package org.jetbrains.dokka.base.translators.psi

import com.intellij.psi.*
import com.intellij.psi.impl.source.javadoc.PsiDocParamRef
import com.intellij.psi.impl.source.tree.JavaDocElementType
import com.intellij.psi.impl.source.tree.LeafPsiElement
import com.intellij.psi.javadoc.*
import com.intellij.psi.util.PsiTreeUtil
import org.intellij.markdown.MarkdownElementTypes
import org.jetbrains.dokka.analysis.from
import org.jetbrains.dokka.links.DRI
import org.jetbrains.dokka.model.doc.*
import org.jetbrains.dokka.model.doc.Deprecated
import org.jetbrains.dokka.utilities.DokkaLogger
import org.jetbrains.kotlin.idea.refactoring.fqName.getKotlinFqName
import org.jetbrains.kotlin.name.FqName
import org.jetbrains.kotlin.utils.addToStdlib.firstIsInstanceOrNull
import org.jetbrains.kotlin.utils.addToStdlib.safeAs
import org.jsoup.Jsoup
import org.jsoup.nodes.Element
import org.jsoup.nodes.Node
import org.jsoup.nodes.TextNode

interface JavaDocumentationParser {
    fun parseDocumentation(element: PsiNamedElement): DocumentationNode
}

class JavadocParser(
    private val logger: DokkaLogger // TODO: Add logging
) : JavaDocumentationParser {

    override fun parseDocumentation(element: PsiNamedElement): DocumentationNode {
        val docComment = findClosestDocComment(element) ?: return DocumentationNode(emptyList())
        val nodes = mutableListOf<TagWrapper>()
        docComment.getDescription()?.let { nodes.add(it) }
        nodes.addAll(docComment.tags.mapNotNull { tag ->
            when (tag.name) {
                "param" -> Param(
                    wrapTagIfNecessary(convertJavadocElements(tag.contentElements())),
                    tag.children.firstIsInstanceOrNull<PsiDocParamRef>()?.text.orEmpty()
                )
                "throws" -> Throws(wrapTagIfNecessary(convertJavadocElements(tag.contentElements())), tag.text)
                "return" -> Return(wrapTagIfNecessary(convertJavadocElements(tag.contentElements())))
                "author" -> Author(wrapTagIfNecessary(convertJavadocElements(tag.authorContentElements()))) // Workaround: PSI returns first word after @author tag as a `DOC_TAG_VALUE_ELEMENT`, then the rest as a `DOC_COMMENT_DATA`, so for `Name Surname` we get them parted
                "see" -> getSeeTagElementContent(tag).let {
                    See(
                        wrapTagIfNecessary(it.first),
                        tag.referenceElement()?.text.orEmpty(),
                        it.second
                    )
                }
                "deprecated" -> Deprecated(wrapTagIfNecessary(convertJavadocElements(tag.dataElements.toList())))
                else -> null
            }
        })
        return DocumentationNode(nodes)
    }

    private fun wrapTagIfNecessary(list: List<DocTag>): CustomDocTag =
        if (list.size == 1 && (list.first() as? CustomDocTag)?.name == MarkdownElementTypes.MARKDOWN_FILE.name)
            list.first() as CustomDocTag
        else
            CustomDocTag(list, name = MarkdownElementTypes.MARKDOWN_FILE.name)

    private fun findClosestDocComment(element: PsiNamedElement): PsiDocComment? {
        (element as? PsiDocCommentOwner)?.docComment?.run { return this }
        if (element is PsiMethod) {
            val superMethods = element.findSuperMethodsOrEmptyArray()
            if (superMethods.isEmpty()) return null

            if (superMethods.size == 1) {
                return findClosestDocComment(superMethods.single())
            }

            val superMethodDocumentation = superMethods.map(::findClosestDocComment)
            if (superMethodDocumentation.size == 1) {
                return superMethodDocumentation.single()
            }

            logger.warn(
                "Conflicting documentation for ${DRI.from(element)}" +
                        "${superMethods.map { DRI.from(it) }}"
            )

            /* Prioritize super class over interface */
            val indexOfSuperClass = superMethods.indexOfFirst { method ->
                val parent = method.parent
                if (parent is PsiClass) !parent.isInterface
                else false
            }

            return if (indexOfSuperClass >= 0) superMethodDocumentation[indexOfSuperClass]
            else superMethodDocumentation.first()
        }
        return element.children.firstIsInstanceOrNull<PsiDocComment>()
    }

