Uri.kt

package android.net

import java.net.URI
import java.util.Collections

class Uri(
    private val uri: URI
) {
    companion object {
        @JvmStatic
        fun parse(uriString: String) = Uri(URI.create(uriString))
    }

    override fun toString(): String = uri.toString()

    val scheme get() = uri.scheme
    val port get() = uri.port
    val host get() = uri.host

    fun getQueryParameterNames(): Set<String> {
        val query: String = uri.query ?: return emptySet()
        val names: MutableSet<String> = LinkedHashSet()
        var start = 0
        do {
            val next = query.indexOf('&', start)
            val end = if ((next == -1)) query.length else next
            var separator = query.indexOf('=', start)
            if (separator > end || separator == -1) {
                separator = end
            }
            val name = query.substring(start, separator)
            names.add(name)
            // Move start to end of name.
            start = end + 1
        } while (start < query.length)
        return Collections.unmodifiableSet(names)
    }

    fun getQueryParameter(key: String?): String? {
        if (key == null) {
            throw NullPointerException("key")
        }
        val query: String = uri.query ?: return null
        val length = query.length
        var start = 0
        do {
            val nextAmpersand = query.indexOf('&', start)
            val end = if (nextAmpersand != -1) nextAmpersand else length
            var separator = query.indexOf('=', start)
            if (separator > end || separator == -1) {
                separator = end
            }
            if (separator - start == key.length &&
                query.regionMatches(start, key, 0, key.length)
            ) {
                if (separator == end) {
                    return ""
                } else {
                    return query.substring(separator + 1, end)
                }
            }
            // Move start to end of name.
            if (nextAmpersand != -1) {
                start = nextAmpersand + 1
            } else {
                break
            }
        } while (true)
        return null
    }
}