package cmd

import (
	"errors"
	"fmt"
	"io"
	"os"

	"github.com/spf13/cobra"
	"github.com/warkanum/unitdore/config"
	"github.com/warkanum/unitdore/initsys"
)

var (
	updateOrder   int
	updateEnable  bool
	updateDisable bool
)

var updateCmd = &cobra.Command{
	Use:   "update <name>",
	Short: "Update a unit's config and recreate its service file",
	Args:  cobra.ExactArgs(1),
	RunE:  runUpdate,
}

func init() {
	updateCmd.Flags().IntVar(&updateOrder, "order", 0, "set startup order")
	updateCmd.Flags().BoolVar(&updateEnable, "enable", false, "enable the unit")
	updateCmd.Flags().BoolVar(&updateDisable, "disable", false, "disable the unit")
	rootCmd.AddCommand(updateCmd)
}

func runUpdate(cmd *cobra.Command, args []string) error {
	if updateEnable && updateDisable {
		return errors.New("--enable and --disable are mutually exclusive")
	}

	cfg, err := config.Load(configPath)
	if err != nil {
		return err
	}
	ini, err := initsys.New(cfg)
	if err != nil {
		return err
	}

	var order *int
	if cmd.Flags().Changed("order") {
		order = &updateOrder
	}
	return applyUpdate(cfg, ini, args[0], order, updateEnable, updateDisable, configPath, os.Stdout)
}

// applyUpdate changes a unit's config, saves it and brings the installed
// service file in line: re-created if enabled, stopped and removed if disabled.
func applyUpdate(cfg *config.Config, ini initsys.Init, name string, order *int, enable, disable bool, path string, w io.Writer) error {
	u := cfg.FindUnit(name)
	if u == nil {
		return fmt.Errorf("unit %q not found", name)
	}

	if order != nil {
		u.Order = *order
		fmt.Fprintf(w, "  order → %d\n", u.Order)
	}
	if enable {
		u.Enabled = true
		u.DisabledReason = ""
		fmt.Fprintf(w, "  enabled\n")
	}
	if disable {
		u.Enabled = false
		fmt.Fprintf(w, "  disabled\n")
	}

	if err := cfg.ResolveOrder(); err != nil {
		return err
	}
	if err := cfg.Save(path); err != nil {
		return err
	}

	prefix, suffix := cfg.Prefix, cfg.Suffix

	// The target is stopped and removed if now disabled
	if ini.IsInstalled(*u, prefix, suffix) && !u.Enabled {
		svcPath, _ := ini.UnitPath(*u, prefix, suffix)
		if err := ini.Disable(*u, prefix, suffix); err != nil {
			return fmt.Errorf("disabling unit: %w", err)
		}
		if err := ini.Uninstall(*u, prefix, suffix); err != nil {
			return fmt.Errorf("removing service file: %w", err)
		}
		fmt.Fprintf(w, "  ✓ service stopped and removed: %s\n", svcPath)
	}

	// Order and enabled state change the After=/delay of other units too, so
	// every installed, enabled unit is regenerated
	for i := range cfg.Units {
		o := cfg.Units[i]
		if !o.Enabled || !ini.IsInstalled(o, prefix, suffix) {
			continue
		}
		if err := ini.Install(o, prefix, suffix); err != nil {
			return fmt.Errorf("recreating service file for %s: %w", o.Name, err)
		}
		svcPath, _ := ini.UnitPath(o, prefix, suffix)
		fmt.Fprintf(w, "  ✓ service file recreated: %s\n", svcPath)
	}
	return nil
}