room/room-compiler/src/main/kotlin/androidx/room/solver/query/result/GuavaImmutableMultimapQueryResultAdapter.kt

/*
 * Copyright 2021 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.query.result

import androidx.room.compiler.codegen.XClassName
import androidx.room.compiler.codegen.XCodeBlock
import androidx.room.compiler.processing.XType
import androidx.room.ext.GuavaTypeNames
import androidx.room.parser.ParsedQuery
import androidx.room.processor.Context
import androidx.room.solver.CodeGenScope

class GuavaImmutableMultimapQueryResultAdapter(
    context: Context,
    private val parsedQuery: ParsedQuery,
    private val keyTypeArg: XType,
    private val valueTypeArg: XType,
    private val keyRowAdapter: RowAdapter,
    private val valueRowAdapter: RowAdapter,
    private val immutableClassName: XClassName,
) : MultimapQueryResultAdapter(context, parsedQuery, listOf(keyRowAdapter, valueRowAdapter)) {
    private val mapType = immutableClassName.parametrizedBy(
        keyTypeArg.asTypeName(),
        valueTypeArg.asTypeName()
    )

    override fun convert(outVarName: String, cursorVarName: String, scope: CodeGenScope) {
        val mapVarName = scope.getTmpVar("_mapBuilder")

        scope.builder.apply {
            val dupeColumnsIndexAdapter: AmbiguousColumnIndexAdapter?
            if (duplicateColumns.isNotEmpty()) {
                // There are duplicate columns in the result objects, generate code that provides
                // us with the indices resolved and pass it to the adapters so it can retrieve
                // the index of each column used by it.
                dupeColumnsIndexAdapter = AmbiguousColumnIndexAdapter(mappings, parsedQuery)
                dupeColumnsIndexAdapter.onCursorReady(cursorVarName, scope)
                rowAdapters.forEach {
                    check(it is QueryMappedRowAdapter)
                    val indexVarNames = dupeColumnsIndexAdapter.getIndexVarsForMapping(it.mapping)
                    it.onCursorReady(
                        indices = indexVarNames,
                        cursorVarName = cursorVarName,
                        scope = scope
                    )
                }
            } else {
                dupeColumnsIndexAdapter = null
                rowAdapters.forEach {
                    it.onCursorReady(cursorVarName = cursorVarName, scope = scope)
                }
            }

            val builderClassName = when (immutableClassName) {
                GuavaTypeNames.IMMUTABLE_LIST_MULTIMAP ->
                    GuavaTypeNames.IMMUTABLE_LIST_MULTIMAP_BUILDER

                GuavaTypeNames.IMMUTABLE_SET_MULTIMAP ->
                    GuavaTypeNames.IMMUTABLE_SET_MULTIMAP_BUILDER

                else ->
                    // Return type is base class ImmutableMultimap, need the case handled here,
                    // but won't actually get here in the code if this is the case as we will
                    // do an early return in TypeAdapterStore.kt.
                    GuavaTypeNames.IMMUTABLE_MULTIMAP_BUILDER
            }

            addLocalVariable(
                name = mapVarName,
                typeName = builderClassName.parametrizedBy(
                    keyTypeArg.asTypeName(),
                    valueTypeArg.asTypeName()
                ),
                assignExpr = XCodeBlock.of(
                    language = language,
                    format = "%T.builder()",
                    immutableClassName
                )
            )

            val tmpKeyVarName = scope.getTmpVar("_key")
            val tmpValueVarName = scope.getTmpVar("_value")
            beginControlFlow("while (%L.moveToNext())", cursorVarName).apply {
                addLocalVariable(
                    name = tmpKeyVarName,
                    typeName = keyTypeArg.asTypeName()
                )
                keyRowAdapter.convert(tmpKeyVarName, cursorVarName, scope)

                // Iterate over all matched fields to check if all are null. If so, we continue in
                // the while loop to the next iteration.
                check(valueRowAdapter is QueryMappedRowAdapter)
                val valueIndexVars =
                    dupeColumnsIndexAdapter?.getIndexVarsForMapping(valueRowAdapter.mapping)
                        ?: valueRowAdapter.getDefaultIndexAdapter().getIndexVars()
                val columnNullCheckCodeBlock = getColumnNullCheckCode(
                    language = language,
                    cursorVarName = cursorVarName,
                    indexVars = valueIndexVars
                )
                // Perform column null check
                beginControlFlow("if (%L)", columnNullCheckCodeBlock).apply {
                    addStatement("continue")
                }.endControlFlow()

                addLocalVariable(
                    name = tmpValueVarName,
                    typeName = valueTypeArg.asTypeName()
                )
                valueRowAdapter.convert(tmpValueVarName, cursorVarName, scope)
                addStatement("%L.put(%L, %L)", mapVarName, tmpKeyVarName, tmpValueVarName)
            }
            endControlFlow()
            addLocalVariable(
                name = outVarName,
                typeName = mapType,
                assignExpr = XCodeBlock.of(
                    language = language,
                    format = "%L.build()",
                    mapVarName
                )
            )
        }
    }
}