package Torello.JDUInternal.Annotations.EntityAnnotations.Processor;

import Torello.Java.StrSource;
import Torello.Java.StringParse;

import Torello.Java.Additional.EffectivelyFinal;

import Torello.JavaDoc.LinkJavaSource;
import Torello.JavaDoc.hidden.LJSRepeatable;

import Torello.JDUInternal.Annotations.HELPER;

import javax.annotation.processing.Messager;

import javax.lang.model.element.Element;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.AnnotationMirror;
import javax.lang.model.element.AnnotationValue;

import javax.tools.Diagnostic;

import java.util.List;

// @LinkJavaSource Annotation:
//
// EXPORTS:
// 
//     public String    handle();
//     public String    typeName()      default "";
//     public Entity    entity();
//     public String    name();
//     public byte      paramCount()    default -1;
//     public String[]  paramNames()    default { };
//     public String[]  paramTypesJOW() default { };
// 
// 
// The following files are relatedf to this Annotation-Mirror Data-Class:
// 
// * Torello.JavaDoc.LinkJavaSource
//      For the actual annotation definition.
//      This is the actual @interface for the @LinkJavaSource Annotation
// 
// * package Torello.JDUInternal.Features.LINK_JAVA_SOURCE
//      This package does the "vast majority" of the work that is needed process a User's
//      Annotation-Placement.  The classes in the packages in this class look for, and load, all 
//      of the External '.java'-Files which have been specified by the programmer's annotation
//      uses.  These classes also perform the Source-Code HiLiting, and save the output to the
//      appropriate packge's '[pkg-javadoc]/ljs-hilite-files/' directory.  They finally, also,
//      generate the appropriate "HREF=..." so that an appropriate '<A HREF...>' link may be
//      inserted
// 
// * Torello.JDUInternal.Annotations.EntityAnnotations.Mirror.LJSMirror
//      The Data-Contents of Annotation that has been placed by the User on the Entity
//      (Entity: Method, Field, Constructor, Enum-Constant, Annotation-Element)
// 
// * Torello.JDUInternal.Annotations.EntityAnnotations.Processor.LinkJSourceProcessor
//      The Annotation-Processor that is invoked by 'javac' when compiling a class that uses the
//      @LinkJavaSource Annotation.  

public class LinkJSourceProcessor
{
    // This is used by the Error-Message Printer
    private static final String LJS_NAME = LinkJavaSource.class.getSimpleName();

    public static boolean process(
            Element             ciet,
            AnnotationMirror    am,
            javax.annotation.processing.Messager messager
        )
    {
        EffectivelyFinal<Boolean> errors = new EffectivelyFinal<>(false);

        EffectivelyFinal<Boolean>
            name            = new EffectivelyFinal<>(false),
            paramNames      = new EffectivelyFinal<>(false),
            paramTypesJOW   = new EffectivelyFinal<>(false),
            paramCount      = new EffectivelyFinal<>(false);

        am.getElementValues().forEach((ExecutableElement ee, AnnotationValue av) ->
        {
            // Understanding the 'terminology' in Annotations and Annotation-Processor's is half of
            // the work in using it.

            final Object val  = av.getValue();

            switch (ee.toString())
            {
                case "handle()" :
                    errors.f |= checkIdentifierAE(messager, ciet, "handle()", (String) val);
                    break;

                case "typeName()" :
                    errors.f |= checkTypeStr(messager, ciet, (String) val);
                    break;

                case "entity()" :
                    break;

                case "name()" :
                    name.f = true;
                    errors.f |= checkIdentifierAE(messager, ciet, "name()", (String) val);
                    break;

                case "paramCount()":
                    paramCount.f = true;
                    errors.f |= checkParamCount(messager, ciet, (Byte) val);
                    break;

                case "paramNames()":
                    paramNames.f = true;
                    errors.f |= checkParamList(messager, ciet, "paramNames()", (List) val);
                    break;

                case "paramTypesJOW()":
                    paramTypesJOW.f = true;
                    errors.f |= checkParamList(messager, ciet, "paramTypesJOW()", (List) val);
                    break;

                default: 

