lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/PrivateApiClass.kt

/*
 * Copyright (C) 2019 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 com.android.tools.lint.checks

import java.nio.ByteBuffer
import java.nio.charset.StandardCharsets
import java.util.HashMap

/**
 * Represents a class and its hidden methods/fields, which are not part
 * of the public SDK.
 * <p>Each member has an attached reflective access {@link Restriction},
 * corresponding to the platform's runtime behavior (e.g. a reflective
 * call to a denied method is forbidden on all API versions, a call
 * to a maybe allowed method will be allowed with a warning, etc.)
 */
class PrivateApiClass(name: String) : ApiClassBase(name) {

    private val fields = HashMap<String, Restriction>()
    private val methods = HashMap<String, Restriction>()

    internal fun addField(name: String, restriction: Restriction) {
        fields[name] = restriction
    }

    internal fun addMethod(name: String, restriction: Restriction) {
        methods[name] = restriction
    }

    internal override fun computeExtraStorageNeeded(info: Api<out ApiClassBase>): Int {
        var estimatedSize = 0
        members = ArrayList<String>(fields.size + methods.size)
        members.addAll(fields.keys)
        members.addAll(methods.keys)
        members.sort()

        for (member in members) {
            estimatedSize += member.length
            estimatedSize += 8
        }
        return estimatedSize
    }

    internal override fun writeSuperInterfaces(info: Api<out ApiClassBase>, buffer: ByteBuffer) {
        // We don't store the class hierarchy.
    }

    internal override fun writeMemberData(
        info: Api<out ApiClassBase>,
        member: String,
        buffer: ByteBuffer
    ) {
        val payload =
            (if (member.indexOf('(') >= 0) methods[member] else fields[member]) ?: return

        val signature = member.toByteArray(StandardCharsets.UTF_8)
        for (b in signature) {
            // Make sure all signatures are really just simple ASCII.
            assert(b.toInt() == (b.toInt() and 0x7f)) { member }
            buffer.put(b)
            // Skip types on methods
            if (b == ')'.toByte()) {
                break
            }
        }
        buffer.put(0.toByte())

        assert(payload.encoding == (payload.encoding and ApiDatabase.API_MASK)) // Must fit in 7 bits.
        buffer.put(payload.encoding.toByte())
    }
}

enum class Restriction(val encoding: Int) {
    UNKNOWN(0),
    ALLOW(1),
    DENY(2),
    MAYBE(3),
    MAYBE_MAX_O(4),
    MAYBE_MAX_P(5),
}

fun decode(encoding: Int): Restriction =
    when (encoding) {
        1 -> Restriction.ALLOW
        2 -> Restriction.DENY
        3 -> Restriction.MAYBE
        4 -> Restriction.MAYBE_MAX_O
        5 -> Restriction.MAYBE_MAX_P
        else -> Restriction.UNKNOWN
    }