src/Kotlin/DocumentationBuilder.kt

package org.jetbrains.dokka

import org.jetbrains.kotlin.descriptors.*
import org.jetbrains.dokka.DocumentationNode.*
import org.jetbrains.kotlin.types.*
import org.jetbrains.kotlin.builtins.*
import org.jetbrains.kotlin.name.*
import org.jetbrains.kotlin.resolve.lazy.*
import org.jetbrains.kotlin.resolve.DescriptorUtils
import org.jetbrains.kotlin.descriptors.annotations.Annotated
import org.jetbrains.kotlin.descriptors.annotations.AnnotationDescriptor
import org.jetbrains.kotlin.resolve.constants.CompileTimeConstant
import com.intellij.openapi.util.text.StringUtil
import org.jetbrains.kotlin.descriptors.impl.EnumEntrySyntheticClassDescriptor

public data class DocumentationOptions(val includeNonPublic: Boolean = false)

private fun isSamePackage(descriptor1: DeclarationDescriptor, descriptor2: DeclarationDescriptor): Boolean {
    val package1 = DescriptorUtils.getParentOfType(descriptor1, javaClass<PackageFragmentDescriptor>())
    val package2 = DescriptorUtils.getParentOfType(descriptor2, javaClass<PackageFragmentDescriptor>())
    return package1 != null && package2 != null && package1.fqName == package2.fqName
}

class DocumentationBuilder(val session: ResolveSession, val options: DocumentationOptions) {
    val visibleToDocumentation = setOf(Visibilities.INTERNAL, Visibilities.PROTECTED, Visibilities.PUBLIC)
    val descriptorToNode = hashMapOf<DeclarationDescriptor, DocumentationNode>()
    val nodeToDescriptor = hashMapOf<DocumentationNode, DeclarationDescriptor>()
    val links = hashMapOf<DocumentationNode, DeclarationDescriptor>()
    val packages = hashMapOf<FqName, DocumentationNode>()

    fun parseDocumentation(descriptor: DeclarationDescriptor): Content {
        val docText = descriptor.getDocumentationElements().map { it.extractText() }.join("\n")
        val tree = parseMarkdown(docText)
        //println(tree.toTestString())
        val content = buildContent(tree, descriptor)
        return content
    }

    fun link(node: DocumentationNode, descriptor: DeclarationDescriptor) {
        links.put(node, descriptor)
    }

    fun register(descriptor: DeclarationDescriptor, node: DocumentationNode) {
        descriptorToNode.put(descriptor, node)
        nodeToDescriptor.put(node, descriptor)
    }

    fun DocumentationNode<T>(descriptor: T, kind: Kind): DocumentationNode where T : DeclarationDescriptor, T : Named {
        val doc = parseDocumentation(descriptor)
        val node = DocumentationNode(descriptor.getName().asString(), doc, kind).withModifiers(descriptor)
        return node
    }

    private fun DocumentationNode.withModifiers(descriptor: DeclarationDescriptor) : DocumentationNode{
        if (descriptor is MemberDescriptor) {
            appendVisibility(descriptor)
            if (descriptor !is ConstructorDescriptor) {
                appendModality(descriptor)
            }
        }
        return this
    }

    fun DocumentationNode.append(child: DocumentationNode, kind: DocumentationReference.Kind) {
        addReferenceTo(child, kind)
        when (kind) {
            DocumentationReference.Kind.Detail -> child.addReferenceTo(this, DocumentationReference.Kind.Owner)
            DocumentationReference.Kind.Member -> child.addReferenceTo(this, DocumentationReference.Kind.Owner)
            DocumentationReference.Kind.Owner -> child.addReferenceTo(this, DocumentationReference.Kind.Member)
        }
    }

    fun DocumentationNode.appendModality(descriptor: MemberDescriptor) {
        val modifier = descriptor.getModality().name().toLowerCase()
        val node = DocumentationNode(modifier, Content.Empty, DocumentationNode.Kind.Modifier)
        append(node, DocumentationReference.Kind.Detail)
    }

