From d300324111ba4fe19e42e5ee6b9ced01debff6c1 Mon Sep 17 00:00:00 2001
From: Jacob Bosco <jacob.bosco3075@gmail.com>
Date: Tue, 18 Oct 2022 21:54:09 +0530
Subject: [PATCH] WTA #44: Added use case to get cached data.

---
 .../usecases/GetCachedHomePageUiData.kt       | 114 ++++++++++++++++++
 1 file changed, 114 insertions(+)
 create mode 100644 home/src/main/java/com/jacob/wakatimeapp/home/domain/usecases/GetCachedHomePageUiData.kt

diff --git a/home/src/main/java/com/jacob/wakatimeapp/home/domain/usecases/GetCachedHomePageUiData.kt b/home/src/main/java/com/jacob/wakatimeapp/home/domain/usecases/GetCachedHomePageUiData.kt
new file mode 100644
index 00000000..bcbb8d0d
--- /dev/null
+++ b/home/src/main/java/com/jacob/wakatimeapp/home/domain/usecases/GetCachedHomePageUiData.kt
@@ -0,0 +1,114 @@
+package com.jacob.wakatimeapp.home.domain.usecases
+
+import arrow.core.computations.either
+import arrow.core.right
+import com.jacob.wakatimeapp.core.common.auth.AuthDataStore
+import com.jacob.wakatimeapp.home.data.local.HomePageCache
+import com.jacob.wakatimeapp.home.domain.InstantProvider
+import com.jacob.wakatimeapp.home.domain.models.HomePageUserDetails
+import com.jacob.wakatimeapp.home.domain.models.Last7DaysStats
+import com.jacob.wakatimeapp.home.domain.models.StreakRange
+import com.jacob.wakatimeapp.home.domain.models.Streaks
+import com.jacob.wakatimeapp.home.domain.models.toHomePageUserDetails
+import com.jacob.wakatimeapp.home.domain.usecases.CacheState.FirstRequest
+import com.jacob.wakatimeapp.home.domain.usecases.CacheState.InvalidData
+import com.jacob.wakatimeapp.home.domain.usecases.CacheState.ValidData
+import com.jacob.wakatimeapp.home.domain.usecases.GetCachedHomePageUiData.CacheValidity.DEFAULT
+import javax.inject.Inject
+import javax.inject.Singleton
+import kotlinx.coroutines.flow.channelFlow
+import kotlinx.coroutines.flow.combine
+import kotlinx.coroutines.flow.flowOn
+import kotlinx.coroutines.flow.onEach
+import kotlinx.datetime.Instant
+import kotlinx.datetime.toLocalDateTime
+
+@Singleton
+class GetCachedHomePageUiData @Inject constructor(
+    private val instantProvider: InstantProvider,
+    private val homePageCache: HomePageCache,
+    private val authDataStore: AuthDataStore,
+) {
+    operator fun invoke(cacheValidity: CacheValidity = DEFAULT) = channelFlow {
+        val lastRequestTime = homePageCache.getLastRequestTime()
+
+        if (firstRequestOfDay(lastRequestTime)) {
+            send(FirstRequest.right())
+            return@channelFlow
+        }
+
+        combine(
+            getLast7DaysStats(),
+            getHomePageUserDetails(),
+            getStreaks()
+        ) { last7DaysStatsEither, userDetails, streaksEither ->
+            either {
+                val last7DaysStats = last7DaysStatsEither.bind()
+                val streakRange = streaksEither.bind()
+                val streaks = Streaks(
+                    currentStreak = streakRange,
+                    longestStreak = StreakRange.ZERO
+                )
+
+                when {
+                    validDataInCache(lastRequestTime, cacheValidity) -> ValidData(
+                        last7DaysStats = last7DaysStats,
+                        userDetails = userDetails.toHomePageUserDetails(),
+                        streaks = streaks
+                    )
+
+                    else -> InvalidData(
+                        last7DaysStats = last7DaysStats,
+                        userDetails = userDetails.toHomePageUserDetails(),
+                        streaks = streaks
+                    )
+                }
+            }
+        }.onEach { send(it) }
+            .flowOn(this.coroutineContext)
+    }
+
+    private fun getHomePageUserDetails() = authDataStore.getUserDetails()
+
+    private fun getLast7DaysStats() = homePageCache.getLast7DaysStats()
+
+    private fun getStreaks() = homePageCache.getCurrentStreak()
+
+    private fun firstRequestOfDay(lastRequestTime: Instant) = lastRequestTime.isPreviousDay()
+
+    private fun validDataInCache(
+        lastRequestTime: Instant,
+        cacheValidityTime: CacheValidity,
+    ): Boolean {
+        val minutesBetweenLastRequest = instantProvider.now() - lastRequestTime
+        return minutesBetweenLastRequest.inWholeMinutes < cacheValidityTime.minutes
+    }
+
+    private fun Instant.isPreviousDay(): Boolean {
+        val lastRequestDate = this.toLocalDateTime(instantProvider.timeZone).date.toEpochDays()
+        val currentDate =
+            instantProvider.now().toLocalDateTime(instantProvider.timeZone).date.toEpochDays()
+
+        return currentDate - lastRequestDate >= 1
+    }
+
+    enum class CacheValidity(val minutes: Long) {
+        DEFAULT(15L),
+        INVALID(0L),
+    }
+}
+
+sealed class CacheState {
+    object FirstRequest : CacheState()
+    data class ValidData(
+        val last7DaysStats: Last7DaysStats,
+        val userDetails: HomePageUserDetails,
+        val streaks: Streaks,
+    ) : CacheState()
+
+    data class InvalidData(
+        val last7DaysStats: Last7DaysStats,
+        val userDetails: HomePageUserDetails,
+        val streaks: Streaks,
+    ) : CacheState()
+}