using System;
using System.Collections.Generic;
using System.Globalization;
using System.Linq;
using SyncEngine.Access;

namespace SyncEngine.SqlServer
{
    internal static class DataSyncPrimaryKeyHelper
    {
        public static IList<string> GetPrimaryKeyColumns(AccessTableSchema table)
        {
            if (table?.PrimaryKeyColumns != null && table.PrimaryKeyColumns.Count > 0)
            {
                return table.PrimaryKeyColumns;
            }

            if (!string.IsNullOrWhiteSpace(table?.PrimaryKeyColumn))
            {
                return new List<string> { table.PrimaryKeyColumn };
            }

            return new List<string>();
        }

        public static string BuildOrderBy(IList<string> pkColumns)
        {
            return string.Join(", ", pkColumns.Select(c => "[" + c + "]"));
        }

        public static string BuildPkKey(IReadOnlyDictionary<string, object> row, IList<string> pkColumns)
        {
            return string.Join(
                "|",
                pkColumns.Select(c =>
                {
                    object value;
                    if (row == null || !row.TryGetValue(c, out value) || value == null)
                    {
                        return string.Empty;
                    }

                    return Convert.ToString(value, CultureInfo.InvariantCulture);
                }));
        }

        /// <summary>Access/Jet lexicographic resume predicate: row &gt; lastRow by PK column order.</summary>
        public static string BuildAccessResumeWhere(IList<string> pkColumns, IReadOnlyDictionary<string, object> lastRow)
        {
            if (lastRow == null || pkColumns == null || pkColumns.Count == 0)
            {
                return string.Empty;
            }

            var branches = new List<string>();
            for (var i = 0; i < pkColumns.Count; i++)
            {
                var equals = new List<string>();
                for (var j = 0; j < i; j++)
                {
                    equals.Add(string.Format(
                        "[{0}] = {1}",
                        pkColumns[j],
                        SqlLiteral(lastRow, pkColumns[j])));
                }

                equals.Add(string.Format(
                    "[{0}] > {1}",
                    pkColumns[i],
                    SqlLiteral(lastRow, pkColumns[i])));

                branches.Add("(" + string.Join(" AND ", equals) + ")");
            }

            return " WHERE (" + string.Join(" OR ", branches) + ")";
        }

        public static string BuildSqlWhereClause(IList<string> pkColumns, string parameterPrefix)
        {
            return string.Join(
                " AND ",
                pkColumns.Select((c, i) => string.Format("[{0}] = {1}{2}", c, parameterPrefix, i)));
        }

        public static void BindPrimaryKeyParameters(
            Microsoft.Data.SqlClient.SqlCommand cmd,
            IReadOnlyDictionary<string, object> row,
            IList<string> pkColumns,
            string parameterPrefix)
        {
            for (var i = 0; i < pkColumns.Count; i++)
            {
                object value;
                row.TryGetValue(pkColumns[i], out value);
                cmd.Parameters.AddWithValue(parameterPrefix + i, value ?? DBNull.Value);
            }
        }

        private static string SqlLiteral(IReadOnlyDictionary<string, object> row, string column)
        {
            object value;
            if (row == null || !row.TryGetValue(column, out value))
            {
                return "NULL";
            }

            return AccessTypeMapper.SqlLiteral(value);
        }
    }
}