"use client";

import { useCallback, useEffect, useMemo, useState } from "react";
import {
  CartesianGrid,
  Legend,
  Line,
  LineChart,
  ResponsiveContainer,
  Tooltip,
  XAxis,
  YAxis,
} from "recharts";
import Card from "@/shared/components/Card";
import ProviderIcon from "@/shared/components/ProviderIcon";
import TimeRangeSelector from "@/shared/components/analytics/TimeRangeSelector";
import type {
  ProviderUtilizationPoint,
  ProviderUtilizationResponse,
  UtilizationTimeRange,
} from "@/shared/types/utilization";

const RANGE_LABELS: Record<UtilizationTimeRange, string> = {
  "1h": "Last hour",
  "24h": "Last 24 hours",
  "7d": "Last 7 days",
  "30d": "Last 30 days",
};

const PROVIDER_COLORS = [
  "var(--color-primary)",
  "var(--color-accent)",
  "var(--color-success)",
  "var(--color-warning)",
  "var(--color-error)",
  "var(--color-text-muted)",
];

function formatTimestamp(value: string, range: UtilizationTimeRange) {
  const date = new Date(value);

  if (Number.isNaN(date.getTime())) {
    return value;
  }

  if (range === "1h" || range === "24h") {
    return new Intl.DateTimeFormat(undefined, {
      hour: "2-digit",
      minute: "2-digit",
    }).format(date);
  }

  return new Intl.DateTimeFormat(undefined, {
    month: "short",
    day: "numeric",
  }).format(date);
}

function formatTooltipTimestamp(value: string, range: UtilizationTimeRange) {
  const date = new Date(value);

  if (Number.isNaN(date.getTime())) {
    return value;
  }

  return new Intl.DateTimeFormat(undefined, {
    month: "short",
    day: "numeric",
    hour: range === "1h" || range === "24h" ? "2-digit" : undefined,
    minute: range === "1h" || range === "24h" ? "2-digit" : undefined,
  }).format(date);
}

function formatPercent(value: number) {
  return `${Math.round(value)}%`;
}

function getLatestPoints(points: ProviderUtilizationPoint[]) {
  const latestByProvider = new Map<string, ProviderUtilizationPoint>();

  for (const point of points) {
    const current = latestByProvider.get(point.provider);
    if (!current || new Date(point.timestamp).getTime() > new Date(current.timestamp).getTime()) {
      latestByProvider.set(point.provider, point);
    }
  }

  return Array.from(latestByProvider.values()).sort((a, b) => b.remainingPct - a.remainingPct);
}

export default function ProviderUtilizationTab() {
  const [range, setRange] = useState<UtilizationTimeRange>("24h");
  const [aggregateBy, setAggregateBy] = useState<"provider" | "connection">("provider");
  const [data, setData] = useState<ProviderUtilizationResponse | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);

  const fetchUtilization = useCallback(
    async (
      selectedRange: UtilizationTimeRange,
      selectedAggregate: "provider" | "connection",
      signal?: AbortSignal
    ) => {
      setLoading(true);

      try {
        const response = await fetch(
          `/api/usage/utilization?range=${selectedRange}&aggregateBy=${selectedAggregate}`,
          {
            signal,
            cache: "no-store",
          }
        );

        if (!response.ok) {
          throw new Error("Failed to fetch utilization data");
        }

        const json = (await response.json()) as ProviderUtilizationResponse;
        setData(json);
        setError(null);
      } catch (fetchError) {
        if (fetchError instanceof DOMException && fetchError.name === "AbortError") {
          return;
        }

        setError(
          fetchError instanceof Error ? fetchError.message : "Failed to fetch utilization data"
        );
        setData(null);
      } finally {
        if (!signal?.aborted) {
          setLoading(false);
        }
      }
    },
    []
  );

  useEffect(() => {
    const controller = new AbortController();

    fetchUtilization(range, aggregateBy, controller.signal);

    return () => controller.abort();
  }, [fetchUtilization, range, aggregateBy]);

  const providerColors = useMemo(() => {
    const colors = new Map<string, string>();

    for (const [index, provider] of (data?.providers ?? []).entries()) {
      colors.set(provider, PROVIDER_COLORS[index % PROVIDER_COLORS.length]);
    }

    return colors;
  }, [data?.providers]);

  const chartData = useMemo(() => {
    if (!data?.data.length) {
      return [];
    }

    const byTimestamp = new Map<string, Record<string, number | string>>();

    for (const point of data.data) {
      const entry = byTimestamp.get(point.timestamp) ?? {
        timestamp: point.timestamp,
        label: formatTimestamp(point.timestamp, data.timeRange),
      };

      entry[point.provider] = Number(point.remainingPct.toFixed(2));
      byTimestamp.set(point.timestamp, entry);
    }

