package budget

import (
	"fmt"
	"io"
	"strings"
)

type application struct {
	config config
	paths  paths
	ctl    unitCtl
	run    func(...string) error
	out    io.Writer
}

func (a application) apply() error {
	files, err := a.config.render()
	if err != nil {
		return err
	}
	if err := writeFiles(a.paths, files); err != nil {
		return err
	}
	if err := a.run("daemon-reload"); err != nil {
		return err
	}
	units, err := a.ctl.Units()
	if err != nil {
		return err
	}
	for _, unit := range units {
		name := a.config.unitProfile(unit.Name)
		if name == "" || unit.Active != "active" {
			continue
		}
		values, err := a.config.properties(name)
		if err != nil {
			return err
		}
		if err := a.ctl.Set(unit.Name, values); err != nil {
			return err
		}
	}
	if err := a.run("enable", "budget.service"); err != nil {
		return err
	}
	if err := a.run("restart", "budget.service"); err != nil {
		return err
	}
	_, err = fmt.Fprintf(a.out, "Applied %d resource configuration files\n", len(files))
	return err
}

func selectUnits(c config, units []unit, target string) []string {
	selected := map[string]bool{}
	if strings.HasSuffix(target, ".slice") || strings.HasSuffix(target, ".scope") || strings.HasSuffix(target, ".service") {
		selected[target] = true
	} else {
		for _, unit := range units {
			if unit.Active == "active" && appMatches(target, unit.Name) {
				selected[unit.Name] = true
			}
		}
		if _, shared := c.Shared[target]; shared {
			selected[c.sharedSlice()] = true
		}
	}
	return keys(selected)
}

func (a application) override(name, target string) error {
	values, err := a.config.properties(name)
	if err != nil {
		return err
	}
	units, err := a.ctl.Units()
	if err != nil {
		return err
	}
	selected := selectUnits(a.config, units, target)
	if len(selected) == 0 {
		return fmt.Errorf("no running unit matches %s", target)
	}
	all := map[string]bool{}
	for _, name := range selected {
		all[name] = true
	}
	for _, unit := range selected {
		if !strings.HasSuffix(unit, ".slice") {
			continue
		}
		group, err := a.ctl.Group(unit)
		if err != nil {
			return err
		}
		for _, child := range units {
			if child.Active != "active" || all[child.Name] || (!strings.HasSuffix(child.Name, ".scope") && !strings.HasSuffix(child.Name, ".service")) {
				continue
			}
			childGroup, err := a.ctl.Group(child.Name)
			if err != nil {
				return err
			}
			if strings.HasPrefix(childGroup, group+"/") {
				all[child.Name] = true
			}
		}
	}
	for _, unit := range keys(all) {
		if err := a.ctl.Set(unit, values); err != nil {
			return err
		}
		if _, err := fmt.Fprintf(a.out, "%s: %s\n", unit, name); err != nil {
			return err
		}
	}
	return nil
}