// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System;
using System.Diagnostics;
using System.Xml;
using System.Xml.XPath;

namespace System.Xml.Xsl.XsltOld
{
    internal abstract class CompiledAction : Action
    {
        internal abstract void Compile(Compiler compiler);

        internal virtual bool CompileAttribute(Compiler compiler)
        {
            return false;
        }

        public void CompileAttributes(Compiler compiler)
        {
            NavigatorInput input = compiler.Input;
            string element = input.LocalName;

            if (input.MoveToFirstAttribute())
            {
                do
                {
                    if (input.NamespaceURI.Length != 0) continue;

                    try
                    {
                        if (!CompileAttribute(compiler))
                        {
                            throw XsltException.Create(SR.Xslt_InvalidAttribute, input.LocalName, element);
                        }
                    }
                    catch
                    {
                        if (!compiler.ForwardCompatibility)
                        {
                            throw;
                        }
                        else
                        {
                            // In ForwardCompatibility mode we ignoreing all unknown or incorrect attributes
                            // If it's mandatory attribute we'll notice it absence later.
                        }
                    }
                }
                while (input.MoveToNextAttribute());
                input.ToParent();
            }
        }

        // For perf reason we precalculating AVTs at compile time.
        // If we can do this we set original AVT to null
        internal static string? PrecalculateAvt(ref Avt? avt)
        {
            string? result = null;
            if (avt != null && avt.IsConstant)
            {
                result = avt.Evaluate(null, null);
                avt = null;
            }
            return result;
        }

        public static void CheckEmpty(Compiler compiler)
        {
            // Really EMPTY means no content at all, but the sake of compatibility with MSXML we allow whitespace
            string elementName = compiler.Input.Name;
            if (compiler.Recurse())
            {
                do
                {
                    // Note: <![CDATA[ ]]> will be reported as XPathNodeType.Text
                    XPathNodeType nodeType = compiler.Input.NodeType;
                    if (
                        nodeType != XPathNodeType.Whitespace &&
                        nodeType != XPathNodeType.Comment &&
                        nodeType != XPathNodeType.ProcessingInstruction
                    )
                    {
                        throw XsltException.Create(SR.Xslt_NotEmptyContents, elementName);
                    }
                }
                while (compiler.Advance());
                compiler.ToParent();
            }
        }

        public static void CheckRequiredAttribute(object? attrValue, string attrName)
        {
            CheckRequiredAttribute(attrValue != null, attrName);
        }

        public static void CheckRequiredAttribute(bool attr, string attrName)
        {
            if (!attr)
            {
                throw XsltException.Create(SR.Xslt_MissingAttribute, attrName);
            }
        }
    }
}