chore: initial commit

command_use.go

@@ -0,0 +1,118 @@
+package main
+
+import (
+	"bytes"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+	"text/template"
+
+	"github.com/spf13/cobra"
+)
+
+func useCommand() (*cobra.Command, error) {
+	cmd := &cobra.Command{
+		Use:               "use <version>",
+		Short:             "Activate specified version.",
+		Aliases:           []string{"activate", "switch"},
+		Args:              cobra.ExactArgs(1),
+		ValidArgsFunction: useValidArgs,
+		RunE:              useRunE,
+	}
+
+	return cmd, nil
+}
+
+func useRunE(_ *cobra.Command, args []string) error {
+	conf, err := getConfig()
+	if err != nil {
+		return err
+	}
+
+	version, err := newEmacsVersion(conf, args[0])
+	if err != nil {
+		return err
+	}
+
+	var shim bytes.Buffer
+	err = useShimTemplate.Execute(&shim, conf)
+	if err != nil {
+		return err
+	}
+
+	err = os.MkdirAll(conf.Path.Shims, 0o755)
+	if err != nil {
+		return err
+	}
+
+	for _, bin := range version.Binaries {
+		shimFile := filepath.Join(conf.Path.Shims, bin)
+		err = os.WriteFile(shimFile, shim.Bytes(), 0o755)
+		if err != nil {
+			return err
+		}
+
+		var f fs.FileInfo
+		f, err = os.Stat(shimFile)
+		if err != nil {
+			return err
+		}
+
+		if f.Mode().Perm() != 0o755 {
+			err = os.Chmod(shimFile, 0o755)
+			if err != nil {
+				return err
+			}
+		}
+	}
+
+	currentFile := filepath.Join(conf.Path.Root, currentFileName)
+	err = os.WriteFile(currentFile, []byte(version.Version), 0o644)
+	if err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func useValidArgs(
+	_ *cobra.Command,
+	args []string,
+	toComplete string,
+) ([]string, cobra.ShellCompDirective) {
+	var r []string
+
+	if len(args) > 0 {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+
+	conf, err := getConfig()
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+
+	versions, err := newEmacsVersions(conf)
+	if err != nil {
+		return nil, cobra.ShellCompDirectiveNoFileComp
+	}
+
+	for _, ver := range versions {
+		if toComplete == "" ||
+			strings.HasPrefix(ver.Version, toComplete) {
+			r = append(r, ver.Version)
+		}
+	}
+
+	return r, cobra.ShellCompDirectiveNoFileComp
+}
+
+var useShimTemplate = template.Must(template.New("other").Parse(
+	`#!/usr/bin/env bash
+set -e
+[ -n "$EVM_DEBUG" ] && set -x
+
+program="${0##*/}"
+export EVM_ROOT="{{.Path.Root}}"
+exec "{{.Path.Binary}}" exec "$program" "$@"
+`))