import React, { useState, useEffect } from "react";
import { Todo } from "@/types";
import { Card, CardContent, CardHeader } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { 
  Pencil, 
  Trash2, 
  CheckCircle2, 
  User, 
  Briefcase, 
  CalendarClock, 
  Clock, 
  ChevronRight,
  CircleCheck,
  Circle,
  CheckCircle
} from "lucide-react";
import { format, isAfter, isPast, formatDistance } from "date-fns";
import { employeeService, projectService } from "@/lib/api";
import { Avatar, AvatarFallback, AvatarImage } from "@/components/ui/avatar";
import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "@/components/ui/tooltip";
import { Progress } from "@/components/ui/progress";
import { cn } from "@/lib/utils";

type TodoItemProps = {
  todo: Todo;
  onEdit?: (todo: Todo) => void;
  onDelete?: (id: number) => void;
  onStatusChange: (id: number, status: Todo['status']) => void;
};

const getPriorityColor = (priority: Todo['priority']) => {
  switch (priority) {
    case 'Low':
      return {
        bg: 'bg-white',
        border: 'border-l-4 border-emerald-400',
        text: 'text-emerald-700',
        badge: 'bg-emerald-50 text-emerald-700 border border-emerald-200'
      };
    case 'Medium':
      return {
        bg: 'bg-white',
        border: 'border-l-4 border-amber-400',
        text: 'text-amber-700',
        badge: 'bg-amber-50 text-amber-700 border border-amber-200'
      };
    case 'High':
      return {
        bg: 'bg-white',
        border: 'border-l-4 border-rose-500',
        text: 'text-rose-700',
        badge: 'bg-rose-50 text-rose-700 border border-rose-200'
      };
    default:
      return {
        bg: 'bg-white',
        border: 'border-l-4 border-slate-400',
        text: 'text-slate-700',
        badge: 'bg-slate-50 text-slate-700 border border-slate-200'
      };
  }
};

const getStatusColor = (status: Todo['status']) => {
  switch (status) {
    case 'Pending':
      return {
        bg: 'bg-slate-50',
        text: 'text-slate-700',
        badge: 'bg-white text-slate-700 border border-slate-200',
        icon: <Clock className="h-3.5 w-3.5 mr-1 text-slate-500" />
      };
    case 'In Progress':
      return {
        bg: 'bg-blue-50',
        text: 'text-blue-700',
        badge: 'bg-white text-blue-700 border border-blue-200',
        icon: <Progress className="h-1.5 w-14 mr-1" value={50} />
      };
    case 'Completed':
      return {
        bg: 'bg-green-50',
        text: 'text-green-700',
        badge: 'bg-white text-green-700 border border-green-200',
        icon: <CircleCheck className="h-3.5 w-3.5 mr-1 text-green-500" />
      };
    default:
      return {
        bg: 'bg-white',
        text: 'text-slate-700',
        badge: 'bg-white text-slate-700 border border-slate-200',
        icon: null
      };
  }
};

const getStatusProgress = (status: Todo['status']): number => {
  switch (status) {
    case 'Pending': return 0;
    case 'In Progress': return 50;
    case 'Completed': return 100;
    default: return 0;
  }
};

export function TodoItem({ todo, onEdit, onDelete, onStatusChange }: TodoItemProps) {
  const [assignee, setAssignee] = useState<{ name: string; email: string } | null>(null);
  const [project, setProject] = useState<{ name: string } | null>(null);
  const [isLoadingAssignee, setIsLoadingAssignee] = useState(false);
  const [isLoadingProject, setIsLoadingProject] = useState(false);
  const [isExpanded, setIsExpanded] = useState(false);
  const [isHovered, setIsHovered] = useState(false);

  const priorityStyles = getPriorityColor(todo.priority);
  const statusStyles = getStatusColor(todo.status);
  const dueDate = new Date(todo.dueDate);
  const isPastDue = isPast(dueDate) && todo.status !== 'Completed';
  const statusProgress = getStatusProgress(todo.status);
  const isCompleted = todo.status === 'Completed';

  useEffect(() => {
    const fetchAssignee = async () => {
      if (!todo.assigneeId) return;
      
      setIsLoadingAssignee(true);
      try {
        const response = await employeeService.getById(todo.assigneeId);
        if (response && response.id) {
          setAssignee({
            name: `${response.firstName} ${response.lastName}`,
            email: response.email
          });
        }
      } catch (error) {
        console.error("Failed to fetch assignee details", error);
      } finally {
        setIsLoadingAssignee(false);
      }
    };

    fetchAssignee();
  }, [todo.assigneeId]);

  useEffect(() => {
    const fetchProject = async () => {
      if (!todo.projectId) return;
      
      setIsLoadingProject(true);
      try {
        const response = await projectService.getById(todo.projectId);
        if (response && response.id) {
          setProject({
            name: response.projectName
          });
        }
      } catch (error) {
        console.error("Failed to fetch project details", error);
      } finally {
        setIsLoadingProject(false);
      }
    };

