using Microsoft.SqlServer.TransactSql.ScriptDom;
using SQLLinter.Common;
using SQLLinter.Common.Helpers;

namespace SQLLinter.Infrastructure.Rules;

public class InformationSchemaRule : BaseRuleVisitor, IRule
{

    public override string Text => "Ожидается использование SYS.Partitions вместо представлений INFORMATION SCHEMA.";

    public override void Visit(SchemaObjectName node)
    {
        var schemaIdentifier = node.SchemaIdentifier?.Value != null;

        if (schemaIdentifier && node.SchemaIdentifier.Value.Equals("INFORMATION_SCHEMA", StringComparison.InvariantCultureIgnoreCase))
        {
            AddViolation(node);
        }
    }

    public override void FixViolation(List<string> fileLines, IRuleViolation ruleViolation, FileLineActions actions)
    {
        var node = FixHelpers.FindNodes<TSqlStatement>(fileLines, x => x.StartLine == ruleViolation.Line);

        if (node.Count == 1)
        {
            switch (node[0])
            {
                case IfStatement ifStatement:
                    HandleFragment(actions, ifStatement.Predicate);
                    break;

                case SelectStatement selectStatement:
                    HandleFragment(actions, selectStatement);
                    break;
            }
        }
    }

    private static void HandleFragment(FileLineActions actions, TSqlFragment statement)
    {
        var fromClauses = FixHelpers.FindNodes<FromClause>(statement);
        var whereClauses = FixHelpers.FindNodes<WhereClause>(statement);

        if (fromClauses.Count == 1 && whereClauses.Count <= 1)
        {
            var fromClause = fromClauses[0];
            var whereClause = whereClauses.FirstOrDefault();
            var tableName = FixHelpers.FindNodes<SchemaObjectName>(fromClause)[0].BaseIdentifier.Value;
            string newFrom = null;

            switch (tableName)
            {
                case "TABLES":
                    newFrom = "FROM sys.tables";
                    UpdateWhereTable(actions, fromClause, whereClause);

                    break;

                case "ROUTINES":
                    newFrom = "FROM sys.procedures";
                    UpdateWhereRoutine(actions, fromClause, whereClause);
                    break;

                case "COLUMNS":
                    newFrom = "FROM sys.columns";
                    UpdateWhereColumns(actions, fromClause, whereClause);
                    break;

                default:
                    break;
            }

            string oldFrom = FixHelpers.GetString(fromClause);

            if (newFrom != null)
            {
                actions.RepaceInlineAt(fromClause.StartLine - 1, fromClause.StartColumn - 1,
                newFrom, oldFrom.Length);
            }
        }
    }

    private static string GetWhereColumnValueName(WhereClause whereClause, string columnName)
    {
        var node = FixHelpers.FindNodes<BooleanComparisonExpression>(whereClause,
            x => FixHelpers.FindNodes<Identifier>(x.FirstExpression)[0].Value == columnName);

        if (node.Count == 1 && node[0].SecondExpression is StringLiteral stringLiteral)
        {
            return stringLiteral.Value;
        }

        return null;
    }

    private static void UpdateWhere(FileLineActions actions, FromClause fromClause, WhereClause whereClause, string newWhere)
    {
        var firstWhereLine = whereClause.ScriptTokenStream[whereClause.FirstTokenIndex].Line;
        var lastWhereLine = whereClause.ScriptTokenStream[whereClause.LastTokenIndex].Line;

        // Delete mutliline where
        var anyDeleted = false;
        for (int line = lastWhereLine; line > firstWhereLine; line--)
        {
            actions.RemoveAt(line - 1);
            anyDeleted = true;
        }
        if (anyDeleted)
        {
            newWhere += ")";
        }

        var oldWhere = string.Join(string.Empty, whereClause.ScriptTokenStream
            .Where((x, i) => x.Line == firstWhereLine
                && x.Column >= whereClause.StartColumn
                && i <= whereClause.LastTokenIndex
                && x.Text != "\n")
            .Select(x => x.Text));

        actions.RepaceInlineAt(whereClause.StartLine - 1, whereClause.StartColumn - 1,
            newWhere, oldWhere.Length);
    }

    private static void UpdateWhereColumns(
       FileLineActions actions,
       FromClause fromClause,
       WhereClause whereClause)
    {
        if (whereClause != null)
        {
            var schema = GetWhereColumnValueName(whereClause, "TABLE_SCHEMA");
            var columnName = GetWhereColumnValueName(whereClause, "COLUMN_NAME");
            var tableName = GetWhereColumnValueName(whereClause, "TABLE_NAME");
            var dataType = GetWhereColumnValueName(whereClause, "DATA_TYPE");

            if (schema != null && tableName != null && columnName != null)
            {
                var newWhere = $"WHERE [object_id] = OBJECT_ID(N'{schema}.{tableName}') AND [name] = '{columnName}'";
                if (dataType != null)
                {
                    newWhere += $" AND [system_type_id] = TYPE_ID(N'{dataType}')";
                }

                UpdateWhere(actions, fromClause, whereClause, newWhere);
            }
        }
    }

    private static void UpdateWhereRoutine(
        FileLineActions actions,
        FromClause fromClause,
        WhereClause whereClause)
    {
        if (whereClause != null)
        {
            var schema = GetWhereColumnValueName(whereClause, "ROUTINE_SCHEMA");
            var name = GetWhereColumnValueName(whereClause, "ROUTINE_NAME");
            var type = GetWhereColumnValueName(whereClause, "ROUTINE_TYPE");

            if (type == "PROCEDURE" && schema != null && name != null)
            {
                var newWhere = $"WHERE [object_id] = OBJECT_ID(N'{schema}.{name}')";

                UpdateWhere(actions, fromClause, whereClause, newWhere);
            }
        }
    }

    private static void UpdateWhereTable(
        FileLineActions actions,
        FromClause fromClause,
        WhereClause whereClause)
    {
        if (whereClause != null)
        {
            var schema = GetWhereColumnValueName(whereClause, "TABLE_SCHEMA");
            var name = GetWhereColumnValueName(whereClause, "TABLE_NAME");
            var type = GetWhereColumnValueName(whereClause, "TABLE_TYPE");

            if (type == "BASE TABLE" && schema != null && name != null)
            {
                var newWhere = $"WHERE [object_id] = OBJECT_ID(N'{schema}.{name}')";

                UpdateWhere(actions, fromClause, whereClause, newWhere);
            }
        }
    }
}