SparqlResultSet.cs

using System;
using System.Collections.Generic;
using System.Xml;
using Waher.Content.Semantic.Model;
using Waher.Content.Semantic.Model.Literals;
using Waher.Content.Xml;
using Waher.Runtime.Inventory;
using Waher.Script.Abstraction.Elements;
using Waher.Script.Objects;
using Waher.Script.Objects.Matrices;
using Waher.Script.Objects.VectorSpaces;
using Waher.Script.Operators.Matrices;
using Waher.Script.Operators.Vectors;
 
namespace Waher.Content.Semantic
{
    public class SparqlResultSet : IToMatrix, IToVector
    {
        public const string Namespace = "http://www.w3.org/2005/sparql-results#";
 
        public const string LocalName = "sparql";
 
        private readonly Dictionary<string, ISemanticLiteral> dataTypes = new Dictionary<string, ISemanticLiteral>();
        private readonly Uri baseUri;
 
        public SparqlResultSet(XmlDocument Xml)
            : this(Xml, null)
        {
        }
 
        public SparqlResultSet(string Xml)
            : this(Xml, null)
        {
        }
 
        public SparqlResultSet(string Xml, Uri BaseUri)
            : this(RdfDocument.ToXml(Xml), BaseUri)
        {
        }
 
        public SparqlResultSet(XmlDocument Xml, Uri BaseUri)
        {
            if (Xml is null ||
                Xml.DocumentElement is null ||
                Xml.DocumentElement.LocalName != LocalName ||
                Xml.DocumentElement.NamespaceURI != Namespace)
            {
                throw new ArgumentException("Invalid SPARQL Result XML document.", nameof(Xml));
            }
 
            this.baseUri = BaseUri;
            this.BooleanResult = null;
 
            List<string> Variables = new List<string>();
            List<Uri> Links = new List<Uri>();
            List<ISparqlResultRecord> Records = new List<ISparqlResultRecord>();
 
            foreach (XmlNode N in Xml.DocumentElement.ChildNodes)
            {
                if (!(N is XmlElement E) || E.NamespaceURI != Namespace)
                    continue;
 
                switch (E.LocalName)
                {
                    case "head":
                        foreach (XmlNode N2 in E.ChildNodes)
                        {
                            if (!(N2 is XmlElement E2) || E2.NamespaceURI != Namespace)
                                continue;
 
                            switch (E2.LocalName)
                            {
                                case "variable":
                                    string Name = XML.Attribute(E2, "name");
                                    if (!string.IsNullOrEmpty(Name))
                                        Variables.Add(Name);
                                    break;
 
                                case "link":
                                    string HRef = XML.Attribute(E2, "href");
                                    if (string.IsNullOrEmpty(HRef))
                                        break;
 
                                    if (this.baseUri is null)
                                    {
                                        if (Uri.TryCreate(HRef, UriKind.RelativeOrAbsolute, out Uri Link))
                                            Links.Add(Link);
                                    }
                                    else
                                    {
                                        if (Uri.TryCreate(this.baseUri, HRef, out Uri Link))
                                            Links.Add(Link);
                                    }
                                    break;
                            }
                        }
                        break;
 
                    case "boolean":
                        if (CommonTypes.TryParse(E.InnerText, out bool b))
                            this.BooleanResult = b;
                        break;
 
                    case "results":
                        foreach (XmlNode N2 in E.ChildNodes)
                        {
                            if (!(N2 is XmlElement E2) || E2.NamespaceURI != Namespace)
                                continue;
 
                            switch (E2.LocalName)
                            {
                                case "result":
                                    Dictionary<string, ISparqlResultItem> Record = new Dictionary<string, ISparqlResultItem>();
                                    int Index = 0;
 
                                    foreach (XmlNode N3 in E2.ChildNodes)
                                    {
                                        if (!(N3 is XmlElement E3) || E3.NamespaceURI != Namespace)
                                            continue;
 
                                        switch (E3.LocalName)
                                        {
                                            case "binding":
                                                string Name = XML.Attribute(E3, "name");
                                                ISemanticElement Value = this.ParseXmlValue(E3);
                                                Record[Name] = new SparqlResultItem(Name, Value, Index++);
                                                break;
                                        }
                                    }
 
                                    Records.Add(new SparqlPatternResultRecord(Record));
                                    break;
                            }
                        }
                        break;
                }
            }
 
            this.Variables = Variables.ToArray();
            this.Links = Links.ToArray();
            this.Records = Records.ToArray();
        }
 
        public SparqlResultSet(Dictionary<string, object> Obj, Uri BaseUri)
        {
            if (Obj is null)
                throw new ArgumentException("Invalid SPARQL Result JSON document.", nameof(Obj));
 
            this.baseUri = BaseUri;
            this.BooleanResult = null;
 
            List<string> Variables = new List<string>();
            List<Uri> Links = new List<Uri>();
            List<ISparqlResultRecord> Records = new List<ISparqlResultRecord>();
 
            foreach (KeyValuePair<string, object> P in Obj)
            {
                switch (P.Key)
                {
                    case "head":
                        if (!(P.Value is Dictionary<string, object> Head))
                            break;
 
