using System.Dynamic;
using AutoMapper;
using Microsoft.EntityFrameworkCore;
using Server.Data;
using Server.Helpers;
using Server.Models;
using SharedModels.DataTransferObjects;
using SharedModels.QueryStringParameters;

namespace Server.Services;

public class CountryManagementService : ICountryManagementService
{
    private readonly ApplicationDbContext _dbContext;
    private readonly IMapper _mapper;
    private readonly ISortHelper<Country> _countrySortHelper;
    private readonly IDataShaper<Country> _countryDataShaper;

    public CountryManagementService(ApplicationDbContext dbContext,
        IMapper mapper, ISortHelper<Country> countrySortHelper, 
        IDataShaper<Country> countryDataShaper)
    {
        _dbContext = dbContext;
        _mapper = mapper;
        _countrySortHelper = countrySortHelper;
        _countryDataShaper = countryDataShaper;
    }

    public async Task<(bool isSucceed, string message, CountryDto country)> AddCountry(CreateCountryDto createCountryDto)
    {
        var country = _mapper.Map<Country>(createCountryDto);
    
        await _dbContext.Countries.AddAsync(country);
        await _dbContext.SaveChangesAsync();
    
        return (true, String.Empty, _mapper.Map<CountryDto>(country));
    }

    public async Task<(bool isSucceed, string message, IEnumerable<CountryDto> countries,
            PagingMetadata<Country> pagingMetadata)> GetCountries(CountryParameters parameters)
    {
        var dbCountries = _dbContext.Countries.Include(c => c.States)
            .ThenInclude(s => s.Cities).ThenInclude(c => c.Addresses)
            .AsQueryable();
        
        SearchByAllCountryFields(ref dbCountries, parameters.Search);
        SearchByCountryCode(ref dbCountries, parameters.Code);
        SearchByCountryName(ref dbCountries, parameters.Name);

        try
        {
            dbCountries = _countrySortHelper.ApplySort(dbCountries, parameters.Sort);
            
            // By calling Any() we will check if LINQ to Entities Query will be
            // executed. If not it will throw an InvalidOperationException exception
            var isExecuted = dbCountries.Any();
        }
        catch (Exception e)
        {
            return (false, "Invalid sorting string", null, null)!;
        }

        var pagingMetadata = ApplyPaging(ref dbCountries, parameters.PageNumber,
            parameters.PageSize);

        var shapedCountiesData = _countryDataShaper.ShapeData(dbCountries, parameters.Fields);
        var countryDtos = shapedCountiesData.ToList().ConvertAll(d => _mapper.Map<CountryDto>(d));
        
        return (true, "", countryDtos, pagingMetadata);

        void SearchByAllCountryFields(ref IQueryable<Country> countries,
            string? search)
        {
            if (!countries.Any() || String.IsNullOrWhiteSpace(search))
            {
                return;
            }

            countries = countries.Where(c =>
                c.Code.ToLower().Contains(search.ToLower()) ||
                c.Name.ToLower().Contains(search.ToLower()));
        }
        
        void SearchByCountryCode(ref IQueryable<Country> countries,
            string? countryCode)
        {
            if (!countries.Any() || String.IsNullOrWhiteSpace(countryCode))
            {
                return;
            }

            countries = countries.Where(c =>
                c.Code.ToLower().Contains(countryCode.Trim().ToLower()));
        }
        
        void SearchByCountryName(ref IQueryable<Country> countries,
            string? countryName)
        {
            if (!countries.Any() || String.IsNullOrWhiteSpace(countryName))
            {
                return;
            }

            countries = countries.Where(c =>
                c.Name.ToLower().Contains(countryName.Trim().ToLower()));
        }

        PagingMetadata<Country> ApplyPaging(ref IQueryable<Country> countries,
            int pageNumber, int pageSize)
        {
            var metadata = new PagingMetadata<Country>(countries,
                pageNumber, pageSize);
            
            countries = countries
                .Skip((pageNumber - 1) * pageSize)
                .Take(pageSize);

            return metadata;
        }
    }
    
    public async Task<(bool isSucceed, string message, CountryDto country)> GetCountry(int id, string? fields)
    {
        var dbCountry = await _dbContext.Countries.Where(c => c.Id == id)
            .Include(c => c.States).ThenInclude(s => s.Cities)
            .ThenInclude(c => c.Addresses)
            .FirstOrDefaultAsync();

        if (dbCountry == null)
        {
            return (false, $"Country doesn't exist", null)!;
        }

        if (String.IsNullOrWhiteSpace(fields))
        {
            fields = CountryParameters.DefaultFields;
        }
        
        var shapedCountryData = _countryDataShaper.ShapeData(dbCountry, fields);
        var countryDto = _mapper.Map<CountryDto>(shapedCountryData);

        return (true, "", countryDto);
    }

    public async Task<(bool isSucceed, string message, UpdateCountryDto country)> UpdateCountry(UpdateCountryDto updateCountryDto)
    {
        var country = _mapper.Map<Country>(updateCountryDto);
        _dbContext.Entry(country).State = EntityState.Modified;
        
        try
        {
            await _dbContext.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!await IsCountryExists(updateCountryDto.Id))
            {
                return (false, $"Country with id:{updateCountryDto.Id} doesn't exist", null)!;
            }
            
            throw;
        }

        var dbCountry = await _dbContext.Countries.FirstOrDefaultAsync(c => c.Id == country.Id);
        
        return (true, String.Empty, _mapper.Map<UpdateCountryDto>(dbCountry));
    }

    public async Task<(bool isSucceed, string message)> DeleteCountry(int id)
    {
        var dbCountry = await _dbContext.Countries.FirstOrDefaultAsync(c => c.Id == id);
    
        if (dbCountry == null)
        {
            return (false, $"Country with id:{id} doesn't exist");
        }
    
        _dbContext.Countries.Remove(dbCountry);
        await _dbContext.SaveChangesAsync();
    
        return (true, String.Empty);
    }

    public async Task<bool> IsCountryExists(int id)
    {
        return await _dbContext.Countries.AnyAsync(c => c.Id == id);
    }
}