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

namespace AyaNova.PickList
{

    internal static class PickListSqlBuilder
    {
        /*Example
        select awidget.id as plId, awidget.active as plActive, awidget.name || ' ' || awidget.serial || ' ' || auser.name as plname, awidget.tags
        from awidget left outer join auser on (awidget.userid=auser.id) 
        where array_to_string(awidget.tags,',') like '%zone-8%'
        and awidget.active = true 
        and ((awidget.name like '%we%') or (cast (awidget.serial as text) like '%we%') or (auser.name like '%we%'))
        order by awidget.name,awidget.serial,auser.name limit 100
        */

        //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, string tagSpecificQuery, bool IncludeInactive, long preId)
        {

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


            //Variables to collect the data needed to create the actual clauses later
            List<string> lSelect = new List<string>();
            List<string> lWhere = new List<string>();
            List<string> lOrderBy = new List<string>();

            string PlIdSelectFragment = string.Empty;
            string ActiveSelectFragment = string.Empty;
            string ActiveWhereFragment = string.Empty;
            string TagSpecificWhereFragment = string.Empty;
            string PredefinedOnlyWhereFragment = string.Empty;

            //PROCESS ROW ID "VALUE" COLUMN 
            //
            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");
            PlIdSelectFragment = rowIdColumn.SqlIdColumnName + " as plId";

            if (preId != 0)
            {
                PredefinedOnlyWhereFragment = rowIdColumn.SqlIdColumnName + " = " + preId.ToString();
            }


            //PROCESS ACTIVE COLUMN
            //
            //NOTE: default is to filter *out* inactive objects because that's the most common need at the Client
            //but we provide the override for that if necessary as there are often (management usually) cases where user needs to select inactive records

            //add active column, fake it if necessary
            AyaPickListFieldDefinition activeColumn = pickList.ColumnDefinitions.FirstOrDefault(x => x.IsActiveColumn == true);
            if (activeColumn == null)
            {
                //no active column which is normal for some types of objects
                //so make a fake one and return them all as active=true as all lists must return the same format
                ActiveSelectFragment = "true as plActive";

            }
            else
            {
                //we have an active column, set accordingly             

                //regardless of wanting to see inactive, we always want to see the column itself
                ActiveSelectFragment = activeColumn.SqlValueColumnName + " as plActive";

                //this is the normal path unless there is an override
                //if there is an override to see inactive too then we just don't set the filter on active
                if (!IncludeInactive)
                {
                    ActiveWhereFragment = activeColumn.SqlValueColumnName + " = true";
                }
            }

            //PROCESS TAG SPECIFIC QUERY
            //
            if (HasTagSpecificQuery)
            {
                //get the tag column
                AyaPickListFieldDefinition tagColumn = pickList.ColumnDefinitions.FirstOrDefault(x => x.ColumnDataType == UiFieldDataType.Tags);
                TagSpecificWhereFragment = $"(array_to_string({tagColumn.GetSqlValueColumnName()},',') like '%{tagSpecificQuery}%')";
            }


            //PROCESS TEMPLATED COLUMNS TO BE RETURNED IN RESULTS
            //
            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();

                    string sWhere = string.Empty;

                    //TAGS COLUMN
                    //
                    if (o.ColumnDataType == UiFieldDataType.Tags)
                    {
                        lSelect.Add($"(array_to_string({valueColumnName},','))");
                        //tags can order by without the arraytostring
                        lOrderBy.Add(valueColumnName);

                        //THIS is the best filter method for a like comparison to each individual tag:
                        //(array_to_string(awidget.tags,',') like '%zo%')
                        //Note that a tag specific query takes precendence over this which exists
                        //in cases where there are tags in the template and the user has not specified a tag specific query
                        //so this will handle it as a like query against all tags as a composite string of text just like
                        //all the other templated fields
                        if (HasAutoCompleteQuery && !HasTagSpecificQuery)
                        {
                            if (ServerGlobalBizSettings.SearchCaseSensitiveOnly)
                                sWhere = $"(array_to_string({valueColumnName},',') like '%{autoCompleteQuery}%')";
                            else
                                sWhere = $"(lower(array_to_string({valueColumnName},',')) like lower('%{autoCompleteQuery}%'))";

