database.kt

/*
 * Copyright (c) 2020 GitLive Ltd.  Use of this source code is governed by the Apache 2.0 license.
 */

package dev.gitlive.firebase.database

import dev.gitlive.firebase.DecodeSettings
import dev.gitlive.firebase.EncodeDecodeSettingsBuilder
import dev.gitlive.firebase.Firebase
import dev.gitlive.firebase.FirebaseApp
import dev.gitlive.firebase.database.externals.CancelCallback
import dev.gitlive.firebase.database.externals.ChangeSnapshotCallback
import dev.gitlive.firebase.database.externals.Database
import dev.gitlive.firebase.database.externals.child
import dev.gitlive.firebase.database.externals.connectDatabaseEmulator
import dev.gitlive.firebase.database.externals.enableLogging
import dev.gitlive.firebase.database.externals.getDatabase
import dev.gitlive.firebase.database.externals.onChildAdded
import dev.gitlive.firebase.database.externals.onChildChanged
import dev.gitlive.firebase.database.externals.onChildMoved
import dev.gitlive.firebase.database.externals.onChildRemoved
import dev.gitlive.firebase.database.externals.onDisconnect
import dev.gitlive.firebase.database.externals.onValue
import dev.gitlive.firebase.database.externals.push
import dev.gitlive.firebase.database.externals.query
import dev.gitlive.firebase.database.externals.ref
import dev.gitlive.firebase.database.externals.remove
import dev.gitlive.firebase.database.externals.set
import dev.gitlive.firebase.database.externals.update
import dev.gitlive.firebase.decode
import dev.gitlive.firebase.reencodeTransformation
import kotlinx.coroutines.asDeferred
import kotlinx.coroutines.channels.awaitClose
import kotlinx.coroutines.coroutineScope
import kotlinx.coroutines.flow.callbackFlow
import kotlinx.coroutines.flow.filter
import kotlinx.coroutines.flow.produceIn
import kotlinx.coroutines.selects.select
import kotlinx.serialization.DeserializationStrategy
import kotlinx.serialization.KSerializer
import kotlin.js.Promise
import kotlin.js.json
import dev.gitlive.firebase.database.externals.DataSnapshot as JsDataSnapshot
import dev.gitlive.firebase.database.externals.DatabaseReference as JsDatabaseReference
import dev.gitlive.firebase.database.externals.OnDisconnect as JsOnDisconnect
import dev.gitlive.firebase.database.externals.Query as JsQuery
import dev.gitlive.firebase.database.externals.endAt as jsEndAt
import dev.gitlive.firebase.database.externals.equalTo as jsEqualTo
import dev.gitlive.firebase.database.externals.limitToFirst as jsLimitToFirst
import dev.gitlive.firebase.database.externals.limitToLast as jsLimitToLast
import dev.gitlive.firebase.database.externals.orderByChild as jsOrderByChild
import dev.gitlive.firebase.database.externals.orderByKey as jsOrderByKey
import dev.gitlive.firebase.database.externals.orderByValue as jsOrderByValue
import dev.gitlive.firebase.database.externals.runTransaction as jsRunTransaction
import dev.gitlive.firebase.database.externals.startAt as jsStartAt

actual val Firebase.database
    get() = rethrow { FirebaseDatabase(getDatabase()) }

actual fun Firebase.database(app: FirebaseApp) =
    rethrow { FirebaseDatabase(getDatabase(app = app.js)) }

actual fun Firebase.database(url: String) =
    rethrow { FirebaseDatabase(getDatabase(url = url)) }

actual fun Firebase.database(app: FirebaseApp, url: String) =
    rethrow { FirebaseDatabase(getDatabase(app = app.js, url = url)) }

actual class FirebaseDatabase internal constructor(val js: Database) {
    actual fun reference(path: String) = rethrow { DatabaseReference(NativeDatabaseReference(ref(js, path), js)) }
    actual fun reference() = rethrow { DatabaseReference(NativeDatabaseReference(ref(js), js)) }
    actual fun setPersistenceEnabled(enabled: Boolean) {}
    actual fun setLoggingEnabled(enabled: Boolean) = rethrow { enableLogging(enabled) }
    actual fun useEmulator(host: String, port: Int) = rethrow { connectDatabaseEmulator(js, host, port) }
}

