Added pagination

composeApp/build.gradle.kts

@@ -72,6 +72,8 @@ kotlin {
 
             implementation(libs.room.runtime)
             implementation(libs.sqlite.bundled)
+
+            implementation(libs.bundles.paging)
         }
 
         commonTest.dependencies {

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/data/datasources/MovieDetailsRepositoryImpl.kt

@@ -1,12 +1,16 @@
 package com.vickbt.composeApp.data.datasources
 
+import androidx.paging.PagingData
+import app.cash.paging.Pager
+import app.cash.paging.PagingConfig
 import com.vickbt.composeApp.data.cache.AppDatabase
 import com.vickbt.composeApp.data.mappers.toDomain
 import com.vickbt.composeApp.data.mappers.toEntity
 import com.vickbt.composeApp.data.network.models.CastDto
 import com.vickbt.composeApp.data.network.models.MovieDetailsDto
 import com.vickbt.composeApp.data.network.models.MovieResultsDto
 import com.vickbt.composeApp.data.network.utils.safeApiCall
+import com.vickbt.composeApp.data.paging.BasePagingSource
 import com.vickbt.composeApp.domain.models.Cast
 import com.vickbt.composeApp.domain.models.Movie
 import com.vickbt.composeApp.domain.models.MovieDetails
@@ -25,6 +29,8 @@ class MovieDetailsRepositoryImpl(
     private val appDatabase: AppDatabase
 ) : MovieDetailsRepository {
 
+    private val pagingConfig = PagingConfig(pageSize = 20, enablePlaceholders = false)
+
     override suspend fun fetchMovieDetails(movieId: Int): Result<Flow<MovieDetails?>> {
         val isMovieCached = isMovieFavorite(movieId = movieId).getOrDefault(flowOf(false))
             .firstOrNull()
@@ -33,8 +39,8 @@ class MovieDetailsRepositoryImpl(
             getFavoriteMovie(movieId = movieId)
         } else {
             safeApiCall {
-            httpClient.get(urlString = "movie/$movieId").body<MovieDetailsDto>().toDomain()
-        }
+                httpClient.get(urlString = "movie/$movieId").body<MovieDetailsDto>().toDomain()
+            }
         }
     }
 
@@ -44,17 +50,21 @@ class MovieDetailsRepositoryImpl(
         }
     }
 
-    override suspend fun fetchSimilarMovies(
-        movieId: Int,
-        page: Int
-    ): Result<Flow<List<Movie>?>> {
-        return safeApiCall {
+    override suspend fun fetchSimilarMovies(movieId: Int): Result<Flow<PagingData<Movie>>> {
+        val pagingSource = BasePagingSource { page ->
             val response = httpClient.get(urlString = "movie/$movieId/similar") {
                 parameter("page", page)
             }.body<MovieResultsDto>()
 
             response.movies?.map { it.toDomain() }
         }
+
+        return runCatching {
+            Pager(
+                config = pagingConfig,
+                pagingSourceFactory = { pagingSource }
+            ).flow
+        }
     }
 
     override suspend fun saveFavoriteMovie(movie: MovieDetails) {

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/data/datasources/MoviesRepositoryImpl.kt

@@ -1,8 +1,12 @@
 package com.vickbt.composeApp.data.datasources
 
+import app.cash.paging.Pager
+import app.cash.paging.PagingConfig
+import app.cash.paging.PagingData
 import com.vickbt.composeApp.data.mappers.toDomain
 import com.vickbt.composeApp.data.network.models.MovieResultsDto
 import com.vickbt.composeApp.data.network.utils.safeApiCall
+import com.vickbt.composeApp.data.paging.BasePagingSource
 import com.vickbt.composeApp.domain.models.Movie
 import com.vickbt.composeApp.domain.repositories.MoviesRepository
 import io.ktor.client.HttpClient
@@ -15,10 +19,12 @@ class MoviesRepositoryImpl(
     private val httpClient: HttpClient
 ) : MoviesRepository {
 
-    override suspend fun fetchNowPlayingMovies(page: Int): Result<Flow<List<Movie>?>> {
+    private val pagingConfig = PagingConfig(pageSize = 20, enablePlaceholders = false)
+
+    override suspend fun fetchNowPlayingMovies(): Result<Flow<List<Movie>?>> {
         return safeApiCall {
             val response = httpClient.get(urlString = "movie/now_playing") {
-                parameter("page", page)
+                parameter("page", 1)
             }.body<MovieResultsDto>()
 
             response.movies?.map { it.toDomain() }
@@ -27,35 +33,55 @@ class MoviesRepositoryImpl(
 
     override suspend fun fetchTrendingMovies(
         mediaType: String,
-        timeWindow: String,
-        page: Int
-    ): Result<Flow<List<Movie>?>> {
-        return safeApiCall {
+        timeWindow: String
+    ): Result<Flow<PagingData<Movie>>> {
+        val pagingSource = BasePagingSource { page ->
             val response = httpClient.get(urlString = "trending/$mediaType/$timeWindow") {
                 parameter("page", page)
-            }.body<MovieResultsDto>()
+            }.body<MovieResultsDto>().movies
 
