PopularMoviesPagingSource.kt

class PopularMoviesPagingSource @Inject constructor(
    val movieApiService: MovieApiService
) : PagingSource<Int, Movie>() {

    override suspend fun load(params: LoadParams<Int>): LoadResult<Int, Movie> {
        val position = params.key ?: STARTING_INDEX
        return try {
            val movies = movieApiService.getPopularMovies(position)
            LoadResult.Page(
                data = movies.results,
                prevKey = if (position == STARTING_INDEX) null else position - 1,
                nextKey = if (movies.results.isEmpty()) null else position + 1
            )
        } catch (e: Exception) {
            LoadResult.Error(e)
        }
    }

    companion object {
        const val STARTING_INDEX = 1
    }