    fun DocumentationNode.appendVisibility(descriptor: DeclarationDescriptorWithVisibility) {
        val modifier = descriptor.getVisibility().toString()
        val node = DocumentationNode(modifier, Content.Empty, DocumentationNode.Kind.Modifier)
        append(node, DocumentationReference.Kind.Detail)
    }

    fun DocumentationNode.appendSupertypes(descriptor: ClassDescriptor) {
        val superTypes = descriptor.getTypeConstructor().getSupertypes()
        for (superType in superTypes) {
            if (!ignoreSupertype(superType))
                appendType(superType, DocumentationNode.Kind.Supertype)
        }
    }

    private fun ignoreSupertype(superType: JetType): Boolean {
        val superClass = superType.getConstructor()?.getDeclarationDescriptor() as? ClassDescriptor
        if (superClass != null) {
            val fqName = DescriptorUtils.getFqNameSafe(superClass).asString()
            return fqName == "kotlin.Annotation" || fqName == "kotlin.Enum" || fqName == "kotlin.Any"
        }
        return false
    }

    fun DocumentationNode.appendProjection(projection: TypeProjection, kind: DocumentationNode.Kind = DocumentationNode.Kind.Type) {
        val prefix = when (projection.getProjectionKind()) {
            Variance.IN_VARIANCE -> "in "
            Variance.OUT_VARIANCE -> "out "
            else -> ""
        }
        appendType(projection.getType(), kind, prefix)
    }

    fun DocumentationNode.appendType(jetType: JetType?, kind: DocumentationNode.Kind = DocumentationNode.Kind.Type, prefix: String = "") {
        if (jetType == null)
            return
        val classifierDescriptor = jetType.getConstructor().getDeclarationDescriptor()
        val name = when (classifierDescriptor) {
            is Named -> prefix + classifierDescriptor.getName().asString() + if (jetType.isMarkedNullable()) "?" else ""
            else -> "<anonymous>"
        }
        val node = DocumentationNode(name, Content.Empty, kind)
        if (classifierDescriptor != null)
            link(node, classifierDescriptor)

        append(node, DocumentationReference.Kind.Detail)
        for (typeArgument in jetType.getArguments())
            node.appendProjection(typeArgument)
    }

    fun DocumentationNode.appendAnnotations(annotated: Annotated) {
        annotated.getAnnotations().forEach {
            val annotationNode = it.build()
            if (annotationNode != null) {
                append(annotationNode,
                        if (annotationNode.name == "deprecated") DocumentationReference.Kind.Deprecation else DocumentationReference.Kind.Annotation)
            }
        }
    }

    fun DocumentationNode.appendChild(descriptor: DeclarationDescriptor, kind: DocumentationReference.Kind) {
        // do not include generated code
        if (descriptor is CallableMemberDescriptor && descriptor.getKind() != CallableMemberDescriptor.Kind.DECLARATION)
            return

        if (options.includeNonPublic
                || descriptor !is MemberDescriptor
                || descriptor.getVisibility() in visibleToDocumentation) {
            append(descriptor.build(), kind)
        }
    }

    fun DocumentationNode.appendChildren(descriptors: Iterable<DeclarationDescriptor>, kind: DocumentationReference.Kind) {
        descriptors.forEach { descriptor -> appendChild(descriptor, kind) }
    }

    fun DocumentationNode.getParentForPackageMember(descriptor: DeclarationDescriptor,
                                                    externalClassNodes: MutableMap<FqName, DocumentationNode>): DocumentationNode {
        if (descriptor is CallableMemberDescriptor) {
            val extensionClassDescriptor = descriptor.getExtensionClassDescriptor()
            if (extensionClassDescriptor != null && !isSamePackage(descriptor, extensionClassDescriptor)) {
                val fqName = DescriptorUtils.getFqNameFromTopLevelClass(extensionClassDescriptor)
                return externalClassNodes.getOrPut(fqName, {
                    val newNode = DocumentationNode(fqName.asString(), Content.Empty, Kind.ExternalClass)
                    append(newNode, DocumentationReference.Kind.Member)
                    newNode
                })
            }
        }
        return this
    }

