feat: parse all Go CLIs with flaggy; dump bash complete. (#36)

stdlib flag dropped --hop after the query. One wrapper in internal/cli,
source <(./bin/cli/complete.go bash). Gitea #34.

bin/git/import.go

@@ -16,9 +16,8 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
-	"strconv"
-	"time"
 
+	cliparse "github.com/eSlider/2dph/internal/cli"
 	"github.com/eSlider/2dph/internal/cmdbin"
 	"github.com/eSlider/2dph/internal/gitlog"
 )
@@ -28,49 +27,16 @@ func main() {
 }
 
 func run(args []string) int {
-	var repo, root, since string
-	limit := 0
-	jsonOut := false
-	i := 0
-	for i < len(args) {
-		a := args[i]
-		switch {
-		case a == "--json":
-			jsonOut = true
-		case a == "--limit" && i+1 < len(args):
-			i++
-			n, err := strconv.Atoi(args[i])
-			if err != nil || n < 0 {
-				fmt.Fprintf(os.Stderr, "git/import: --limit must be a non-negative integer\n")
-				return 2
-			}
-			limit = n
-		case a == "--since" && i+1 < len(args):
-			i++
-			since = args[i]
-		case a == "--root" && i+1 < len(args):
-			i++
-			root = args[i]
-		case a == "-h" || a == "--help":
-			fmt.Fprintln(os.Stderr, `usage: bin/git/import.go [REPO] [--json] [--limit N] [--since DATE] [--root DIR]`)
-			return 0
-		case len(a) > 0 && a[0] != '-':
-			repo = a
-		default:
-			fmt.Fprintf(os.Stderr, "git/import: unknown flag %s\n", a)
-			return 2
-		}
-		i++
+	c, err := gitlog.ParseArgs(args)
+	if err != nil {
+		return cliparse.Fail(err)
 	}
+	repo, root, since, limit, jsonOut := c.Repo, c.Root, c.Since, c.Limit, c.JSONOut
 
-	var sinceT time.Time
-	if since != "" {
-		var err error
-		sinceT, err = parseSince(since)
-		if err != nil {
-			fmt.Fprintf(os.Stderr, "git/import: %v\n", err)
-			return 2
-		}
+	sinceT, err := gitlog.ParseSince(since)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "git/import: %v\n", err)
+		return 2
 	}
 
 	repos := []string{}
@@ -132,12 +98,3 @@ func run(args []string) int {
 	}
 	return 0
 }
-
-func parseSince(s string) (time.Time, error) {
-	for _, layout := range []string{time.RFC3339, "2006-01-02"} {
-		if t, err := time.Parse(layout, s); err == nil {
-			return t, nil
-		}
-	}
-	return time.Time{}, fmt.Errorf("cannot parse --since %q", s)
-}