"use client";

import { useEffect, useState } from "react";
import { useSession } from "next-auth/react";
import {
  Card,
  CardContent,
  CardDescription,
  CardHeader,
  CardTitle,
} from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { Plus, Sparkles, Loader2, MoreVertical, Trash2 } from "lucide-react";
import Link from "next/link";
import { useParams } from "next/navigation";
import { ProjectCreationModal } from "@/components/project-creation-modal";
import {
  DropdownMenu,
  DropdownMenuContent,
  DropdownMenuItem,
  DropdownMenuTrigger,
} from "@/components/ui/dropdown-menu";
import {
  AlertDialog,
  AlertDialogAction,
  AlertDialogCancel,
  AlertDialogContent,
  AlertDialogDescription,
  AlertDialogFooter,
  AlertDialogHeader,
  AlertDialogTitle,
} from "@/components/ui/alert-dialog";
import { toast } from "sonner";

interface ProjectWithStats {
  id: string;
  name: string;
  slug: string;
  productName: string;
  productVision?: string;
  workspacePath?: string;
  status?: string;
  createdAt: string | null;
  updatedAt: string | null;
  stats: {
    sessions: number;
    costs: number;
  };
}

function getTimeAgo(dateStr: string | null | undefined): string {
  if (!dateStr) return "Unknown";
  const date = new Date(dateStr);
  if (isNaN(date.getTime())) return "Unknown";
  const now = new Date();
  const diff = now.getTime() - date.getTime();
  const days = Math.floor(diff / (1000 * 60 * 60 * 24));
  if (days === 0) return "Today";
  if (days === 1) return "Yesterday";
  if (days < 7) return `${days} days ago`;
  if (days < 30) return `${Math.floor(days / 7)} weeks ago`;
  if (days < 365) return `${Math.floor(days / 30)} months ago`;
  return `${Math.floor(days / 365)} years ago`;
}

export default function ProjectsPage() {
  const params = useParams();
  const workspace = params.workspace as string;
  const { data: session, status } = useSession();

  const [projects, setProjects] = useState<ProjectWithStats[]>([]);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const [showCreationModal, setShowCreationModal] = useState(false);
  const [projectToDelete, setProjectToDelete] = useState<ProjectWithStats | null>(null);
  const [isDeleting, setIsDeleting] = useState(false);

  const fetchProjects = async () => {
    try {
      setLoading(true);
      const res = await fetch("/api/projects");
      if (!res.ok) {
        const err = await res.json();
        throw new Error(err.error || "Failed to fetch projects");
      }
      const data = await res.json();
      setProjects(data.projects || []);
      setError(null);
    } catch (err: unknown) {
      console.error("Error fetching projects:", err);
      setError(err instanceof Error ? err.message : "Unknown error");
    } finally {
      setLoading(false);
    }
  };

  useEffect(() => {
    if (status === "authenticated") {
      fetchProjects();
    } else if (status === "unauthenticated") {
      setLoading(false);
    }
  }, [status]);

  const handleDeleteProject = async () => {
    if (!projectToDelete) return;
    setIsDeleting(true);
    try {
      const res = await fetch("/api/projects/delete", {
        method: "POST",
        headers: { "Content-Type": "application/json" },
        body: JSON.stringify({ projectId: projectToDelete.id }),
      });

      if (res.ok) {
        toast.success("Project deleted");
        setProjectToDelete(null);
        fetchProjects();
      } else {
        const err = await res.json();
        toast.error(err.error || "Failed to delete project");
      }
    } catch (err) {
      console.error("Delete error:", err);
      toast.error("An error occurred");
    } finally {
      setIsDeleting(false);
    }
  };

  if (status === "loading") {
    return (
      <div className="flex items-center justify-center py-16">
        <Loader2 className="h-8 w-8 animate-spin text-muted-foreground" />
      </div>
    );
  }

  return (
    <>
      <div className="container mx-auto py-8 px-4 max-w-6xl">
        <div className="flex items-center justify-between mb-8">
          <div>
            <h1 className="text-2xl font-bold">Projects</h1>
            <p className="text-muted-foreground text-sm mt-1">
              {session?.user?.email}
            </p>
          </div>
          <Button onClick={() => setShowCreationModal(true)}>
            <Plus className="mr-2 h-4 w-4" />
            New Project
          </Button>
        </div>

        <div className="space-y-6">
          {loading && (
            <div className="flex items-center justify-center py-16">
              <Loader2 className="h-8 w-8 animate-spin text-muted-foreground" />
            </div>
          )}

          {error && (
            <Card className="border-red-500/50 bg-red-500/5">
              <CardContent className="py-6">
                <p className="text-sm text-red-600">Error: {error}</p>
              </CardContent>
            </Card>
          )}

