package forge

import (
	"context"
	"fmt"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"time"
)

func backup(root, dir string, keep int) error {
	if strings.HasSuffix(dir, ".db") {
		return mustStore(root).Backup(dir)
	}
	if err := os.MkdirAll(filepath.Join(dir, "repos"), 0o750); err != nil {
		return err
	}
	snapshot := filepath.Join(dir, "gitpocket-"+time.Now().UTC().Format("2006-01-02")+".db")
	os.Remove(snapshot)
	if err := mustStore(root).Backup(snapshot); err != nil {
		return err
	}
	old, _ := filepath.Glob(filepath.Join(dir, "gitpocket-*.db"))
	for i := 0; i+keep < len(old); i++ {
		os.Remove(old[i])
	}
	var failed []string
	repos, _ := filepath.Glob(filepath.Join(root, "repos", "*", "*.git"))
	live := map[string]bool{}
	for _, repo := range repos {
		rel, _ := filepath.Rel(filepath.Join(root, "repos"), repo)
		out := filepath.Join(dir, "repos", strings.TrimSuffix(rel, ".git")+".bundle")
		live[out] = true
		if info, err := os.Stat(out); err == nil && !repoUpdated(repo).After(info.ModTime()) {
			continue
		}
		if err := bundle(repo, out); err != nil {
			failed = append(failed, rel+": "+err.Error())
		}
	}
	stale, _ := filepath.Glob(filepath.Join(dir, "repos", "*", "*.bundle"))
	for _, b := range stale {
		if !live[b] {
			os.Remove(b)
		}
	}
	if err := copyAttachments(filepath.Join(root, "attachments"), filepath.Join(dir, "attachments")); err != nil {
		failed = append(failed, "attachments: "+err.Error())
	}
	if len(failed) > 0 {
		return fmt.Errorf("could not bundle %s", strings.Join(failed, "; "))
	}
	return nil
}

func bundle(repo, out string) error {
	g := Git{Dir: repo}
	if _, err := g.run(nil, "rev-parse", "--verify", "--quiet", "HEAD"); err != nil {
		if refs, _ := g.run(nil, "for-each-ref", "--count=1"); len(refs) == 0 {
			return nil
		}
	}
	if err := os.MkdirAll(filepath.Dir(out), 0o750); err != nil {
		return err
	}
	tmp := out + ".tmp"
	ctx, cancel := context.WithTimeout(context.Background(), 30*time.Minute)
	defer cancel()
	cmd := exec.CommandContext(ctx, "git", "-C", repo, "bundle", "create", "--quiet", tmp, "--all")
	cmd.Env = []string{"GIT_CONFIG_NOSYSTEM=1", "HOME=/nonexistent", "PATH=" + os.Getenv("PATH")}
	if out, err := cmd.CombinedOutput(); err != nil {
		os.Remove(tmp)
		return fmt.Errorf("%v: %s", err, strings.TrimSpace(string(out)))
	}
	return os.Rename(tmp, out)
}

func copyAttachments(src, dst string) error {
	files, err := os.ReadDir(src)
	if err != nil || len(files) == 0 {
		return nil
	}
	if err := os.MkdirAll(dst, 0o750); err != nil {
		return err
	}
	for _, f := range files {
		out := filepath.Join(dst, f.Name())
		if !attachName.MatchString(f.Name()) {
			continue
		}
		if _, err := os.Stat(out); err == nil {
			continue
		}
		data, err := os.ReadFile(filepath.Join(src, f.Name()))
		if err == nil {
			err = os.WriteFile(out, data, 0o640)
		}
		if err != nil {
			return err
		}
	}
	return nil
}