package cmd

import (
	"encoding/json"
	"fmt"

	"github.com/ory/viper"
	"github.com/spf13/cobra"

	"knative.dev/func/pkg/config"
	fn "knative.dev/func/pkg/functions"
)

func NewLanguagesCmd(newClient ClientFactory) *cobra.Command {
	cmd := &cobra.Command{
		Use:   "languages",
		Short: "List available function language runtimes",
		Long: `
NAME
	{{rootCmdUse}} languages - list available language runtimes.

SYNOPSIS
	{{rootCmdUse}} languages [--json] [-r|--repository]

DESCRIPTION
	List the language runtimes that are currently available.
	This includes embedded (included) language runtimes as well as any installed
	via the 'repositories add' command.

	To specify a URI of a single, specific repository for which languages
	should be displayed, use the --repository flag.

	Installed repositories are by default located at ~/.func/repositories
	($XDG_CONFIG_HOME/.func/repositories).  This can be overridden with
	$FUNC_REPOSITORIES_PATH.

	To see templates available for a given language, see the 'templates' command.


EXAMPLES

	o Show a list of all available language runtimes
	  $ {{rootCmdUse}} languages

	o Return a list of all language runtimes in JSON
	  $ {{rootCmdUse}} languages --json

	o Return language runtimes in a specific repository
		$ {{rootCmdUse}} languages --repository=https://github.com/boson-project/templates
`,
		SuggestFor: []string{"language", "runtime", "runtimes", "lnaguages", "languagse",
			"panguages", "manguages", "kanguages", "lsnguages", "lznguages"},
		PreRunE: bindEnv("json", "repository", "verbose"),
		RunE: func(cmd *cobra.Command, args []string) error {
			return runLanguages(cmd, newClient)
		},
	}

	// Global Config
	cfg, err := config.NewDefault()
	if err != nil {
		fmt.Fprintf(cmd.OutOrStdout(), "error loading config at '%v'. %v\n", config.File(), err)
	}

	cmd.Flags().BoolP("json", "", false, "Set output to JSON format. ($FUNC_JSON)")
	cmd.Flags().StringP("repository", "r", "", "URI to a specific repository to consider ($FUNC_REPOSITORY)")
	addVerboseFlag(cmd, cfg.Verbose)

	return cmd
}

func runLanguages(cmd *cobra.Command, newClient ClientFactory) (err error) {
	cfg, err := newLanguagesConfig()
	if err != nil {
		return
	}

	client, done := newClient(
		ClientConfig{Verbose: cfg.Verbose},
		fn.WithRepository(cfg.Repository))
	defer done()

	runtimes, err := client.Runtimes()
	if err != nil {
		return
	}

	if cfg.JSON {
		var s []byte
		s, err = json.MarshalIndent(runtimes, "", "  ")
		if err != nil {
			return
		}
		fmt.Fprintln(cmd.OutOrStdout(), string(s))
	} else {
		for _, runtime := range runtimes {
			fmt.Fprintln(cmd.OutOrStdout(), runtime)
		}
	}
	return
}

type languagesConfig struct {
	Verbose    bool
	Repository string // Consider only a specific repository (URI)
	JSON       bool   // output as JSON
}

func newLanguagesConfig() (cfg languagesConfig, err error) {
	cfg = languagesConfig{
		Verbose:    viper.GetBool("verbose"),
		Repository: viper.GetString("repository"),
		JSON:       viper.GetBool("json"),
	}

	return
}