using System;

using System.Collections.Generic;

using System.IO;

using System.Linq;

using System.Xml;

using System.Xml.Schema;

namespace KetoLibrary.Xml

{

    public class XsdValidator

    {

        public List<XmlSchema> Schemas { get; set; }

        public List<String> Errors { get; set; }

        public List<String> Warnings { get; set; }

        public XsdValidator()

        {

            Schemas = new List<XmlSchema>();

        }

        /// <summary>

        /// Add a schema to be used during the validation of the XML document

        /// </summary>

        /// <param name="schemaFileLocation">The file path for the XSD schema file to be added for validation</param>

        /// <returns>True if the schema file was successfully loaded, else false (if false, view Errors/Warnings for reason why)</returns>

        public bool AddSchema(string schemaFileLocation)

        {

            if (String.IsNullOrEmpty(schemaFileLocation)) return false;

            if (!File.Exists(schemaFileLocation)) return false;

            // Reset the Error/Warning collections

            Errors = new List<string>();

            Warnings = new List<string>();

            XmlSchema schema;

            using (var fs = File.OpenRead(schemaFileLocation))

            {

                schema = XmlSchema.Read(fs, ValidationEventHandler);

            }

            var isValid = !Errors.Any() && !Warnings.Any();

            if (isValid)

            {

                Schemas.Add(schema);

            }

            return isValid;

        }

        /// <summary>

        /// Perform the XSD validation against the specified XML document

        /// </summary>

        /// <param name="xmlLocation">The full file path of the file to be validated</param>

        /// <returns>True if the XML file conforms to the schemas, else false</returns>

        public bool IsValid(string xmlLocation)

        {

            if (!File.Exists(xmlLocation))

            {

                throw new FileNotFoundException("The specified XML file does not exist", xmlLocation);

            }

            using (var xmlStream = File.OpenRead(xmlLocation))

            {

                return IsValid(xmlStream);

            }

        }

        /// <summary>

        /// Perform the XSD validation against the supplied XML stream

        /// </summary>

        /// <param name="xmlStream">The XML stream to be validated</param>

        /// <returns>True is the XML stream conforms to the schemas, else false</returns>

        private bool IsValid(Stream xmlStream)

        {

            // Reset the Error/Warning collections

            Errors = new List<string>();

            Warnings = new List<string>();

            var settings = new XmlReaderSettings

            {

                ValidationType = ValidationType.Schema

            };

            settings.ValidationEventHandler += ValidationEventHandler;

            foreach (var xmlSchema in Schemas)

            {

                settings.Schemas.Add(xmlSchema);

            }

            var xmlFile = XmlReader.Create(xmlStream, settings);

            try

            {

                while (xmlFile.Read()) { }

            }

            catch (XmlException xex)

            {

                Errors.Add(xex.Message);

            }

            return !Errors.Any() && !Warnings.Any();

        }

        private void ValidationEventHandler(object sender, ValidationEventArgs e)

        {

            switch (e.Severity)

            {

                case XmlSeverityType.Error:

                    Errors.Add(e.Message);

                    break;

                case XmlSeverityType.Warning:

                    Warnings.Add(e.Message);

                    break;

            }

        }

    }

}

public void MultipleSchemas()

{

    var validator = new XsdValidator();

    validator.AddSchema(@"SchemaDoc1.xsd");

    validator.AddSchema(@"SchemaDoc2.xsd");

    var isValid = validator.IsValid(@"ValidXmlDoc1.xml");

}