internal actual open class NativeQuery(
    open val js: JsQuery,
    val database: Database
)

actual open class Query internal actual constructor(
    nativeQuery: NativeQuery
) {

    internal constructor(js: JsQuery, database: Database) : this(NativeQuery(js, database))

    open val js: JsQuery = nativeQuery.js
    val database: Database = nativeQuery.database

    actual fun orderByKey() = Query(query(js, jsOrderByKey()), database)
    actual fun orderByValue() = Query(query(js, jsOrderByValue()), database)
    actual fun orderByChild(path: String) = Query(query(js, jsOrderByChild(path)), database)

    actual val valueEvents
        get() = callbackFlow<DataSnapshot> {
            val unsubscribe = rethrow {
                onValue(
                    query = js,
                    callback = { trySend(DataSnapshot(it, database)) },
                    cancelCallback = { close(DatabaseException(it)).run { } }
                )
            }
            awaitClose { rethrow { unsubscribe() } }
        }

    actual fun childEvents(vararg types: ChildEvent.Type) = callbackFlow<ChildEvent> {
        val unsubscribes = rethrow {
            types.map { type ->
                val callback: ChangeSnapshotCallback = { snapshot, previousChildName ->
                    trySend(
                        ChildEvent(
                            DataSnapshot(snapshot, database),
                            type,
                            previousChildName
                        )
                    )
                }

                val cancelCallback: CancelCallback = {
                    close(DatabaseException(it)).run { }
                }

                when (type) {
                    ChildEvent.Type.ADDED -> onChildAdded(js, callback, cancelCallback)
                    ChildEvent.Type.CHANGED -> onChildChanged(js, callback, cancelCallback)
                    ChildEvent.Type.MOVED -> onChildMoved(js, callback, cancelCallback)
                    ChildEvent.Type.REMOVED -> onChildRemoved(js, callback, cancelCallback)
                }
            }
        }
        awaitClose { rethrow { unsubscribes.forEach { it.invoke() } } }
    }

    actual fun startAt(value: String, key: String?) = Query(query(js, jsStartAt(value, key ?: undefined)), database)

    actual fun startAt(value: Double, key: String?) = Query(query(js, jsStartAt(value, key ?: undefined)), database)

    actual fun startAt(value: Boolean, key: String?) = Query(query(js, jsStartAt(value, key ?: undefined)), database)

    actual fun endAt(value: String, key: String?) = Query(query(js, jsEndAt(value, key ?: undefined)), database)

    actual fun endAt(value: Double, key: String?) = Query(query(js, jsEndAt(value, key ?: undefined)), database)

    actual fun endAt(value: Boolean, key: String?) = Query(query(js, jsEndAt(value, key ?: undefined)), database)

    actual fun limitToFirst(limit: Int) = Query(query(js, jsLimitToFirst(limit)), database)

    actual fun limitToLast(limit: Int) = Query(query(js, jsLimitToLast(limit)), database)

    actual fun equalTo(value: String, key: String?) = Query(query(js, jsEqualTo(value, key ?: undefined)), database)

    actual fun equalTo(value: Double, key: String?) = Query(query(js, jsEqualTo(value, key ?: undefined)), database)

    actual fun equalTo(value: Boolean, key: String?) = Query(query(js, jsEqualTo(value, key ?: undefined)), database)

    override fun toString() = js.toString()