    fun DocumentationNode.appendFragments(fragments: Collection<PackageFragmentDescriptor>) {
        val descriptors = hashMapOf<String, List<DeclarationDescriptor>>()
        for ((name, parts) in fragments.groupBy { it.fqName }) {
            descriptors.put(name.asString(), parts.flatMap { it.getMemberScope().getAllDescriptors() })
        }
        for ((packageName, declarations) in descriptors) {
            println("  package $packageName: ${declarations.count()} declarations")
            val packageNode = DocumentationNode(packageName, Content.Empty, Kind.Package)
            val externalClassNodes = hashMapOf<FqName, DocumentationNode>()
            declarations.forEach { descriptor ->
                val parent = packageNode.getParentForPackageMember(descriptor, externalClassNodes)
                parent.appendChild(descriptor, DocumentationReference.Kind.Member)
            }
            append(packageNode, DocumentationReference.Kind.Member)
        }
    }

    fun DeclarationDescriptor.build(): DocumentationNode = when (this) {
        is ClassDescriptor -> build()
        is ConstructorDescriptor -> build()
        is ScriptDescriptor -> build()
        is PropertyDescriptor -> build()
        is PropertyAccessorDescriptor -> build()
        is FunctionDescriptor -> build()
        is TypeParameterDescriptor -> build()
        is ValueParameterDescriptor -> build()
        is ReceiverParameterDescriptor -> build()
        else -> throw IllegalStateException("Descriptor $this is not known")
    }

    fun ScriptDescriptor.build(): DocumentationNode = getClassDescriptor().build()
    fun ClassDescriptor.build(): DocumentationNode {
        val kind = when (getKind()) {
            ClassKind.OBJECT -> Kind.Object
            ClassKind.CLASS_OBJECT -> Kind.Object
            ClassKind.TRAIT -> Kind.Interface
            ClassKind.ENUM_CLASS -> Kind.Enum
            ClassKind.ANNOTATION_CLASS -> Kind.AnnotationClass
            ClassKind.ENUM_ENTRY -> Kind.EnumItem
            else -> Kind.Class
        }
        val node = DocumentationNode(this, kind)
        node.appendSupertypes(this)
        if (getKind() != ClassKind.OBJECT && getKind() != ClassKind.ENUM_ENTRY) {
            node.appendChildren(getTypeConstructor().getParameters(), DocumentationReference.Kind.Detail)
            node.appendChildren(getConstructors(), DocumentationReference.Kind.Member)
        }
        node.appendChildren(getDefaultType().getMemberScope().getAllDescriptors(), DocumentationReference.Kind.Member)
        val classObjectDescriptor = getClassObjectDescriptor()
        if (classObjectDescriptor != null) {
            node.appendChildren(classObjectDescriptor.getDefaultType().getMemberScope().getAllDescriptors(),
                    DocumentationReference.Kind.Member)
        }
        node.appendAnnotations(this)
        register(this, node)
        return node
    }

    fun ConstructorDescriptor.build(): DocumentationNode {
        val node = DocumentationNode(this, Kind.Constructor)
        node.appendChildren(getValueParameters(), DocumentationReference.Kind.Detail)
        register(this, node)
        return node
    }

    private fun DeclarationDescriptor.inClassObject() =
            getContainingDeclaration().let { it is ClassDescriptor && it.getKind() == ClassKind.CLASS_OBJECT }

    fun CallableMemberDescriptor.getExtensionClassDescriptor(): ClassifierDescriptor? {
        val extensionReceiver = getExtensionReceiverParameter()
        if (extensionReceiver != null) {
            val type = extensionReceiver.getType()
            return type.getConstructor().getDeclarationDescriptor() as? ClassDescriptor
        }
        return null
    }

    fun FunctionDescriptor.build(): DocumentationNode {
        val node = DocumentationNode(this, if (inClassObject()) Kind.ClassObjectFunction else Kind.Function)

        node.appendChildren(getTypeParameters(), DocumentationReference.Kind.Detail)
        getExtensionReceiverParameter()?.let { node.appendChild(it, DocumentationReference.Kind.Detail) }
        node.appendChildren(getValueParameters(), DocumentationReference.Kind.Detail)
        node.appendType(getReturnType())
        node.appendAnnotations(this)
        register(this, node)
        return node

