1 files changed, 335 insertions, 0 deletions
diff --git a/repo.go b/repo.go
new file mode 100644
index 0000000..820e8b2
--- /dev/null
+++ b/repo.go
@@ -0,0 +1,335 @@
+package syw
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"tildegit.org/tjp/sliderule/logging"
+)
+
+type Repository string
+
+func Open(dirpath string) *Repository {
+	check := []string{dirpath}
+	if !strings.HasSuffix(dirpath, ".git") {
+		check = append(check, dirpath+".git")
+	}
+	check = append(check, filepath.Join(dirpath, ".git"))
+
+	for _, p := range check {
+		if st, err := os.Stat(filepath.Join(p, "objects")); err != nil || !st.IsDir() {
+			continue
+		}
+		if st, err := os.Stat(filepath.Join(p, "refs")); err != nil || !st.IsDir() {
+			continue
+		}
+
+		r := Repository(p)
+		return &r
+	}
+
+	return nil
+}
+
+func (r *Repository) Name() string {
+	name := filepath.Base(string(*r))
+	if name == ".git" {
+		name = filepath.Base(filepath.Dir(string(*r)))
+	}
+	return strings.TrimSuffix(name, ".git")
+}
+
+func (r *Repository) cmd(ctx context.Context, cmdname string, args ...string) (*cmdResult, error) {
+	args = append([]string{"--git-dir=" + string(*r), cmdname}, args...)
+	start := time.Now()
+
+	result, err := runCmd(ctx, args)
+
+	log, ok := ctx.Value("debuglog").(logging.Logger)
+	if ok {
+		_ = log.Log("msg", "ran git command", "args", fmt.Sprintf("%+v", args), "dur", time.Since(start))
+	}
+
+	return result, err
+}
+
+func (r *Repository) Type(ctx context.Context, hash string) (string, error) {
+	res, err := r.cmd(ctx, "cat-file", "-t", hash)
+	if err != nil {
+		return "", err
+	}
+	if res.status != 0 {
+		return "", errors.New(res.err.String())
+	}
+
+	return strings.Trim(res.out.String(), "\n"), nil
+}
+
+func (r *Repository) Refs(ctx context.Context) ([]Ref, error) {
+	res, err := r.cmd(ctx, "show-ref", "--head", "--heads", "--tags")
+	if err != nil {
+		return nil, err
+	}
+
+	lines := strings.Split(res.out.String(), "\n")
+
+	branches := make([]Ref, 0, len(lines))
+	for _, line := range lines {
+		hash, name, found := strings.Cut(line, " ")
+		if !found {
+			continue
+		}
+		branches = append(branches, Ref{
+			Repo: r,
+			Name: name,
+			Hash: hash,
+		})
+	}
+	return branches, nil
+}
+
+var badRevListOutput = errors.New("unexpected 'git rev-list' output")
+
+func (r *Repository) Commits(ctx context.Context, head string, count int) ([]Commit, error) {
+	res, err := r.cmd(ctx, "rev-list",
+		"--format=%an%n%ae%n%aI%n%cn%n%ce%n%cI%n%P%n%B$$END$$",
+		"-n", strconv.Itoa(count),
+		head,
+	)
+	if err != nil {
+		return nil, err
+	}
+
+	commits := make([]Commit, 0, count)
+	for _, revstr := range strings.Split(res.out.String(), "\n$$END$$\n") {
+		if revstr == "" {
+			continue
+		}
+		commits = append(commits, Commit{Repo: r})
+		commit := &commits[len(commits)-1]
+
+		commitHash, rest, found := strings.Cut(revstr, "\n")
+		if !found {
+			return nil, badRevListOutput
+		}
+		commit.Hash = commitHash[7:]
+
+		commit.AuthorName, rest, found = strings.Cut(rest, "\n")
+		if !found {
+			return nil, badRevListOutput
+		}
+		commit.AuthorEmail, rest, found = strings.Cut(rest, "\n")
+		if !found {
+			return nil, badRevListOutput
+		}
+
+		adate, rest, found := strings.Cut(rest, "\n")
+		if !found {
+			return nil, badRevListOutput
+		}
+		commit.AuthorDate, err = time.Parse(time.RFC3339, adate)
+		if err != nil {
+			return nil, err
+		}
+
+		commit.CommitterName, rest, found = strings.Cut(rest, "\n")
+		if !found {
+			return nil, badRevListOutput
+		}
+		commit.CommitterEmail, rest, found = strings.Cut(rest, "\n")
+		if !found {
+			return nil, badRevListOutput
+		}
+
+		cdate, rest, found := strings.Cut(rest, "\n")
+		if !found {
+			return nil, badRevListOutput
+		}
+		commit.CommitDate, err = time.Parse(time.RFC3339, cdate)
