import { useState, useMemo, useEffect } from 'react';
import { useLocation } from 'react-router-dom';
import { Plus, FolderKanban, Layers, PlayCircle, CheckCircle2, Search } from 'lucide-react';
import { useQuery } from '@tanstack/react-query';
import api from '@/lib/api';
import type { Project } from '@/types';
import { Button } from '@/components/ui/button';
import { Select } from '@/components/ui/select';
import { Input } from '@/components/ui/input';
import { Card, CardContent } from '@/components/ui/card';
import { GridSkeleton } from '@/components/ui/skeleton';
import { EmptyState } from '@/components/ui/empty-state';
import ProjectCard from './ProjectCard';
import ProjectForm from './ProjectForm';

const statusFilters = [
  { value: '', label: 'All' },
  { value: 'not_started', label: 'Not Started' },
  { value: 'in_progress', label: 'In Progress' },
  { value: 'completed', label: 'Completed' },
] as const;

export default function ProjectsPage() {
  const location = useLocation();
  const [showForm, setShowForm] = useState(false);
  const [editingProject, setEditingProject] = useState<Project | null>(null);
  const [statusFilter, setStatusFilter] = useState('');
  const [search, setSearch] = useState('');

  // Handle navigation state from dashboard
  useEffect(() => {
    const state = location.state as { filter?: string } | null;
    if (state?.filter) {
      setStatusFilter(state.filter);
      window.history.replaceState({}, '');
    }
  }, [location.state]);

  const { data: projects = [], isLoading } = useQuery({
    queryKey: ['projects'],
    queryFn: async () => {
      const { data } = await api.get<Project[]>('/projects');
      return data;
    },
  });

  const filteredProjects = useMemo(() => {
    let list = statusFilter ? projects.filter((p) => p.status === statusFilter) : projects;
    if (search) {
      const q = search.toLowerCase();
      list = list.filter(
        (p) => p.name.toLowerCase().includes(q) || p.description?.toLowerCase().includes(q)
      );
    }
    return list;
  }, [projects, statusFilter, search]);

  const inProgressCount = projects.filter((p) => p.status === 'in_progress').length;
  const completedCount = projects.filter((p) => p.status === 'completed').length;

  const handleEdit = (project: Project) => {
    setEditingProject(project);
    setShowForm(true);
  };

  const handleCloseForm = () => {
    setShowForm(false);
    setEditingProject(null);
  };

  return (
    <div className="flex flex-col h-full animate-fade-in">
      {/* Header */}
      <div className="border-b bg-card px-4 md:px-6 min-h-[4rem] flex items-center gap-2 md:gap-4 flex-wrap py-2 md:py-0 md:h-16 md:flex-nowrap shrink-0">
        <h1 className="font-heading text-xl md:text-2xl font-bold tracking-tight">Projects</h1>

        <Select
          value={statusFilter}
          onChange={(e) => setStatusFilter(e.target.value as typeof statusFilter)}
          className="h-8 text-sm w-auto pr-8 md:hidden"
        >
          {statusFilters.map((sf) => (
            <option key={sf.value} value={sf.value}>{sf.label}</option>
          ))}
        </Select>
        <div className="hidden md:flex items-center rounded-md border border-border overflow-hidden ml-4">
          {statusFilters.map((sf) => (
            <button
              key={sf.value}
              onClick={() => setStatusFilter(sf.value)}
              className={`px-3 py-1.5 text-sm font-medium transition-colors duration-150 ${
                statusFilter === sf.value
                  ? 'bg-accent/15 text-accent'
                  : 'text-muted-foreground hover:text-foreground hover:bg-card-elevated'
              }`}
              style={{
                backgroundColor: statusFilter === sf.value ? 'hsl(var(--accent-color) / 0.15)' : undefined,
                color: statusFilter === sf.value ? 'hsl(var(--accent-color))' : undefined,
              }}
            >
              {sf.label}
            </button>
          ))}
        </div>

        <div className="flex-1" />

        <div className="relative">
          <Search className="absolute left-2.5 top-1/2 -translate-y-1/2 h-3.5 w-3.5 text-muted-foreground" />
          <Input
            placeholder="Search..."
            value={search}
            onChange={(e) => setSearch(e.target.value)}
            className="w-32 sm:w-52 h-8 pl-8 text-sm"
          />
        </div>

        <Button onClick={() => setShowForm(true)} size="sm">
          <Plus className="h-4 w-4 md:mr-2" /><span className="hidden md:inline">New Project</span>
        </Button>
      </div>

      <div className="flex-1 overflow-y-auto px-4 md:px-6 py-5">
        {/* Summary stats */}
        {!isLoading && projects.length > 0 && (
          <div className="grid gap-1.5 md:gap-2.5 grid-cols-3 mb-5">
            <Card className="bg-gradient-to-br from-accent/[0.03] to-transparent">
              <CardContent className="p-2.5 md:p-4 flex items-center gap-2 md:gap-3">
                <div className="p-1.5 rounded-md bg-blue-500/10 hidden sm:block">
                  <Layers className="h-4 w-4 text-blue-400" />
                </div>
                <div>
                  <p className="text-[9px] md:text-[10px] tracking-wider uppercase text-muted-foreground">Total</p>
                  <p className="font-heading text-lg md:text-xl font-bold tabular-nums">{projects.length}</p>
                </div>
              </CardContent>
            </Card>
            <Card className="bg-gradient-to-br from-accent/[0.03] to-transparent">
              <CardContent className="p-2.5 md:p-4 flex items-center gap-2 md:gap-3">
                <div className="p-1.5 rounded-md bg-purple-500/10 hidden sm:block">
                  <PlayCircle className="h-4 w-4 text-purple-400" />
                </div>
                <div>
                  <p className="text-[9px] md:text-[10px] tracking-wider uppercase text-muted-foreground">In Progress</p>
                  <p className="font-heading text-lg md:text-xl font-bold tabular-nums">{inProgressCount}</p>
                </div>
              </CardContent>
            </Card>
            <Card className="bg-gradient-to-br from-accent/[0.03] to-transparent">
              <CardContent className="p-2.5 md:p-4 flex items-center gap-2 md:gap-3">
                <div className="p-1.5 rounded-md bg-green-500/10 hidden sm:block">
                  <CheckCircle2 className="h-4 w-4 text-green-400" />
                </div>
                <div>
                  <p className="text-[9px] md:text-[10px] tracking-wider uppercase text-muted-foreground">Completed</p>
                  <p className="font-heading text-lg md:text-xl font-bold tabular-nums">{completedCount}</p>
                </div>
              </CardContent>
            </Card>
          </div>
        )}

        {isLoading ? (
          <GridSkeleton cards={6} />
        ) : filteredProjects.length === 0 ? (
          <EmptyState
            icon={FolderKanban}
            title="No projects yet"
            description="Create your first project to start tracking tasks and progress."
            actionLabel="New Project"
            onAction={() => setShowForm(true)}
          />
        ) : (
          <div className="grid gap-4 md:grid-cols-2 lg:grid-cols-3">
            {filteredProjects.map((project) => (
              <ProjectCard key={project.id} project={project} onEdit={handleEdit} />
            ))}
          </div>
        )}
      </div>

      {showForm && <ProjectForm project={editingProject} onClose={handleCloseForm} />}
    </div>
  );
}