}

@PublishedApi
internal actual class NativeDatabaseReference internal constructor(
    override val js: JsDatabaseReference,
    database: Database
) : NativeQuery(js, database) {

    actual val key get() = rethrow { js.key }
    actual fun push() = rethrow { NativeDatabaseReference(push(js), database) }
    actual fun child(path: String) = rethrow { NativeDatabaseReference(child(js, path), database) }

    actual fun onDisconnect() = rethrow { NativeOnDisconnect(onDisconnect(js), database) }

    actual suspend fun removeValue() = rethrow { remove(js).awaitWhileOnline(database) }

    actual suspend fun setValueEncoded(encodedValue: Any?) = rethrow {
        set(js, encodedValue).awaitWhileOnline(database)
    }

    actual suspend fun updateEncodedChildren(encodedUpdate: Any?) =
        rethrow { update(js, encodedUpdate ?: json()).awaitWhileOnline(database) }


    actual suspend fun <T> runTransaction(strategy: KSerializer<T>, buildSettings: EncodeDecodeSettingsBuilder.() -> Unit, transactionUpdate: (currentData: T) -> T): DataSnapshot {
        return DataSnapshot(jsRunTransaction<Any?>(js, transactionUpdate = { currentData ->
            reencodeTransformation(strategy, currentData ?: json(), buildSettings, transactionUpdate)
        }).awaitWhileOnline(database).snapshot, database)
    }
}

actual class DataSnapshot internal constructor(
    val js: JsDataSnapshot,
    val database: Database
) {
    actual val value get(): Any? {
        check(!hasChildren) { "DataSnapshot.value can only be used for primitive values (snapshots without children)" }
        return js.`val`()
    }

    actual inline fun <reified T> value() =
        rethrow { decode<T>(value = js.`val`()) }

    actual inline fun <T> value(strategy: DeserializationStrategy<T>, buildSettings: DecodeSettings.Builder.() -> Unit) =
        rethrow { decode(strategy, js.`val`(), buildSettings) }

    actual val exists get() = rethrow { js.exists() }
    actual val key get() = rethrow { js.key }
    actual fun child(path: String) = DataSnapshot(js.child(path), database)
    actual val hasChildren get() = js.hasChildren()
    actual val children: Iterable<DataSnapshot> = rethrow {
        ArrayList<DataSnapshot>(js.size).also {
            js.forEach { snapshot -> it.add(DataSnapshot(snapshot, database)); false /* don't cancel enumeration */ }
        }
    }
    actual val ref: DatabaseReference
        get() = DatabaseReference(NativeDatabaseReference(js.ref, database))

}

@PublishedApi
internal actual class NativeOnDisconnect internal constructor(
    val js: JsOnDisconnect,
    val database: Database
) {

    actual suspend fun removeValue() = rethrow { js.remove().awaitWhileOnline(database) }
    actual suspend fun cancel() =  rethrow { js.cancel().awaitWhileOnline(database) }

    actual suspend fun setValue(encodedValue: Any?) =
        rethrow { js.set(encodedValue).awaitWhileOnline(database) }

    actual suspend fun updateEncodedChildren(encodedUpdate: Map<String, Any?>) =
        rethrow { js.update(encodedUpdate.mapValues { (_, value) -> value ?: undefined }).awaitWhileOnline(database) }

}

val OnDisconnect.js get() = native.js
val OnDisconnect.database get() = native.database

actual class DatabaseException actual constructor(message: String?, cause: Throwable?) : RuntimeException(message, cause) {
    constructor(error: dynamic) : this("${error.code ?: "UNKNOWN"}: ${error.message}", error.unsafeCast<Throwable>())
}

inline fun <T, R> T.rethrow(function: T.() -> R): R = dev.gitlive.firebase.database.rethrow { function() }

inline fun <R> rethrow(function: () -> R): R {
    try {
        return function()
    } catch (e: Exception) {
        throw e
    } catch (e: dynamic) {
        throw DatabaseException(e)
    }
}

suspend fun <T> Promise<T>.awaitWhileOnline(database: Database): T = coroutineScope {

    val notConnected = FirebaseDatabase(database)
        .reference(".info/connected")
        .valueEvents
        .filter { !it.value<Boolean>() }
        .produceIn(this)

    select<T> {
        this@awaitWhileOnline.asDeferred().onAwait { it.also { notConnected.cancel() } }
        notConnected.onReceive { throw DatabaseException("Database not connected", null) }
    }

}