using Microsoft.EntityFrameworkCore;
using NDB.Infrastructure.DatabaseMigration.Constants;
using NDB.Infrastructure.DatabaseMigration.DbContexts;
using NDB.Infrastructure.DatabaseMigration.Entities;
using System;
using System.Linq;
using System.Threading.Tasks;

namespace NDB.Infrastructure.DatabaseMigration.Repositories
{
    internal class MigrationRepository : IMigrationRepository
    {
        private readonly MigrationDbContext _dbContext;

        public MigrationRepository(MigrationDbContext dbContext)
        {
            _dbContext = dbContext;
        }

        public async Task ExecuteSqlRaw(string sqlRaw)
        {
            await _dbContext.Database.ExecuteSqlRawAsync(sqlRaw);
        }

        public async Task<bool> MigrationTablesAreSet(DatabaseType databaseType)
        {
            var query = databaseType switch
            {
                DatabaseType.SQLServer => "select count(1) from sys.objects where name = 'MigrationSignature' and type = 'U' and SCHEMA_NAME(schema_id)='migration'",
                DatabaseType.SQLite => "select count(1) from sqlite_master where type='table' and name='MigrationSignature';",
                _ => throw new NotImplementedException($"DatabaseMigration type {databaseType} is not implemented"),
            };

            using (var command = _dbContext.Database.GetDbConnection().CreateCommand())
            {
                command.CommandText = query;
                await _dbContext.Database.OpenConnectionAsync();
                var result = await command.ExecuteScalarAsync();

                return result != null && result != DBNull.Value && Convert.ToInt32(result) > 0;
            }
        }

        public Task<MigrationSignature> GetLastMigrationSignature()
        {
            var query = _dbContext.MigrationSignatures
                .Include(z => z.MigratedVersions).ThenInclude(z => z.Scripts)
                .OrderByDescending(z => z.MigrationDate)
                .AsSplitQuery();

            return query.FirstOrDefaultAsync();
        }

        public async Task AddMigrationSignature(MigrationSignature migrationSignature)
        {
            await _dbContext.MigrationSignatures.AddAsync(migrationSignature);
            await _dbContext.SaveChangesAsync();
        }
    }
}