blog3000/Blog3000/Server/Controllers/ViewStatsController.cs

using Blog3000.Shared;
using System;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;
using Microsoft.AspNetCore.Mvc;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Caching.Memory;
using System.Text;
using System.IO;
using Microsoft.AspNetCore.StaticFiles;
using Microsoft.CodeAnalysis.CSharp.Syntax;
using Blog3000.Client;
using System.Text.Json;
using System.Xml.Linq;
using System.Threading;

namespace Blog3000.Server.Controllers
{
    [ApiController]
    [Route("[controller]")]
    public class ViewStatsController : ControllerBase
    {
    
        private readonly ILogger<BlogPostsController> logger;     
        private readonly BlogPostRepo blogPostRepo;        

        private readonly string statsFile;

        private static readonly SemaphoreSlim myLock = new SemaphoreSlim(1);
        
        public ViewStatsController(ILogger<BlogPostsController> logger, BlogPostRepo blogPostRepo)
        {
            this.logger = logger;
            this.blogPostRepo = blogPostRepo;            

            statsFile = System.IO.Path.Combine(
              (string)AppDomain.CurrentDomain.GetData("AppDataPath"),
              "stats.json");
        }


        [HttpGet]
        public async Task<ActionResult<Dictionary<string, int>>> GetAsync()
        {
            logger.LogInformation($"ViewStats|{HttpContext.Connection.RemoteIpAddress}|GetAsync");

            await myLock.WaitAsync();
            try 
            {
                var res = await LoadAsync();
                return res;
            }
            finally
            {
                myLock.Release();
            }
        }


        [HttpPost]
        public async Task <ActionResult<Dictionary<string, int>>> PostAsync(Dictionary<string, int> newStats)
        {
            // Only add 1 view for each read post to prevent user manipulating stats to much
            // Ignoew unknwon posts

            logger.LogInformation($"ViewStats|{HttpContext.Connection.RemoteIpAddress}|PostAsync");
            await myLock.WaitAsync();
            try
            {
                var stats = await LoadAsync();
                foreach (var k in newStats.Keys)
                {
                    if (blogPostRepo.GetHeaders().FirstOrDefault(p => p.Id.Equals(k)) != null)
                    {
                        int nv;
                        stats.TryGetValue(k, out nv);
                        nv++;
                        stats.Remove(k);
                        stats.Add(k, nv);
                    }
                }
                await SaveAsync(stats);
                return stats;
            }
            finally
            {
                myLock.Release();
            }
        }

        private async Task<Dictionary<String, int>> LoadAsync()
        {
            Dictionary<string, int> res = null;

            try
            {
                if (System.IO.File.Exists(statsFile))
                {
                    var text = await System.IO.File.ReadAllTextAsync(statsFile);
                    res = JsonSerializer.Deserialize<Dictionary<string, int>>(text);
                }
            }
            catch(Exception ex)
            {
                logger.LogWarning(ex, $"Error reading stats file ${statsFile}");
            }

            return res ?? new Dictionary<string, int>();

        }


        private async Task<bool> SaveAsync(Dictionary<string, int> stats)
        {
            stats ??= new Dictionary<string, int>();

            try
            {
                var text = JsonSerializer.Serialize(stats);
                await System.IO.File.WriteAllTextAsync(statsFile, text);
                return true;
            }
            catch (Exception ex)
            {
                logger.LogWarning(ex, $"Error writing stats file ${statsFile}");
            }

            return false;
        }




    }
}