// Copyright 2024 Kelvin Clement Mwinuka
//
// 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 echovault

import (
	"github.com/tidwall/resp"
	"math"
	"strings"
	"testing"
)

func Test_raftApplyDeleteKey(t *testing.T) {
	nodes, err := makeCluster(5)
	if err != nil {
		t.Error(err)
		return
	}

	// Prepare the write data for the cluster
	tests := []struct {
		key   string
		value string
	}{
		{
			key:   "key1",
			value: "value1",
		},
		{
			key:   "key2",
			value: "value2",
		},
		{
			key:   "key3",
			value: "value3",
		},
	}

	// Write all the data to the cluster leader.
	for i, test := range tests {
		node := nodes[0]
		if err := node.client.WriteArray([]resp.Value{
			resp.StringValue("SET"),
			resp.StringValue(test.key),
			resp.StringValue(test.value),
		}); err != nil {
			t.Errorf("could not write data to leader node (test %d): %v", i, err)
		}
		// Read response and make sure we received "ok" response.
		rd, _, err := node.client.ReadValue()
		if err != nil {
			t.Errorf("could not read response from leader node (test %d): %v", i, err)
		}
		if !strings.EqualFold(rd.String(), "ok") {
			t.Errorf("expected response for test %d to be \"OK\", got %s", i, rd.String())
		}
	}

	// Check if the data has been replicated on a quorum (majority of the cluster).
	quorum := int(math.Ceil(float64(len(nodes)/2)) + 1)
	for i, test := range tests {
		count := 0
		for j := 0; j < len(nodes); j++ {
			node := nodes[j]
			if err := node.client.WriteArray([]resp.Value{
				resp.StringValue("GET"),
				resp.StringValue(test.key),
			}); err != nil {
				t.Errorf("could not write data to follower node %d (test %d): %v", j, i, err)
			}
			rd, _, err := node.client.ReadValue()
			if err != nil {
				t.Errorf("could not read data from follower node %d (test %d): %v", j, i, err)
			}
			if rd.String() == test.value {
				count += 1 // If the expected value is found, increment the count.
			}
		}
		// Fail if count is less than quorum.
		if count < quorum {
			t.Errorf("could not find value %s at key %s in cluster quorum", test.value, test.key)
		}
		// Delete key across raft cluster.
		if err = nodes[0].server.raftApplyDeleteKey(nodes[0].server.context, test.key); err != nil {
			t.Error(err)
		}
	}

	// Check if the data is absent in quorum (majority of the cluster).
	for i, test := range tests {
		count := 0
		for j := 0; j < len(nodes); j++ {
			node := nodes[j]
			if err := node.client.WriteArray([]resp.Value{
				resp.StringValue("GET"),
				resp.StringValue(test.key),
			}); err != nil {
				t.Errorf("could not write command to follower node %d (test %d): %v", j, i, err)
			}
			rd, _, err := node.client.ReadValue()
			if err != nil {
				t.Errorf("could not read data from follower node %d (test %d): %v", j, i, err)
			}
			if rd.IsNull() {
				count += 1 // If the expected value is found, increment the count.
			}
		}
		// Fail if count is less than quorum.
		if count < quorum {
			t.Errorf("could not find value %s at key %s in cluster quorum", test.value, test.key)
		}
	}
}