/**
 * TrackerMap
 * Copyright (C) 2021-2022  Iván Ávalos <avalos@disroot.org>, Henoch Ojeda <imhenoch@protonmail.com>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */
package mx.trackermap.TrackerMap.controllers

import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.DelicateCoroutinesApi
import kotlinx.coroutines.GlobalScope
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.collect
import kotlinx.coroutines.flow.combine
import kotlinx.coroutines.flow.*
import kotlinx.coroutines.launch
import mx.trackermap.TrackerMap.client.apis.DevicesApi
import mx.trackermap.TrackerMap.client.apis.PositionsApi
import mx.trackermap.TrackerMap.client.models.Position
import mx.trackermap.TrackerMap.client.models.UnitInformation
import mx.trackermap.TrackerMap.utils.Coroutines
import kotlin.time.Duration.Companion.seconds
import kotlin.time.ExperimentalTime
import kotlinx.coroutines.Job

@DelicateCoroutinesApi
@ExperimentalTime
class UnitsController(
    private val devicesApi: DevicesApi,
    private val positionsApi: PositionsApi
) {
    private companion object {
        const val UPDATE_TIME = 20
    }

    val displayedUnitsFlow = MutableStateFlow<List<UnitInformation>>(emptyList())
    private val unitsFlow = MutableStateFlow<List<UnitInformation>>(emptyList())
    private val queryFlow = MutableStateFlow("")

    private var unitsUpdateJob: Job? = null

    init {
        GlobalScope.launch {
            fetchUnits(this)
        }
        GlobalScope.launch {
            setupFlows()
        }
    }

    private suspend fun fetchUnits(scope: CoroutineScope) {
        unitsUpdateJob = Coroutines.tickerFlow(UPDATE_TIME.seconds)
            .map {
                print("Fetching new positions...\n")
                positionsApi.positionsGet()
            }
            .distinctUntilChanged { old, new ->
                old.contentEquals(new)
            }
            .onEach { positions ->
                print("Position(s) changed! Reloading data...\n")
                val devices = devicesApi.devicesGet()
                val positionsMap: MutableMap<Int, Position> = mutableMapOf()

                positions.forEach { position ->
                    position.deviceId?.let {
                        positionsMap[it] = position
                    }
                }

                val units = devices.map {
                    UnitInformation(it, positionsMap[it.id])
                }
                unitsFlow.value = units
            }
            .catch {
                print("Could not retrieve positions\n")
            }
            .launchIn(scope)
    }

    fun stopUpdates() {
        unitsUpdateJob?.cancel()
    }

    fun search(query: String) {
        queryFlow.value = query
    }

    suspend fun getUnit(deviceId: Int): UnitInformation {
        val device = devicesApi.devicesGet(id = deviceId).first()
        val position = positionsApi.positionsGet(id = device.positionId).first()

        return UnitInformation(device, position)
    }

    private suspend fun setupFlows() {
        unitsFlow.combine(queryFlow) { units, query ->
            units.filter { unit ->
                unit.device.name.contains(query, true) ||
                        unit.device.contact?.contains(query, true) == true ||
                        unit.position?.address?.contains(query, true) == true
            }
        }.collect { units ->
            this.displayedUnitsFlow.value = units
        }
    }
}