//                           _       _
// __      _____  __ ___   ___  __ _| |_ ___
// \ \ /\ / / _ \/ _` \ \ / / |/ _` | __/ _ \
//  \ V  V /  __/ (_| |\ V /| | (_| | ||  __/
//   \_/\_/ \___|\__,_| \_/ |_|\__,_|\__\___|
//
//  Copyright © 2016 - 2024 Weaviate B.V. All rights reserved.
//
//  CONTACT: hello@weaviate.io
//

package cluster

import (
	"context"
	"fmt"
	"strings"
	"sync"
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

func TestBroadcastOpenTransaction(t *testing.T) {
	client := &fakeClient{}
	state := &fakeState{hosts: []string{"host1", "host2", "host3"}}

	bc := NewTxBroadcaster(state, client)

	tx := &Transaction{ID: "foo"}

	err := bc.BroadcastTransaction(context.Background(), tx)
	require.Nil(t, err)

	assert.ElementsMatch(t, []string{"host1", "host2", "host3"}, client.openCalled)
}

func TestBroadcastOpenTransactionWithReturnPayload(t *testing.T) {
	client := &fakeClient{}
	state := &fakeState{hosts: []string{"host1", "host2", "host3"}}

	bc := NewTxBroadcaster(state, client)
	bc.SetConsensusFunction(func(ctx context.Context,
		in []*Transaction,
	) (*Transaction, error) {
		// instead of actually reaching a consensus this test mock simply merged
		// all the individual results. For testing purposes this is even better
		// because now we can be sure that every element was considered.
		merged := ""
		for _, tx := range in {
			if len(merged) > 0 {
				merged += ","
			}
			merged += tx.Payload.(string)
		}

		return &Transaction{
			Payload: merged,
		}, nil
	})

	tx := &Transaction{ID: "foo"}

	err := bc.BroadcastTransaction(context.Background(), tx)
	require.Nil(t, err)

	assert.ElementsMatch(t, []string{"host1", "host2", "host3"}, client.openCalled)

	results := strings.Split(tx.Payload.(string), ",")
	assert.ElementsMatch(t, []string{
		"hello_from_host1",
		"hello_from_host2",
		"hello_from_host3",
	}, results)
}

func TestBroadcastOpenTransactionAfterNodeHasDied(t *testing.T) {
	client := &fakeClient{}
	state := &fakeState{hosts: []string{"host1", "host2", "host3"}}
	bc := NewTxBroadcaster(state, client)

	waitUntilIdealStateHasReached(t, bc, 3, 4*time.Second)

	// host2 is dead
	state.updateHosts([]string{"host1", "host3"})

	tx := &Transaction{ID: "foo"}

	err := bc.BroadcastTransaction(context.Background(), tx)
	require.NotNil(t, err)
	assert.Contains(t, err.Error(), "host2")

	// no node is should have received an open
	assert.ElementsMatch(t, []string{}, client.openCalled)
}

func waitUntilIdealStateHasReached(t *testing.T, bc *TxBroadcaster, goal int,
	max time.Duration,
) {
	ctx, cancel := context.WithTimeout(context.Background(), max)
	defer cancel()

	interval := time.NewTicker(250 * time.Millisecond)
	defer interval.Stop()

	for {
		select {
		case <-ctx.Done():
			t.Error(fmt.Errorf("waiting to reach state goal %d: %w", goal, ctx.Err()))
			return
		case <-interval.C:
			if len(bc.ideal.Members()) == goal {
				return
			}
		}
	}
}

func TestBroadcastAbortTransaction(t *testing.T) {
	client := &fakeClient{}
	state := &fakeState{hosts: []string{"host1", "host2", "host3"}}

	bc := NewTxBroadcaster(state, client)

	tx := &Transaction{ID: "foo"}

	err := bc.BroadcastAbortTransaction(context.Background(), tx)
	require.Nil(t, err)

	assert.ElementsMatch(t, []string{"host1", "host2", "host3"}, client.abortCalled)
}

func TestBroadcastCommitTransaction(t *testing.T) {
	client := &fakeClient{}
	state := &fakeState{hosts: []string{"host1", "host2", "host3"}}

	bc := NewTxBroadcaster(state, client)

	tx := &Transaction{ID: "foo"}

	err := bc.BroadcastCommitTransaction(context.Background(), tx)
	require.Nil(t, err)

	assert.ElementsMatch(t, []string{"host1", "host2", "host3"}, client.commitCalled)
}

func TestBroadcastCommitTransactionAfterNodeHasDied(t *testing.T) {
	client := &fakeClient{}
	state := &fakeState{hosts: []string{"host1", "host2", "host3"}}
	bc := NewTxBroadcaster(state, client)

	waitUntilIdealStateHasReached(t, bc, 3, 4*time.Second)

	state.updateHosts([]string{"host1", "host3"})

	tx := &Transaction{ID: "foo"}

	err := bc.BroadcastCommitTransaction(context.Background(), tx)
	require.NotNil(t, err)
	assert.Contains(t, err.Error(), "host2")

	// no node should have received the commit
	assert.ElementsMatch(t, []string{}, client.commitCalled)
}

type fakeState struct {
	hosts []string
	sync.Mutex
}

func (f *fakeState) updateHosts(newHosts []string) {
	f.Lock()
	defer f.Unlock()

	f.hosts = newHosts
}

func (f *fakeState) Hostnames() []string {
	f.Lock()
	defer f.Unlock()

	return f.hosts
}

func (f *fakeState) AllNames() []string {
	f.Lock()
	defer f.Unlock()

	return f.hosts
}

type fakeClient struct {
	sync.Mutex
	openCalled   []string
	abortCalled  []string
	commitCalled []string
}

func (f *fakeClient) OpenTransaction(ctx context.Context, host string, tx *Transaction) error {
	f.Lock()
	defer f.Unlock()

	f.openCalled = append(f.openCalled, host)
	tx.Payload = "hello_from_" + host
	return nil
}

func (f *fakeClient) AbortTransaction(ctx context.Context, host string, tx *Transaction) error {
	f.Lock()
	defer f.Unlock()

	f.abortCalled = append(f.abortCalled, host)
	return nil
}

func (f *fakeClient) CommitTransaction(ctx context.Context, host string, tx *Transaction) error {
	f.Lock()
	defer f.Unlock()

	f.commitCalled = append(f.commitCalled, host)
	return nil
}