                    // This should be UNREACHABLE-CODE.  The Java-Compiler, itself, should do the
                    // complaining that the user supplied an Annotation-Element name that is not
                    // among those listed above.  Unless 'javac' changes, this cannot execute.

                    throw new InternalError(
                        "There was an annotation parameter whose name wasn't recognized: " +
                        ee.toString() + "\n" +
                        "The only parameter's that may be passed to @LinkJavaSource:\n" +
                        "'handle()', 'typeName()', 'entity()', 'name()', 'paramCount()', " +
                        "'paramNames()' and 'paramTypesJOW()'"
                    );
            }
        });        

        return errors.f;
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Checks both the "name()" and "handle()" Annotation-Elements
    // ********************************************************************************************
    // ********************************************************************************************


    private static boolean checkIdentifierAE(
            javax.annotation.processing.Messager messager,
            Element ciet,
            String  aeName,
            String  aeValAsStr
        )
    {
        if (StrSource.isValidJavaIdentifier(aeValAsStr)) return true;

        // NOTE: Torello.JDUInternal.Messager **DOES NOT** ALLOW '\t'
        messager.printMessage(
            Diagnostic.Kind.ERROR,
            HELPER.LOCATION(ciet, LJS_NAME) +
            "\tString Annotation-Parameter '" + aeName + "' was passed " +
                "[" + aeValAsStr + "]\n" +
            "\tHowever, this is not a valid Java-Identifier."
        );

        return false;
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Checks the "typeName()" Annotation-Elements
    // ********************************************************************************************
    // ********************************************************************************************


    private static boolean checkTypeStr
        (javax.annotation.processing.Messager messager, Element ciet, String aeValAsStr)
    {
        if (! StrSource.isJavaTypeStr(aeValAsStr))
        {
            messager.printMessage(
                Diagnostic.Kind.ERROR,
                HELPER.LOCATION(ciet, LJS_NAME) +

                // NOTE: Torello.JDUInternal.Messager **DOES NOT** ALLOW '\t'
                "\tString Annotation-Parameter 'typeName()' was passed " +
                    "[" + aeValAsStr + "]\n" +
                "\tHowever, this is not a valid Java Type-Name."
            );

            return false;
        }

        return true;
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Check "paramCount()"
    // ********************************************************************************************
    // ********************************************************************************************


    private static boolean checkParamCount
        (javax.annotation.processing.Messager messager, Element ciet, byte paramCount)
    {
        if (paramCount < 0)
        {
            // NOTE: Torello.JDUInternal.Messager **DOES NOT** ALLOW '\t'
            messager.printMessage(
                Diagnostic.Kind.ERROR,
                HELPER.LOCATION(ciet, LJS_NAME) +
                "\t'paramCount' was passed a negative number: [" + paramCount + "]"
            );

            return false;
        }

        return true;
    }


    // ********************************************************************************************
    // ********************************************************************************************
    // Check the "paramNames()" and "paramTypes()" Annotation-Elements
    // ********************************************************************************************
    // ********************************************************************************************


    @SuppressWarnings("rawtypes")
    private static boolean checkParamList(
            javax.annotation.processing.Messager messager,
            Element ciet,
            String  aeName,
            List    aeValList
        )
    {
        String aeValAsStr;

        for (Object val : aeValList)

            if (! StrSource.isValidJavaIdentifier
                (aeValAsStr = StringParse.ifQuotesStripQuotes(val.toString()))
            )
            {
                messager.printMessage(
                    Diagnostic.Kind.ERROR,
                    HELPER.LOCATION(ciet, LJS_NAME) +

                    // NOTE: Torello.JDUInternal.Messager **DOES NOT** ALLOW '\t'
                    "\tString Annotation-Parameter '" + aeName + "' was passed " +
                        "String[]-Array Element [" + aeValAsStr + "]\n" +
                    "\tHowever, this is not a valid Java-Identifier."
                );

                return false;
            }

        return true;
    }
}