PagingSourceQueryResultBinderProvider.kt

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package androidx.room.solver.binderprovider

import androidx.room.compiler.processing.XRawType
import androidx.room.compiler.processing.XType
import androidx.room.ext.PagingTypeNames
import androidx.room.parser.ParsedQuery
import androidx.room.processor.Context
import androidx.room.processor.ProcessorErrors
import androidx.room.solver.QueryResultBinderProvider
import androidx.room.solver.query.result.ListQueryResultAdapter
import androidx.room.solver.query.result.CompatPagingSourceQueryResultBinder
import androidx.room.solver.query.result.PagingSourceQueryResultBinder
import androidx.room.solver.query.result.PositionalDataSourceQueryResultBinder
import androidx.room.solver.query.result.QueryResultBinder
import com.squareup.javapoet.TypeName

class PagingSourceQueryResultBinderProvider(val context: Context) : QueryResultBinderProvider {
    private val pagingSourceType: XRawType? by lazy {
        context.processingEnv.findType(PagingTypeNames.PAGING_SOURCE)?.rawType
    }

    override fun provide(declared: XType, query: ParsedQuery): QueryResultBinder {
        if (query.tables.isEmpty()) {
            context.logger.e(ProcessorErrors.OBSERVABLE_QUERY_NOTHING_TO_OBSERVE)
        }
        val typeArg = declared.typeArguments.last()
        val listAdapter = context.typeAdapterStore.findRowAdapter(typeArg, query)?.let {
            ListQueryResultAdapter(typeArg, it)
        }
        val tableNames = (
            (listAdapter?.accessedTableNames() ?: emptyList()) +
                query.tables.map { it.name }
            ).toSet()

        // If limitOffsetPagingSource is null, then it is not in the compile classpath
        val limitOffsetPagingSource = context.processingEnv.findType(
            "androidx.room.paging.LimitOffsetPagingSource"
        )
        return if (limitOffsetPagingSource != null) {
            PagingSourceQueryResultBinder(
                listAdapter = listAdapter,
                tableNames = tableNames,
            )
        } else {
            CompatPagingSourceQueryResultBinder(
                PositionalDataSourceQueryResultBinder(
                    listAdapter = listAdapter,
                    tableNames = tableNames,
                    forPaging3 = true
                )
            )
        }
    }

    override fun matches(declared: XType): Boolean {
        val collectionTypeRaw = context.COMMON_TYPES.READONLY_COLLECTION.rawType

        if (pagingSourceType == null) {
            return false
        }

        if (declared.typeArguments.isEmpty()) {
            return false
        }

        if (!pagingSourceType!!.isAssignableFrom(declared)) {
            return false
        }

        if (declared.typeArguments.first().typeName != TypeName.INT.box()) {
            context.logger.e(ProcessorErrors.PAGING_SPECIFY_PAGING_SOURCE_TYPE)
        }

        if (collectionTypeRaw.isAssignableFrom(declared.typeArguments.last().rawType)) {
            context.logger.e(ProcessorErrors.PAGING_SPECIFY_PAGING_SOURCE_VALUE_TYPE)
        }

        return true
    }
}