/*
 * Copyright (C) 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 com.android.modules.utils.build;

import android.os.Build;
import android.util.ArraySet;
import android.util.SparseArray;

import androidx.annotation.NonNull;

import com.android.internal.annotations.VisibleForTesting;

import java.util.Set;

/**
 * Utility class to check SDK level on a device.
 *
 * <p>Prefer using {@link SdkLevel} if the version is known at build time. This should only be used
 * when a dynamic runtime check is needed.
 */
public final class UnboundedSdkLevel {

    /**
     * Checks if the device is running on a given or newer version of Android.
     */
    public static boolean isAtLeast(@NonNull String version) {
        return sInstance.isAtLeastInternal(version);
    }

    /**
     * Checks if the device is running on a given or older version of Android.
     */
    public static boolean isAtMost(@NonNull String version) {
        return sInstance.isAtMostInternal(version);
    }

    private static final SparseArray<Set<String>> PREVIOUS_CODENAMES = new SparseArray<>(4);

    static {
        PREVIOUS_CODENAMES.put(29, setOf("Q"));
        PREVIOUS_CODENAMES.put(30, setOf("Q", "R"));
        PREVIOUS_CODENAMES.put(31, setOf("Q", "R", "S"));
        PREVIOUS_CODENAMES.put(32, setOf("Q", "R", "S", "Sv2"));
    }

    private static Set<String> setOf(String ... contents) {
        if (SdkLevel.isAtLeastR()) {
            return Set.of(contents);
        }
        // legacy code for Q
        Set<String> set = new ArraySet(contents.length);
        for (String codename : contents) {
            set.add(codename);
        }
        return set;
    }

    private static final UnboundedSdkLevel sInstance =
            new UnboundedSdkLevel(
                    Build.VERSION.SDK_INT,
                    Build.VERSION.CODENAME,
                    SdkLevel.isAtLeastT()
                            ? Build.VERSION.KNOWN_CODENAMES
                            : PREVIOUS_CODENAMES.get(Build.VERSION.SDK_INT));

    private final int mSdkInt;
    private final String mCodename;
    private final boolean mIsReleaseBuild;
    private final Set<String> mKnownCodenames;

    @VisibleForTesting
    UnboundedSdkLevel(int sdkInt, String codename, Set<String> knownCodenames) {
        mSdkInt = sdkInt;
        mCodename = codename;
        mIsReleaseBuild = "REL".equals(codename);
        mKnownCodenames = knownCodenames;
    }

    @VisibleForTesting
    boolean isAtLeastInternal(@NonNull String version) {
        version = removeFingerprint(version);
        if (mIsReleaseBuild) {
            if (isCodename(version)) {
                // On release builds only accept future codenames
                if (mKnownCodenames.contains(version)) {
                    throw new IllegalArgumentException("Artifact with a known codename " + version
                            + " must be recompiled with a finalized integer version.");
                }
                // mSdkInt is always less than future codenames
                return false;
            }
            return mSdkInt >= Integer.parseInt(version);
        }
        if (isCodename(version)) {
            return mKnownCodenames.contains(version);
        }
        // Never assume what the next SDK level is until SDK finalization completes.
        // SDK_INT is always assigned the latest finalized value of the SDK.
        return mSdkInt >= Integer.parseInt(version);
    }

    @VisibleForTesting
    boolean isAtMostInternal(@NonNull String version) {
        version = removeFingerprint(version);
        if (mIsReleaseBuild) {
            if (isCodename(version)) {
                // On release builds only accept future codenames
                if (mKnownCodenames.contains(version)) {
                    throw new IllegalArgumentException("Artifact with a known codename " + version
                            + " must be recompiled with a finalized integer version.");
                }
                // mSdkInt is always less than future codenames
                return true;
            }
            return mSdkInt <= Integer.parseInt(version);
        }
        if (isCodename(version)) {
            return !mKnownCodenames.contains(version) || mCodename.equals(version);
        }
        // Never assume what the next SDK level is until SDK finalization completes.
        // SDK_INT is always assigned the latest finalized value of the SDK.
        //
        // Note: multiple releases can be in development at the same time. For example, during
        // Sv2 and Tiramisu development, both builds have SDK_INT=31 which is not sufficient
        // information to differentiate between them. Also, "31" at that point already corresponds
        // to a previously finalized API level, meaning that the current build is not at most "31".
        // This is why the comparison is strict, instead of <=.
        return mSdkInt < Integer.parseInt(version);
    }

    /**
     * Checks if a string is a codename and contains a fingerprint. Returns the codename without the
     * fingerprint if that is the case. Returns the original string otherwise.
     */
    @VisibleForTesting
    String removeFingerprint(@NonNull String version) {
        if (isCodename(version)) {
            int index = version.indexOf('.');
            if (index != -1) {
                return version.substring(0, index);
            }
        }
        return version;
    }

    private boolean isCodename(String version) {
        if (version.length() == 0) {
            throw new IllegalArgumentException();
        }
        // assume Android codenames start with upper case letters.
        return Character.isUpperCase((version.charAt(0)));
    }

}