core/src/main/kotlin/Model/SourceLinks.kt

package org.jetbrains.dokka

import com.intellij.psi.PsiDocumentManager
import com.intellij.psi.PsiElement
import com.intellij.psi.PsiNameIdentifierOwner
import org.jetbrains.dokka.DokkaConfiguration.SourceLinkDefinition
import org.jetbrains.kotlin.psi.psiUtil.startOffset
import java.io.File


fun DocumentationNode.appendSourceLink(psi: PsiElement?, sourceLinks: List<SourceLinkDefinition>) {
    val path = psi?.containingFile?.virtualFile?.path ?: return

    val target = if (psi is PsiNameIdentifierOwner) psi.nameIdentifier else psi
    val absPath = File(path).absolutePath
    val linkDef = sourceLinks.firstOrNull { absPath.startsWith(it.path) }
    if (linkDef != null) {
        var url = linkDef.url + path.substring(linkDef.path.length)
        if (linkDef.lineSuffix != null) {
            val line = target?.lineNumber()
            if (line != null) {
                url += linkDef.lineSuffix + line.toString()
            }
        }
        append(DocumentationNode(url, Content.Empty, NodeKind.SourceUrl),
                RefKind.Detail);
    }

    if (target != null) {
        append(DocumentationNode(target.sourcePosition(), Content.Empty, NodeKind.SourcePosition), RefKind.Detail)
    }
}

private fun PsiElement.sourcePosition(): String {
    val path = containingFile.virtualFile.path
    val lineNumber = lineNumber()
    val columnNumber = columnNumber()

    return when {
        lineNumber == null -> path
        columnNumber == null -> "$path:$lineNumber"
        else -> "$path:$lineNumber:$columnNumber"
    }
}

fun PsiElement.lineNumber(): Int? {
    val doc = PsiDocumentManager.getInstance(project).getDocument(containingFile)
    // IJ uses 0-based line-numbers; external source browsers use 1-based
    return doc?.getLineNumber(textRange.startOffset)?.plus(1)
}

fun PsiElement.columnNumber(): Int? {
    val doc = PsiDocumentManager.getInstance(project).getDocument(containingFile) ?: return null
    val lineNumber = doc.getLineNumber(textRange.startOffset)
    return startOffset - doc.getLineStartOffset(lineNumber)
}