// Copyright The OpenTelemetry Authors
//
// 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 resource

import (
	"errors"
	"io"
	"os"
	"strings"
	"testing"

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

func setDefaultContainerProviders() {
	setContainerProviders(
		getContainerIDFromCGroup,
	)
}

func setContainerProviders(
	idProvider containerIDProvider,
) {
	containerID = idProvider
}

func TestGetContainerIDFromLine(t *testing.T) {
	testCases := []struct {
		name                string
		line                string
		expectedContainerID string
	}{
		{
			name:                "with suffix",
			line:                "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23.aaaa",
			expectedContainerID: "ac679f8a8319c8cf7d38e1adf263bc08d23",
		},
		{
			name:                "with prefix and suffix",
			line:                "13:name=systemd:/podruntime/docker/kubepods/crio-dc679f8a8319c8cf7d38e1adf263bc08d23.stuff",
			expectedContainerID: "dc679f8a8319c8cf7d38e1adf263bc08d23",
		},
		{
			name:                "no prefix and suffix",
			line:                "13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356",
			expectedContainerID: "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356",
		},
		{
			name:                "with space",
			line:                " 13:name=systemd:/pod/d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356 ",
			expectedContainerID: "d86d75589bf6cc254f3e2cc29debdf85dde404998aa128997a819ff991827356",
		},
		{
			name: "invalid hex string",
			line: "13:name=systemd:/podruntime/docker/kubepods/ac679f8a8319c8cf7d38e1adf263bc08d23zzzz",
		},
		{
			name: "no container id - 1",
			line: "pids: /",
		},
		{
			name: "no container id - 2",
			line: "pids: ",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			containerID := getContainerIDFromLine(tc.line)
			assert.Equal(t, tc.expectedContainerID, containerID)
		})
	}
}

func TestGetContainerIDFromReader(t *testing.T) {
	testCases := []struct {
		name                string
		reader              io.Reader
		expectedContainerID string
	}{
		{
			name: "multiple lines",
			reader: strings.NewReader(`//
1:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23
1:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d24
`),
			expectedContainerID: "dc579f8a8319c8cf7d38e1adf263bc08d23",
		},
		{
			name: "no container id",
			reader: strings.NewReader(`//
1:name=systemd:/podruntime/docker
`),
			expectedContainerID: "",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			containerID := getContainerIDFromReader(tc.reader)
			assert.Equal(t, tc.expectedContainerID, containerID)
		})
	}
}

func TestGetContainerIDFromCGroup(t *testing.T) {
	t.Cleanup(func() {
		osStat = defaultOSStat
		osOpen = defaultOSOpen
	})

	testCases := []struct {
		name                string
		cgroupFileNotExist  bool
		openFileError       error
		content             string
		expectedContainerID string
		expectedError       bool
	}{
		{
			name:               "the cgroup file does not exist",
			cgroupFileNotExist: true,
		},
		{
			name:          "error when opening cgroup file",
			openFileError: errors.New("test"),
			expectedError: true,
		},
		{
			name:                "cgroup file",
			content:             "1:name=systemd:/podruntime/docker/kubepods/docker-dc579f8a8319c8cf7d38e1adf263bc08d23",
			expectedContainerID: "dc579f8a8319c8cf7d38e1adf263bc08d23",
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			osStat = func(name string) (os.FileInfo, error) {
				if tc.cgroupFileNotExist {
					return nil, os.ErrNotExist
				}
				return nil, nil
			}

			osOpen = func(name string) (io.ReadCloser, error) {
				if tc.openFileError != nil {
					return nil, tc.openFileError
				}
				return io.NopCloser(strings.NewReader(tc.content)), nil
			}

			containerID, err := getContainerIDFromCGroup()
			assert.Equal(t, tc.expectedError, err != nil)
			assert.Equal(t, tc.expectedContainerID, containerID)
		})
	}
}