using System;
using System.Collections.Generic;
using System.Data;
using System.Linq;
using System.Reflection;
using System.Text;
using System.Threading.Tasks;

using Dapper;

#pragma warning disable 1573, 1591 // xml comments

namespace Dapper.Contrib.Extensions
{

    public static partial class SqlMapperExtensions
    {



        /// <summary>
        /// Returns a single entity by a single id from table "Ts" asynchronously using .NET 4.5 Task. T must be of interface type. 
        /// Id must be marked with [Key] attribute.
        /// Created entity is tracked/intercepted for changes and used by the Update() extension. 
        /// </summary>
        /// <typeparam name="T">Interface type to create and populate</typeparam>
        /// <param name="connection">Open SqlConnection</param>
        /// <param name="id">Id of the entity to get, must be marked with [Key] attribute</param>
        /// <returns>Entity of T</returns>
        public static async Task<T> GetAsync<T>(this IDbConnection connection, dynamic id, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
        {
            var type = typeof(T);
            string sql;
            if (!GetQueries.TryGetValue(type.TypeHandle, out sql))
            {
                var keys = KeyPropertiesCache(type);
                if (keys.Count() > 1)
                    throw new DataException("Get<T> only supports an entity with a single [Key] property");
                if (!keys.Any())
                    throw new DataException("Get<T> only supports en entity with a [Key] property");

                var onlyKey = keys.First();

                var name = GetTableName(type);

                // TODO: pluralizer 
                // TODO: query information schema and only select fields that are both in information schema and underlying class / interface 
                sql = "select * from " + name + " where " + onlyKey.Name + " = @id";
                GetQueries[type.TypeHandle] = sql;
            }

            var dynParms = new DynamicParameters();
            dynParms.Add("@id", id);

            T obj;

            if (type.IsInterface)
            {
                var res = (await connection.QueryAsync<dynamic>(sql, dynParms).ConfigureAwait(false)).FirstOrDefault() as IDictionary<string, object>;

                if (res == null)
                    return null;

                obj = ProxyGenerator.GetInterfaceProxy<T>();

                foreach (var property in TypePropertiesCache(type))
                {
                    var val = res[property.Name];
                    property.SetValue(obj, val, null);
                }

                ((IProxy)obj).IsDirty = false;   //reset change tracking and return
            }
            else
            {
                obj = (await connection.QueryAsync<T>(sql, dynParms, transaction, commandTimeout).ConfigureAwait(false)).FirstOrDefault();
            }
            return obj;
        }




        /// <summary>
        /// Inserts an entity into table "Ts" asynchronously using .NET 4.5 Task and returns identity id.
        /// </summary>
        /// <param name="connection">Open SqlConnection</param>
        /// <param name="entityToInsert">Entity to insert</param>
        /// <returns>Identity of inserted entity</returns>
        public static Task<int> InsertAsync<T>(this IDbConnection connection, T entityToInsert, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
        {
            var type = typeof(T);
            var name = GetTableName(type);
            var sbColumnList = new StringBuilder(null);
            var allProperties = TypePropertiesCache(type);
            var keyProperties = KeyPropertiesCache(type);
            var computedProperties = ComputedPropertiesCache(type);
            var allPropertiesExceptKeyAndComputed = allProperties.Except(keyProperties.Union(computedProperties)).ToList();

            for (var i = 0; i < allPropertiesExceptKeyAndComputed.Count(); i++)
            {
                var property = allPropertiesExceptKeyAndComputed.ElementAt(i);
                sbColumnList.AppendFormat("[{0}]", property.Name);
                if (i < allPropertiesExceptKeyAndComputed.Count() - 1)
                    sbColumnList.Append(", ");
            }

            var sbParameterList = new StringBuilder(null);
            for (var i = 0; i < allPropertiesExceptKeyAndComputed.Count(); i++)
            {
                var property = allPropertiesExceptKeyAndComputed.ElementAt(i);
                sbParameterList.AppendFormat("@{0}", property.Name);
                if (i < allPropertiesExceptKeyAndComputed.Count() - 1)
                    sbParameterList.Append(", ");
            }
            var adapter = GetFormatter(connection);
            return adapter.InsertAsync(connection, transaction, commandTimeout, name, sbColumnList.ToString(), 
                sbParameterList.ToString(), keyProperties, entityToInsert);
        }

