using Microsoft.AspNetCore.Mvc;
using Google.Apis.AnalyticsData.v1beta;
using Google.Apis.AnalyticsData.v1beta.Data;
using Google.Apis.Auth.OAuth2;
using Google.Apis.Services;
using System;
using System.Collections.Generic;
using System.IO;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Caching.Memory;

namespace YourApp.Controllers
{
    [ApiController]
    [Route("api/[controller]")]
    public class VisitorController : ControllerBase
    {
        private readonly IMemoryCache _cache;
        private static string[] Scopes = { AnalyticsDataService.Scope.AnalyticsReadonly };
        private static string ApplicationName = "web-dlh";
        private static string PropertyId = "493898388";
        private static readonly TimeSpan CacheDuration = TimeSpan.FromMinutes(30);

        public VisitorController(IMemoryCache cache)
        {
            _cache = cache;
        }

        private static string GetCredentialsPath()
        {
            return Path.Combine(
                Directory.GetCurrentDirectory(),
                "AppData",
                "web-dlh-cd5131789ece.json"
            );
        }


        // Endpoint to get daily visitor count
        [HttpGet("daily-visitor")]
        public async Task<IActionResult> GetDailyVisitor()
        {
            try
            {
                var visitorCount = await GetVisitorCountAsync("yesterday", "yesterday");
                return Ok(new { dailyVisitorCount = visitorCount });
            }
            catch (Exception ex)
            {
                return StatusCode(500, new { message = "Error fetching daily visitor data", details = ex.Message });
            }
        }

        // Endpoint to get monthly visitor count
        [HttpGet("monthly-visitor")]
        public async Task<IActionResult> GetMonthlyVisitor()
        {
            try
            {
                var visitorCount = await GetVisitorCountAsync("30daysAgo", "yesterday");
                return Ok(new { monthlyVisitorCount = visitorCount });
            }
            catch (Exception ex)
            {
                return StatusCode(500, new { message = "Error fetching monthly visitor data", details = ex.Message });
            }
        }

        // Endpoint to get both daily and monthly visitor counts
        [HttpGet("visitor-stats")]
        public async Task<IActionResult> GetVisitorStats()
        {
            const string cacheKey = "visitor_stats";

            try
            {
                // Check cache first
                if (_cache.TryGetValue(cacheKey, out var cachedStats))
                {
                    return Ok(cachedStats);
                }

                // Fetch from GA4
                var dailyTask = GetVisitorCountAsync("yesterday", "yesterday");
                var monthlyTask = GetVisitorCountAsync("30daysAgo", "yesterday");

                await Task.WhenAll(dailyTask, monthlyTask);

                var stats = new
                {
                    dailyVisitorCount = await dailyTask,
                    monthlyVisitorCount = await monthlyTask,
                    lastUpdated = DateTime.UtcNow
                };

                _cache.Set(cacheKey, stats, CacheDuration);

                return Ok(stats);
            }
            catch (Exception ex)
            {
                if (_cache.TryGetValue(cacheKey, out var expiredStats))
                {
                    return Ok(expiredStats);
                }

                return StatusCode(500, new
                {
                    message = "Error fetching visitor statistics",
                    details = ex.Message
                });
            }
        }

        // Private method to fetch visitor count from Google Analytics Data API
        private async Task<long> GetVisitorCountAsync(string startDate, string endDate)
        {
            GoogleCredential credential;

            var credentialsPath = GetCredentialsPath();

            Console.WriteLine($"Using credentials path: {credentialsPath}");

            // Check if credentials file exists
            if (!System.IO.File.Exists(credentialsPath))
            {
                throw new FileNotFoundException($"Credentials file not found at: {credentialsPath}");
            }

            // Authenticate using Service Account
            using (var stream = new FileStream(credentialsPath, FileMode.Open, FileAccess.Read))
            {
                credential = GoogleCredential.FromStream(stream).CreateScoped(Scopes);
            }

            // Create the AnalyticsDataService instance
            var analyticsDataService = new AnalyticsDataService(new BaseClientService.Initializer()
            {
                HttpClientInitializer = credential,
                ApplicationName = ApplicationName,
            });

            // Prepare the request for the report
            var request = new RunReportRequest
            {
                DateRanges = new List<DateRange>
                {
                    new DateRange
                    {
                        StartDate = startDate,
                        EndDate = endDate
                    }
                },
                Metrics = new List<Metric>
                {
                    new Metric { Name = "activeUsers" }
                }
            };

            // Execute the request and get the response
            var response = await analyticsDataService.Properties.RunReport(request, $"properties/{PropertyId}").ExecuteAsync();

            long visitorCount = 0;

            if (response?.Rows?.Count > 0 && response.Rows[0].MetricValues?.Count > 0)
            {
                if (long.TryParse(response.Rows[0].MetricValues[0].Value, out visitorCount))
                {
                    return visitorCount;
                }
            }

            return visitorCount;
        }
        
         [HttpPost("clear-cache")]
        public IActionResult ClearCache()
        {
            _cache.Remove("visitor_stats");
            return Ok(new { message = "Cache cleared successfully" });
        }
    }
}