using back.DataModels;
using back.services.Crypto;
using Microsoft.EntityFrameworkCore;
using System.Net;

namespace back.context;

public class UserContext : DbContext
{
    public record HttpErrorMap(HttpStatusCode Code, string Description);

    public static class Errors
    {
        public static readonly HttpErrorMap Unauthorized = 
            new(HttpStatusCode.Unauthorized, "Invalid user data. Email or password are wrong.");
        public static readonly HttpErrorMap BadRequest =
            new(HttpStatusCode.BadRequest, "Missing user data.");
    }

    public DbSet<UserModel> Users { get; set; }
    private readonly ICryptoService _cryptoService;
    public UserContext(
        DbContextOptions<UserContext> options,
        ICryptoService cryptoService
        ) : base(options)
    {
        _cryptoService = cryptoService ?? throw new ArgumentNullException(nameof(cryptoService));
        // Ensure database is created
        Database.EnsureCreated();
    }

    public async Task<UserModel?> Create(string clientId, UserModel user)
    {
        ArgumentNullException.ThrowIfNull(user);

        if (await Exists(user))
        {
            return await GetById(Guid.Parse(user.Id)) ?? null;
        }

        if (string.IsNullOrEmpty(user.Id)) 
        {
            user.Id = Guid.NewGuid().ToString(); 
        }

        if (string.IsNullOrEmpty(user.Salt))
        {
            user.Salt = _cryptoService.Salt();
        }
        user.Password = _cryptoService.Decrypt(clientId, user.Password) ?? string.Empty;
        user.Password = _cryptoService.Hash(user.Password + user.Salt + _cryptoService.Pepper()) ?? string.Empty;

        user.CreatedAt = DateTime.UtcNow;
        Users.Add(user);
        await SaveChangesAsync();
        return user;
    }

    public async Task<UserModel?> Update(UserModel user)
    {
        ArgumentNullException.ThrowIfNull(user);
        if (!await Exists(user))
        {
            return null;
        }
        var existingUser = await GetById(Guid.Parse(user.Id));
        if (existingUser == null) return null;
        existingUser.Name = user.Name;
        existingUser.Email = user.Email;
        existingUser.UpdatedAt = DateTime.UtcNow;
        Users.Update(existingUser);
        await SaveChangesAsync();
        return existingUser;
    }

    public async Task<bool> Delete(Guid id)
    {
        var user = await GetById(id);
        if (user == null) return false;
        Users.Remove(user);
        await SaveChangesAsync();
        return true;
    }

    public async Task<UserModel?> GetByEmail(string email)
    {
        if (string.IsNullOrEmpty(email)) return null;
        return await Users.FirstOrDefaultAsync(u => u.Email == email);
    }

    public async Task<string> GetUserSaltByEmail(string email)
    {
        if (string.IsNullOrEmpty(email)) return string.Empty;
        var user = await Users.FirstOrDefaultAsync(u => u.Email == email);
        return user?.Salt ?? string.Empty;
    }

    public async Task<UserModel?> Login(string email, string password, string clientId)
    {
        if (string.IsNullOrEmpty(email) || string.IsNullOrEmpty(password)) return null;
        
        var pass = _cryptoService.Decrypt(clientId, password) + await GetUserSaltByEmail(email) + _cryptoService.Pepper();
        var hashedPassword = _cryptoService.Hash(pass);
        var user = await Users
            .FirstOrDefaultAsync(u => u.Email == email && u.Password == hashedPassword);
        return user;
    }

    public async Task<UserModel?> GetById(Guid id)
    {
        return await Users.FindAsync(id);
    }

    public async Task<int> GetTotalItems()
    {
        return await Users.CountAsync();
    }

    public async Task<IEnumerable<UserModel>> GetPage(int page = 1, int pageSize = 20)
    {
        if (page < 1) page = 1;
        if (pageSize < 1) pageSize = 20;

        return await Users
            .OrderByDescending(p => p.CreatedAt)
            .Skip((page - 1) * pageSize)
            .Take(pageSize)
            .ToListAsync();
    }

    public async Task<bool> Exists(UserModel? photo)
    {
        if (photo == null) return false;
        if (string.IsNullOrEmpty(photo.Id)) return false;
        return await Users.AnyAsync(p => p.Id == photo.Id);
    }

    public async Task<bool> Exists(string id)
    {
        return await Users.AnyAsync(p => p.Id == id);
    }
}