                        foreach (KeyValuePair<string, object> P2 in Head)
                        {
                            switch (P2.Key)
                            {
                                case "vars":
                                    if (P2.Value is Array VariableArray)
                                    {
                                        foreach (object Item in VariableArray)
                                        {
                                            if (Item is string Name)
                                                Variables.Add(Name);
                                        }
                                    }
                                    break;
 
                                case "link":
                                    if (P2.Value is Array LinkArray)
                                    {
                                        foreach (object Item in LinkArray)
                                        {
                                            if (Item is string HRef &&
                                                !string.IsNullOrEmpty(HRef))
                                            {
                                                if (this.baseUri is null)
                                                {
                                                    if (Uri.TryCreate(HRef, UriKind.RelativeOrAbsolute, out Uri Link))
                                                        Links.Add(Link);
                                                }
                                                else
                                                {
                                                    if (Uri.TryCreate(this.baseUri, HRef, out Uri Link))
                                                        Links.Add(Link);
                                                }
                                            }
                                        }
                                    }
                                    break;
                            }
                        }
                        break;
 
                    case "boolean":
                        if (P.Value is bool b)
                            this.BooleanResult = b;
                        break;
 
                    case "results":
                        if (!(P.Value is Dictionary<string, object> Results))
                            break;
 
                        foreach (KeyValuePair<string, object> P2 in Results)
                        {
                            if (P2.Key != "bindings")
                                continue;
 
                            if (!(P2.Value is Array Bindings))
                                continue;
 
                            foreach (object BindingObj in Bindings)
                            {
                                if (!(BindingObj is Dictionary<string, object> Binding))
                                    continue;
 
                                Dictionary<string, ISparqlResultItem> Record = new Dictionary<string, ISparqlResultItem>();
                                int Index = 0;
 
                                foreach (KeyValuePair<string, object> P3 in Binding)
                                {
                                    ISemanticElement Value = this.ParseJsonValue(P3.Value);
                                    Record[P3.Key] = new SparqlResultItem(P3.Key, Value, Index++);
                                }
 
                                Records.Add(new SparqlPatternResultRecord(Record));
                            }
                        }
                        break;
                }
            }
 
            this.Variables = Variables.ToArray();
            this.Links = Links.ToArray();
            this.Records = Records.ToArray();
        }
 
        private ISemanticElement ParseXmlValue(XmlElement Xml)
        {
            foreach (XmlNode N in Xml.ChildNodes)
            {
                if (!(N is XmlElement E) || E.NamespaceURI != Namespace)
                    continue;
 
                switch (E.LocalName)
                {
                    case "uri":
                        if (this.baseUri is null)
                        {
                            if (Uri.TryCreate(E.InnerText, UriKind.RelativeOrAbsolute, out Uri UriValue))
                                return new UriNode(UriValue, E.InnerText);
                            else
                                return new StringLiteral(E.InnerText);
                        }
                        else
                        {
                            if (Uri.TryCreate(this.baseUri, E.InnerText, out Uri UriValue))
                                return new UriNode(UriValue, E.InnerText);
                            else
                                return new StringLiteral(E.InnerText);
                        }
 
                    case "bnode":
                        return new BlankNode(E.InnerText);
 
                    case "literal":
                        string s = E.InnerText;
                        string DataType = null;
                        string Language = null;
 
                        foreach (XmlAttribute Attr in E.Attributes)
                        {
                            switch (Attr.Name)
                            {
                                case "xml:lang":
                                    Language = Attr.Value;
                                    break;
 
                                case "datatype":
                                    DataType = Attr.Value;
                                    break;
                            }
                        }
 
                        if (!string.IsNullOrEmpty(DataType))
                        {
                            if (!this.dataTypes.TryGetValue(DataType, out ISemanticLiteral LiteralType))
                            {
                                LiteralType = Types.FindBest<ISemanticLiteral, string>(DataType)
                                    ?? new CustomLiteral(string.Empty, DataType);
 
                                this.dataTypes[DataType] = LiteralType;
                            }
 
                            return LiteralType.Parse(s, DataType, Language);
                        }
                        else if (!string.IsNullOrEmpty(Language))
                            return new StringLiteral(s, Language);
                        else
                            return new StringLiteral(s);
 
                    case "triple":
                        ISemanticElement Subject = null;
                        ISemanticElement Predicate = null;
                        ISemanticElement Object = null;
 
                        foreach (XmlNode N2 in E.ChildNodes)
                        {
                            if (!(N2 is XmlElement E2) || E2.NamespaceURI != Namespace)
                                continue;
 
                            switch (E2.LocalName)
                            {
                                case "subject":
                                    Subject = this.ParseXmlValue(E2);
                                    break;
 
                                case "predicate":
                                    Predicate = this.ParseXmlValue(E2);
                                    break;
 
