package owners

import (
	"context"
	"flag"
	"fmt"
	"os"
	"path/filepath"

	"github.com/peterbourgon/ff/v3"
	"github.com/peterbourgon/ff/v3/ffcli"
	"gopkg.in/yaml.v2"

	repoowners "edge-infra.dev/pkg/f8n/devinfra/repo/owners"
)

type update struct {
	*owners
}

func newUpdate(o *owners) *ffcli.Command {
	u := &update{owners: o}

	fs := flag.NewFlagSet("hack owners update", flag.ExitOnError)
	u.owners.RegisterFlags(fs)

	return &ffcli.Command{
		Name:    "update",
		FlagSet: fs,
		Exec:    u.Exec,
		Options: []ff.Option{
			ff.WithEnvVarNoPrefix(),
		},
	}
}

func (u *update) Exec(_ context.Context, _ []string) error {
	data, err := u.generatePBotCfg()
	if err != nil {
		return err
	}
	return u.createFile(data)
}

func (u *update) generatePBotCfg() ([]byte, error) {
	keys, ownersFiles, err := u.collectOwners()
	if err != nil {
		return nil, fmt.Errorf("failed to collect OWNERS files: %w", err)
	}

	root, err := u.loadOwnersFile(filepath.Join(u.Paths.RepoRoot, u.rootRulesFile))
	if err != nil {
		return nil, err
	}

	pbotConfig, err := repoowners.GeneratePolicyBotConfig(
		keys, ownersFiles, root.Rules,
	)
	if err != nil {
		return nil, fmt.Errorf("failed to generate policy-bot config: %w", err)
	}

	return yaml.Marshal(pbotConfig)
}

func (u *update) createFile(d []byte) error {
	if err := os.WriteFile(u.policyBotFile, d, 0644); err != nil {
		return fmt.Errorf("failed to write %s: %w", u.policyBotFile, err)
	}
	return nil
}