import React, { useState } from "react";
import { useNavigate, useParams } from "react-router-dom";
import { useQuery, useMutation, useQueryClient } from "@tanstack/react-query";
import { format, parseISO } from "date-fns";
import { toast } from "@/lib/custom-toast";
import { Calendar, Edit, Trash } from "lucide-react";

// UI Components
import Layout from "@/components/layout/layout";
import { Button } from "@/components/ui/button";
import {
  Card,
  CardContent,
  CardDescription,
  CardHeader,
  CardTitle,
} from "@/components/ui/card";
import {
  AlertDialog,
  AlertDialogAction,
  AlertDialogCancel,
  AlertDialogContent,
  AlertDialogDescription,
  AlertDialogFooter,
  AlertDialogHeader,
  AlertDialogTitle,
} from "@/components/ui/alert-dialog";
import { Separator } from "@/components/ui/separator";

// Types & API
import { Deliverable, ProjectApi } from "@/types";
import { deliverablesApi, projectService } from "@/lib/api";

const DeliverablePage = () => {
  const { id } = useParams<{ id: string }>();
  const deliverableId = parseInt(id || "0", 10);
  const [deleteDialogOpen, setDeleteDialogOpen] = useState(false);
  const navigate = useNavigate();
  const queryClient = useQueryClient();
  
  // Fetch deliverable data
  const { 
    isLoading: isLoadingDeliverable, 
    error: deliverableError, 
    data: deliverable 
  } = useQuery({
    queryKey: ['deliverable', deliverableId],
    queryFn: () => deliverablesApi.getById(deliverableId),
    enabled: deliverableId > 0,
  });

  // Fetch project data for the deliverable
  const { 
    isLoading: isLoadingProject, 
    error: projectError, 
    data: project 
  } = useQuery({
    queryKey: ['project', deliverable?.projectId],
    queryFn: () => projectService.getById(deliverable?.projectId || 0),
    enabled: !!deliverable?.projectId,
  });

  // Delete mutation
  const deleteDeliverableMutation = useMutation({
    mutationFn: (id: number) => deliverablesApi.delete(id),
    onSuccess: () => {
      queryClient.invalidateQueries({ queryKey: ['deliverables'] });
      toast.success('Deliverable deleted successfully');
      navigate('/deliverables');
    },
    onError: (error) => {
      console.error('Delete error:', error);
      toast.error('Failed to delete deliverable');
    }
  });

  // Handle delete deliverable
  const handleDeleteDeliverable = () => {
    setDeleteDialogOpen(true);
  };

  // Confirm delete
  const confirmDelete = () => {
    deleteDeliverableMutation.mutate(deliverableId);
  };

  // Handle edit
  const handleEdit = () => {
    navigate(`/deliverable-edit/${deliverableId}`);
  };

  if (isLoadingDeliverable || (deliverable?.projectId && isLoadingProject)) {
    return (
      <Layout>
        <div className="flex items-center justify-center min-h-screen">
          <p>Loading deliverable data...</p>
        </div>
      </Layout>
    );
  }

  if (deliverableError || (deliverable?.projectId && projectError)) {
    return (
      <Layout>
        <div className="flex flex-col items-center justify-center min-h-screen gap-4">
          <p className="text-red-500">Error loading deliverable data</p>
          <Button 
            variant="outline" 
            onClick={() => navigate("/deliverables")}
          >
            Back to Deliverables
          </Button>
        </div>
      </Layout>
    );
  }

  if (!deliverable) {
    return (
      <Layout>
        <div className="flex flex-col items-center justify-center min-h-screen gap-4">
          <p className="text-red-500">Deliverable not found</p>
          <Button 
            variant="outline" 
            onClick={() => navigate("/deliverables")}
          >
            Back to Deliverables
          </Button>
        </div>
      </Layout>
    );
  }

  return (
    <Layout>
      <div className="flex flex-col w-full min-h-screen p-4 md:p-6">
        <div className="flex flex-col md:flex-row md:items-center justify-between gap-4 mb-6">
          <div>
            <Button 
              variant="outline" 
              onClick={() => navigate("/deliverables")}
              className="mb-2"
            >
              Back to Deliverables
            </Button>
            <h1 className="text-2xl font-bold tracking-tight">{deliverable.name}</h1>
            {project && (
              <p className="text-muted-foreground">
                Project: {project.projectName}
              </p>
            )}
          </div>
          <div className="flex gap-2">
            <Button 
              variant="outline"
              onClick={handleEdit}
              className="flex items-center gap-1"
            >
              <Edit className="h-4 w-4" />
              Edit
            </Button>
            <Button 
              variant="destructive"
              onClick={handleDeleteDeliverable}
              className="flex items-center gap-1"
            >
              <Trash className="h-4 w-4" />
              Delete
            </Button>
          </div>
        </div>

        <div className="grid gap-6">
          <Card>
            <CardHeader>
              <CardTitle className="text-xl">Deliverable Details</CardTitle>
            </CardHeader>
            <CardContent className="space-y-4">
              <div>
                <h3 className="text-sm font-medium text-muted-foreground mb-1">Name</h3>
                <p>{deliverable.name}</p>
              </div>
              <Separator />
              <div>
                <h3 className="text-sm font-medium text-muted-foreground mb-1">Description</h3>
                <p className="whitespace-pre-line">{deliverable.description}</p>
              </div>
              <Separator />
              <div>
                <h3 className="text-sm font-medium text-muted-foreground mb-1">Delivery Date</h3>
                <div className="flex items-center gap-2">
                  <Calendar className="h-4 w-4 text-muted-foreground" />
                  <span>{format(parseISO(deliverable.deliveryDate), "MMMM d, yyyy")}</span>
                </div>
              </div>
              <Separator />
              <div>
                <h3 className="text-sm font-medium text-muted-foreground mb-1">Project</h3>
                <p>{project ? project.projectName : "Loading project..."}</p>
              </div>
            </CardContent>
          </Card>
        </div>

        <AlertDialog open={deleteDialogOpen} onOpenChange={setDeleteDialogOpen}>
          <AlertDialogContent>
            <AlertDialogHeader>
              <AlertDialogTitle>Are you absolutely sure?</AlertDialogTitle>
              <AlertDialogDescription>
                This action cannot be undone. This will permanently delete the deliverable.
              </AlertDialogDescription>
            </AlertDialogHeader>
            <AlertDialogFooter>
              <AlertDialogCancel>Cancel</AlertDialogCancel>
              <AlertDialogAction
                onClick={confirmDelete}
                className="bg-destructive hover:bg-destructive/90"
              >
                Delete
              </AlertDialogAction>
            </AlertDialogFooter>
          </AlertDialogContent>
        </AlertDialog>
      </div>
    </Layout>
  );
};

export default DeliverablePage;