+		if err != nil {
+			return nil, err
+		}
+
+		parents, rest, found := strings.Cut(rest, "\n")
+		if !found {
+			return nil, badRevListOutput
+		}
+		commit.Parents = strings.Split(parents, " ")
+		if len(commit.Parents) == 1 && commit.Parents[0] == "" {
+			commit.Parents = nil
+		}
+
+		commit.Message = rest
+	}
+
+	return commits, nil
+}
+
+func (r *Repository) Commit(ctx context.Context, ref string) (*Commit, error) {
+	commits, err := r.Commits(ctx, ref, 1)
+	if err != nil {
+		return nil, err
+	}
+	return &commits[0], nil
+}
+
+func (r *Repository) Diffstat(ctx context.Context, fromref, toref string) (string, error) {
+	res, err := r.cmd(ctx, "diff-tree", "-r", "--stat", fromref, toref)
+	if err != nil {
+		return "", err
+	}
+	if res.status != 0 {
+		return "", errors.New(res.err.String())
+	}
+	return res.out.String(), nil
+}
+
+func (r *Repository) Diff(ctx context.Context, fromref, toref string) (string, error) {
+	res, err := r.cmd(ctx, "diff-tree", "-r", "-p", "-u", fromref, toref)
+	if err != nil {
+		return "", err
+	}
+	if res.status != 0 {
+		return "", errors.New(res.err.String())
+	}
+	return res.out.String(), nil
+}
+
+type Readme struct {
+	Filename    string
+	RawContents string
+}
+
+func (r Readme) EscapedContents() string {
+	return strings.ReplaceAll(r.RawContents, "\n```", "\n ```")
+}
+
+func (r *Repository) Readme(ctx context.Context, ref string) (*Readme, error) {
+	dir, err := r.Tree(ctx, ref, "")
+	if err != nil {
+		return nil, err
+	}
+
+	filename := ""
+	for i := range dir {
+		if dir[i].Type == "blob" && strings.HasPrefix(strings.ToLower(dir[i].Path), "readme") {
+			filename = dir[i].Path
+			break
+		}
+	}
+
+	if filename != "" {
+		body, err := r.Blob(ctx, ref, filename)
+		if err != nil {
+			return nil, err
+		}
+
+		return &Readme{
+			Filename:    filename,
+			RawContents: string(body),
+		}, nil
+	}
+
+	return nil, nil
+}
+
+func (r *Repository) Description() string {
+	f, err := os.Open(filepath.Join(string(*r), "description"))
+	if err != nil {
+		return ""
+	}
+	defer func() { _ = f.Close() }()
+
+	b, err := io.ReadAll(f)
+	if err != nil {
+		return ""
+	}
+
+	return strings.TrimRight(string(b), "\n")
+}
+
+func (r *Repository) Blob(ctx context.Context, ref, path string) ([]byte, error) {
+	res, err := r.cmd(ctx, "cat-file", "blob", ref+":"+path)
+	switch {
+	case res == nil:
+		return nil, err
+	case res.status == 0:
+		return res.out.Bytes(), nil
+	case res.status == 128:
+		return nil, objectDoesNotExist
+	default:
+		return nil, errors.New(res.err.String())
+	}
+}
+
+type ObjectDescription struct {
+	Mode int
+	Type string
+	Hash string
+	Size int
+	Path string
+}
+
+func (r *Repository) Tree(ctx context.Context, ref, path string) ([]ObjectDescription, error) {
+	pattern := ref
+	if path != "" && path != "." {
+		pattern += ":" + path
+	}
+
+	res, err := r.cmd(ctx, "ls-tree", "-l", pattern)
+	if err != nil {
+		return nil, err
+	}
+
+	out := []ObjectDescription{}
+	for _, line := range strings.Split(res.out.String(), "\n") {
+		if line == "" {
+			continue
+		}
+
+		spl := dropEmpty(strings.Split(strings.ReplaceAll(line, "\t", " "), " "))
+
+		mode, err := strconv.ParseInt(spl[0], 8, 64)
+		if err != nil {
+			return nil, err
+		}
+
+		var size int
+		if spl[3] != "-" {
+			size, err = strconv.Atoi(spl[3])
+			if err != nil {
+				return nil, err
+			}
+		}
+
+		out = append(out, ObjectDescription{
+			Mode: int(mode),
+			Type: spl[1],
+			Hash: spl[2],
+			Size: size,
+			Path: spl[4],
+		})
+	}
+	return out, nil
+}
+
+func dropEmpty(sl []string) []string {
+	n := 0
+	for i := 0; i < len(sl); i += 1 {
+		if sl[i] == "" {
+			copy(sl[i:], sl[i+1:])
+			i -= 1
+			n += 1
+		}
+	}
+	return sl[:len(sl)-n]
+}
+
+var objectDoesNotExist = errors.New("object does not exist")