using eprintServer.Data;
using eprintServer.Entities;
using Microsoft.EntityFrameworkCore;
using System.Collections.Generic;
using System.Linq;
using System.Threading.Tasks;

namespace eprintServer.Services;


public class TranslationService
{
    private readonly DataContext _context;
    
    private readonly List<string> MandatoryTags = new List<string> { "en", "ar" };

    public TranslationService(DataContext context)
    {
        _context = context;
    }

    public async Task<List<Language>> GetAllAvailableLanguagesAsync()
    {
        return await _context.Languages.OrderBy(l => l.Id).ToListAsync();
    }

 
    public async Task<TranslationSetting> GetTranslationSettingAsync()
    {
        var setting = await _context.TranslationSettings.FindAsync(1L);
        
        if (setting == null)
        {
            setting = new TranslationSetting { 
                Id = 1,
                ActiveLanguageTags = MandatoryTags
            };
            _context.TranslationSettings.Add(setting);
            await _context.SaveChangesAsync();
        }
        
        if (setting.ActiveLanguageTags != null && setting.ActiveLanguageTags.Any())
        {
            var activeTags = setting.ActiveLanguageTags;
            setting.ActiveLanguages = await _context.Languages
                .Where(l => activeTags.Contains(l.Tag))
                .ToListAsync();
        }

        return setting;
    }

     public async Task<TranslationSetting> UpdateActiveLanguagesAsync(List<string> selectedTags)
        {
            var setting = await GetTranslationSettingAsync();
            
            var validDatabaseTags = await _context.Languages
                .Select(l => l.Tag)
                .ToListAsync();

            var confirmedActiveTags = selectedTags
                .Where(tag => validDatabaseTags.Contains(tag))
                .Distinct()
                .ToList();
            
        
            var finalActiveTags = confirmedActiveTags
                .Union(MandatoryTags.Where(m => validDatabaseTags.Contains(m))) 
                .ToList();

            setting.ActiveLanguageTags = finalActiveTags;

            _context.TranslationSettings.Update(setting); 
            await _context.SaveChangesAsync();
       
            return setting;
        }
        
    }