"use client";

import { useState, useEffect, useCallback, useRef } from "react";
import { FolderKanban, RefreshCw, LayoutDashboard, ListTodo, FileText, GanttChartSquare } from "lucide-react";
import { toast } from "sonner";

import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
import { Button } from "@/components/ui/button";
import { Skeleton } from "@/components/ui/skeleton";
import { Card, CardContent } from "@/components/ui/card";

import { ProjectHeader } from "./project-header";
import { ProjectStats } from "./project-stats";
import { ProjectInfo } from "./project-info";
import { TasksSection } from "./tasks-section";
import { ProjectTaskGantt } from "./project-task-gantt";

import { Project } from "@/types/project";
import { Task } from "@/types/task";
import { getTasksByProjectId, calculateTaskStats } from "@/lib/tasksService";

interface ProjectDetailViewProps {
  project: Project;
}

// Skeleton para loading (exportado para uso externo)
export function ProjectDetailSkeleton() {
  return (
    <div className="space-y-6 p-6">
      {/* Header skeleton */}
      <div className="flex items-start gap-4">
        <Skeleton className="h-16 w-16 rounded-full" />
        <div className="space-y-2">
          <Skeleton className="h-8 w-64" />
          <Skeleton className="h-4 w-32" />
        </div>
      </div>
      
      {/* Stats skeleton */}
      <div className="grid grid-cols-4 gap-4">
        {Array.from({ length: 4 }).map((_, i) => (
          <Card key={i}>
            <CardContent className="p-4">
              <Skeleton className="h-4 w-20 mb-2" />
              <Skeleton className="h-8 w-24" />
            </CardContent>
          </Card>
        ))}
      </div>
      
      {/* Content skeleton */}
      <div className="grid grid-cols-3 gap-6">
        <div className="col-span-2 space-y-4">
          <Skeleton className="h-48 w-full" />
          <Skeleton className="h-48 w-full" />
        </div>
        <div className="space-y-4">
          <Skeleton className="h-64 w-full" />
          <Skeleton className="h-48 w-full" />
        </div>
      </div>
    </div>
  );
}

// Estado de error
function ErrorState({ onRetry }: { onRetry: () => void }) {
  return (
    <div className="flex flex-col items-center justify-center py-12 text-center">
      <div className="p-3 rounded-full bg-destructive/10 mb-4">
        <FolderKanban className="h-8 w-8 text-destructive" />
      </div>
      <h3 className="text-lg font-semibold mb-1">Error al cargar las tareas</h3>
      <p className="text-sm text-muted-foreground mb-4 max-w-sm">
        No se pudieron cargar las tareas del proyecto. Por favor, intenta de nuevo.
      </p>
      <Button onClick={onRetry} variant="outline">
        <RefreshCw className="h-4 w-4 mr-2" />
        Reintentar
      </Button>
    </div>
  );
}

export function ProjectDetailView({ project: initialProject }: ProjectDetailViewProps) {
  const [project, setProject] = useState<Project>(initialProject);
  const [tasks, setTasks] = useState<Task[]>([]);
  const [isLoadingTasks, setIsLoadingTasks] = useState(true);
  const [tasksError, setTasksError] = useState<string | null>(null);
  const hasShownReminders = useRef(false);

  // Cargar tareas
  const fetchTasks = useCallback(async () => {
    setIsLoadingTasks(true);
    setTasksError(null);
    try {
      const projectTasks = await getTasksByProjectId(project.id);
      setTasks(projectTasks);
    } catch (error) {
      console.error("Error fetching tasks:", error);
      setTasksError("Error al cargar las tareas");
    } finally {
      setIsLoadingTasks(false);
    }
  }, [project.id]);

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

  useEffect(() => {
    if (isLoadingTasks || tasksError || hasShownReminders.current) return;

    const now = new Date();
    const today = new Date(now.getFullYear(), now.getMonth(), now.getDate());
    const upcomingThreshold = new Date(today);
    upcomingThreshold.setDate(upcomingThreshold.getDate() + 7);

    const overdueTasks = tasks.filter((task) => {
      const endDate = task.endDate || task.plannedEndDate;
      if (!endDate) return false;
      return new Date(endDate) < today && task.status !== "2";
    });

    const upcomingTasks = tasks.filter((task) => {
      const endDate = task.endDate || task.plannedEndDate;
      if (!endDate) return false;
      const due = new Date(endDate);
      return due >= today && due <= upcomingThreshold && task.status !== "2";
    });

    const undatedTasks = tasks.filter((task) => {
      return !task.startDate && !task.endDate && !task.plannedStartDate && !task.plannedEndDate;
    });

    if (overdueTasks.length === 0 && upcomingTasks.length === 0 && undatedTasks.length === 0) {
      hasShownReminders.current = true;
      return;
    }

    const lines: string[] = [];
    if (overdueTasks.length > 0) lines.push(`• ${overdueTasks.length} tareas retrasadas`);
    if (upcomingTasks.length > 0) lines.push(`• ${upcomingTasks.length} próximas a vencer (≤ 7 días)`);
    if (undatedTasks.length > 0) lines.push(`• ${undatedTasks.length} sin fecha asignada`);

    toast("Recordatorios del proyecto", {
      description: lines.join("\n"),
    });

    hasShownReminders.current = true;
  }, [isLoadingTasks, tasksError, tasks]);