                                case "object":
                                    Object = this.ParseXmlValue(E2);
                                    break;
                            }
                        }
 
                        return new SemanticTriple(Subject, Predicate, Object);
 
                    default:
                        continue;
                }
            }
 
            return null;
        }
 
        private ISemanticElement ParseJsonValue(object Obj)
        {
            if (!(Obj is Dictionary<string, object> Object) ||
                !(Object.TryGetValue("type", out object TypeObject)) ||
                !(TypeObject is string Type))
            {
                return null;
            }
 
            switch (Type)
            {
                case "uri":
                    if (!(Object.TryGetValue("value", out object ValueObject)) ||
                       !(ValueObject is string Value))
                    {
                        return null;
                    }
 
                    if (this.baseUri is null)
                    {
                        if (Uri.TryCreate(Value, UriKind.RelativeOrAbsolute, out Uri UriValue))
                            return new UriNode(UriValue, Value);
                        else
                            return new StringLiteral(Value);
                    }
                    else
                    {
                        if (Uri.TryCreate(this.baseUri, Value, out Uri UriValue))
                            return new UriNode(UriValue, Value);
                        else
                            return new StringLiteral(Value);
                    }
 
                case "bnode":
                    if (!(Object.TryGetValue("value", out ValueObject)) ||
                       (Value = ValueObject as string) is null)
                    {
                        return null;
                    }
 
                    return new BlankNode(Value);
 
                case "literal":
                    if (!(Object.TryGetValue("value", out ValueObject)) ||
                       (Value = ValueObject as string) is null)
                    {
                        return null;
                    }
 
                    if (!Object.TryGetValue("datatype", out object DataTypeObject) ||
                        !(DataTypeObject is string DataType))
                    {
                        DataType = null;
                    }
 
                    if (!Object.TryGetValue("xml:lang", out object LanguageObject) ||
                        !(LanguageObject is string Language))
                    {
                        Language = null;
                    }
 
                    if (!string.IsNullOrEmpty(DataType))
                    {
                        if (!this.dataTypes.TryGetValue(DataType, out ISemanticLiteral LiteralType))
                        {
                            LiteralType = Types.FindBest<ISemanticLiteral, string>(DataType)
                                ?? new CustomLiteral(string.Empty, DataType);
 
                            this.dataTypes[DataType] = LiteralType;
                        }
 
                        return LiteralType.Parse(Value, DataType, Language);
                    }
                    else if (!string.IsNullOrEmpty(Language))
                        return new StringLiteral(Value, Language);
                    else
                        return new StringLiteral(Value);
 
                case "triple":
                    if (!(Object.TryGetValue("value", out ValueObject)) ||
                        !(ValueObject is Dictionary<string,object> Triple))
                    {
                        return null;
                    }
 
                    ISemanticElement TripleSubject = null;
                    ISemanticElement TriplePredicate = null;
                    ISemanticElement TripleObject = null;
 
                    foreach (KeyValuePair<string, object> P in Triple)
                    {
                        switch (P.Key)
                        {
                            case "subject":
                                TripleSubject = this.ParseJsonValue(P.Value);
                                break;
 
                            case "predicate":
                                TriplePredicate = this.ParseJsonValue(P.Value);
                                break;
 
                            case "object":
                                TripleObject = this.ParseJsonValue(P.Value);
                                break;
                        }
                    }
 
                    return new SemanticTriple(TripleSubject, TriplePredicate, TripleObject);
 
                default:
                    return null;
            }
        }
 
        public SparqlResultSet(bool Result)
        {
            this.Variables = null;
            this.Links = null;
            this.Records = null;
            this.baseUri = null;
            this.BooleanResult = Result;
        }
 
        public SparqlResultSet(string[] Variables, Uri[] Links, ISparqlResultRecord[] Records)
        {
            this.Variables = Variables;
            this.Links = Links;
            this.Records = Records;
            this.baseUri = null;
            this.BooleanResult = null;
        }
 
        public bool? BooleanResult { get; }
 
        public string[] Variables { get; }
 
        public Uri[] Links { get; }
 
        public ISparqlResultRecord[] Records { get; }
 
        public bool Pretty { get; set; }
 
        public IMatrix ToMatrix()
        {
            if (this.BooleanResult.HasValue)
                return new BooleanMatrix(new bool[1, 1] { { this.BooleanResult.Value } });
 
            int Columns = this.Variables.Length;
            int Rows = this.Records.Length;
            IElement[,] Elements = new IElement[Rows, Columns];
            int x, y;
 
            for (y = 0; y < Rows; y++)
            {
                ISparqlResultRecord Record = this.Records[y];
 
                for (x = 0; x < Columns; x++)
                    Elements[y, x] = (IElement)Record[this.Variables[x]] ?? ObjectValue.Null;
            }
 
            return new ObjectMatrix(Elements)
            {
                ColumnNames = this.Variables
            };
        }
 
        public IElement ToVector()
        {
            return new ObjectVector(((ObjectMatrix)this.ToMatrix()).VectorElements);
        }
 
    }
}