<?php
  namespace App\Http\Controllers;
  use Illuminate\Http\Request;
  use Cache;
  use App\Models\Post;
  use App\Http\Requests;
  use App\Http\Controllers\Controller;
  class PostController extends Controller
  {
    /**
     * 显示文章列表.
     *
     * @return Response
     */
    public function index()
    {
      //使用all获取所有数据，如果数据量大采用分页获取
      $posts = Post::all();
      if(!$posts)
        exit('还没有发布任何文章！');
      $html = '<ul>';
      foreach ($posts as $post) {
        $html .= '<li><a href='.route('post.show',['post'=>$post]).'>'.$post->title.'</li>';
      }
      $html .= '</ul>';
      return $html;
    }
    /**
     * 创建新文章表单页面
     *
     * @return Response
     */
    public function create()
    {
      $postUrl = route('post.store');
      $csrf_field = csrf_field();
      $html = <<<CREATE
        <form action="$postUrl" method="POST">
          $csrf_field
          <input type="text" name="title"><br/><br/>
          <textarea name="content" cols="50" rows="5"></textarea><br/><br/>
          <input type="submit" value="提交"/>
        </form>
CREATE;
      return $html;
}
    /**
     * 将新创建的文章存储到存储器
     *
     * @param Request $request
     * @return Response
     */
    public function store(Request $request)
    {
      $title = $request->input('title');
      $content = $request->input('content');
      $post = new Post;
      $post->title = $title;
      $post->content = $content;
      $post->save();
      return redirect()->route('post.show',['post'=>$post]);
    }
    /**
     * 显示指定文章
     *
     * @param int $id
     * @return Response
     */
    public function show($id)
    {
      $post = Cache::get('post_'.$id);
      if(!$post){
        $post = Post::find($id);
        if(!$post)
          exit('指定文章不存在！');
        Cache::put('post_'.$id,$post,60*24*7);
      }
      if(!Cache::get('post_views_'.$id))
        Cache::forever('post_views_'.$id,0);
      $views = Cache::increment('post_views_'.$id);
      Cache::forever('post_views_'.$id,$views);
      $editUrl = route('post.edit',['post'=>$post]);
      $deleteUrl = route('post.destroy',['post'=>$post]);
      $html = <<<POST
        <h3>{$post->title}</h3>
        <p>{$post->content}</p>
        <i>已有{$views}人阅读</i>
        <p>
          <a href="{$editUrl}">编辑</a>
        </p>
POST;
      return $html;
    }
    /**
     * 显示编辑指定文章的表单页面
     *
     * @param int $id
     * @return Response
     */
    public function edit($id)
    {
      $post = Post::find($id);
      if(!$post)
        exit('指定文章不存在！');
      $postUrl = route('post.update',['post'=>$post]);
      $csrf_field = csrf_field();
      $html = <<<CREATE
        <form action="$postUrl" method="POST">
          $csrf_field
          <input type="hidden" name="_method" value="PUT"/>
          <input type="text" name="title" value="{$post->title}"><br/><br/>
          <textarea name="content" cols="50" rows="5">{$post->content}</textarea><br/><br/>
          <input type="submit" value="提交"/>
        </form>
CREATE;
      return $html;
    }
    /**
     * 在存储器中更新指定文章
     *
     * @param Request $request
     * @param int $id
     * @return Response
     */
    public function update(Request $request, $id)
    {
      $post = Post::find($id);
      if(!$post)
        exit('指定文章不存在！');
      $title = $request->input('title');
      $content = $request->input('content');
      $post->title = $title;
      $post->content = $content;
      $post->save();
      return redirect()->route('post.show',['post'=>$post]);
    }
    /**
     * 从存储器中移除指定文章
     *
     * @param int $id
     * @return Response
     */
    public function destroy($id)
    {
      $post = Post::find($id);
      if(!$post)
        exit('指定被删除文章不存在！');
      if($post->delete()){
        redirect()->route('post.index');
      }else{
        exit('删除文章失败！');
      }
    }
  }

//保存之后更新缓存数据
Post::saved(function($post){
  $cacheKey = 'post_'.$post->id;
  $cacheData = Cache::get($cacheKey);
  if(!$cacheData){
    Cache::add($cacheKey,$post,60*24*7);
  }else{
    Cache::put($cacheKey,$post,60*24*7);
  }
});
//删除之后清除缓存数据
Post::deleted(function($post){
  $cacheKey = 'post_'.$post->id;
  $cacheData = Cache::get($cacheKey);
  if($cacheData){
    Cache::forget($cacheKey);
  }
  if(Cache::get('post_views_'.$post->id))
    Cache::forget('post_views_'.$post->id);
});