  // Handler para cuando se actualiza el proyecto
  const handleProjectUpdated = (updatedProject: Project) => {
    setProject(updatedProject);
  };

  // Handler para cuando se crea una tarea
  const handleTaskCreated = (newTask: Task) => {
    setTasks(prevTasks => [newTask, ...prevTasks]);
  };

  // Handler para cuando se actualiza una tarea
  const handleTaskUpdated = (updatedTask: Task) => {
    setTasks(prevTasks => 
      prevTasks.map(task => task.id === updatedTask.id ? updatedTask : task)
    );
  };

  // Handler para cuando se elimina una tarea
  const handleTaskDeleted = (taskId: number) => {
    setTasks(prevTasks => prevTasks.filter(task => task.id !== taskId));
  };

  // Calcular estadísticas de tareas
  const taskStats = calculateTaskStats(tasks);

  return (
    <div className="min-h-screen bg-background">
      {/* Header del proyecto */}
      <ProjectHeader 
        project={project} 
        tasks={tasks}
        onProjectUpdated={handleProjectUpdated}
      />

      {/* Contenido principal */}
      <div className="min-w-0 p-6 space-y-6">
        {/* Stats cards */}
        <ProjectStats project={project} taskStats={taskStats} />

        {/* Tabs de contenido */}
        <Tabs defaultValue="overview" className="space-y-6">
          <TabsList className="flex flex-wrap items-center gap-1">
            <TabsTrigger value="overview" className="gap-2">
              <LayoutDashboard className="h-4 w-4" />
              Resumen
            </TabsTrigger>
            <TabsTrigger value="tasks" className="gap-2">
              <ListTodo className="h-4 w-4" />
              Tareas
              {tasks.length > 0 && (
                <span className="ml-1 px-1.5 py-0.5 text-xs rounded-full bg-muted">
                  {tasks.length}
                </span>
              )}
            </TabsTrigger>
            <TabsTrigger value="gantt" className="gap-2">
              <GanttChartSquare className="h-4 w-4" />
              Gantt
            </TabsTrigger>
            <TabsTrigger value="details" className="gap-2">
              <FileText className="h-4 w-4" />
              Detalles
            </TabsTrigger>
          </TabsList>

          {/* Tab: Resumen */}
          <TabsContent value="overview" className="space-y-6">
            <ProjectInfo project={project} />
            
            {/* Preview de tareas */}
            {!isLoadingTasks && tasks.length > 0 && (
              <Card>
                <CardContent className="pt-6">
                  <div className="flex items-center justify-between mb-4">
                    <h3 className="font-semibold flex items-center gap-2">
                      <ListTodo className="h-4 w-4" />
                      Tareas recientes
                    </h3>
                    <Button variant="ghost" size="sm" asChild>
                      <a href="#tasks">Ver todas</a>
                    </Button>
                  </div>
                  <TasksSection 
                    tasks={tasks.slice(0, 5)} 
                    projectId={project.id}
                    onTaskCreated={handleTaskCreated}
                    onTaskUpdated={handleTaskUpdated}
                    onTaskDeleted={handleTaskDeleted}
                  />
                </CardContent>
              </Card>
            )}
          </TabsContent>

          {/* Tab: Tareas */}
          <TabsContent value="tasks">
            {isLoadingTasks ? (
              <div className="space-y-4">
                <div className="flex items-center gap-2">
                  <Skeleton className="h-9 w-[250px]" />
                  <Skeleton className="h-9 w-[130px]" />
                  <Skeleton className="h-9 w-[130px]" />
                </div>
                <div className="space-y-2">
                  {Array.from({ length: 5 }).map((_, i) => (
                    <Skeleton key={i} className="h-16 w-full" />
                  ))}
                </div>
              </div>
            ) : tasksError ? (
              <ErrorState onRetry={fetchTasks} />
            ) : (
              <TasksSection 
                tasks={tasks} 
                projectId={project.id}
                onTaskCreated={handleTaskCreated}
                onTaskUpdated={handleTaskUpdated}
                onTaskDeleted={handleTaskDeleted}
              />
            )}
          </TabsContent>

          {/* Tab: Gantt de tareas */}
          <TabsContent value="gantt">
            {isLoadingTasks ? (
              <div className="space-y-2">
                <Skeleton className="h-10 w-48" />
                <Skeleton className="h-[420px] w-full" />
              </div>
            ) : tasksError ? (
              <ErrorState onRetry={fetchTasks} />
            ) : (
              <ProjectTaskGantt tasks={tasks} />
            )}
          </TabsContent>

          {/* Tab: Detalles */}
          <TabsContent value="details">
            <ProjectInfo project={project} />
          </TabsContent>
        </Tabs>
      </div>
    </div>
  );
}