        /// <summary>
        /// Updates entity in table "Ts" asynchronously using .NET 4.5 Task, checks if the entity is modified if the entity is tracked by the Get() extension.
        /// </summary>
        /// <typeparam name="T">Type to be updated</typeparam>
        /// <param name="connection">Open SqlConnection</param>
        /// <param name="entityToUpdate">Entity to be updated</param>
        /// <returns>true if updated, false if not found or not modified (tracked entities)</returns>
        public static async Task<bool> UpdateAsync<T>(this IDbConnection connection, T entityToUpdate, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
        {
            var proxy = entityToUpdate as IProxy;
            if (proxy != null)
            {
                if (!proxy.IsDirty) return false;
            }

            var type = typeof(T);

            var keyProperties = KeyPropertiesCache(type);
            if (!keyProperties.Any())
                throw new ArgumentException("Entity must have at least one [Key] property");

            var name = GetTableName(type);

            var sb = new StringBuilder();
            sb.AppendFormat("update {0} set ", name);

            var allProperties = TypePropertiesCache(type);
            var computedProperties = ComputedPropertiesCache(type);
            var nonIdProps = allProperties.Except(keyProperties.Union(computedProperties)).ToList();

            for (var i = 0; i < nonIdProps.Count(); i++)
            {
                var property = nonIdProps.ElementAt(i);
                sb.AppendFormat("{0} = @{1}", property.Name, property.Name);
                if (i < nonIdProps.Count() - 1)
                    sb.AppendFormat(", ");
            }
            sb.Append(" where ");
            for (var i = 0; i < keyProperties.Count(); i++)
            {
                var property = keyProperties.ElementAt(i);
                sb.AppendFormat("{0} = @{1}", property.Name, property.Name);
                if (i < keyProperties.Count() - 1)
                    sb.AppendFormat(" and ");
            }
            var updated = await connection.ExecuteAsync(sb.ToString(), entityToUpdate, commandTimeout: commandTimeout, transaction: transaction).ConfigureAwait(false);
            return updated > 0;
        }

        /// <summary>
        /// Delete entity in table "Ts" asynchronously using .NET 4.5 Task.
        /// </summary>
        /// <typeparam name="T">Type of entity</typeparam>
        /// <param name="connection">Open SqlConnection</param>
        /// <param name="entityToDelete">Entity to delete</param>
        /// <returns>true if deleted, false if not found</returns>
        public static async Task<bool> DeleteAsync<T>(this IDbConnection connection, T entityToDelete, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
        {
            if (entityToDelete == null)
                throw new ArgumentException("Cannot Delete null Object", "entityToDelete");

            var type = typeof(T);

            var keyProperties = KeyPropertiesCache(type);
            if (!keyProperties.Any())
                throw new ArgumentException("Entity must have at least one [Key] property");

            var name = GetTableName(type);

            var sb = new StringBuilder();
            sb.AppendFormat("delete from {0} where ", name);

            for (var i = 0; i < keyProperties.Count(); i++)
            {
                var property = keyProperties.ElementAt(i);
                sb.AppendFormat("{0} = @{1}", property.Name, property.Name);
                if (i < keyProperties.Count() - 1)
                    sb.AppendFormat(" and ");
            }
            var deleted = await connection.ExecuteAsync(sb.ToString(), entityToDelete, transaction, commandTimeout).ConfigureAwait(false);
            return deleted > 0;
        }