    fetchProject();
  }, [todo.projectId]);

  const handleStatusChange = (e: React.MouseEvent) => {
    e.preventDefault();
    e.stopPropagation();
    
    let newStatus: Todo['status'] = 'Pending';
    
    switch (todo.status) {
      case 'Pending':
        newStatus = 'In Progress';
        break;
      case 'In Progress':
        newStatus = 'Completed';
        break;
      case 'Completed':
        newStatus = 'Pending';
        break;
    }

    onStatusChange(todo.id, newStatus);
  };

  const toggleComplete = (e: React.MouseEvent) => {
    e.preventDefault();
    e.stopPropagation();
    
    const newStatus = isCompleted ? 'Pending' : 'Completed';
    onStatusChange(todo.id, newStatus);
  };

  const getInitials = (name: string) => {
    return name.split(' ')
      .map(part => part.charAt(0))
      .join('')
      .toUpperCase();
  };

  const toggleExpand = () => {
    setIsExpanded(!isExpanded);
  };

  return (
    <Card 
      className={cn(
        "transition-all duration-200 hover:shadow-lg",
        priorityStyles.bg,
        priorityStyles.border,
        "border border-slate-200 rounded-xl",
        isCompleted && "opacity-90 bg-slate-50",
        "shadow-sm overflow-hidden"
      )}
    >
      <div className="cursor-pointer group">
        <CardHeader className="p-3 sm:p-4 pb-2">
          {/* Mobile-first layout */}
          <div className="flex items-start gap-3">
            {/* Checkbox */}
            <div 
              className="mt-1 flex-shrink-0 relative"
              onClick={toggleComplete}
              onMouseEnter={() => setIsHovered(true)}
              onMouseLeave={() => setIsHovered(false)}
            >
              <div className={cn(
                "size-5 rounded-full flex items-center justify-center transition-colors",
                isCompleted ? 
                  "text-blue-600 bg-blue-50 border border-blue-300" : 
                  "text-gray-400 border border-gray-300 bg-white",
                isHovered && !isCompleted && "border-blue-500 text-blue-500",
                isHovered && isCompleted && "bg-blue-100"
              )}>
                {isCompleted ? (
                  <CheckCircle className="size-5 fill-blue-600 text-white" />
                ) : (
                  <Circle className="size-5" />
                )}
              </div>
            </div>
            
            {/* Main content */}
            <div className="flex-1 min-w-0" onClick={toggleExpand}>
              {/* Title and Priority - Mobile responsive */}
              <div className="flex flex-col sm:flex-row sm:items-center gap-1 sm:gap-2 mb-2">
                <h3 className={cn(
                  "text-sm sm:text-base font-medium flex-1", 
                  priorityStyles.text,
                  isCompleted && "line-through text-gray-500"
                )}>
                  {todo.title}
                </h3>
                <Badge className={cn(
                  "font-normal text-xs rounded-full px-2 py-0.5 self-start sm:self-center", 
                  priorityStyles.badge
                )}>
                  {todo.priority}
                </Badge>
              </div>
              
              {/* Description */}
              <p className={cn(
                "text-xs sm:text-sm text-gray-500 line-clamp-2 mb-2",
                isCompleted && "line-through"
              )}>
                {todo.description}
              </p>
              
              {/* Status and Date - Mobile responsive */}
              <div className="flex flex-col sm:flex-row sm:items-center gap-2 sm:gap-4">
                <TooltipProvider>
                  <Tooltip>
                    <TooltipTrigger asChild>
                      <Badge className={cn(
                        "font-normal flex items-center rounded-full px-2 py-1 text-xs w-fit", 
                        statusStyles.badge
                      )}>
                        {statusStyles.icon}
                        <span className="hidden sm:inline">{todo.status}</span>
                        <span className="sm:hidden">
                          {todo.status === 'In Progress' ? 'In Prog.' : todo.status}
                        </span>
                      </Badge>
                    </TooltipTrigger>
                    <TooltipContent>
                      <p>Status: {todo.status}</p>
                    </TooltipContent>
                  </Tooltip>
                </TooltipProvider>
                
                <div className={cn(
                  "flex items-center text-xs", 
                  isPastDue ? "text-rose-600" : "text-gray-500"
                )}>
                  <CalendarClock className="h-3 w-3 mr-1" />
                  <span className="hidden sm:inline">{format(dueDate, 'MMM dd, yyyy')}</span>
                  <span className="sm:hidden">{format(dueDate, 'MMM dd')}</span>
                  {isPastDue && (
                    <span className="ml-1 font-medium text-rose-600">
                      <span className="hidden sm:inline">(Overdue)</span>
                      <span className="sm:hidden">!</span>
                    </span>
                  )}
                </div>
              </div>
            </div>
          </div>
        </CardHeader>
        
