yaotp/app/src/main/java/com/chameth/yaotp/accounts/UriParser.kt

package com.chameth.yaotp.accounts

import com.chameth.yaotp.algos.HotpParams
import com.chameth.yaotp.algos.TotpParams
import com.chameth.yaotp.algos.getHmacFunc
import com.chameth.yaotp.util.base32Decode
import java.net.URI

fun parseUri(uri: String) : Account? {
    return try {
        toAccount(URI.create(uri))
    } catch (_ : Exception) {
        null
    }
}

@Throws(IllegalArgumentException::class)
internal fun toAccount(uri: URI): Account? {
    require(uri.scheme == "otpauth") { "Scheme must be 'otpauth', got '${uri.scheme}'" }
    require(uri.path.length > 1) { "No label specified" }
    requireNotNull(uri.query) { "No query string supplied" }

    val label = uri.path.substring(1)
    val params = uri.queryParameters()
    require("secret" in params) { "No 'secret' parameter specified, got ${params.keys}"}

    return when(uri.host) {
        "hotp" -> getHotpAccount(label, params)
        "totp" -> getTotpAccount(label, params)
        else -> throw IllegalArgumentException("Unrecognised type: ${uri.host}")
    }
}

internal fun getHotpAccount(label: String, uriParams: Map<String, String>): HotpAccount {
    val counter = uriParams["counter"]?.toLongOrNull()
    requireNotNull(counter) { "No 'counter' parameter specified for HOTP" }
    return HotpAccount(label, uriParams["issuer"], counter!!, getHotpParameters(uriParams))
}

fun getTotpAccount(label: String, uriParams: Map<String, String>): TotpAccount {
    val step = uriParams["step"]?.toIntOrNull() ?: 30
    return TotpAccount(label, uriParams["issuer"], TotpParams(getHotpParameters(uriParams), step = step))
}

internal fun getHotpParameters(uriParams : Map<String, String>) : HotpParams {
    return HotpParams(
            base32Decode(uriParams["secret"] ?: ""),
            uriParams["digits"]?.toIntOrNull() ?: 6,
            getHmacFunc(uriParams["algorithm"])
    )
}

internal fun URI.queryParameters(): Map<String, String> {
    return query.split('&').map { with(it.split('=', limit = 2)) { this[0] to this[1] } }.toMap()
}