    return Array.from(byTimestamp.entries())
      .sort(([left], [right]) => new Date(left).getTime() - new Date(right).getTime())
      .map(([, value]) => value);
  }, [data]);

  const latestPoints = useMemo(() => getLatestPoints(data?.data ?? []), [data?.data]);

  const hasData = Boolean(data?.data.length);
  const [retrying, setRetrying] = useState(false);

  const handleRetry = useCallback(() => {
    setRetrying(true);
    setError(null);
    fetchUtilization(range, aggregateBy).finally(() => setRetrying(false));
  }, [range, aggregateBy, fetchUtilization]);

  return (
    <div className="flex flex-col gap-6">
      <Card
        title="Provider utilization"
        subtitle={RANGE_LABELS[range]}
        icon="monitoring"
        action={
          <div className="flex items-center gap-4">
            <div className="flex rounded-lg border border-border/50 bg-black/5 p-1 dark:bg-white/5">
              <button
                onClick={() => setAggregateBy("provider")}
                className={`flex items-center gap-2 rounded-md px-3 py-1.5 text-xs font-medium transition-colors ${
                  aggregateBy === "provider"
                    ? "bg-surface text-text-main shadow-sm"
                    : "text-text-muted hover:text-text-main"
                }`}
              >
                <span className="material-symbols-outlined text-[14px]">dns</span>
                Global View
              </button>
              <button
                onClick={() => setAggregateBy("connection")}
                className={`flex items-center gap-2 rounded-md px-3 py-1.5 text-xs font-medium transition-colors ${
                  aggregateBy === "connection"
                    ? "bg-surface text-text-main shadow-sm"
                    : "text-text-muted hover:text-text-main"
                }`}
              >
                <span className="material-symbols-outlined text-[14px]">account_tree</span>
                Account Split
              </button>
            </div>
            <TimeRangeSelector value={range} onChange={setRange} />
          </div>
        }
        className="overflow-hidden"
      >
        {loading && !hasData ? (
          <div className="flex min-h-80 items-center justify-center text-sm text-text-muted">
            <span className="material-symbols-outlined mr-2 animate-spin text-[18px]">
              progress_activity
            </span>
            Loading utilization data…
          </div>
        ) : error ? (
          <div className="flex min-h-80 flex-col items-center justify-center gap-4 text-center">
            <span className="material-symbols-outlined text-[32px] text-error">error</span>
            <div className="flex flex-col gap-1">
              <p className="text-sm font-medium text-text-main">Failed to load utilization data</p>
              <p className="text-sm text-text-muted">{error}</p>
            </div>
            <button
              type="button"
              onClick={handleRetry}
              disabled={retrying}
              className="inline-flex items-center gap-2 rounded-lg bg-primary px-4 py-2 text-sm font-medium text-white hover:bg-primary-hover disabled:opacity-50 disabled:cursor-not-allowed"
            >
              {retrying ? (
                <>
                  <span className="material-symbols-outlined animate-spin text-[18px]">
                    progress_activity
                  </span>
                  Retrying…
                </>
              ) : (
                <>
                  <span className="material-symbols-outlined text-[18px]">refresh</span>
                  Retry
                </>
              )}
            </button>
          </div>
        ) : !hasData ? (
          <div className="flex min-h-80 flex-col items-center justify-center gap-4 text-center">
            <span className="material-symbols-outlined text-[40px] text-text-muted/70">
              timeline
            </span>
            <div className="flex flex-col gap-2">
              <p className="text-sm font-medium text-text-main">No utilization data available</p>
              <p className="max-w-md text-sm text-text-muted">
                Provider quota snapshots will appear here after utilization data is collected.
              </p>
            </div>
            <div className="rounded-lg border border-black/5 bg-black/[0.02] p-4 dark:border-white/5 dark:bg-white/[0.02]">
              <p className="text-xs font-medium text-text-main">Getting started</p>
              <ul className="mt-2 text-left text-xs text-text-muted">
                <li className="flex items-start gap-2">
                  <span className="material-symbols-outlined text-[14px] text-primary">
                    check_circle
                  </span>
                  <span>
                    Connect providers via OAuth or API keys in <strong>Providers</strong>
                  </span>
                </li>
                <li className="mt-1 flex items-start gap-2">
                  <span className="material-symbols-outlined text-[14px] text-primary">
                    check_circle
                  </span>
                  <span>
                    Enable quota tracking by using the provider in a combo or direct request
                  </span>
                </li>
                <li className="mt-1 flex items-start gap-2">
                  <span className="material-symbols-outlined text-[14px] text-primary">
                    check_circle
                  </span>
                  <span>Data will appear automatically as quota snapshots are collected</span>
                </li>
              </ul>
            </div>
          </div>
        ) : (
          <div className="flex flex-col gap-5">
            <div className="h-80 w-full rounded-xl border border-black/5 bg-black/[0.02] px-3 py-4 dark:border-white/5 dark:bg-white/[0.02]">
              <ResponsiveContainer width="100%" height="100%">
                <LineChart data={chartData} margin={{ top: 8, right: 16, bottom: 0, left: 0 }}>
                  <CartesianGrid
                    stroke="var(--color-border)"
                    strokeDasharray="3 3"
                    vertical={false}
                  />
                  <XAxis
                    dataKey="timestamp"
                    tickFormatter={(value) => formatTimestamp(String(value), range)}
                    tick={{ fill: "var(--color-text-muted)", fontSize: 12 }}
                    axisLine={{ stroke: "var(--color-border)" }}
                    tickLine={{ stroke: "var(--color-border)" }}
                    minTickGap={24}
                  />
                  <YAxis
                    domain={[0, 100]}
                    tickFormatter={formatPercent}
                    tick={{ fill: "var(--color-text-muted)", fontSize: 12 }}
                    axisLine={{ stroke: "var(--color-border)" }}
                    tickLine={{ stroke: "var(--color-border)" }}
                    width={44}
                  />
                  <Tooltip
                    labelFormatter={(value) => formatTooltipTimestamp(String(value), range)}
                    formatter={(value: number, name: string) => [formatPercent(value), name]}
                    contentStyle={{
                      backgroundColor: "var(--color-surface)",
                      borderColor: "var(--color-border)",
                      borderRadius: 12,
                      color: "var(--color-text-main)",
                      boxShadow: "var(--shadow-soft)",
                    }}
                    itemStyle={{ color: "var(--color-text-main)" }}
                    labelStyle={{ color: "var(--color-text-main)", fontWeight: 600 }}
                  />
                  <Legend />
                  {data?.providers.map((provider) => (
                    <Line
                      key={provider}
                      type="monotone"
                      dataKey={provider}
                      name={provider}
                      stroke={providerColors.get(provider) ?? "var(--color-primary)"}
                      strokeWidth={2.5}
                      dot={false}
                      activeDot={{ r: 4, strokeWidth: 0 }}
                      connectNulls
                    />
                  ))}
                </LineChart>
              </ResponsiveContainer>
            </div>

