// Copyright 2015 The Vanadium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

package flowtest

import (
	"fmt"
	"io"
	"sync"

	"v.io/v23"
	"v.io/v23/context"
	"v.io/v23/naming"
	"v.io/v23/security"

	"v.io/x/ref/internal/logger"
)

type Wire struct {
	ctx    *context.T
	mu     sync.Mutex
	c      *sync.Cond
	closed bool
}

func (w *Wire) Close() {
	w.mu.Lock()
	w.closed = true
	w.c.Broadcast()
	w.mu.Unlock()
}

func (w *Wire) IsClosed() bool {
	w.mu.Lock()
	c := w.closed
	w.mu.Unlock()
	return c
}

type MRW struct {
	wire      *Wire
	in        []byte
	peers     []*MRW
	noencrypt bool
}

func NewMRWPair(ctx *context.T) (*MRW, *MRW, *Wire) {
	w := &Wire{ctx: ctx}
	w.c = sync.NewCond(&w.mu)
	a, b := &MRW{wire: w}, &MRW{wire: w}
	a.peers, b.peers = []*MRW{b}, []*MRW{a}
	return a, b, w
}

func NewUnencryptedMRWPair(ctx *context.T) (*MRW, *MRW, *Wire) {
	a, b, w := NewMRWPair(ctx)
	a.noencrypt = true
	b.noencrypt = true
	return a, b, w
}

func (f *MRW) UnsafeDisableEncryption() bool {
	return f.noencrypt
}

func (f *MRW) WriteMsg(data ...[]byte) (int, error) {
	buf := []byte{}
	for _, d := range data {
		buf = append(buf, d...)
	}
	if len(buf) == 0 {
		return 0, nil
	}
	logbuf := buf
	if len(buf) > 128 {
		logbuf = buf[:128]
	}
	logger.Global().VI(2).Infof("Writing %d bytes to the wire: %#v", len(buf), logbuf)
	defer f.wire.mu.Unlock()
	f.wire.mu.Lock()
	if f.peers == nil {
		f.wire.mu.Unlock()
		return 0, fmt.Errorf("Attempting to write to read-only fork.")
	}
	for !f.wire.closed {
		ready := true
		for _, peer := range f.peers {
			if peer.in != nil {
				ready = false
			}
		}
		if ready {
			break
		}
		f.wire.c.Wait()
	}
	if f.wire.closed {
		return 0, io.EOF
	}
	for _, peer := range f.peers {
		peer.in = append([]byte{}, buf...)
	}
	f.wire.c.Broadcast()
	return len(buf), nil
}

func (f *MRW) ReadMsg() (buf []byte, err error) {
	defer f.wire.mu.Unlock()
	f.wire.mu.Lock()
	for f.in == nil && !f.wire.closed {
		f.wire.c.Wait()
	}
	buf, f.in = f.in, nil
	f.wire.c.Broadcast()

	logbuf := buf
	if len(buf) > 128 {
		logbuf = buf[:128]
	}
	logger.Global().VI(2).Infof("Reading %d bytes from the wire: %#v", len(buf), logbuf)

	if buf == nil {
		return nil, io.EOF
	}
	return buf, nil
}

func (f *MRW) Close() error {
	f.wire.Close()
	return nil
}

func (f *MRW) ForkForRead() *MRW {
	defer f.wire.mu.Unlock()
	f.wire.mu.Lock()
	fork := &MRW{
		wire:      f.wire,
		peers:     nil,
		noencrypt: f.noencrypt,
	}
	for _, fp := range f.peers {
		fp.peers = append(fp.peers, fork)
	}
	if f.in != nil {
		fork.in = append([]byte{}, f.in...)
	}
	return fork
}

type AllowAllPeersAuthorizer struct{}

func (AllowAllPeersAuthorizer) AuthorizePeer(
	ctx *context.T,
	localEndpoint, remoteEndpoint naming.Endpoint,
	remoteBlessings security.Blessings,
	remoteDischarges map[string]security.Discharge,
) ([]string, []security.RejectedBlessing, error) {
	return nil, nil, nil
}

func (AllowAllPeersAuthorizer) BlessingsForPeer(ctx *context.T, _ []string) (
	security.Blessings, map[string]security.Discharge, error) {
	return v23.GetPrincipal(ctx).BlessingStore().Default(), nil, nil
}