    /**
     * Workaround for failing [PsiMethod.findSuperMethods].
     * This might be resolved once ultra light classes are enabled for dokka
     * See [KT-39518](https://youtrack.jetbrains.com/issue/KT-39518)
     */
    private fun PsiMethod.findSuperMethodsOrEmptyArray(): Array<PsiMethod> {
        return try {
            /*
            We are not even attempting to call "findSuperMethods" on all methods called "getGetter" or "getSetter"
            on any object implementing "kotlin.reflect.KProperty", since we know that those methods will fail
            (KT-39518). Just catching the exception is not good enough, since "findSuperMethods" will
            print the whole exception to stderr internally and then spoil the console.
             */
            val kPropertyFqName = FqName("kotlin.reflect.KProperty")
            if (
                this.parent?.safeAs<PsiClass>()?.implementsInterface(kPropertyFqName) == true &&
                (this.name == "getSetter" || this.name == "getGetter")
            ) {
                logger.warn("Skipped lookup of super methods for ${getKotlinFqName()} (KT-39518)")
                return emptyArray()
            }
            findSuperMethods()
        } catch (exception: Throwable) {
            logger.warn("Failed to lookup of super methods for ${getKotlinFqName()} (KT-39518)")
            emptyArray()
        }
    }

    private fun PsiClass.implementsInterface(fqName: FqName): Boolean {
        return allInterfaces().any { it.getKotlinFqName() == fqName }
    }

    private fun PsiClass.allInterfaces(): Sequence<PsiClass> {
        return sequence {
            this.yieldAll(interfaces.toList())
            interfaces.forEach { yieldAll(it.allInterfaces()) }
        }
    }

    private fun getSeeTagElementContent(tag: PsiDocTag): Pair<List<DocumentationLink>, DRI?> {
        val content = tag.referenceElement()?.toDocumentationLink()
        return Pair(listOfNotNull(content), content?.dri)
    }

    private fun PsiDocComment.getDescription(): Description? {
        return convertJavadocElements(descriptionElements.asIterable()).takeIf { it.isNotEmpty() }?.let {
            Description(wrapTagIfNecessary(it))
        }
    }

    private inner class Parse : (Iterable<PsiElement>, Boolean) -> List<DocTag> {
        val driMap = mutableMapOf<String, DRI>()

        private fun PsiElement.stringify(): String? = when (this) {
            is PsiReference -> children.joinToString("") { it.stringify().orEmpty() }
            is PsiInlineDocTag -> convertInlineDocTag(this)
            is PsiDocParamRef -> toDocumentationLinkString()
            is PsiDocTagValue,
            is LeafPsiElement -> text.let {
                if ((prevSibling as? PsiDocToken)?.isLeadingAsterisk() == true) it?.drop(1) else it
            }.let {
                if ((nextSibling as? PsiDocToken)?.isLeadingAsterisk() == true) it?.dropLastWhile { it == ' ' } else it
            }
            else -> null
        }

        private fun PsiElement.toDocumentationLinkString(
            labelElement: List<PsiElement>? = null
        ): String {
            val label = labelElement?.toList().takeUnless { it.isNullOrEmpty() } ?: listOf(defaultLabel())

            val dri = reference?.resolve()?.takeIf { it !is PsiParameter }?.let {
                val dri = DRI.from(it)
                driMap[dri.toString()] = dri
                dri.toString()
            } ?: UNRESOLVED_PSI_ELEMENT

            return """<a data-dri=$dri>${label.joinToString(" ") { it.text }}</a>"""
        }

        private fun convertInlineDocTag(tag: PsiInlineDocTag) = when (tag.name) {
            "link", "linkplain" -> tag.referenceElement()
                ?.toDocumentationLinkString(tag.dataElements.filterIsInstance<PsiDocToken>())
            "code", "literal" -> "<code data-inline>${tag.text}</code>"
            "index" -> "<index>${tag.children.filterIsInstance<PsiDocTagValue>().joinToString { it.text }}</index>"
            else -> tag.text
        }

