package io.oxygenhub.android.update

import androidx.compose.foundation.layout.fillMaxWidth

import androidx.compose.material.icons.Icons

import androidx.compose.material.icons.outlined.SystemUpdate

import androidx.compose.material3.Icon

import androidx.compose.material3.ListItem

import androidx.compose.material3.Text

import androidx.compose.material3.TextButton

import androidx.compose.runtime.Composable

import androidx.compose.runtime.getValue

import androidx.compose.runtime.produceState

import androidx.compose.runtime.remember

import androidx.compose.ui.Modifier

import androidx.compose.ui.platform.LocalContext

import androidx.compose.ui.platform.LocalUriHandler

import androidx.lifecycle.Lifecycle

import androidx.lifecycle.compose.LocalLifecycleOwner

import androidx.lifecycle.repeatOnLifecycle

import io.oxygenhub.android.api.HubApi

import io.oxygenhub.android.api.Release

import io.oxygenhub.android.ui.common.Panel

import io.oxygenhub.android.ui.theme.Tones

/** Where the app's own releases are (#7), built and signed by OxygenFlow. */

const val APP_HUB = "https://oxygenhub.io"

const val APP_OWNER = "andymccall"

const val APP_REPO = "oxygenhub-android"

/** `v1.2.3` or `1.2.3` as numbers; null for anything else (a pre-release such as `1.2.3-rc1`). */

fun versionOf(text: String): List<Int>? {

    val parts = text.trim().removePrefix("v").split(".")

    if (parts.size != 3) return null

    return parts.map { p -> p.toIntOrNull()?.takeIf { it >= 0 } ?: return null }

}

/** Whether [candidate] is a later version than [installed]. */

fun isNewer(candidate: String, installed: String): Boolean {

    val a = versionOf(candidate) ?: return false

    val b = versionOf(installed) ?: return true

    return a.zip(b).firstOrNull { (x, y) -> x != y }?.let { (x, y) -> x > y } ?: false

}

/** An update: the newest full release later than [installed], with its APK's address. */

data class Update(val version: String, val apkUrl: String, val pageUrl: String)

/** The newest full release of [releases] later than [installed] that carries an APK, if any. */

fun updateFrom(releases: List<Release>, installed: String, hub: String = APP_HUB): Update? {

    val newest = releases

        .filter { !it.prerelease && versionOf(it.tag) != null }

        .maxWithOrNull { a, b -> if (isNewer(a.tag, b.tag)) 1 else if (isNewer(b.tag, a.tag)) -1 else 0 }

        ?: return null

    if (!isNewer(newest.tag, installed)) return null

    val apk = newest.assets.firstOrNull { it.name.endsWith(".apk") } ?: return null

    fun absolute(u: String) = if (u.startsWith("http")) u else hub.trimEnd('/') + "/" + u.trimStart('/')

    val page = newest.url.ifEmpty { "/$APP_OWNER/$APP_REPO/releases" }

    return Update(newest.tag.removePrefix("v"), absolute(apk.url), absolute(page))

}

/**

 * The app's version and, when the hub signed in to is [APP_HUB] and it has

 * a later release, a link to its APK: Android installs it from the

 * download, as the same key signs every release.

 */

@Composable

fun UpdateCard(api: HubApi, hub: String) {

    val context = LocalContext.current

    val installed = remember(context) { context.packageManager.getPackageInfo(context.packageName, 0).versionName ?: "" }

    // Asked again each time the app comes to the front, so an app left

    // open sees a release made since without a restart (#34).

    val owner = LocalLifecycleOwner.current

    val update by produceState<Update?>(null, hub, owner) {

        if (hub.trimEnd('/') == APP_HUB) {

            owner.repeatOnLifecycle(Lifecycle.State.RESUMED) {

                runCatching { updateFrom(api.releases(APP_OWNER, APP_REPO), installed) }.onSuccess { value = it }

            }

        }

    }

    val uri = LocalUriHandler.current

    Panel(Modifier.fillMaxWidth()) {

        ListItem(

            leadingContent = { Icon(Icons.Outlined.SystemUpdate, contentDescription = null, tint = Tones.info) },

            headlineContent = { Text(update?.let { "Version ${it.version} is out" } ?: "OxygenHub $installed") },

            supportingContent = {

                Text(if (update != null) "You have $installed. Download it and open the file to update." else "Releases are at $APP_HUB/$APP_OWNER/$APP_REPO.")

            },

            trailingContent = update?.let { u -> { TextButton(onClick = { uri.openUri(u.apkUrl) }) { Text("Download") } } },

        )

    }

}