"use client";

import { useState, useEffect } from 'react';
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card';
import { auth } from '@/lib/firebase/config';
import { toast } from 'sonner';
import { DollarSign, TrendingUp, TrendingDown, Calendar } from 'lucide-react';
import { useParams } from 'next/navigation';

interface CostData {
  total: number;
  thisMonth: number;
  lastMonth: number;
  byProject: Array<{
    projectId: string;
    projectName: string;
    cost: number;
  }>;
  byDate: Array<{
    date: string;
    cost: number;
  }>;
}

export default function CostsPage() {
  const params = useParams();
  const workspace = params.workspace as string;
  const [costs, setCosts] = useState<CostData | null>(null);
  const [loading, setLoading] = useState(true);

  useEffect(() => {
    loadCosts();
  }, []);

  const loadCosts = async () => {
    try {
      const user = auth.currentUser;
      if (!user) return;

      const token = await user.getIdToken();
      const response = await fetch('/api/costs', {
        headers: {
          'Authorization': `Bearer ${token}`,
        },
      });

      if (response.ok) {
        const data = await response.json();
        setCosts(data);
      }
    } catch (error) {
      console.error('Error loading costs:', error);
      toast.error('Failed to load cost data');
    } finally {
      setLoading(false);
    }
  };

  const percentageChange = costs && costs.lastMonth > 0
    ? ((costs.thisMonth - costs.lastMonth) / costs.lastMonth) * 100
    : 0;

  return (
    <div className="flex h-full flex-col overflow-auto">
      <div className="flex-1 p-8 space-y-8 max-w-7xl">
        {/* Header */}
        <div>
          <h1 className="text-4xl font-bold mb-2">Costs</h1>
          <p className="text-muted-foreground text-lg">
            Track your AI usage costs across all projects
          </p>
        </div>

        {/* Summary Cards */}
        {loading ? (
          <Card>
            <CardContent className="pt-6">
              <p className="text-center text-muted-foreground">Loading cost data...</p>
            </CardContent>
          </Card>
        ) : (
          <>
            <div className="grid gap-4 md:grid-cols-3">
              <Card>
                <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
                  <CardTitle className="text-sm font-medium">Total Costs</CardTitle>
                  <DollarSign className="h-4 w-4 text-muted-foreground" />
                </CardHeader>
                <CardContent>
                  <div className="text-2xl font-bold">${costs?.total.toFixed(2) || '0.00'}</div>
                  <p className="text-xs text-muted-foreground">All time</p>
                </CardContent>
              </Card>

              <Card>
                <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
                  <CardTitle className="text-sm font-medium">This Month</CardTitle>
                  <Calendar className="h-4 w-4 text-muted-foreground" />
                </CardHeader>
                <CardContent>
                  <div className="text-2xl font-bold">${costs?.thisMonth.toFixed(2) || '0.00'}</div>
                  <p className="text-xs text-muted-foreground">
                    {new Date().toLocaleDateString('en-US', { month: 'long', year: 'numeric' })}
                  </p>
                </CardContent>
              </Card>

              <Card>
                <CardHeader className="flex flex-row items-center justify-between space-y-0 pb-2">
                  <CardTitle className="text-sm font-medium">vs Last Month</CardTitle>
                  {percentageChange >= 0 ? (
                    <TrendingUp className="h-4 w-4 text-red-500" />
                  ) : (
                    <TrendingDown className="h-4 w-4 text-green-500" />
                  )}
                </CardHeader>
                <CardContent>
                  <div className="text-2xl font-bold">
                    {percentageChange >= 0 ? '+' : ''}{percentageChange.toFixed(1)}%
                  </div>
                  <p className="text-xs text-muted-foreground">
                    Last month: ${costs?.lastMonth.toFixed(2) || '0.00'}
                  </p>
                </CardContent>
              </Card>
            </div>

            {/* Costs by Project */}
            <Card>
              <CardHeader>
                <CardTitle>Costs by Project</CardTitle>
                <CardDescription>Your spending broken down by project</CardDescription>
              </CardHeader>
              <CardContent>
                {costs?.byProject && costs.byProject.length > 0 ? (
                  <div className="space-y-3">
                    {costs.byProject.map((project) => (
                      <div key={project.projectId} className="flex items-center justify-between p-3 rounded-lg border">
                        <div>
                          <p className="font-medium">{project.projectName}</p>
                          <p className="text-sm text-muted-foreground">Project ID: {project.projectId}</p>
                        </div>
                        <div className="text-right">
                          <p className="text-lg font-semibold">${project.cost.toFixed(2)}</p>
                          <p className="text-xs text-muted-foreground">
                            {((project.cost / (costs.total || 1)) * 100).toFixed(1)}% of total
                          </p>
                        </div>
                      </div>
                    ))}
                  </div>
                ) : (
                  <p className="text-center text-muted-foreground py-8">No project costs yet</p>
                )}
              </CardContent>
            </Card>

            {/* Info Card */}
            <Card className="border-blue-500/20 bg-blue-500/5">
              <CardHeader>
                <CardTitle className="text-base">About Cost Tracking</CardTitle>
              </CardHeader>
              <CardContent className="space-y-2 text-sm text-muted-foreground">
                <p>
                  <strong>📊 Automatic Tracking:</strong> All AI API costs are automatically tracked when you use Vibn features.
                </p>
                <p>
                  <strong>💰 Your Keys, Your Costs:</strong> Costs reflect usage of your own API keys - Vibn doesn't add any markup.
                </p>
                <p>
                  <strong>📈 Project Attribution:</strong> Costs are attributed to projects based on session metadata.
                </p>
              </CardContent>
            </Card>
          </>
        )}
      </div>
    </div>
  );
}