Implements MainPresenter to interact with both data source and MainActivity

Author: Sothearith Sreang

GitHub-Search/app/src/main/java/thearith/github/com/github_search/presentation/presenter/search/MainPresenter.kt

@@ -0,0 +1,76 @@
+package thearith.github.com.github_search.presentation.presenter.search
+
+import android.text.TextUtils
+import io.reactivex.Observable
+import thearith.github.com.github_search.data.search.repository.GitHubSearchRepository
+import thearith.github.com.github_search.presentation.executor.PostExecutionThread
+import thearith.github.com.github_search.presentation.executor.ThreadExecutor
+import thearith.github.com.github_search.presentation.presenter.base.BasePresenter
+import thearith.github.com.github_search.view.model.SearchFeedResponse
+import thearith.github.com.github_search.view.model.Status
+import thearith.github.com.github_search.view.activities.search.MainContract
+import javax.inject.Inject
+
+/**
+ * Created by Thearith on 10/31/17.
+ */
+class MainPresenter : BasePresenter, MainContract.Presenter {
+
+    private val mGitHubSearchRepository : GitHubSearchRepository
+
+    private var mPageNumber : Int = 1
+
+    @Inject
+    constructor(threadExecutor: ThreadExecutor,
+                postExecutionThread: PostExecutionThread,
+                gitHubSearchRepository: GitHubSearchRepository) : super(threadExecutor, postExecutionThread) {
+        mGitHubSearchRepository = gitHubSearchRepository
+    }
+
+
+    /**
+     * UI states
+     * */
+
+    private fun initializePageNumber() {
+        mPageNumber = 1
+    }
+
+    private fun incrementPageNumber() {
+        mPageNumber++
+    }
+
+
+    override fun loadNewSearch(searchParam: String) : Observable<SearchFeedResponse> {
+        initializePageNumber()
+        return loadSearch(searchParam, mPageNumber)
+                .startWith(SearchFeedResponse(Status.IN_PROGRESS_WITH_REFRESH))
+                .applySchedulers()
+    }
+
+    override fun loadNextSearch(searchParam: String) : Observable<SearchFeedResponse> {
+        incrementPageNumber()
+        return loadSearch(searchParam, mPageNumber)
+                .startWith(SearchFeedResponse(Status.IN_PROGRESS))
+                .applySchedulers()
+    }
+
+    private fun loadSearch(searchParam : String, pageNumber : Int) =
+            if(TextUtils.isEmpty(searchParam))
+                loadEmptyQuerySearch()
+            else
+                loadNonEmptyQuerySearch(searchParam, pageNumber)
+
+    private fun loadEmptyQuerySearch() =
+            Observable.just(SearchFeedResponse(Status.IDLE))
+
+    private fun loadNonEmptyQuerySearch(searchParam : String, pageNumber : Int) =
+            mGitHubSearchRepository.searchGitHubRepo(searchParam, pageNumber)
+                    .map {
+                        val isNotEmpty = it.items?.isNotEmpty()
+                        val mode = if(isNotEmpty == true) Status.COMPLETE else Status.NO_RESULT
+
+                        SearchFeedResponse(mode, it)
+                    }
+                    .onErrorReturn { SearchFeedResponse(Status.ERROR) }
+}