Function to SQL

ts

import { debug } from 'util';
import * as ts from 'typescript';

function getArrowFunction(func: Function): ts.ArrowFunction {
    let src = ts.createSourceFile("test.ts", func.toString(), ts.ScriptTarget.ES2016, false);
    var expr = <ts.ExpressionStatement> src.statements[0];
    return <ts.ArrowFunction> expr.expression;    
}

function toSql(expr: ts.Node): string {
    switch(expr.kind) {
        case ts.SyntaxKind.PropertyAccessExpression:
            var paExpr = <ts.PropertyAccessExpression> expr;
            var idObject = <ts.Identifier> paExpr.expression;
            return idObject.text + "." + paExpr.name.text;
        case ts.SyntaxKind.ParenthesizedExpression:
            var parExpr = <ts.ParenthesizedExpression> expr;
            return "(" + toSql(parExpr.expression) + ")";
        case ts.SyntaxKind.BinaryExpression:
            var bExpr = <ts.BinaryExpression> expr;
            
            var op = "";
            switch (bExpr.operatorToken.kind) {
                case ts.SyntaxKind.EqualsEqualsToken:
                    op = "=";
                    break;
                case ts.SyntaxKind.GreaterThanToken:
                    op = ">";
                    break;
                case ts.SyntaxKind.GreaterThanEqualsToken:
                    op = ">=";
                    break;
                case ts.SyntaxKind.LessThanToken:
                    op = "<";
                    break;
                case ts.SyntaxKind.LessThanEqualsToken:
                    op = "<=";
                    break;
                case ts.SyntaxKind.AmpersandAmpersandToken:
                    op = "and";
                    break;
                case ts.SyntaxKind.BarBarToken:
                    op = "or";
                    break;
                default:
                    op = "[UndefinedOperator]";
            }
            
            return toSql(bExpr.left) + " " + op + " " + toSql(bExpr.right);
        case ts.SyntaxKind.NumericLiteral:
            var nlExpr = <ts.NumericLiteral> expr;
            return nlExpr.text;
        case ts.SyntaxKind.StringLiteral:
            var slExpr = <ts.StringLiteral> expr;
            return "'" + slExpr.text + "'";        
        case ts.SyntaxKind.CallExpression:
            var cExpr = <ts.CallExpression> expr;
            if (cExpr.expression.kind == ts.SyntaxKind.PropertyAccessExpression) {
                var cpaExpr = <ts.PropertyAccessExpression> cExpr.expression;
                var funcName = "";
                var args = "";

                switch (cpaExpr.name.text) {
                    case "toUpperCase":
                        funcName = "UPPER";
                        break;
                    case "toLowerCase":
                        funcName = "LOWER";
                        break;
                    case "substring":
                        funcName = "SUBSTRING"
                        args = ", " + cExpr.arguments.map(e => toSql(e)).join(", ");
                        break;
                    default:
                        funcName = "[UndefinedFunction]";
                        break;
                }
                return funcName + "(" + toSql(cpaExpr.expression) + args + ")";
            }
        default:
            return "[undefined]";
    }
}

var arrFunc = getArrowFunction(e => (e.Param.toUpperCase().toLowerCase() == "3".toLowerCase().substring(0, 10) || e.Param2 >= 4) && e.Param3 <= 2);

console.log(toSql(arrFunc.body));