"use client";

import { useState, useEffect, memo, useMemo, useCallback } from "react";
import {
  Card,
  CardContent,
  CardDescription,
  CardHeader,
  CardTitle,
} from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import {
  Select,
  SelectContent,
  SelectItem,
  SelectTrigger,
  SelectValue,
} from "@/components/ui/select";
import {
  TrendingUp,
  TrendingDown,
  Package,
  DollarSign,
  AlertTriangle,
  RefreshCw,
  Calendar,
  BarChart3,
  Brain,
  Layers,
  Zap,
  Info,
} from "lucide-react";
import { useToast } from "@/hooks/use-toast";
import { Skeleton } from "@/components/ui/skeleton";
import {
  getPredictionsOverviewWithStore,
  getStockPredictionsWithStore,
  type PredictionsOverview,
  type StockPredictionsResponse,
} from "@/lib/services/analytics-service";
import { formatGBP } from "@/utils/format";
import {
  Table,
  TableBody,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
} from "@/components/ui/table";
import { format } from "date-fns";
import {
  AreaChart,
  Area,
  XAxis,
  YAxis,
  CartesianGrid,
  Tooltip as RechartsTooltip,
  ResponsiveContainer,
} from "recharts";
import {
  Tooltip,
  TooltipContent,
  TooltipProvider,
  TooltipTrigger,
} from "@/components/ui/tooltip";
import { Alert, AlertDescription, AlertTitle } from "@/components/ui/alert";

interface PredictionsChartProps {
  timeRange?: number;
}

export default function PredictionsChart({
  timeRange = 90,
}: PredictionsChartProps) {
  const [predictions, setPredictions] = useState<PredictionsOverview | null>(
    null,
  );
  const [stockPredictions, setStockPredictions] =
    useState<StockPredictionsResponse | null>(null);
  const [loading, setLoading] = useState(true);
  const [daysAhead, setDaysAhead] = useState(7);
  const [activeTab, setActiveTab] = useState<"overview" | "stock">("overview");
  const { toast } = useToast();

  const fetchPredictions = async () => {
    try {
      setLoading(true);
      const [overview, stock] = await Promise.all([
        getPredictionsOverviewWithStore(daysAhead, timeRange),
        getStockPredictionsWithStore(timeRange),
      ]);
      setPredictions(overview);
      setStockPredictions(stock);
    } catch (error) {
      console.error("Error fetching predictions:", error);
      toast({
        title: "Error",
        description: "Failed to load predictions",
        variant: "destructive",
      });
    } finally {
      setLoading(false);
    }
  };

  useEffect(() => {
    fetchPredictions();
  }, [daysAhead, timeRange]);

  const getConfidenceColor = (confidence: string) => {
    switch (confidence) {
      case "very_high":
        return "bg-emerald-600/20 text-emerald-700 dark:text-emerald-400 border-emerald-600/30";
      case "high":
        return "bg-green-500/10 text-green-700 dark:text-green-400";
      case "medium":
        return "bg-yellow-500/10 text-yellow-700 dark:text-yellow-400";
      case "low":
        return "bg-red-500/10 text-red-700 dark:text-red-400";
      default:
        return "bg-gray-500/10 text-gray-700 dark:text-gray-400";
    }
  };

  const getConfidenceLabel = (confidence: string) => {
    switch (confidence) {
      case "very_high":
        return "Very High";
      case "high":
        return "High";
      case "medium":
        return "Medium";
      case "low":
        return "Low";
      default:
        return confidence;
    }
  };

  if (loading) {
    return (
      <Card>
        <CardHeader>
          <Skeleton className="h-6 w-48" />
          <Skeleton className="h-4 w-72" />
        </CardHeader>
        <CardContent>
          <div className="space-y-4">
            <Skeleton className="h-32 w-full" />
            <Skeleton className="h-32 w-full" />
            <Skeleton className="h-32 w-full" />
          </div>
        </CardContent>
      </Card>
    );
  }