        {/* Progress bar */}
        <div className="px-3 sm:px-4 pb-2" onClick={toggleExpand}>
          <Progress 
            value={statusProgress} 
            className={cn(
              "h-1.5",
              todo.status === 'Pending' ? "bg-slate-100" : 
              todo.status === 'In Progress' ? "bg-blue-100" : "bg-green-100"
            )}
          />
        </div>
      </div>
          
      {isExpanded && (
        <CardContent className="p-3 sm:p-4 pt-2 bg-slate-50 border-t border-slate-200">
          {/* Full description */}
          <div className="text-xs sm:text-sm text-gray-600 mb-4">
            {todo.description}
          </div>
          
          {/* Details grid - Mobile responsive */}
          <div className="grid grid-cols-1 gap-3 text-xs sm:text-sm mb-4">
            <div className="flex items-center text-gray-600">
              <CalendarClock className="h-4 w-4 mr-2 text-gray-500 flex-shrink-0" />
              <span className="font-medium mr-1">Due:</span>
              <span>{format(dueDate, 'PPP')}</span>
            </div>
            
            {todo.assigneeId && (
              <div className="flex items-center text-gray-600">
                <User className="h-4 w-4 mr-2 text-gray-500 flex-shrink-0" />
                <span className="font-medium mr-1">Assigned to:</span>
                {isLoadingAssignee ? (
                  <span className="italic">Loading...</span>
                ) : assignee ? (
                  <div className="flex items-center">
                    <Avatar className="h-5 w-5 mr-2">
                      <AvatarFallback className="text-[10px] bg-blue-100 text-blue-700">
                        {getInitials(assignee.name)}
                      </AvatarFallback>
                    </Avatar>
                    <span className="font-medium">{assignee.name}</span>
                  </div>
                ) : (
                  <span>Employee {todo.assigneeId}</span>
                )}
              </div>
            )}
            
            {todo.projectId && (
              <div className="flex items-center text-gray-600">
                <Briefcase className="h-4 w-4 mr-2 text-gray-500 flex-shrink-0" />
                <span className="font-medium mr-1">Project:</span>
                {isLoadingProject ? (
                  <span className="italic">Loading...</span>
                ) : project ? (
                  <span className="font-medium">{project.name}</span>
                ) : (
                  <span>Project {todo.projectId}</span>
                )}
              </div>
            )}
            
            <div className="flex items-center text-gray-600">
              <Clock className="h-4 w-4 mr-2 text-gray-500 flex-shrink-0" />
              <span className="font-medium mr-1">Created:</span>
              <span>{format(new Date(todo.createdAt || Date.now()), 'MMM dd, yyyy')}</span>
            </div>
          </div>
          
          {/* Action buttons - Mobile responsive */}
          <div className="flex flex-col sm:flex-row gap-2 sm:justify-between sm:items-center pt-3 border-t border-slate-200">
            <div className="flex flex-wrap gap-2">
              {onEdit && (
                <Button 
                  size="sm" 
                  variant="outline" 
                  onClick={(e) => {
                    e.stopPropagation();
                    onEdit(todo);
                  }}
                  className="bg-white hover:bg-gray-50 border-gray-200 text-gray-700 flex-1 sm:flex-none"
                >
                  <Pencil className="h-3.5 w-3.5 mr-1" /> 
                  <span className="hidden sm:inline">Edit</span>
                  <span className="sm:hidden">Edit</span>
                </Button>
              )}
              {onDelete && (
                <Button 
                  size="sm" 
                  variant="outline" 
                  className="text-rose-600 hover:text-rose-700 hover:bg-rose-50 bg-white border-rose-200 flex-1 sm:flex-none" 
                  onClick={(e) => {
                    e.stopPropagation();
                    onDelete(todo.id);
                  }}
                >
                  <Trash2 className="h-3.5 w-3.5 mr-1" /> 
                  <span className="hidden sm:inline">Delete</span>
                  <span className="sm:hidden">Delete</span>
                </Button>
              )}
            </div>
            
            <Button 
              size="sm" 
              variant="outline" 
              className={cn(
                "bg-white border w-full sm:w-auto",
                todo.status === 'Pending' ? "text-blue-600 hover:text-blue-700 hover:bg-blue-50 border-blue-200" : 
                todo.status === 'In Progress' ? "text-blue-600 hover:text-blue-700 hover:bg-blue-50 border-blue-200" :
                "text-green-600 hover:text-green-700 hover:bg-green-50 border-green-200"
              )}
              onClick={handleStatusChange}
            >
              <CheckCircle2 className="h-3.5 w-3.5 mr-1" /> 
              {todo.status === 'Pending' ? 'Start Task' : 
               todo.status === 'In Progress' ? 'Mark Complete' : 'Reopen Task'}
            </Button>
          </div>
        </CardContent>
      )}
    </Card>
  );
}