          {!loading && !error && projects.length > 0 && (
            <section>
              <h2 className="text-base font-semibold mb-4">Your Projects</h2>
              <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-3">
                {projects.map((project) => {
                  const projectHref = `/${workspace}/project/${project.id}/overview`;
                  return (
                    <div key={project.id} className="relative">
                      <Link href={projectHref}>
                        <Card className="hover:border-primary transition-all cursor-pointer h-full">
                          <CardHeader>
                            <div className="flex items-start justify-between">
                              <div className="flex items-center gap-3">
                                <div className="text-3xl">📦</div>
                                <div>
                                  <CardTitle className="text-base">{project.productName}</CardTitle>
                                  <CardDescription className="text-xs mt-0.5">
                                    {getTimeAgo(project.updatedAt)}
                                  </CardDescription>
                                </div>
                              </div>
                              <div className="flex items-center gap-2">
                                <div
                                  className={`px-2 py-0.5 rounded-full text-xs font-medium ${
                                    project.status === "active"
                                      ? "bg-green-500/10 text-green-600"
                                      : "bg-gray-500/10 text-gray-600"
                                  }`}
                                >
                                  {project.status}
                                </div>
                                <DropdownMenu>
                                  <DropdownMenuTrigger asChild onClick={(e: React.MouseEvent) => e.preventDefault()}>
                                    <Button variant="ghost" size="sm" className="h-8 w-8 p-0">
                                      <MoreVertical className="h-4 w-4" />
                                    </Button>
                                  </DropdownMenuTrigger>
                                  <DropdownMenuContent align="end">
                                    <DropdownMenuItem
                                      className="text-red-600 focus:text-red-600"
                                      onClick={(e: React.MouseEvent) => {
                                        e.preventDefault();
                                        setProjectToDelete(project);
                                      }}
                                    >
                                      <Trash2 className="mr-2 h-4 w-4" />
                                      Delete Project
                                    </DropdownMenuItem>
                                  </DropdownMenuContent>
                                </DropdownMenu>
                              </div>
                            </div>
                          </CardHeader>
                          <CardContent>
                            <p className="text-sm text-muted-foreground mb-4 line-clamp-2">
                              {project.productVision || "No description"}
                            </p>
                            {project.workspacePath && (
                              <p className="text-xs text-muted-foreground font-mono mb-4 truncate" title={project.workspacePath}>
                                📁 {project.workspacePath.split("/").pop()}
                              </p>
                            )}
                            <div className="flex items-center justify-between text-xs">
                              <div>
                                <span className="text-muted-foreground">Sessions:</span>{" "}
                                <span className="font-medium">{project.stats.sessions}</span>
                              </div>
                              <div>
                                <span className="text-muted-foreground">Costs:</span>{" "}
                                <span className="font-medium">${project.stats.costs.toFixed(2)}</span>
                              </div>
                            </div>
                          </CardContent>
                        </Card>
                      </Link>
                    </div>
                  );
                })}

                <Card
                  className="hover:border-primary transition-all cursor-pointer border-dashed h-full"
                  onClick={() => setShowCreationModal(true)}
                >
                  <CardContent className="flex flex-col items-center justify-center h-full min-h-[200px] p-6">
                    <div className="rounded-full bg-muted p-4 mb-4">
                      <Plus className="h-6 w-6 text-muted-foreground" />
                    </div>
                    <h3 className="font-semibold mb-1">Create New Project</h3>
                    <p className="text-sm text-muted-foreground text-center">
                      Start tracking a new product
                    </p>
                  </CardContent>
                </Card>
              </div>
            </section>
          )}

          {!loading && !error && projects.length === 0 && (
            <Card className="border-dashed">
              <CardContent className="flex flex-col items-center justify-center py-16">
                <div className="rounded-full bg-muted p-6 mb-4">
                  <Sparkles className="h-12 w-12 text-muted-foreground" />
                </div>
                <h3 className="text-lg font-semibold mb-2">No projects yet</h3>
                <p className="text-sm text-muted-foreground text-center max-w-md mb-6">
                  Create your first project to start tracking your AI-powered development workflow.
                </p>
                <Button size="lg" onClick={() => setShowCreationModal(true)}>
                  <Plus className="mr-2 h-4 w-4" />
                  Create Your First Project
                </Button>
              </CardContent>
            </Card>
          )}
        </div>
      </div>

      <ProjectCreationModal
        open={showCreationModal}
        onOpenChange={(open) => {
          setShowCreationModal(open);
          if (!open) fetchProjects();
        }}
        workspace={workspace}
      />

      <AlertDialog open={!!projectToDelete} onOpenChange={(open) => !open && setProjectToDelete(null)}>
        <AlertDialogContent>
          <AlertDialogHeader>
            <AlertDialogTitle>Are you absolutely sure?</AlertDialogTitle>
            <AlertDialogDescription>
              This will delete &quot;{projectToDelete?.productName}&quot;. Sessions will be preserved but unlinked.
            </AlertDialogDescription>
          </AlertDialogHeader>
          <AlertDialogFooter>
            <AlertDialogCancel disabled={isDeleting}>Cancel</AlertDialogCancel>
            <AlertDialogAction onClick={handleDeleteProject} disabled={isDeleting} className="bg-red-600 hover:bg-red-700">
              {isDeleting ? <Loader2 className="mr-2 h-4 w-4 animate-spin" /> : <Trash2 className="mr-2 h-4 w-4" />}
              Delete Project
            </AlertDialogAction>
          </AlertDialogFooter>
        </AlertDialogContent>
      </AlertDialog>
    </>
  );
}