// 
// Decompiled by Procyon v0.6.0
// 

package io.netty.handler.codec.http3;

import io.netty.handler.codec.http.HttpStatusClass;
import org.jetbrains.annotations.Nullable;
import io.netty.channel.ChannelPromise;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelOutboundHandlerAdapter;

final class Http3RequestStreamEncodeStateValidator extends ChannelOutboundHandlerAdapter implements Http3RequestStreamCodecState
{
    private State state;
    
    Http3RequestStreamEncodeStateValidator() {
        this.state = State.None;
    }
    
    @Override
    public void write(final ChannelHandlerContext ctx, final Object msg, final ChannelPromise promise) throws Exception {
        if (!(msg instanceof Http3RequestStreamFrame)) {
            super.write(ctx, msg, promise);
            return;
        }
        final Http3RequestStreamFrame frame = (Http3RequestStreamFrame)msg;
        final State nextState = evaluateFrame(this.state, frame);
        if (nextState == null) {
            Http3FrameValidationUtils.frameTypeUnexpected(ctx, msg);
            return;
        }
        this.state = nextState;
        super.write(ctx, msg, promise);
    }
    
    @Override
    public boolean started() {
        return isStreamStarted(this.state);
    }
    
    @Override
    public boolean receivedFinalHeaders() {
        return isFinalHeadersReceived(this.state);
    }
    
    @Override
    public boolean terminated() {
        return isTrailersReceived(this.state);
    }
    
    @Nullable
    static State evaluateFrame(final State state, final Http3RequestStreamFrame frame) {
        if (frame instanceof Http3PushPromiseFrame || frame instanceof Http3UnknownFrame) {
            return state;
        }
        switch (state) {
            case None:
            case Headers: {
                if (!(frame instanceof Http3HeadersFrame)) {
                    return null;
                }
                return isInformationalResponse((Http3HeadersFrame)frame) ? State.Headers : State.FinalHeaders;
            }
            case FinalHeaders: {
                if (!(frame instanceof Http3HeadersFrame)) {
                    return state;
                }
                if (isInformationalResponse((Http3HeadersFrame)frame)) {
                    return null;
                }
                return State.Trailers;
            }
            case Trailers: {
                return null;
            }
            default: {
                throw new Error("Unexpected frame state: " + state);
            }
        }
    }
    
    static boolean isStreamStarted(final State state) {
        return state != State.None;
    }
    
    static boolean isFinalHeadersReceived(final State state) {
        return isStreamStarted(state) && state != State.Headers;
    }
    
    static boolean isTrailersReceived(final State state) {
        return state == State.Trailers;
    }
    
    private static boolean isInformationalResponse(final Http3HeadersFrame headersFrame) {
        return HttpStatusClass.valueOf(headersFrame.headers().status()) == HttpStatusClass.INFORMATIONAL;
    }
    
    enum State
    {
        None, 
        Headers, 
        FinalHeaders, 
        Trailers;
    }
}