MindMachine/app/src/main/java/com/mindmachine/mvp/billing/BillingManager.kt

package com.mindmachine.mvp.billing

import android.app.Activity
import android.content.Context
import com.android.billingclient.api.AcknowledgePurchaseParams
import com.android.billingclient.api.BillingClient
import com.android.billingclient.api.BillingClientStateListener
import com.android.billingclient.api.BillingFlowParams
import com.android.billingclient.api.BillingResult
import com.android.billingclient.api.ProductDetails
import com.android.billingclient.api.ProductDetailsResponseListener
import com.android.billingclient.api.Purchase
import com.android.billingclient.api.PurchasesResponseListener
import com.android.billingclient.api.QueryProductDetailsParams
import com.android.billingclient.api.QueryPurchasesParams
import kotlinx.coroutines.flow.MutableStateFlow
import kotlinx.coroutines.flow.StateFlow
import kotlinx.coroutines.flow.asStateFlow

class BillingManager(
    context: Context,
    private val onNoAdsEntitlementChanged: (Boolean) -> Unit,
) {
    private val appContext = context.applicationContext

    private val _hasNoAds = MutableStateFlow(false)
    val hasNoAds: StateFlow<Boolean> = _hasNoAds.asStateFlow()

    private val _productDetails = MutableStateFlow<Map<String, ProductDetails>>(emptyMap())
    val productDetails: StateFlow<Map<String, ProductDetails>> = _productDetails.asStateFlow()

    private val billingClient: BillingClient = BillingClient.newBuilder(appContext)
        .setListener { _, purchases ->
            if (purchases != null) {
                handlePurchases(purchases)
            }
        }
        .enablePendingPurchases()
        .build()

    fun start() {
        if (billingClient.isReady) {
            refresh()
            return
        }
        billingClient.startConnection(object : BillingClientStateListener {
            override fun onBillingSetupFinished(result: BillingResult) {
                if (result.responseCode == BillingClient.BillingResponseCode.OK) {
                    refresh()
                }
            }

            override fun onBillingServiceDisconnected() {
                // No-op, will retry on next call.
            }
        })
    }

    fun refresh() {
        queryProductDetails()
        queryActivePurchases()
    }

    fun launchPurchase(activity: Activity, productId: String) {
        val details = _productDetails.value[productId] ?: return

        val productDetailsParams = when (details.productType) {
            BillingClient.ProductType.SUBS -> {
                val offerToken = details.subscriptionOfferDetails
                    ?.firstOrNull()
                    ?.offerToken
                    ?: return
                BillingFlowParams.ProductDetailsParams.newBuilder()
                    .setProductDetails(details)
                    .setOfferToken(offerToken)
                    .build()
            }

            BillingClient.ProductType.INAPP -> {
                BillingFlowParams.ProductDetailsParams.newBuilder()
                    .setProductDetails(details)
                    .build()
            }

            else -> return
        }

        val params = BillingFlowParams.newBuilder()
            .setProductDetailsParamsList(listOf(productDetailsParams))
            .build()

        billingClient.launchBillingFlow(activity, params)
    }

    private fun queryProductDetails() {
        if (!billingClient.isReady) return

        val products = listOf(
            QueryProductDetailsParams.Product.newBuilder()
                .setProductId(BillingProducts.SUB_REMOVE_ADS_MONTHLY)
                .setProductType(BillingClient.ProductType.SUBS)
                .build(),
            QueryProductDetailsParams.Product.newBuilder()
                .setProductId(BillingProducts.INAPP_REMOVE_ADS_FOREVER)
                .setProductType(BillingClient.ProductType.INAPP)
                .build(),
        )

        val params = QueryProductDetailsParams.newBuilder()
            .setProductList(products)
            .build()

        billingClient.queryProductDetailsAsync(params, ProductDetailsResponseListener { result, detailsList ->
            if (result.responseCode == BillingClient.BillingResponseCode.OK) {
                _productDetails.value = detailsList.associateBy { it.productId }
            }
        })
    }

    private fun queryActivePurchases() {
        if (!billingClient.isReady) return

        val listener = PurchasesResponseListener { result, purchases ->
            if (result.responseCode == BillingClient.BillingResponseCode.OK) {
                handlePurchases(purchases)
            }
        }

        billingClient.queryPurchasesAsync(
            QueryPurchasesParams.newBuilder().setProductType(BillingClient.ProductType.SUBS).build(),
            listener
        )
        billingClient.queryPurchasesAsync(
            QueryPurchasesParams.newBuilder().setProductType(BillingClient.ProductType.INAPP).build(),
            listener
        )
    }

    private fun handlePurchases(purchases: List<Purchase>) {
        val active = purchases.any { p ->
            p.purchaseState == Purchase.PurchaseState.PURCHASED &&
                p.products.any { it == BillingProducts.SUB_REMOVE_ADS_MONTHLY || it == BillingProducts.INAPP_REMOVE_ADS_FOREVER }
        }

        if (_hasNoAds.value != active) {
            _hasNoAds.value = active
            onNoAdsEntitlementChanged(active)
        }

        // Acknowledge where needed
        purchases.filter { it.purchaseState == Purchase.PurchaseState.PURCHASED && !it.isAcknowledged }
            .forEach { purchase ->
                val params = AcknowledgePurchaseParams.newBuilder()
                    .setPurchaseToken(purchase.purchaseToken)
                    .build()
                billingClient.acknowledgePurchase(params) { /* no-op */ }
            }
    }
}