        /// <summary>
        /// Delete all entities in the table related to the type T asynchronously using .NET 4.5 Task.
        /// </summary>
        /// <typeparam name="T">Type of entity</typeparam>
        /// <param name="connection">Open SqlConnection</param>
        /// <returns>true if deleted, false if none found</returns>
        public static async Task<bool> DeleteAllAsync<T>(this IDbConnection connection, IDbTransaction transaction = null, int? commandTimeout = null) where T : class
        {
            var type = typeof(T);
            var name = GetTableName(type);
            var statement = String.Format("delete from {0}", name);
            var deleted = await connection.ExecuteAsync(statement, null, transaction, commandTimeout).ConfigureAwait(false);
            return deleted > 0;
        }
    }
}

public partial interface ISqlAdapter
{
    Task<int> InsertAsync(IDbConnection connection, IDbTransaction transaction, int? commandTimeout, String tableName, string columnList, string parameterList, IEnumerable<PropertyInfo> keyProperties, object entityToInsert);
}

public partial class SqlServerAdapter
{
    public async Task<int> InsertAsync(IDbConnection connection, IDbTransaction transaction, int? commandTimeout, String tableName, string columnList, string parameterList, IEnumerable<PropertyInfo> keyProperties, object entityToInsert)
    {
        var cmd = String.Format("insert into {0} ({1}) values ({2})", tableName, columnList, parameterList);

        await connection.ExecuteAsync(cmd, entityToInsert, transaction, commandTimeout).ConfigureAwait(false);

        //NOTE: would prefer to use IDENT_CURRENT('tablename') or IDENT_SCOPE but these are not available on SQLCE
        var r = await connection.QueryAsync<dynamic>("select @@IDENTITY id", transaction: transaction, commandTimeout: commandTimeout).ConfigureAwait(false);
        var id = (int)r.First().id;
        var propertyInfos = keyProperties as PropertyInfo[] ?? keyProperties.ToArray();
        if (propertyInfos.Any())
            propertyInfos.First().SetValue(entityToInsert, id, null);
        return id;
    }
}

public partial class PostgresAdapter
{

    public async Task<int> InsertAsync(IDbConnection connection, IDbTransaction transaction, int? commandTimeout, String tableName, string columnList, string parameterList, IEnumerable<PropertyInfo> keyProperties, object entityToInsert)
    {
        var sb = new StringBuilder();
        sb.AppendFormat("insert into {0} ({1}) values ({2})", tableName, columnList, parameterList);

        // If no primary key then safe to assume a join table with not too much data to return
        var propertyInfos = keyProperties as PropertyInfo[] ?? keyProperties.ToArray();
        if (!propertyInfos.Any())
            sb.Append(" RETURNING *");
        else
        {
            sb.Append(" RETURNING ");
            bool first = true;
            foreach (var property in propertyInfos)
            {
                if (!first)
                    sb.Append(", ");
                first = false;
                sb.Append(property.Name);
            }
        }

        var results = await connection.QueryAsync<dynamic>(sb.ToString(), entityToInsert, transaction, commandTimeout).ConfigureAwait(false);

        // Return the key by assinging the corresponding property in the object - by product is that it supports compound primary keys
        var id = 0;
        foreach (var p in propertyInfos)
        {
            var value = ((IDictionary<string, object>)results.First())[p.Name.ToLower()];
            p.SetValue(entityToInsert, value, null);
            if (id == 0)
                id = Convert.ToInt32(value);
        }
        return id;
    }
}

public partial class SQLiteAdapter
{

    public async Task<int> InsertAsync(IDbConnection connection, IDbTransaction transaction, int? commandTimeout, String tableName, string columnList, string parameterList, IEnumerable<PropertyInfo> keyProperties, object entityToInsert)
    {
        var cmd = String.Format("insert into {0} ({1}) values ({2})", tableName, columnList, parameterList);

        await connection.ExecuteAsync(cmd, entityToInsert, transaction: transaction, commandTimeout: commandTimeout).ConfigureAwait(false);

        var r = await connection.QueryAsync<dynamic>("select last_insert_rowid() id", transaction: transaction, commandTimeout: commandTimeout).ConfigureAwait(false);
        var id = (int)r.First().id;
        var propertyInfos = keyProperties as PropertyInfo[] ?? keyProperties.ToArray();
        if (propertyInfos.Any())
            propertyInfos.First().SetValue(entityToInsert, id, null);
        return id;
    }
}