// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.

using System;
using System.Linq;
using Microsoft.AspNetCore.Http;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Infrastructure;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Options;

namespace Microsoft.AspNetCore.Identity.EntityFrameworkCore
{
    /// <summary>
    /// Base class for the Entity Framework database context used for identity.
    /// </summary>
    /// <typeparam name="TUser">The type of the user objects.</typeparam>
    public class IdentityUserContext<TUser> : IdentityUserContext<TUser, string> where TUser : IdentityUser
    {
        /// <summary>
        /// Initializes a new instance of <see cref="IdentityUserContext{TUser}"/>.
        /// </summary>
        /// <param name="options">The options to be used by a <see cref="DbContext"/>.</param>
        public IdentityUserContext(DbContextOptions options) : base(options) { }

        /// <summary>
        /// Initializes a new instance of the <see cref="IdentityUserContext{TUser}" /> class.
        /// </summary>
        protected IdentityUserContext() { }
    }

    /// <summary>
    /// Base class for the Entity Framework database context used for identity.
    /// </summary>
    /// <typeparam name="TUser">The type of user objects.</typeparam>
    /// <typeparam name="TKey">The type of the primary key for users and roles.</typeparam>
    public class IdentityUserContext<TUser, TKey> : IdentityUserContext<TUser, TKey, IdentityUserClaim<TKey>, IdentityUserLogin<TKey>, IdentityUserToken<TKey>>
        where TUser : IdentityUser<TKey>
        where TKey : IEquatable<TKey>
    {
        /// <summary>
        /// Initializes a new instance of the db context.
        /// </summary>
        /// <param name="options">The options to be used by a <see cref="DbContext"/>.</param>
        public IdentityUserContext(DbContextOptions options) : base(options) { }

        /// <summary>
        /// Initializes a new instance of the class.
        /// </summary>
        protected IdentityUserContext() { }
    }

    /// <summary>
    /// Base class for the Entity Framework database context used for identity.
    /// </summary>
    /// <typeparam name="TUser">The type of user objects.</typeparam>
    /// <typeparam name="TKey">The type of the primary key for users and roles.</typeparam>
    /// <typeparam name="TUserClaim">The type of the user claim object.</typeparam>
    /// <typeparam name="TUserLogin">The type of the user login object.</typeparam>
    /// <typeparam name="TUserToken">The type of the user token object.</typeparam>
    public abstract class IdentityUserContext<TUser, TKey, TUserClaim, TUserLogin, TUserToken> : DbContext
        where TUser : IdentityUser<TKey>
        where TKey : IEquatable<TKey>
        where TUserClaim : IdentityUserClaim<TKey>
        where TUserLogin : IdentityUserLogin<TKey>
        where TUserToken : IdentityUserToken<TKey>
    {
        /// <summary>
        /// Initializes a new instance of the class.
        /// </summary>
        /// <param name="options">The options to be used by a <see cref="DbContext"/>.</param>
        public IdentityUserContext(DbContextOptions options) : base(options) { }

        /// <summary>
        /// Initializes a new instance of the class.
        /// </summary>
        protected IdentityUserContext() { }

        /// <summary>
        /// Gets or sets the <see cref="DbSet{TEntity}"/> of Users.
        /// </summary>
        public DbSet<TUser> Users { get; set; }

        /// <summary>
        /// Gets or sets the <see cref="DbSet{TEntity}"/> of User claims.
        /// </summary>
        public DbSet<TUserClaim> UserClaims { get; set; }

        /// <summary>
        /// Gets or sets the <see cref="DbSet{TEntity}"/> of User logins.
        /// </summary>
        public DbSet<TUserLogin> UserLogins { get; set; }

        /// <summary>
        /// Gets or sets the <see cref="DbSet{TEntity}"/> of User tokens.
        /// </summary>
        public DbSet<TUserToken> UserTokens { get; set; }

        private int GetMaxLengthForKeys()
        {
            // Need to get the actual application service provider, fallback will cause
            // options to not work since IEnumerable<IConfigureOptions> don't flow across providers
            var options = this.GetService<IDbContextOptions>()
                            .Extensions.OfType<CoreOptionsExtension>()
                            .FirstOrDefault()?.ApplicationServiceProvider
                            ?.GetService<IOptions<IdentityOptions>>()
                            ?.Value?.Stores;
            return options != null ? options.MaxLengthForKeys : 0;
        }

        /// <summary>
        /// Configures the schema needed for the identity framework.
        /// </summary>
        /// <param name="builder">
        /// The builder being used to construct the model for this context.
        /// </param>
        protected override void OnModelCreating(ModelBuilder builder)
        {
            var maxKeyLength = GetMaxLengthForKeys();

            builder.Entity<TUser>(b =>
            {
                b.HasKey(u => u.Id);
                b.HasIndex(u => u.NormalizedUserName).HasName("UserNameIndex").IsUnique();
                b.HasIndex(u => u.NormalizedEmail).HasName("EmailIndex");
                b.ToTable("AspNetUsers");
                b.Property(u => u.ConcurrencyStamp).IsConcurrencyToken();

                b.Property(u => u.UserName).HasMaxLength(256);
                b.Property(u => u.NormalizedUserName).HasMaxLength(256);
                b.Property(u => u.Email).HasMaxLength(256);
                b.Property(u => u.NormalizedEmail).HasMaxLength(256);

                b.HasMany<TUserClaim>().WithOne().HasForeignKey(uc => uc.UserId).IsRequired();
                b.HasMany<TUserLogin>().WithOne().HasForeignKey(ul => ul.UserId).IsRequired();
                b.HasMany<TUserToken>().WithOne().HasForeignKey(ut => ut.UserId).IsRequired();
            });

            builder.Entity<TUserClaim>(b =>
            {
                b.HasKey(uc => uc.Id);
                b.ToTable("AspNetUserClaims");
            });

            builder.Entity<TUserLogin>(b =>
            {
                b.HasKey(l => new { l.LoginProvider, l.ProviderKey });

                if (maxKeyLength > 0)
                {
                    b.Property(l => l.LoginProvider).HasMaxLength(maxKeyLength);
                    b.Property(l => l.ProviderKey).HasMaxLength(maxKeyLength);
                }

                b.ToTable("AspNetUserLogins");
            });

            builder.Entity<TUserToken>(b => 
            {
                b.HasKey(t => new { t.UserId, t.LoginProvider, t.Name });

                if (maxKeyLength > 0)
                {
                    b.Property(t => t.LoginProvider).HasMaxLength(maxKeyLength);
                    b.Property(t => t.Name).HasMaxLength(maxKeyLength);
                }

                b.ToTable("AspNetUserTokens");
            });
        }
    }
}