-            response.movies?.map { it.toDomain() }
+            response?.map { it.toDomain() }
+        }
+
+        return runCatching {
+            Pager(
+                config = pagingConfig,
+                pagingSourceFactory = { pagingSource }
+            ).flow
         }
     }
 
-    override suspend fun fetchPopularMovies(page: Int): Result<Flow<List<Movie>?>> {
-        return safeApiCall {
+    override suspend fun fetchPopularMovies(): Result<Flow<PagingData<Movie>>> {
+        val pagingSource = BasePagingSource { page ->
             val response = httpClient.get(urlString = "movie/popular") {
                 parameter("page", page)
-            }.body<MovieResultsDto>()
+            }.body<MovieResultsDto>().movies
 
-            response.movies?.map { it.toDomain() }
+            response?.map { it.toDomain() }
+        }
+
+        return runCatching {
+            Pager(
+                config = pagingConfig,
+                pagingSourceFactory = { pagingSource }
+            ).flow
         }
     }
 
-    override suspend fun fetchUpcomingMovies(page: Int): Result<Flow<List<Movie>?>> {
-        return safeApiCall {
+    override suspend fun fetchUpcomingMovies(): Result<Flow<PagingData<Movie>>> {
+        val pagingSource = BasePagingSource { page ->
             val response = httpClient.get(urlString = "movie/upcoming") {
                 parameter("page", page)
-            }.body<MovieResultsDto>()
+            }.body<MovieResultsDto>().movies
 
-            response.movies?.map { it.toDomain() }
+            response?.map { it.toDomain() }
+        }
+
+        return runCatching {
+            Pager(
+                config = pagingConfig,
+                pagingSourceFactory = { pagingSource }
+            ).flow
         }
     }
 }

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/data/datasources/SearchRepositoryImpl.kt

@@ -1,8 +1,11 @@
 package com.vickbt.composeApp.data.datasources
 
+import app.cash.paging.Pager
+import app.cash.paging.PagingConfig
+import app.cash.paging.PagingData
 import com.vickbt.composeApp.data.mappers.toDomain
 import com.vickbt.composeApp.data.network.models.MovieResultsDto
-import com.vickbt.composeApp.data.network.utils.safeApiCall
+import com.vickbt.composeApp.data.paging.BasePagingSource
 import com.vickbt.composeApp.domain.models.Movie
 import com.vickbt.composeApp.domain.repositories.SearchRepository
 import io.ktor.client.HttpClient
@@ -15,17 +18,23 @@ class SearchRepositoryImpl(
     private val httpClient: HttpClient
 ) : SearchRepository {
 
-    override suspend fun searchMovie(
-        movieName: String,
-        page: Int
-    ): Result<Flow<List<Movie>?>> {
-        return safeApiCall {
+    private val pagingConfig = PagingConfig(pageSize = 20, enablePlaceholders = false)
+
+    override suspend fun searchMovie(movieName: String): Result<Flow<PagingData<Movie>>> {
+        val pagingSource = BasePagingSource { page ->
             val response = httpClient.get(urlString = "search/movie") {
                 parameter("query", movieName)
                 parameter("page", page)
-            }.body<MovieResultsDto>()
+            }.body<MovieResultsDto>().movies
+
+            response?.map { it.toDomain() }
+        }
 
-            response.movies?.map { it.toDomain() }
+        return runCatching {
+            Pager(
+                config = pagingConfig,
+                pagingSourceFactory = { pagingSource }
+            ).flow
         }
     }
 }

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/data/network/models/MovieDetailsDto.kt

@@ -10,7 +10,7 @@ data class MovieDetailsDto(
     val adult: Boolean? = null,
 
     @SerialName("backdrop_path")
-    val backdropPath: String,
+    val backdropPath: String? = null,
 
     @SerialName("genres")
     val genres: List<GenreDto>? = null,
@@ -37,7 +37,7 @@ data class MovieDetailsDto(
     val popularity: Double? = null,
 
     @SerialName("poster_path")
-    val posterPath: String,
+    val posterPath: String? = null,
 
     @SerialName("release_date")
     val releaseDate: String? = null,

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/data/network/models/MovieDto.kt

