="mt-0">
              <OverviewTab ups={ups} />
            </TabsContent>
            <TabsContent value="battery" className="mt-0">
              <BatteryTab history={history} />
            </TabsContent>
            <TabsContent value="load" className="mt-0">
              <LoadTab history={history} />
            </TabsContent>
          </Tabs>
        </div>
      </SheetContent>
    </Sheet>
  );
}