add support for custom vcs handlers

pkg/vcs/cmd.go

@@ -0,0 +1,75 @@
+package vcs
+
+import (
+	"bytes"
+	"context"
+	"encoding/json"
+	"errors"
+	"io"
+	"io/ioutil"
+	"os"
+	"os/exec"
+	"strconv"
+	"strings"
+	"time"
+)
+
+type cmdVCS struct {
+	log    logger
+	module string
+	cmd    string
+}
+
+func NewCommand(l logger, cmd string, module string) VCS {
+	return &cmdVCS{log: l, cmd: cmd, module: module}
+}
+
+func (c *cmdVCS) List(ctx context.Context) ([]Version, error) {
+	b, err := c.exec(ctx, "MODULE="+c.module, "ACTION=list", "VERSION=latest", "FILEPATH="+c.module+"/@v/list")
+	if err != nil {
+		return nil, err
+	}
+	versions := []Version{}
+	for _, line := range strings.Split(string(b), "\n") {
+		versions = append(versions, Version(line))
+	}
+	return versions, nil
+}
+
+func (c *cmdVCS) Timestamp(ctx context.Context, version Version) (time.Time, error) {
+	b, err := c.exec(ctx, "MODULE="+c.module, "ACTION=timestamp", "VERSION="+version.String(),
+		"FILEPATH="+c.module+"/@v/"+version.String()+".info")
+	if err != nil {
+		return time.Time{}, err
+	}
+	info := struct {
+		Version string
+		Time    time.Time
+	}{}
+	if json.Unmarshal(b, &info) == nil {
+		return info.Time, nil
+	}
+	if t, err := time.Parse(time.RFC3339, string(b)); err == nil {
+		return t, nil
+	}
+	if sec, err := strconv.ParseInt(string(b), 10, 64); err == nil {
+		return time.Unix(sec, 0), nil
+	}
+	return time.Time{}, errors.New("unknown time format")
+}
+
+func (c *cmdVCS) Zip(ctx context.Context, version Version) (io.ReadCloser, error) {
+	b, err := c.exec(ctx, "MODULE="+c.module, "ACTION=zip", "VERSION="+version.String(),
+		"FILEPATH="+c.module+"/@v/"+version.String()+".zip")
+	if err != nil {
+		return nil, err
+	}
+	return ioutil.NopCloser(bytes.NewReader(b)), nil
+}
+
+func (c *cmdVCS) exec(ctx context.Context, env ...string) ([]byte, error) {
+	cmd := exec.Command("sh", "-c", c.cmd)
+	cmd.Env = append(os.Environ(), env...)
+	cmd.Stderr = os.Stderr
+	return cmd.Output()
+}

pkg/vcs/vcs.go

@@ -27,6 +27,11 @@ func (v Version) Hash() string {
 	return fields[2]
 }
 
+// String returns a string representation of a version
+func (v Version) String() string {
+	return string(v)
+}
+
 // Module is a source code snapshot for which one can get the commit timestamp
 // or the actual ZIP with the source code in it.
 type Module interface {