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/*
 * 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 io.trino.sql.planner.rowpattern;

import com.fasterxml.jackson.annotation.JsonCreator;
import com.fasterxml.jackson.annotation.JsonProperty;
import io.trino.operator.window.pattern.LogicalIndexNavigation;
import io.trino.sql.planner.rowpattern.ir.IrLabel;

import java.util.Map;
import java.util.Objects;
import java.util.Set;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.collect.ImmutableSet.toImmutableSet;
import static java.util.Objects.requireNonNull;

public class LogicalIndexPointer
{
    // a set of labels to navigate over:
    // LAST(A.price, 3) => this is a navigation over rows with label A, so labels = {A}
    // LAST(Union.price, 3) => this is a navigation over rows matching a union variable Union, so for SUBSET Union = (A, B, C), we have labels = {A, B, C}
    // LAST(price, 3) => this is a navigation over "universal pattern variable", which is effectively over all rows, no matter the assigned labels. In such case labels = {}
    private final Set labels;

    // logical position is a position among rows tagged with certain label (or label from a certain set)
    // it has the following semantics:
    // start from FIRST or LAST row tagged with the label (with RUNNING or FINAL semantics), and go logicalOffset steps forward (for FIRST) or backward (for LAST),
    // skipping to consecutive rows with matching label
    // Default: RUNNING LAST offset = 0
    private final boolean last;
    private final boolean running;
    private final int logicalOffset;

    // physical offset is the offset in physical rows, starting from the logical position. negative for PREV, positive for NEXT. The default is -1 for PREV and 1 for NEXT.
    // Unspecified physical offset defaults to 0.
    private final int physicalOffset;

    @JsonCreator
    public LogicalIndexPointer(Set labels, boolean last, boolean running, int logicalOffset, int physicalOffset)
    {
        this.labels = requireNonNull(labels, "labels is null");
        this.last = last;
        this.running = running;
        checkArgument(logicalOffset >= 0, "logical offset must be >= 0, actual: %s", logicalOffset);
        this.logicalOffset = logicalOffset;
        this.physicalOffset = physicalOffset;
    }

    @JsonProperty
    public Set getLabels()
    {
        return labels;
    }

    @JsonProperty
    public boolean isLast()
    {
        return last;
    }

    @JsonProperty
    public boolean isRunning()
    {
        return running;
    }

    @JsonProperty
    public int getLogicalOffset()
    {
        return logicalOffset;
    }

    @JsonProperty
    public int getPhysicalOffset()
    {
        return physicalOffset;
    }

    public LogicalIndexNavigation toLogicalIndexNavigation(Map mapping)
    {
        return new LogicalIndexNavigation(
                labels.stream()
                        .map(mapping::get)
                        .collect(toImmutableSet()),
                last,
                running,
                logicalOffset,
                physicalOffset);
    }

    @Override
    public boolean equals(Object o)
    {
        if (this == o) {
            return true;
        }

        if (o == null || getClass() != o.getClass()) {
            return false;
        }

        LogicalIndexPointer that = (LogicalIndexPointer) o;
        return last == that.last &&
                running == that.running &&
                logicalOffset == that.logicalOffset &&
                physicalOffset == that.physicalOffset &&
                labels.equals(that.labels);
    }

    @Override
    public int hashCode()
    {
        return Objects.hash(labels, last, running, logicalOffset, physicalOffset);
    }
}