using System.Text.Json;
using HealthManager.Domain.Entities;
using HealthManager.Infrastructure.Data;
using Microsoft.EntityFrameworkCore;

namespace HealthManager.Application.Services;

public class CacheService(AppDbContext db)
{
    private static readonly JsonSerializerOptions JsonOptions = new() { PropertyNameCaseInsensitive = true };

    public async Task<T?> GetAsync<T>(string key) where T : class
    {
        var entry = await db.CacheEntries
            .FirstOrDefaultAsync(c => c.Key == key && c.ExpiresAt > DateTime.UtcNow);
        if (entry == null) return default;
        return JsonSerializer.Deserialize<T>(entry.Value.RootElement.GetRawText(), JsonOptions);
    }

    public async Task SetAsync<T>(string key, T value, TimeSpan ttl)
    {
        var json = JsonSerializer.SerializeToDocument(value);
        var existing = await db.CacheEntries.FirstOrDefaultAsync(c => c.Key == key);
        if (existing != null)
        {
            existing.Value = json;
            existing.ExpiresAt = DateTime.UtcNow.Add(ttl);
        }
        else
        {
            db.CacheEntries.Add(new CacheEntry
            {
                Key = key,
                Value = json,
                ExpiresAt = DateTime.UtcNow.Add(ttl),
            });
        }
        await db.SaveChangesAsync();
    }

    public async Task<T> GetOrSetAsync<T>(string key, Func<Task<T>> factory, TimeSpan ttl) where T : class
    {
        var cached = await GetAsync<T>(key);
        if (cached != null) return cached;
        var value = await factory();
        await SetAsync(key, value, ttl);
        return value;
    }

    public async Task RemoveAsync(string key)
    {
        await db.CacheEntries.Where(c => c.Key == key).ExecuteDeleteAsync();
    }
}