/*
Copyright 2024 The KubeSphere 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 modules

import (
	"context"
	"os"
	"path/filepath"

	utilruntime "k8s.io/apimachinery/pkg/util/runtime"

	"github.com/kubesphere/kubekey/v4/pkg/variable"
)

/*
The Fetch module retrieves files from remote hosts to the local machine.
This module allows users to download files from remote hosts to specified local destinations.

Configuration:
Users can specify the source and destination paths:

fetch:
  src: /remote/path/file    # required: source file path on remote host
  dest: /local/path/file    # required: destination path on local machine

Usage Examples in Playbook Tasks:
1. Basic file fetch:
   ```yaml
   - name: Download configuration file
     fetch:
       src: /etc/app/config.yaml
       dest: ./configs/
     register: fetch_result
   ```

2. Fetch with variables:
   ```yaml
   - name: Download log file
     fetch:
       src: /var/log/{{ app_name }}.log
       dest: ./logs/
     register: log_file
   ```

Return Values:
- On success: Returns "Success" in stdout
- On failure: Returns error message in stderr
*/

// ModuleFetch handles the "fetch" module, retrieving files from remote hosts
func ModuleFetch(ctx context.Context, options ExecOptions) (string, string, error) {
	// get host variable
	ha, err := options.getAllVariables()
	if err != nil {
		return StdoutFailed, StderrGetHostVariable, err
	}
	// check args
	args := variable.Extension2Variables(options.Args)
	srcParam, err := variable.StringVar(ha, args, "src")
	if err != nil {
		return StdoutFailed, "\"src\" in args should be string", err
	}
	destParam, err := variable.StringVar(ha, args, "dest")
	if err != nil {
		return StdoutFailed, "\"dest\" in args should be string", err
	}

	// get connector
	conn, err := options.getConnector(ctx)
	if err != nil {
		return StdoutFailed, StderrGetConnector, err
	}
	defer conn.Close(ctx)

	// fetch file
	if _, err := os.Stat(filepath.Dir(destParam)); os.IsNotExist(err) {
		if err := os.MkdirAll(filepath.Dir(destParam), os.ModePerm); err != nil {
			return StdoutFailed, "failed to create dest dir", err
		}
	}

	destFile, err := os.Create(destParam)
	if err != nil {
		return StdoutFailed, "failed to create dest file", err
	}
	defer destFile.Close()

	if err := conn.FetchFile(ctx, srcParam, destFile); err != nil {
		return StdoutFailed, "failed to fetch file", err
	}

	return StdoutSuccess, "", nil
}

func init() {
	utilruntime.Must(RegisterModule("fetch", ModuleFetch))
}