        private fun createLink(element: Element, children: List<DocTag>): DocTag {
            return when {
                element.hasAttr("docref") ->
                    A(children, params = mapOf("docref" to element.attr("docref")))
                element.hasAttr("href") ->
                    A(children, params = mapOf("href" to element.attr("href")))
                element.hasAttr("data-dri") && driMap.containsKey(element.attr("data-dri")) ->
                    DocumentationLink(driMap[element.attr("data-dri")]!!, children)
                else -> Text(body = children.filterIsInstance<Text>().joinToString { it.body })
            }
        }

        private fun createBlock(element: Element, insidePre: Boolean = false): DocTag? {
            val children = element.childNodes()
                .mapNotNull { convertHtmlNode(it, insidePre = insidePre || element.tagName() == "pre") }

            fun ifChildrenPresent(operation: () -> DocTag): DocTag? {
                return if (children.isNotEmpty()) operation() else null
            }
            return when (element.tagName()) {
                "blockquote" -> ifChildrenPresent { BlockQuote(children) }
                "p" -> ifChildrenPresent { P(children) }
                "b" -> ifChildrenPresent { B(children) }
                "strong" -> ifChildrenPresent { Strong(children) }
                "index" -> Index(children)
                "i" -> ifChildrenPresent { I(children) }
                "em" -> Em(children)
                "code" -> ifChildrenPresent { CodeInline(children) }
                "pre" -> Pre(children)
                "ul" -> ifChildrenPresent { Ul(children) }
                "ol" -> ifChildrenPresent { Ol(children) }
                "li" -> Li(children)
                "a" -> createLink(element, children)
                else -> Text(body = element.ownText())
            }
        }

        private fun convertHtmlNode(node: Node, insidePre: Boolean = false): DocTag? = when (node) {
            is TextNode -> (if (insidePre) node.wholeText else node.text()
                .takeIf { it.isNotBlank() })?.let { Text(body = it) }
            is Element -> createBlock(node)
            else -> null
        }

        override fun invoke(elements: Iterable<PsiElement>, asParagraph: Boolean): List<DocTag> =
            Jsoup.parseBodyFragment(elements.mapNotNull { it.stringify() }.dropWhile { it.isBlank() }
                .dropLastWhile { it.isBlank() }.joinToString(
                    "",
                    prefix = if (asParagraph) "<p>" else "",
                    postfix = if (asParagraph) "</p>" else ""
                )
            ).body().childNodes().mapNotNull { convertHtmlNode(it) }
    }

    private fun PsiDocTag.contentElements(): List<PsiElement> =
        dataElements.mapNotNull { it.takeIf { it is PsiDocToken && it.text.isNotBlank() } }

    private fun PsiDocTag.authorContentElements(): List<PsiElement> = listOfNotNull(
        dataElements[0],
        dataElements[0].nextSibling?.takeIf { it.text != dataElements.drop(1).firstOrNull()?.text },
        *dataElements.drop(1).toTypedArray()
    )

    private fun convertJavadocElements(elements: Iterable<PsiElement>, asParagraph: Boolean = true): List<DocTag> =
        Parse()(elements, asParagraph)

    private fun PsiDocToken.isSharpToken() = tokenType.toString() == "DOC_TAG_VALUE_SHARP_TOKEN"

    private fun PsiDocToken.isLeadingAsterisk() = tokenType.toString() == "DOC_COMMENT_LEADING_ASTERISKS"

    private fun PsiElement.toDocumentationLink(labelElement: PsiElement? = null) =
        reference?.resolve()?.let {
            val dri = DRI.from(it)
            val label = labelElement ?: defaultLabel()
            DocumentationLink(dri, convertJavadocElements(listOfNotNull(label), asParagraph = false))
        }

    private fun PsiDocTag.referenceElement(): PsiElement? =
        linkElement()?.let {
            if (it.node.elementType == JavaDocElementType.DOC_REFERENCE_HOLDER) {
                PsiTreeUtil.findChildOfType(it, PsiJavaCodeReferenceElement::class.java)
            } else {
                it
            }
        }

    private fun PsiElement.defaultLabel() = children.firstOrNull {
        it is PsiDocToken && it.text.isNotBlank() && !it.isSharpToken()
    } ?: this

    private fun PsiDocTag.linkElement(): PsiElement? =
        valueElement ?: dataElements.firstOrNull { it !is PsiWhiteSpace }

    companion object {
        private const val UNRESOLVED_PSI_ELEMENT = "UNRESOLVED_PSI_ELEMENT"
    }
}