  if (!predictions) {
    return (
      <Card>
        <CardHeader>
          <CardTitle>Predictions</CardTitle>
          <CardDescription>
            Forecast future sales, demand, and stock levels
          </CardDescription>
        </CardHeader>
        <CardContent>
          <p className="text-muted-foreground text-center py-8">
            No prediction data available. Need more historical data.
          </p>
        </CardContent>
      </Card>
    );
  }

  return (
    <Card>
      <CardHeader>
        <div className="flex items-center justify-between">
          <div>
            <CardTitle className="flex items-center gap-2">
              <BarChart3 className="h-5 w-5" />
              Predictions & Forecasting
            </CardTitle>
            <CardDescription>
              {predictions.sales.aiModel?.used
                ? "AI neural network + statistical models for sales, demand, and inventory"
                : "AI-powered predictions for sales, demand, and inventory"}
            </CardDescription>
          </div>
          <div className="flex items-center gap-2">
            <Select
              value={daysAhead.toString()}
              onValueChange={(value) => setDaysAhead(parseInt(value))}
            >
              <SelectTrigger className="w-32">
                <SelectValue />
              </SelectTrigger>
              <SelectContent>
                <SelectItem value="7">7 days</SelectItem>
                <SelectItem value="14">14 days</SelectItem>
                <SelectItem value="30">30 days</SelectItem>
                <SelectItem value="60">60 days</SelectItem>
                <SelectItem value="90">90 days</SelectItem>
              </SelectContent>
            </Select>
            <Button
              variant="outline"
              size="icon"
              onClick={fetchPredictions}
              disabled={loading}
            >
              <RefreshCw
                className={`h-4 w-4 ${loading ? "animate-spin" : ""}`}
              />
            </Button>
          </div>
        </div>
      </CardHeader>
      <CardContent>
        <div className="flex gap-2 mb-6">
          <Button
            variant={activeTab === "overview" ? "default" : "outline"}
            onClick={() => setActiveTab("overview")}
            size="sm"
          >
            Overview
          </Button>
          <Button
            variant={activeTab === "stock" ? "default" : "outline"}
            onClick={() => setActiveTab("stock")}
            size="sm"
          >
            Stock Predictions
          </Button>
        </div>

        {activeTab === "overview" && (
          <div className="space-y-6">
            {/* Sales Predictions */}
            <div className="grid grid-cols-1 md:grid-cols-2 gap-4">
              <TooltipProvider delayDuration={0}>
                <Card>
                  <CardHeader className="pb-3">
                    <CardTitle className="text-sm font-medium flex items-center gap-2">
                      <DollarSign className="h-4 w-4" />
                      Revenue Prediction
                    </CardTitle>
                  </CardHeader>
                  <CardContent>
                    {predictions.sales.predicted !== null ? (
                      <div className="space-y-2">
                        <Tooltip>
                          <TooltipTrigger asChild>
                            <div className="text-2xl font-bold w-fit cursor-help">
                              {formatGBP(predictions.sales.predicted)}
                            </div>
                          </TooltipTrigger>
                          <TooltipContent>
                            <p>Predicted daily average revenue for the next {daysAhead} days</p>
                          </TooltipContent>
                        </Tooltip>

                        <div className="flex items-center gap-2 flex-wrap">
                          <Tooltip>
                            <TooltipTrigger asChild>
                              <span className="inline-flex cursor-help">
                                <Badge
                                  className={getConfidenceColor(
                                    predictions.sales.confidence,
                                  )}
                                >
                                  {getConfidenceLabel(predictions.sales.confidence)} Confidence
                                  {predictions.sales.confidenceScore !== undefined && (
                                    <span className="ml-1 opacity-75">
                                      ({Math.round(predictions.sales.confidenceScore * 100)}%)
                                    </span>
                                  )}
                                </Badge>
                              </span>
                            </TooltipTrigger>
                            <TooltipContent>
                              <p>Based on data consistency, historical accuracy, and model agreement</p>
                            </TooltipContent>
                          </Tooltip>