    }

    fun PropertyAccessorDescriptor.build(): DocumentationNode {
        val doc = parseDocumentation(this)
        val specialName = getName().asString().drop(1).takeWhile { it != '-' }
        val node = DocumentationNode(specialName, doc, Kind.PropertyAccessor).withModifiers(this)

        node.appendChildren(getValueParameters(), DocumentationReference.Kind.Detail)
        node.appendType(getReturnType())
        register(this, node)
        return node
    }

    fun PropertyDescriptor.build(): DocumentationNode {
        val node = DocumentationNode(this, if (inClassObject()) Kind.ClassObjectProperty else Kind.Property)
        node.appendChildren(getTypeParameters(), DocumentationReference.Kind.Detail)
        getExtensionReceiverParameter()?.let { node.appendChild(it, DocumentationReference.Kind.Detail) }
        node.appendType(getReturnType())
        node.appendAnnotations(this)
        getGetter()?.let {
            if (!it.isDefault())
                node.appendChild(it, DocumentationReference.Kind.Member)
        }
        getSetter()?.let {
            if (!it.isDefault())
                node.appendChild(it, DocumentationReference.Kind.Member)
        }

        register(this, node)
        return node
    }

    fun ValueParameterDescriptor.build(): DocumentationNode {
        val node = DocumentationNode(this, Kind.Parameter)
        node.appendType(getType())
        node.appendAnnotations(this)
        register(this, node)
        return node
    }

    fun TypeParameterDescriptor.build(): DocumentationNode {
        val doc = parseDocumentation(this)
        val name = getName().asString()
        val prefix = when (getVariance()) {
            Variance.IN_VARIANCE -> "in "
            Variance.OUT_VARIANCE -> "out "
            else -> ""
        }

        val node = DocumentationNode(prefix + name, doc, DocumentationNode.Kind.TypeParameter)

        val builtIns = KotlinBuiltIns.getInstance()
        for (constraint in getUpperBounds()) {
            if (constraint == builtIns.getDefaultBound())
                continue
            val constraintNode = DocumentationNode(constraint.toString(), Content.Empty, DocumentationNode.Kind.UpperBound)
            node.append(constraintNode, DocumentationReference.Kind.Detail)
        }

        for (constraint in getLowerBounds()) {
            if (KotlinBuiltIns.isNothing(constraint))
                continue
            val constraintNode = DocumentationNode(constraint.toString(), Content.Empty, DocumentationNode.Kind.LowerBound)
            node.append(constraintNode, DocumentationReference.Kind.Detail)
        }
        return node
    }

    fun ReceiverParameterDescriptor.build(): DocumentationNode {
        val node = DocumentationNode(getName().asString(), Content.Empty, Kind.Receiver)
        node.appendType(getType())
        return node
    }

    fun AnnotationDescriptor.build(): DocumentationNode? {
        val annotationClass = getType().getConstructor().getDeclarationDescriptor()
        if (ErrorUtils.isError(annotationClass)) {
            return null
        }
        val node = DocumentationNode(annotationClass.getName().asString(), Content.Empty, DocumentationNode.Kind.Annotation)
        val arguments = getAllValueArguments().toList().sortBy { it.first.getIndex() }
        arguments.forEach {
            val valueNode = it.second.build()
            if (valueNode != null) {
                val paramNode = DocumentationNode(it.first.getName().asString(), Content.Empty, DocumentationNode.Kind.Parameter)
                paramNode.append(valueNode, DocumentationReference.Kind.Detail)
                node.append(paramNode, DocumentationReference.Kind.Detail)
            }
        }
        return node
    }

