package org.jetbrains.dokka

import java.io.File

public interface Location {
    val path: String get
    fun relativePathTo(other: Location, anchor: String? = null): String
}

/**
 * Represents locations in the documentation in the form of [path](File).
 *
 * Locations are provided by [LocationService.location] function.
 *
 * $file: [File] for this location
 * $path: [String] representing path of this location
 */
public data class FileLocation(val file: File): Location {
    override val path : String
        get() = file.path

    override fun relativePathTo(other: Location, anchor: String?): String {
        if (other !is FileLocation) {
            throw IllegalArgumentException("$other is not a FileLocation")
        }
        if (file.path.substringBeforeLast(".") == other.file.path.substringBeforeLast(".") && anchor == null) {
            return "."
        }
        val ownerFolder = file.parentFile!!
        val relativePath = ownerFolder.toPath().relativize(other.file.toPath()).toString()
        return if (anchor == null) relativePath else relativePath + "#" + anchor
    }
}

/**
 * Provides means of retrieving locations for [DocumentationNode](documentation nodes)
 *
 * `LocationService` determines where documentation for particular node should be generated
 *
 * * [FoldersLocationService] – represent packages and types as folders, members as files in those folders.
 * * [SingleFolderLocationService] – all documentation is generated into single folder using fully qualified names
 * for file names.
 */
public interface LocationService {
    fun withExtension(newExtension: String) = this

    fun location(node: DocumentationNode): Location = location(node.path.map { it.name }, node.members.any())

    /**
     * Calculates a location corresponding to the specified [qualifiedName].
     * @param hasMembers if true, the node for which the location is calculated has member nodes.
     */
    fun location(qualifiedName: List<String>, hasMembers: Boolean): Location

    val root: Location
}


public interface FileLocationService: LocationService {
    override fun withExtension(newExtension: String): FileLocationService = this

    override fun location(node: DocumentationNode): FileLocation = location(node.path.map { it.name }, node.members.any())
    override fun location(qualifiedName: List<String>, hasMembers: Boolean): FileLocation
}


public fun identifierToFilename(path: String): String {
    val escaped = path.replace('<', '-').replace('>', '-')
    val lowercase = escaped.replace("[A-Z]".toRegex()) { matchResult -> "-" + matchResult.value.toLowerCase() }
    return if (lowercase == "index") "--index--" else lowercase
}

/**
 * Returns relative location between two nodes. Used for relative links in documentation.
 */
fun LocationService.relativePathToLocation(owner: DocumentationNode, node: DocumentationNode): String {
    return location(owner).relativePathTo(location(node), null)
}