                          {predictions.sales.aiModel?.used && (
                            <Tooltip>
                              <TooltipTrigger asChild>
                                <span className="inline-flex cursor-help">
                                  <Badge variant="outline" className="bg-purple-500/10 text-purple-700 dark:text-purple-400 border-purple-500/30">
                                    🤖 AI Powered
                                    {predictions.sales.aiModel.modelAccuracy !== undefined && (
                                      <span className="ml-1 opacity-75">
                                        ({Math.round(predictions.sales.aiModel.modelAccuracy * 100)}%)
                                      </span>
                                    )}
                                  </Badge>
                                </span>
                              </TooltipTrigger>
                              <TooltipContent>
                                <p>Predictions generated using a Deep Learning Ensemble Model (TensorFlow.js)</p>
                              </TooltipContent>
                            </Tooltip>
                          )}
                          {predictions.sales.trend && (
                            <Tooltip>
                              <TooltipTrigger asChild>
                                <span className="inline-flex cursor-help">
                                  <Badge
                                    variant="outline"
                                    className={
                                      predictions.sales.trend.direction === "up"
                                        ? "text-green-600 border-green-600"
                                        : predictions.sales.trend.direction === "down"
                                          ? "text-red-600 border-red-600"
                                          : ""
                                    }
                                  >
                                    {predictions.sales.trend.direction === "up" && (
                                      <TrendingUp className="h-3 w-3 mr-1" />
                                    )}
                                    {predictions.sales.trend.direction === "down" && (
                                      <TrendingDown className="h-3 w-3 mr-1" />
                                    )}
                                    {predictions.sales.trend.direction === "up"
                                      ? "Trending Up"
                                      : predictions.sales.trend.direction === "down"
                                        ? "Trending Down"
                                        : "Stable"}
                                  </Badge>
                                </span>
                              </TooltipTrigger>
                              <TooltipContent>
                                <p>Direction of the recent sales trend (slope analysis)</p>
                              </TooltipContent>
                            </Tooltip>
                          )}
                          <span className="text-xs text-muted-foreground">
                            Next {daysAhead} days
                          </span>
                        </div>
                        {predictions.sales.predictedOrders && (
                          <div className="text-sm text-muted-foreground">
                            ~{Math.round(predictions.sales.predictedOrders)}{" "}
                            orders
                          </div>
                        )}
                        {!predictions.sales.confidenceIntervals &&
                          predictions.sales.minPrediction &&
                          predictions.sales.maxPrediction && (
                            <div className="text-xs text-muted-foreground">
                              Range: {formatGBP(predictions.sales.minPrediction)} -{" "}
                              {formatGBP(predictions.sales.maxPrediction)}
                            </div>
                          )}
                      </div>
                    ) : (
                      <div className="text-sm text-muted-foreground">
                        {predictions.sales.message ||
                          "Insufficient data for prediction"}
                      </div>
                    )}
                  </CardContent>
                </Card>