            <div className="grid grid-cols-1 gap-4 md:grid-cols-2 xl:grid-cols-3">
              {latestPoints.map((point) => {
                const isLow = point.remainingPct <= 20;

                return (
                  <Card.Section key={point.provider} className="flex h-full flex-col gap-4">
                    <div className="flex items-start justify-between gap-3">
                      <div className="flex items-center gap-3">
                        <div className="flex h-11 w-11 items-center justify-center rounded-xl border border-black/5 bg-surface text-text-main dark:border-white/5">
                          <ProviderIcon providerId={point.provider} size={22} />
                        </div>
                        <div>
                          <p className="text-sm font-semibold text-text-main">{point.provider}</p>
                          <p className="text-xs text-text-muted">Latest quota snapshot</p>
                        </div>
                      </div>
                      <span
                        className={`inline-flex items-center rounded-full px-2.5 py-1 text-xs font-medium ${
                          point.isExhausted
                            ? "bg-error/10 text-error"
                            : isLow
                              ? "bg-warning/10 text-warning"
                              : "bg-success/10 text-success"
                        }`}
                      >
                        {point.isExhausted ? "Exhausted" : isLow ? "Low" : "Healthy"}
                      </span>
                    </div>

                    <div className="flex items-end justify-between gap-3">
                      <div>
                        <p className="text-3xl font-bold text-text-main">
                          {point.remainingPct.toFixed(point.remainingPct < 10 ? 1 : 0)}%
                        </p>
                        <p className="mt-1 text-xs text-text-muted">Remaining capacity</p>
                      </div>
                      <div className="text-right text-xs text-text-muted">
                        <p>{formatTooltipTimestamp(point.timestamp, range)}</p>
                        <p className="mt-1 uppercase tracking-[0.14em]">{point.windowKey}</p>
                      </div>
                    </div>

                    <div className="flex flex-col gap-2">
                      <div className="h-2 overflow-hidden rounded-full bg-black/5 dark:bg-white/5">
                        <div
                          className={`h-full rounded-full transition-all ${
                            point.isExhausted ? "bg-error" : isLow ? "bg-warning" : "bg-primary"
                          }`}
                          style={{ width: `${Math.max(point.remainingPct, 0)}%` }}
                        />
                      </div>
                      <div className="flex items-center justify-between text-xs text-text-muted">
                        <span>0%</span>
                        <span>Remaining quota</span>
                        <span>100%</span>
                      </div>
                    </div>
                  </Card.Section>
                );
              })}
            </div>
          </div>
        )}
      </Card>
    </div>
  );
}