@@ -9,7 +9,7 @@ data class MovieDto(
     val adult: Boolean? = null,
 
     @SerialName("backdrop_path")
-    val backdropPath: String,
+    val backdropPath: String? = null,
 
     @SerialName("genre_ids")
     val genreIds: List<Int>? = null,
@@ -21,22 +21,22 @@ data class MovieDto(
     val originalLanguage: String? = null,
 
     @SerialName("original_title")
-    val originalTitle: String,
+    val originalTitle: String? = null,
 
     @SerialName("overview")
-    val overview: String,
+    val overview: String? = null,
 
     @SerialName("popularity")
     val popularity: Double? = null,
 
     @SerialName("poster_path")
-    val posterPath: String,
+    val posterPath: String? = null,
 
     @SerialName("release_date")
     val releaseDate: String? = null,
 
     @SerialName("title")
-    val title: String,
+    val title: String? = null,
 
     @SerialName("video")
     val video: Boolean? = null,

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/data/paging/BasePagingSource.kt

@@ -0,0 +1,32 @@
+package com.vickbt.composeApp.data.paging
+
+import app.cash.paging.PagingSource
+import app.cash.paging.PagingState
+import com.vickbt.composeApp.domain.utils.Constants.STARTING_PAGE_INDEX
+
+class BasePagingSource<T : Any>(val fetchData: suspend (page: Int) -> List<T>?) :
+    PagingSource<Int, T>() {
+
+    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, T> {
+        val page = params.key ?: STARTING_PAGE_INDEX
+
+        val data = fetchData(page) ?: emptyList()
+
+        return try {
+            LoadResult.Page(
+                data = data,
+                prevKey = if (page == 1) null else page - 1,
+                nextKey = if (data.isEmpty()) null else page + 1
+            )
+        } catch (e: Exception) {
+            LoadResult.Error(e)
+        }
+    }
+
+    override fun getRefreshKey(state: PagingState<Int, T>): Int? {
+        return state.anchorPosition?.let { anchorPosition ->
+            state.closestPageToPosition(anchorPosition)?.prevKey?.plus(1)
+                ?: state.closestPageToPosition(anchorPosition)?.nextKey?.minus(1)
+        }
+    }
+}

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/domain/models/Movie.kt

@@ -3,23 +3,23 @@ package com.vickbt.composeApp.domain.models
 data class Movie(
     val adult: Boolean? = null,
 
-    val backdropPath: String,
+    val backdropPath: String? = null,
 
     val id: Int,
 
     val originalLanguage: String? = null,
 
-    val originalTitle: String,
+    val originalTitle: String? = null,
 
-    val overview: String,
+    val overview: String? = null,
 
     val popularity: Double? = null,
 
-    val posterPath: String,
+    val posterPath: String? = null,
 
     val releaseDate: String? = null,
 
-    val title: String,
+    val title: String? = null,
 
     val video: Boolean? = null,
 

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/domain/models/MovieDetails.kt

@@ -4,7 +4,7 @@ data class MovieDetails(
 
     val adult: Boolean? = null,
 
-    val backdropPath: String,
+    val backdropPath: String? = null,
 
     val homepage: String? = null,
 
@@ -20,7 +20,7 @@ data class MovieDetails(
 
     val popularity: Double? = null,
 
-    val posterPath: String,
+    val posterPath: String? = null,
 
     val releaseDate: String? = null,
 

composeApp/src/commonMain/kotlin/com/vickbt/composeApp/domain/repositories/MovieDetailsRepository.kt

@@ -1,9 +1,9 @@
 package com.vickbt.composeApp.domain.repositories
 
+import androidx.paging.PagingData
 import com.vickbt.composeApp.domain.models.Cast
 import com.vickbt.composeApp.domain.models.Movie
 import com.vickbt.composeApp.domain.models.MovieDetails
-import com.vickbt.composeApp.domain.utils.Constants.STARTING_PAGE_INDEX
 import kotlinx.coroutines.flow.Flow
 
 interface MovieDetailsRepository {
@@ -15,10 +15,7 @@ interface MovieDetailsRepository {
     suspend fun fetchMovieCast(movieId: Int): Result<Flow<Cast>>
 
     /** Fetches similar movies from network source*/
-    suspend fun fetchSimilarMovies(
-        movieId: Int,
-        page: Int = STARTING_PAGE_INDEX
-    ): Result<Flow<List<Movie>?>>
+    suspend fun fetchSimilarMovies(movieId: Int): Result<Flow<PagingData<Movie>>>
 
     /**Save movie details to local cache*/
     suspend fun saveFavoriteMovie(movie: MovieDetails)