room/compiler-processing/src/main/java/androidx/room/compiler/processing/ksp/KspMethodElement.kt

/*
 * Copyright 2020 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.compiler.processing.ksp

import androidx.room.compiler.processing.XDeclaredType
import androidx.room.compiler.processing.XExecutableParameterElement
import androidx.room.compiler.processing.XMethodElement
import androidx.room.compiler.processing.XMethodType
import androidx.room.compiler.processing.XType
import androidx.room.compiler.processing.XTypeElement
import androidx.room.compiler.processing.ksp.synthetic.KspSyntheticContinuationParameterElement
import androidx.room.compiler.processing.ksp.synthetic.KspSyntheticPropertyMethodElement
import org.jetbrains.kotlin.ksp.symbol.ClassKind
import org.jetbrains.kotlin.ksp.symbol.KSClassDeclaration
import org.jetbrains.kotlin.ksp.symbol.KSFunctionDeclaration
import org.jetbrains.kotlin.ksp.symbol.Modifier
import org.jetbrains.kotlin.ksp.symbol.Origin

internal sealed class KspMethodElement(
    env: KspProcessingEnv,
    containing: KspTypeElement,
    declaration: KSFunctionDeclaration
) : KspExecutableElement(
    env = env,
    containing = containing,
    declaration = declaration
),
    XMethodElement {

    override val name: String by lazy {
        declaration.simpleName.asString()
    }

    override val executableType: XMethodType by lazy {
        KspMethodType.create(
            env = env,
            origin = this,
            containing = this.containing.type
        )
    }

    override fun isJavaDefault(): Boolean {
        return declaration.modifiers.contains(Modifier.JAVA_DEFAULT) || declaration.isJvmDefault()
    }

    override fun asMemberOf(other: XDeclaredType): XMethodType {
        check(other is KspDeclaredType)
        return KspMethodType.create(
            env = env,
            origin = this,
            containing = other
        )
    }

    override fun hasKotlinDefaultImpl(): Boolean {
        // see https://github.com/google/ksp/issues/32
        val parentDeclaration = declaration.parentDeclaration
        // if parent declaration is an interface and we are not marked as an abstract method,
        // we should have a default implementation
        return parentDeclaration is KSClassDeclaration &&
            parentDeclaration.classKind == ClassKind.INTERFACE &&
            !declaration.isAbstract
    }

    override fun overrides(other: XMethodElement, owner: XTypeElement): Boolean {
        if (other is KspMethodElement) {
            return try {
                declaration.overrides(other.declaration)
            } catch (castException: ClassCastException) {
                // TODO remove the try catch once that bug is fixed.
                // see https://github.com/google/ksp/issues/94
                false
            }
        }
        // TODO https://github.com/google/ksp/issues/93
        //  remove this custom implementation when KSP supports this out of the box
        // if our declaration is coming from java, it can override property getters/setters as well
        val checkForJavaToKotlinOverride = other.isOverrideableIgnoringContainer() &&
            (declaration.origin == Origin.JAVA || declaration.origin == Origin.CLASS)
        return if (checkForJavaToKotlinOverride && name == other.name) {
            when (other) {
                is KspSyntheticPropertyMethodElement.Getter -> {
                    return parameters.isEmpty() &&
                        asMemberOf(owner.type).returnType.isSameType(
                            other.asMemberOf(owner.type).returnType
                        )
                }
                is KspSyntheticPropertyMethodElement.Setter -> {
                    return parameters.size == 1 &&
                        parameters.first().asMemberOf(owner.type).isSameType(
                            other.parameters.first().asMemberOf(owner.type)
                        )
                }
                else -> false
            }
        } else {
            false
        }
    }

    override fun copyTo(newContainer: XTypeElement): KspMethodElement {
        check(newContainer is KspTypeElement)
        return create(
            env = env,
            containing = newContainer,
            declaration = declaration
        )
    }

    private class KspNormalMethodElement(
        env: KspProcessingEnv,
        containing: KspTypeElement,
        declaration: KSFunctionDeclaration
    ) : KspMethodElement(
        env, containing, declaration
    ) {
        override val returnType: XType by lazy {
            env.wrap(
                checkNotNull(declaration.returnType) {
                    "return type on a method declaration cannot be null"
                }
            )
        }
        override fun isSuspendFunction() = false
    }

    private class KspSuspendMethodElement(
        env: KspProcessingEnv,
        containing: KspTypeElement,
        declaration: KSFunctionDeclaration
    ) : KspMethodElement(
        env, containing, declaration
    ) {
        override fun isSuspendFunction() = true

        override val returnType: XType by lazy {
            env.wrap(env.resolver.builtIns.anyType.makeNullable())
        }

        override val parameters: List<XExecutableParameterElement>
            get() = super.parameters + KspSyntheticContinuationParameterElement(
                env = env,
                containing = this
            )
    }

    companion object {
        fun create(
            env: KspProcessingEnv,
            containing: KspTypeElement,
            declaration: KSFunctionDeclaration
        ): KspMethodElement {
            return if (declaration.modifiers.contains(Modifier.SUSPEND)) {
                KspSuspendMethodElement(env, containing, declaration)
            } else {
                KspNormalMethodElement(env, containing, declaration)
            }
        }
    }
}