package org.onlab.onos.net.flow;

import org.onlab.onos.net.PortNumber;
import org.onlab.onos.net.flow.instructions.Instruction;
import org.onlab.onos.net.flow.instructions.Instructions;
import org.onlab.packet.IpPrefix;
import org.onlab.packet.MacAddress;
import org.onlab.packet.VlanId;

import java.util.Collections;
import java.util.LinkedList;
import java.util.List;
import java.util.Objects;

/**
 * Default traffic treatment implementation.
 */
public final class DefaultTrafficTreatment implements TrafficTreatment {

    private final List<Instruction> instructions;

    /**
     * Creates a new traffic treatment from the specified list of instructions.
     *
     * @param instructions treatment instructions
     */
    private DefaultTrafficTreatment(List<Instruction> instructions) {
        this.instructions = Collections.unmodifiableList(instructions);
    }

    @Override
    public List<Instruction> instructions() {
        return instructions;
    }

    /**
     * Returns a new traffic treatment builder.
     *
     * @return traffic treatment builder
     */
    public static TrafficTreatment.Builder builder() {
        return new Builder();
    }

    //FIXME: Order of instructions may affect hashcode
    @Override
    public int hashCode() {
        return Objects.hash(instructions);
    }

    @Override
    public boolean equals(Object obj) {
        if (this == obj) {
            return true;
        }
        if (obj instanceof DefaultTrafficTreatment) {
            DefaultTrafficTreatment that = (DefaultTrafficTreatment) obj;
            return Objects.equals(instructions, that.instructions);

        }
        return false;
    }

    /**
     * Builds a list of treatments following the following order.
     * Modifications -> Group -> Output (including drop)
     */
    public static final class Builder implements TrafficTreatment.Builder {

        boolean drop = false;

        List<Instruction> outputs = new LinkedList<>();

        // TODO: should be a list of instructions based on group objects
        List<Instruction> groups = new LinkedList<>();

        // TODO: should be a list of instructions based on modification objects
        List<Instruction> modifications = new LinkedList<>();

        // Creates a new builder
        private Builder() {
        }

        @Override
        public Builder add(Instruction instruction) {
            if (drop) {
                return this;
            }
            switch (instruction.type()) {
                case DROP:
                    drop = true;
                    break;
                case OUTPUT:
                    outputs.add(instruction);
                    break;
                case L2MODIFICATION:
                case L3MODIFICATION:
                    // TODO: enforce modification order if any
                    modifications.add(instruction);
                    break;
                case GROUP:
                    groups.add(instruction);
                    break;
                default:
                    throw new IllegalArgumentException("Unknown instruction type: " +
                                                               instruction.type());
            }
            return this;
        }

        @Override
        public void drop() {
            add(Instructions.createDrop());
        }

        @Override
        public Builder setOutput(PortNumber number) {
            return add(Instructions.createOutput(number));
        }

        @Override
        public Builder setEthSrc(MacAddress addr) {
            return add(Instructions.modL2Src(addr));
        }

        @Override
        public Builder setEthDst(MacAddress addr) {
            return add(Instructions.modL2Dst(addr));
        }

        @Override
        public Builder setVlanId(VlanId id) {
            return add(Instructions.modVlanId(id));
        }

        @Override
        public Builder setVlanPcp(Byte pcp) {
            return add(Instructions.modVlanPcp(pcp));
        }

        @Override
        public Builder setIpSrc(IpPrefix addr) {
            return add(Instructions.modL3Src(addr));
        }

        @Override
        public Builder setIpDst(IpPrefix addr) {
            return add(Instructions.modL3Dst(addr));
        }

        @Override
        public TrafficTreatment build() {

            //If we are dropping should we just return an emptry list?
            List<Instruction> instructions = new LinkedList<Instruction>();
            instructions.addAll(modifications);
            instructions.addAll(groups);
            if (!drop) {
                instructions.addAll(outputs);
            }

            return new DefaultTrafficTreatment(instructions);
        }

    }

}