                        }

                    }
                    else if (o.ColumnDataType == UiFieldDataType.Text || o.ColumnDataType == UiFieldDataType.EmailAddress || o.ColumnDataType == UiFieldDataType.HTTP)
                    {
                        //TEXT COLUMN
                        // 
                        lSelect.Add(valueColumnName);
                        lOrderBy.Add(valueColumnName);
                        if (HasAutoCompleteQuery)
                            if (ServerGlobalBizSettings.SearchCaseSensitiveOnly)
                                sWhere = $"({valueColumnName} like '%{autoCompleteQuery}%')";
                            else
                                sWhere = $"(lower({valueColumnName}) like lower('%{autoCompleteQuery}%'))";

                    }
                    else
                    {
                        //NON-TEXT COLUMN
                        //

                        //Note: if any part of a select contatenation query using the || postgres concat is text then all fields are automatically converted to text
                        //so no need to make it text here as the automatic spacing character will force the whole thing to a text concat anyway 
                        //ref: https://stackoverflow.com/a/19943343/8939
                        lSelect.Add(valueColumnName);

                        //order by for now seems to be best as just order by it's value whatever it is
                        lOrderBy.Add(valueColumnName);

                        //Where fragment is different for non text fields: it needs to be cast to text to like query on it
                        //(cast (awidget.serial as text) like '%some%')
                        if (HasAutoCompleteQuery)
                        if (ServerGlobalBizSettings.SearchCaseSensitiveOnly)
                            sWhere = $"(cast ({valueColumnName} as text) like '%{autoCompleteQuery}%')";
                            else
                            sWhere = $"(lower(cast ({valueColumnName} as text)) like lower('%{autoCompleteQuery}%'))";
                    }


                    if (HasAutoCompleteQuery && !string.IsNullOrWhiteSpace(sWhere))//swhere can be empty on a tag in a tag specific query
                        lWhere.Add(sWhere);


                }
            }

            StringBuilder sb = new StringBuilder();

            //SELECT
            sb.Append("select ");

            //ID COLUMN
            sb.Append(PlIdSelectFragment);
            sb.Append(", ");

            //ACTIVE COLUMN
            sb.Append(ActiveSelectFragment);
            sb.Append(", ");

            //nope, this will return null if any of the values are null, very bad for this use, instead
            //select name || ' ' || serial || ' ' || array_to_string(tags,',') as display from awidget
            //this, on the other hand will work even if all of them are null
            //concat_ws(' ', awidget.name, awidget.serial, auser.name)

            sb.Append("concat_ws(' ', ");
            foreach (string s in lSelect)
            {
                sb.Append(s);
                sb.Append(",");
            }
            //clear trailing comma
            sb.Length -= 1;
            sb.Append(") as plname");

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


            //WHERE   
            //there is a condition where there is no where (inactive=true and no query of any kind)        
            if (preId > 0 || lWhere.Count > 0 || HasTagSpecificQuery || IncludeInactive == false)
            {
                sb.Append(" where ");

                if (HasTagSpecificQuery)
                {
                    sb.Append(TagSpecificWhereFragment);
                    sb.Append(" and ");
                }

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

                if (preId > 0)
                {
                    sb.Append(PredefinedOnlyWhereFragment);
                    sb.Append(" and ");
                }

                if (lWhere.Count > 0)
                {
                    //Put all the regular query terms in parenthesis to ensure it's all treated as one criteria

                    sb.Append("(");
                    foreach (string s in lWhere)
                    {
                        sb.Append(s);
                        sb.Append(" or ");
                    }
                    //clear trailing or

                    sb.Length -= 4;
                    //enclosing parenthesis


                    sb.Append(")");
                }
                else
                {
                    //we might have a trailing and to remove
                    //jesus this stuff sucks, there must be a better way, it seems so fragile
                    if (!IncludeInactive || HasTagSpecificQuery)
                    {
                        //trailing " and " to remove
                        sb.Length -= 5;
                    }
                }
            }

            //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();

        }
        //"select awidget.id as plId || ' 'awidget.active as plActive || ' 'awidget.name || ' 'awidget.serial || ' 'auser.name as plname from awidget left outer join auser on (awidget.userid=auser.id) 
        //where awidget.active = true and ((awidget.name like '%on%') or (cast (awidget.serial as text) like '%on%') or (auser.name like '%on%')) order by awidget.name,awidget.serial,auser.name limit 100"


    }//eoc
}//ens