                {/* Model Intelligence Card */}
                <Card>
                  <CardHeader className="pb-3">
                    <CardTitle className="text-sm font-medium flex items-center gap-2">
                      <Brain className="h-4 w-4" />
                      Model Intelligence
                      <Tooltip>
                        <TooltipTrigger>
                          <Info className="h-3 w-3 text-muted-foreground cursor-help" />
                        </TooltipTrigger>
                        <TooltipContent>
                          <p>Technical details about the active prediction model</p>
                        </TooltipContent>
                      </Tooltip>
                    </CardTitle>
                  </CardHeader>
                  <CardContent>
                    <div className="space-y-4">
                      <div className="flex justify-between items-center">
                        <span className="text-sm text-muted-foreground">Architecture</span>
                        <Tooltip>
                          <TooltipTrigger asChild>
                            <span className="text-sm font-medium flex items-center gap-1 cursor-help">
                              <Layers className="h-3 w-3 text-purple-500" />
                              Hybrid Ensemble (Deep Learning)
                            </span>
                          </TooltipTrigger>
                          <TooltipContent>
                            <p>Combines LSTM Neural Networks with Statistical Methods (Holt-Winters, ARIMA)</p>
                          </TooltipContent>
                        </Tooltip>
                      </div>
                      {stockPredictions?.predictions && (
                        <div className="flex justify-between items-center">
                          <span className="text-sm text-muted-foreground">Features</span>
                          <span className="text-xs font-medium bg-secondary px-2 py-1 rounded-md">
                            Multi-Feature Enabled
                          </span>
                        </div>
                      )}
                      <div className="flex justify-between items-center">
                        <span className="text-sm text-muted-foreground">Optimization</span>
                        <span className="text-sm font-medium flex items-center gap-1">
                          <Zap className="h-3 w-3 text-amber-500" />
                          Performance Tuned
                        </span>
                      </div>
                      <div className="pt-2 border-t text-xs text-muted-foreground">
                        Model automatically retrains with new sales data.
                      </div>
                    </div>
                  </CardContent>
                </Card>
              </TooltipProvider>
            </div>

            <Alert className="bg-yellow-500/10 border-yellow-500/30 text-yellow-700 dark:text-yellow-400">
              <AlertTriangle className="h-4 w-4 stroke-yellow-700 dark:stroke-yellow-400" />
              <AlertTitle>Prediction Accuracy Warning</AlertTitle>
              <AlertDescription>
                These predictions are estimates based on historical sales data. Actual results may vary due to external factors, market conditions, and unforeseen events. Use these insights as a guide, not a guarantee.
              </AlertDescription>
            </Alert>

            {/* Daily Predictions Chart */}
            {predictions.sales.dailyPredictions &&
              predictions.sales.dailyPredictions.length > 0 && (
                <Card>
                  <CardHeader className="pb-3">
                    <CardTitle className="text-sm font-medium">
                      Daily Revenue Forecast
                    </CardTitle>
                  </CardHeader>
                  <CardContent>
                    <div className="h-[300px] w-full mt-4">
                      <ResponsiveContainer width="100%" height="100%">
                        <AreaChart
                          data={predictions.sales.dailyPredictions.map(d => ({
                            ...d,
                            formattedDate: format(new Date(d.date), "MMM d"),
                            value: d.predicted
                          }))}
                          margin={{
                            top: 5,
                            right: 10,
                            left: 0,
                            bottom: 0,
                          }}
                        >
                          <defs>
                            <linearGradient id="colorValue" x1="0" y1="0" x2="0" y2="1">
                              <stop offset="5%" stopColor="#8884d8" stopOpacity={0.8} />
                              <stop offset="95%" stopColor="#8884d8" stopOpacity={0} />
                            </linearGradient>
                          </defs>
                          <CartesianGrid strokeDasharray="3 3" vertical={false} stroke="hsl(var(--border))" />
                          <XAxis
                            dataKey="formattedDate"
                            stroke="hsl(var(--muted-foreground))"
                            fontSize={12}
                            tickLine={false}
                            axisLine={false}
                          />
                          <YAxis
                            stroke="hsl(var(--muted-foreground))"
                            fontSize={12}
                            tickLine={false}
                            axisLine={false}
                            tickFormatter={(value) => `£${value}`}
                          />
                          <RechartsTooltip
                            contentStyle={{
                              backgroundColor: "hsl(var(--background))",
                              borderColor: "hsl(var(--border))",
                              borderRadius: "var(--radius)",
                            }}
                            formatter={(value: number) => [formatGBP(value), "Revenue"]}
                          />
                          <Area
                            type="monotone"
                            dataKey="value"
                            stroke="#8884d8"
                            fillOpacity={1}
                            fill="url(#colorValue)"
                          />
                        </AreaChart>
                      </ResponsiveContainer>
                    </div>
                  </CardContent>
                </Card>
              )}
          </div>
        )}

