package main

import (
	"flag"
	"fmt"
	"os"
	"text/tabwriter"

	"mgit.msbls.de/m/ImaGen/internal/backend"
	"mgit.msbls.de/m/ImaGen/internal/config"
)

func runBackends(args []string) error {
	fs := flag.NewFlagSet("backends", flag.ContinueOnError)
	var configPath string
	fs.StringVar(&configPath, "config", "", "config file path (default: ~/.config/imagen.yaml)")
	if err := fs.Parse(args); err != nil {
		return err
	}

	cfg, cfgErr := config.Load(configPath)
	if cfgErr != nil && !os.IsNotExist(cfgErr) {
		return cfgErr
	}

	tw := tabwriter.NewWriter(os.Stdout, 0, 0, 2, ' ', 0)
	fmt.Fprintln(tw, "INSTANCE\tTYPE\tSTATUS")
	if cfg != nil {
		for name, spec := range cfg.Backends {
			status := "registered"
			if !backend.Default.Has(spec.Type) {
				status = fmt.Sprintf("type %q not compiled in", spec.Type)
			}
			marker := ""
			if name == cfg.DefaultBackend {
				marker = " (default)"
			}
			fmt.Fprintf(tw, "%s%s\t%s\t%s\n", name, marker, spec.Type, status)
		}
	}
	if cfg == nil {
		for _, t := range backend.Default.Types() {
			fmt.Fprintf(tw, "%s\t%s\t%s\n", t, t, "no config — type registered, no instance defined")
		}
	}
	if err := tw.Flush(); err != nil {
		return err
	}
	fmt.Fprintln(os.Stderr, "registered types:", backend.Default.Types())
	return nil
}