    fun CompileTimeConstant<out Any?>.build(): DocumentationNode? {
        val value = getValue()
        val valueString = when(value) {
            is String ->
                "\"" + StringUtil.escapeStringCharacters(value) + "\""
            is EnumEntrySyntheticClassDescriptor ->
                value.getContainingDeclaration().getName().asString() + "." + value.getName()
            else -> value?.toString()
        }
        return if (valueString != null) DocumentationNode(valueString, Content.Empty, DocumentationNode.Kind.Value) else null
    }

    /**
     * Generates cross-references for documentation such as extensions for a type, inheritors, etc
     *
     * $receiver: [DocumentationContext] for node/descriptor resolutions
     * $node: [DocumentationNode] to visit
     */
    public fun resolveReferences(node: DocumentationNode) {
        if (node.kind != Kind.PropertyAccessor) {
            node.details(DocumentationNode.Kind.Receiver).forEach { receiver ->
                val receiverType = receiver.detail(DocumentationNode.Kind.Type)
                val descriptor = links[receiverType]
                if (descriptor != null) {
                    val typeNode = descriptorToNode[descriptor]
                    // if typeNode is null, extension is to external type like in a library
                    // should we create dummy node here?
                    typeNode?.addReferenceTo(node, DocumentationReference.Kind.Extension)
                }
            }
        }
        node.details(DocumentationNode.Kind.Supertype).forEach { detail ->
            val descriptor = links[detail]
            if (descriptor != null) {
                val typeNode = descriptorToNode[descriptor]
                typeNode?.addReferenceTo(node, DocumentationReference.Kind.Inheritor)
            }
        }
        node.details.forEach { detail ->
            val descriptor = links[detail]
            if (descriptor != null) {
                val typeNode = descriptorToNode[descriptor]
                if (typeNode != null) {
                    detail.addReferenceTo(typeNode, DocumentationReference.Kind.Link)
                }
            }
        }

        resolveContentLinks(node, node.content)

        for (child in node.members) {
            resolveReferences(child)
        }
        for (child in node.details) {
            resolveReferences(child)
        }
    }

    fun getResolutionScope(node: DocumentationNode): DeclarationDescriptor {
        val descriptor = nodeToDescriptor[node] ?: throw IllegalArgumentException("Node is not known to this context")
        return descriptor
    }

    fun resolveContentLinks(node: DocumentationNode, content: ContentNode) {
        val snapshot = content.children.toList()
        for (child in snapshot) {
            if (child is ContentExternalLink) {
                val referenceText = child.href
                val symbol = resolveReference(getResolutionScope(node), referenceText)
                if (symbol != null) {
                    val targetNode = descriptorToNode[symbol]
                    val contentLink = if (targetNode != null) ContentNodeLink(targetNode) else ContentExternalLink("#")

                    val index = content.children.indexOf(child)
                    content.children.remove(index)
                    contentLink.children.addAll(child.children)
                    content.children.add(index, contentLink)
                }

            }
            resolveContentLinks(node, child)
        }
    }

    private fun resolveReference(context: DeclarationDescriptor, reference: String): DeclarationDescriptor? {
        if (Name.isValidIdentifier(reference)) {
            val scope = getResolutionScope(context)
            val symbolName = Name.guess(reference)
            return scope.getLocalVariable(symbolName) ?:
                    scope.getProperties(symbolName).firstOrNull() ?:
                    scope.getFunctions(symbolName).firstOrNull() ?:
                    scope.getClassifier(symbolName)

        }

        if ("." !in reference)
            return null

        val names = reference.split('.')
        val result = names.fold<String, DeclarationDescriptor?>(context) {(nextContext, name) ->
            nextContext?.let { resolveReference(it, name) }
        }

        return result
    }
}