using System.Collections.Generic;
using System.Text;
using System.Linq;
using AyaNova.Biz;

namespace AyaNova.PickList
{

    internal static class PickListSqlBuilder
    {
        //Maximum number of results to return at any given time
        //did a little research and may adjust this but it can be fairly girthy in this day and age
        //and many people might not want or need to autocomplete type if we provide enough leeway.
        //for example, if you're selecting a 
        const int MAXIMUM_RESULT_COUNT = 100;

        //Build the query for a picklist request
        internal static string Build(IAyaPickList pickList, List<string> templateColumnNames, string autoCompleteQuery, bool IncludeInactive)
        {

            //TODO: if no autocompletequery returns the first XX results without querying in natural order by column names
            //if autocomplete returns teh first XX results with query in natural order by column names

            //TODO: build a sql List<AyaPickListFieldDefinition> columnDefinitionsselect and order by and a where clause that searches appropriately in each field (tags)
            //it should return results based on the query where there is a single name (display) column and an id column for rowid
            //and the fields should be combined in a standard way separated by spaces "Widget widgetserial username" for compactness
            //WORKING QUERY
            //select awidget.id AS rowid,awidget.active,awidget.name,awidget.serial,auser.name from awidget left outer join auser on (awidget.userid=auser.id) 
            //where awidget.active = true and ((awidget.name like '%some%') or (cast (awidget.serial as text) like '%some%') or (auser.name like '%some%') ) order by awidget.name,awidget.serial,auser.name limit 100


            //TODO: TAGS
            //TODO: Clean out unnneeded stuff in AyaPickListFieldDefinition (stuff from datalist copied over)

            //determine this in advance as it will be used in a loop later
            bool HasAutoCompleteQuery = !string.IsNullOrWhiteSpace(autoCompleteQuery);

            //lists to collect the clauses so to avoid comma fuckery
            List<string> lSelect = new List<string>();
            string ActiveWhereFragment = string.Empty;
            List<string> lWhere = new List<string>();
            List<string> lOrderBy = new List<string>();


            //Add rowid column as it's always required
            AyaPickListFieldDefinition rowIdColumn = pickList.ColumnDefinitions.FirstOrDefault(x => x.IsRowId == true);
            //this should only happen with a development error
            if (rowIdColumn == null)
                throw new System.ArgumentNullException($"DEV ERROR in PickListSqlBuilder.cs: picklist for {pickList.DefaultListObjectType.ToString()} has no rowId column specified in columnDefinitions list");
            lSelect.Add(rowIdColumn.SqlIdColumnName + " AS rowid");

            //add active only as default for all lists unless inactive is specified
            if (!IncludeInactive)
            {
                AyaPickListFieldDefinition activeColumn = pickList.ColumnDefinitions.FirstOrDefault(x => x.IsActiveColumn == true);
                //it's ok if there is no active column, it could happen so just roll with it
                if (activeColumn != null)
                {
                    lSelect.Add(activeColumn.SqlValueColumnName);
                    ActiveWhereFragment = activeColumn.SqlValueColumnName + " = true";
                }
            }

            foreach (string ColumnName in templateColumnNames)
            {

                AyaPickListFieldDefinition o = pickList.ColumnDefinitions.FirstOrDefault(x => x.FieldKey == ColumnName);
#if (DEBUG)                
                if (o == null)
                {
                    throw new System.ArgumentNullException($"DEV ERROR in PickListSqlBuilder.cs: field {ColumnName} specified in template was NOT found in columnDefinitions list");
                }
#endif
                if (o != null)
                {//Ignore missing fields in production

                    var valueColumnName = o.GetSqlValueColumnName();

                    lSelect.Add(valueColumnName);
                    lOrderBy.Add(valueColumnName);

                    if (HasAutoCompleteQuery)
                    {
                        string sWhere = string.Empty;

                        //Tag?
                        if (o.ColumnDataType == UiFieldDataType.Tags)
                        {

                        }
                        else if (o.ColumnDataType == UiFieldDataType.Text || o.ColumnDataType == UiFieldDataType.EmailAddress || o.ColumnDataType == UiFieldDataType.HTTP)
                        {
                            //regular text field 
                            sWhere = $"({valueColumnName} LIKE '%{autoCompleteQuery}%')";
                        }
                        else
                        {
                            //needs to be cast to text
                            //(cast (awidget.serial as text) like '%some%')
                            sWhere = $"(cast ({valueColumnName} as text) LIKE '%{autoCompleteQuery}%')";
                        }



                        lWhere.Add(sWhere);
                    }

                }
            }

            StringBuilder sb = new StringBuilder();

            //SELECT
            sb.Append("select ");
            foreach (string s in lSelect)
            {
                sb.Append(s);
                sb.Append(",");
            }
            //clear trailing comma
            sb.Length--;

            //FROM
            sb.Append(" ");
            sb.Append(pickList.SQLFrom);


            //WHERE           
            sb.Append(" where ");
            if (!IncludeInactive)
            {
                sb.Append(ActiveWhereFragment);
                sb.Append(" and (");
            }

            foreach (string s in lWhere)
            {
                sb.Append(s);
                sb.Append(" or ");
            }
            //clear trailing or
            sb.Length -= 4;
            //enclosing parenthesis
            if (!IncludeInactive)
            {
                sb.Append(")");
            }

            //ORDER BY
            sb.Append(" order by ");
            foreach (string s in lOrderBy)
            {
                sb.Append(s);
                sb.Append(",");
            }
            //clear trailing comma
            sb.Length--;

            //LIMIT          
            sb.Append($" limit {MAXIMUM_RESULT_COUNT}");

            return sb.ToString();

        }



    }//eoc
}//ens