// Copyright 2022 Google LLC

//

// 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

//

// https://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 dev.cel.parser;

import static com.google.common.base.Preconditions.checkArgument;

import static com.google.common.base.Preconditions.checkNotNull;

import static com.google.common.base.Strings.isNullOrEmpty;

import com.google.auto.value.AutoValue;

import com.google.errorprone.annotations.CheckReturnValue;

import com.google.errorprone.annotations.Immutable;

/** Describes a function signature to match and the {@link CelMacroExpander} to apply. */

@AutoValue

@Immutable

public abstract class CelMacro implements Comparable<CelMacro> {

// Package-private default constructor to prevent extensions outside of the codebase.

CelMacro() {}

/** Returns the function name for this macro. */

public abstract String getFunction();

/** Returns the number of arguments this macro expects. For variadic macros, this is 0. */

public abstract int getArgumentCount();

abstract boolean getReceiverStyle();

/** True if this macro is receiver-style, false if it is global. */

public final boolean isReceiverStyle() {

return getReceiverStyle();

}

/** Returns the unique string used to identify this macro. */

public abstract String getKey();

abstract boolean getVariadic();

/** Returns true if this macro accepts any number of arguments, false otherwise. */

public final boolean isVariadic() {

return getVariadic();

}

/** Returns the expander for this macro. */

public abstract CelMacroExpander getExpander();

@Override

public final int compareTo(CelMacro other) {

if (other == null) {

return 1;

}

int diff = getFunction().compareTo(other.getFunction());

if (diff != 0) {

return diff;

}

diff = Boolean.compare(!isVariadic(), !other.isVariadic());

if (diff != 0) {

return diff;

}

if (!isVariadic()) {

diff = Integer.compare(getArgumentCount(), other.getArgumentCount());

if (diff != 0) {

return diff;

}

}

return Boolean.compare(isReceiverStyle(), other.isReceiverStyle());

}

@Override

public final String toString() {

return getKey();

}

@Override

public final int hashCode() {

return getKey().hashCode();

}

@Override

public final boolean equals(Object other) {

return other instanceof CelMacro && getKey().equals(((CelMacro) other).getKey());

}

static Builder newBuilder() {

return new AutoValue_CelMacro.Builder();

}

/** Creates a new global macro that accepts a fixed number of arguments. */

public static CelMacro newGlobalMacro(String function, int argCount, CelMacroExpander expander) {

checkArgument(!isNullOrEmpty(function));

checkArgument(argCount >= 0);

checkNotNull(expander);

return newBuilder()

.setFunction(function)

.setArgumentCount(argCount)

.setReceiverStyle(false)

.setKey(formatKey(function, argCount, false))

.setVariadic(false)

.setExpander(expander)

.build();

}

/** Creates a new global macro that accepts a variable number of arguments. */

public static CelMacro newGlobalVarArgMacro(String function, CelMacroExpander expander) {

checkArgument(!isNullOrEmpty(function));

checkNotNull(expander);

return newBuilder()

.setFunction(function)

.setArgumentCount(0)

.setReceiverStyle(false)

.setKey(formatVarArgKey(function, false))

.setVariadic(true)

.setExpander(expander)

.build();

}

/** Creates a new receiver-style macro that accepts a fixed number of arguments. */

public static CelMacro newReceiverMacro(

String function, int argCount, CelMacroExpander expander) {

checkArgument(!isNullOrEmpty(function));

checkArgument(argCount >= 0);

checkNotNull(expander);

return newBuilder()

.setFunction(function)

.setArgumentCount(argCount)

.setReceiverStyle(true)

.setKey(formatKey(function, argCount, true))

.setVariadic(false)

.setExpander(expander)

.build();

}

/** Creates a new receiver-style macro that accepts a variable number of arguments. */

public static CelMacro newReceiverVarArgMacro(String function, CelMacroExpander expander) {

checkArgument(!isNullOrEmpty(function));

checkNotNull(expander);

return newBuilder()

.setFunction(function)

.setArgumentCount(0)

.setReceiverStyle(true)

.setKey(formatVarArgKey(function, true))

.setVariadic(true)

.setExpander(expander)

.build();

}

static String formatKey(String function, int argCount, boolean receiverStyle) {

checkArgument(!isNullOrEmpty(function));

checkArgument(argCount >= 0);

return String.format("%s:%d:%s", function, argCount, receiverStyle);

}

static String formatVarArgKey(String function, boolean receiverStyle) {

checkArgument(!isNullOrEmpty(function));

return String.format("%s:*:%s", function, receiverStyle);

}

@AutoValue.Builder

abstract static class Builder {

abstract Builder setFunction(String function);

abstract Builder setArgumentCount(int argumentCount);

abstract Builder setReceiverStyle(boolean receiverStyle);

abstract Builder setKey(String key);

abstract Builder setVariadic(boolean variadic);

abstract Builder setExpander(CelMacroExpander expander);

@CheckReturnValue

abstract CelMacro build();

}

}