        {activeTab === "stock" && (
          <div className="space-y-4">
            {stockPredictions && stockPredictions.predictions.length > 0 ? (
              <>
                <div className="flex items-center justify-between">
                  <div>
                    <p className="text-sm text-muted-foreground">
                      {stockPredictions.totalProducts} products tracked
                    </p>
                    {stockPredictions.productsNeedingRestock > 0 && (
                      <p className="text-sm font-medium text-orange-600 dark:text-orange-400 mt-1">
                        {stockPredictions.productsNeedingRestock} products
                        need restocking soon
                      </p>
                    )}
                  </div>
                </div>

                <div className="rounded-md border">
                  <Table>
                    <TableHeader>
                      <TableRow>
                        <TableHead>Product</TableHead>
                        <TableHead>Current Stock</TableHead>
                        <TableHead>Days Until Out</TableHead>
                        <TableHead>Estimated Date</TableHead>
                        <TableHead>Confidence</TableHead>
                        <TableHead>Status</TableHead>
                      </TableRow>
                    </TableHeader>
                    <TableBody>
                      {stockPredictions.predictions.map((prediction) => (
                        <TableRow key={prediction.productId}>
                          <TableCell className="font-medium">
                            {prediction.productName}
                          </TableCell>
                          <TableCell>
                            {prediction.currentStock} {prediction.unitType}
                          </TableCell>
                          <TableCell>
                            {prediction.prediction.daysUntilOutOfStock !== null ? (
                              <div className="space-y-1">
                                <div className="font-medium">
                                  {prediction.prediction.daysUntilOutOfStock} days
                                </div>
                                {prediction.prediction.optimisticDays !== null &&
                                  prediction.prediction.pessimisticDays && (
                                    <div className="text-xs text-muted-foreground">
                                      {prediction.prediction.optimisticDays} -{" "}
                                      {prediction.prediction.pessimisticDays} days
                                    </div>
                                  )}
                              </div>
                            ) : (
                              "N/A"
                            )}
                          </TableCell>
                          <TableCell>
                            {prediction.prediction.estimatedDate ? (
                              <div className="space-y-1">
                                <div>
                                  {format(
                                    new Date(
                                      prediction.prediction.estimatedDate,
                                    ),
                                    "MMM d, yyyy",
                                  )}
                                </div>
                                {prediction.prediction.optimisticDate &&
                                  prediction.prediction.pessimisticDate && (
                                    <div className="text-xs text-muted-foreground">
                                      {format(
                                        new Date(
                                          prediction.prediction.optimisticDate,
                                        ),
                                        "MMM d",
                                      )}{" "}
                                      -{" "}
                                      {format(
                                        new Date(
                                          prediction.prediction.pessimisticDate,
                                        ),
                                        "MMM d",
                                      )}
                                    </div>
                                  )}
                              </div>
                            ) : (
                              "N/A"
                            )}
                          </TableCell>
                          <TableCell>
                            <Badge
                              className={getConfidenceColor(
                                prediction.prediction.confidence,
                              )}
                            >
                              {getConfidenceLabel(prediction.prediction.confidence)}
                            </Badge>
                          </TableCell>
                          <TableCell>
                            {prediction.needsRestock ? (
                              <Badge
                                variant="destructive"
                                className="flex items-center gap-1 w-fit"
                              >
                                <AlertTriangle className="h-3 w-3" />
                                Restock Soon
                              </Badge>
                            ) : (
                              <Badge variant="outline">OK</Badge>
                            )}
                          </TableCell>
                        </TableRow>
                      ))}
                    </TableBody>
                  </Table>
                </div>
              </>
            ) : (
              <div className="text-center py-8 text-muted-foreground">
                <Package className="h-12 w-12 mx-auto mb-2 opacity-50" />
                <p>No stock predictions available</p>
                <p className="text-sm mt-1">
                  Enable stock tracking on products to get predictions
                </p>
              </div>
            )}
          </div>
        )}
      </CardContent>
    </Card>
  );
}