package cmd

import (
	"context"
	"os"
	"strings"

	"github.com/docker/docker/api/types"
	"github.com/docker/docker/api/types/filters"
	"github.com/docker/docker/client"

	"github.com/spf13/cobra"
)

// completionCmd represents the completion command
var completionCmd = &cobra.Command{
	Hidden: true,
	Use:    "completion [bash|zsh|fish]",
	Short:  "Generate a shell completion for Syft (listing local docker images)",
	Long: `To load completions (docker image list):

Bash:

$ source <(syft completion bash)

# To load completions for each session, execute once:
Linux:
  $ syft completion bash > /etc/bash_completion.d/syft
MacOS:
  $ syft completion bash > /usr/local/etc/bash_completion.d/syft

Zsh:

# If shell completion is not already enabled in your environment you will need
# to enable it.  You can execute the following once:

$ echo "autoload -U compinit; compinit" >> ~/.zshrc

# To load completions for each session, execute once:
$ syft completion zsh > "${fpath[1]}/_syft"

# You will need to start a new shell for this setup to take effect.

Fish:

$ syft completion fish | source

# To load completions for each session, execute once:
$ syft completion fish > ~/.config/fish/completions/syft.fish
`,
	DisableFlagsInUseLine: true,
	ValidArgs:             []string{"bash", "zsh", "fish"},
	Args:                  cobra.ExactValidArgs(1),
	Run: func(cmd *cobra.Command, args []string) {
		var err error
		switch args[0] {
		case "bash":
			err = cmd.Root().GenBashCompletion(os.Stdout)
		case "zsh":
			err = cmd.Root().GenZshCompletion(os.Stdout)
		case "fish":
			err = cmd.Root().GenFishCompletion(os.Stdout, true)
		}
		if err != nil {
			panic(err)
		}
	},
}

func init() {
	rootCmd.AddCommand(completionCmd)
}

func dockerImageValidArgsFunction(cmd *cobra.Command, args []string, toComplete string) ([]string, cobra.ShellCompDirective) {
	// Since we use ValidArgsFunction, Cobra will call this AFTER having parsed all flags and arguments provided
	dockerImageRepoTags, err := listLocalDockerImages(toComplete)
	if err != nil {
		// Indicates that an error occurred and completions should be ignored
		return []string{"completion failed"}, cobra.ShellCompDirectiveError
	}
	if len(dockerImageRepoTags) == 0 {
		return []string{"no docker images found"}, cobra.ShellCompDirectiveError
	}
	// ShellCompDirectiveDefault indicates that the shell will perform its default behavior after completions have
	// been provided (without implying other possible directives)
	return dockerImageRepoTags, cobra.ShellCompDirectiveDefault
}

func listLocalDockerImages(prefix string) ([]string, error) {
	var repoTags = make([]string, 0)
	ctx := context.Background()
	cli, err := client.NewClientWithOpts(client.FromEnv, client.WithAPIVersionNegotiation())
	if err != nil {
		return repoTags, err
	}

	// Only want to return tagged images
	imageListArgs := filters.NewArgs()
	imageListArgs.Add("dangling", "false")
	images, err := cli.ImageList(ctx, types.ImageListOptions{All: false, Filters: imageListArgs})
	if err != nil {
		return repoTags, err
	}

	for _, image := range images {
		// image may have multiple tags
		for _, tag := range image.RepoTags {
			if strings.HasPrefix(tag, prefix) {
				repoTags = append(repoTags, tag)
			}
		}
	}
	return repoTags, nil
}