/*
 Copyright 2021 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 plugin

import (
	"bytes"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"runtime"
	"strings"

	"github.com/kubesphere/kubekey/cmd/ctl/options"
	"github.com/spf13/cobra"
	cmdutil "k8s.io/kubectl/pkg/cmd/util"
	"k8s.io/kubectl/pkg/util/i18n"
)

type PluginListOptions struct {
	Verifier    PathVerifier
	NameOnly    bool
	PluginPaths []string
	options.IOStreams
}

// NewCmdPluginList provides a way to list all plugin executables visible to kubectl
func NewCmdPluginList(streams options.IOStreams) *cobra.Command {
	o := &PluginListOptions{
		IOStreams: streams,
	}

	cmd := &cobra.Command{
		Use:   "list",
		Short: i18n.T("List all visible plugin executables on a user's PATH"),
		Run: func(cmd *cobra.Command, args []string) {
			cmdutil.CheckErr(o.Complete(cmd))
			cmdutil.CheckErr(o.Run())
		},
	}

	cmd.Flags().BoolVar(&o.NameOnly, "name-only", o.NameOnly, "If true, display only the binary name of each plugin, rather than its full path")
	return cmd
}

func (o *PluginListOptions) Complete(cmd *cobra.Command) error {
	o.Verifier = &CommandOverrideVerifier{
		root:        cmd.Root(),
		seenPlugins: make(map[string]string),
	}

	o.PluginPaths = filepath.SplitList(os.Getenv("PATH"))
	return nil
}

func (o *PluginListOptions) Run() error {
	pluginsFound := false
	isFirstFile := true
	pluginErrors := []error{}
	pluginWarnings := 0

	for _, dir := range uniquePathsList(o.PluginPaths) {
		if len(strings.TrimSpace(dir)) == 0 {
			continue
		}

		files, err := ioutil.ReadDir(dir)
		if err != nil {
			if _, ok := err.(*os.PathError); ok {
				fmt.Fprintf(o.ErrOut, "Unable to read directory %q from your PATH: %v. Skipping...\n", dir, err)
				continue
			}

			pluginErrors = append(pluginErrors, fmt.Errorf("error: unable to read directory %q in your PATH: %v", dir, err))
			continue
		}

		for _, f := range files {
			if f.IsDir() {
				continue
			}
			if !hasValidPrefix(f.Name(), ValidPluginFilenamePrefixes) {
				continue
			}

			if isFirstFile {
				fmt.Fprintf(o.Out, "The following compatible plugins are available:\n\n")
				pluginsFound = true
				isFirstFile = false
			}

			pluginPath := f.Name()
			if !o.NameOnly {
				pluginPath = filepath.Join(dir, pluginPath)
			}

			fmt.Fprintf(o.Out, "%s\n", pluginPath)
			if errs := o.Verifier.Verify(filepath.Join(dir, f.Name())); len(errs) != 0 {
				for _, err := range errs {
					fmt.Fprintf(o.ErrOut, "  - %s\n", err)
					pluginWarnings++
				}
			}
		}
	}

	if !pluginsFound {
		pluginErrors = append(pluginErrors, fmt.Errorf("error: unable to find any kubectl plugins in your PATH"))
	}

	if pluginWarnings > 0 {
		if pluginWarnings == 1 {
			pluginErrors = append(pluginErrors, fmt.Errorf("error: one plugin warning was found"))
		} else {
			pluginErrors = append(pluginErrors, fmt.Errorf("error: %v plugin warnings were found", pluginWarnings))
		}
	}
	if len(pluginErrors) > 0 {
		errs := bytes.NewBuffer(nil)
		for _, e := range pluginErrors {
			fmt.Fprintln(errs, e)
		}
		return fmt.Errorf("%s", errs.String())
	}

	return nil
}

type PathVerifier interface {
	// Verify determines if a given path is valid
	Verify(path string) []error
}

type CommandOverrideVerifier struct {
	root        *cobra.Command
	seenPlugins map[string]string
}

// Verify implements PathVerifier and determines if a given path
// is valid depending on whether or not it overwrites an existing
// kubectl command path, or a previously seen plugin.
func (v *CommandOverrideVerifier) Verify(path string) []error {
	if v.root == nil {
		return []error{fmt.Errorf("unable to verify path with nil root")}
	}

	// extract the plugin binary name
	segs := strings.Split(path, "/")
	binName := segs[len(segs)-1]

	cmdPath := strings.Split(binName, "-")
	if len(cmdPath) > 1 {
		// the first argument is always "kubectl" for a plugin binary
		cmdPath = cmdPath[1:]
	}

	errors := []error{}

	if isExec, err := isExecutable(path); err == nil && !isExec {
		errors = append(errors, fmt.Errorf("warning: %s identified as a kubectl plugin, but it is not executable", path))
	} else if err != nil {
		errors = append(errors, fmt.Errorf("error: unable to identify %s as an executable file: %v", path, err))
	}

	if existingPath, ok := v.seenPlugins[binName]; ok {
		errors = append(errors, fmt.Errorf("warning: %s is overshadowed by a similarly named plugin: %s", path, existingPath))
	} else {
		v.seenPlugins[binName] = path
	}

	if cmd, _, err := v.root.Find(cmdPath); err == nil {
		errors = append(errors, fmt.Errorf("warning: %s overwrites existing command: %q", binName, cmd.CommandPath()))
	}

	return errors
}

func isExecutable(fullPath string) (bool, error) {
	info, err := os.Stat(fullPath)
	if err != nil {
		return false, err
	}

	if runtime.GOOS == "windows" {
		fileExt := strings.ToLower(filepath.Ext(fullPath))

		switch fileExt {
		case ".bat", ".cmd", ".com", ".exe", ".ps1":
			return true, nil
		}
		return false, nil
	}

	if m := info.Mode(); !m.IsDir() && m&0111 != 0 {
		return true, nil
	}

	return false, nil
}

// uniquePathsList deduplicates a given slice of strings without
// sorting or otherwise altering its order in any way.
func uniquePathsList(paths []string) []string {
	seen := map[string]bool{}
	newPaths := []string{}
	for _, p := range paths {
		if seen[p] {
			continue
		}
		seen[p] = true
		newPaths = append(newPaths, p)
	}
	return newPaths
}

func hasValidPrefix(filepath string, validPrefixes []string) bool {
	for _, prefix := range validPrefixes {
		if strings.HasPrefix(filepath, prefix+"-") {
			return true
		}
	}
	return false
}