Support passing config options as CLI arguments (#15)

1 files changed, 97 insertions, 0 deletions

diff --git a/cmd/args.go b/cmd/args.go
new file mode 100644
index 0000000..e11308b
--- /dev/null
+++ b/cmd/args.go
@@ -0,0 +1,97 @@
+// This Source Code Form is subject to the terms of the Mozilla Public
+// License, v. 2.0. If a copy of the MPL was not distributed with this
+// file, You can obtain one at http://mozilla.org/MPL/2.0/.
+
+package cmd
+
+import (
+	"fmt"
+	"slices"
+	"strconv"
+	"strings"
+)
+
+var arrayFields = []string{
+	"urls",
+	"follow",
+	"allowedDomains",
+	"blockedDomains",
+	"allowedURLs",
+	"blockedURLs",
+	"proxies",
+}
+
+func parseConfigArgs(args []string) (map[string]any, error) {
+	updates := map[string]any{}
+
+	flag := ""
+	for _, arg := range normalizeArgs(args) {
+		if flag == "" && !isFlag(arg) {
+			return nil, fmt.Errorf("expected flag, got %q instead", arg)
+		}
+
+		if flag != "" && isFlag(arg) {
+			updates[flag[2:]] = true
+			flag = ""
+			continue
+		}
+
+		if flag != "" {
+			if v, ok := updates[flag[2:]]; ok {
+				if vv, ok := v.([]any); ok {
+					updates[flag[2:]] = append(vv, parseArg(arg))
+				} else {
+					updates[flag[2:]] = []any{v, parseArg(arg)}
+				}
+			} else {
+				if slices.Contains(arrayFields, flag[2:]) {
+					updates[flag[2:]] = []any{parseArg(arg)}
+				} else {
+					updates[flag[2:]] = parseArg(arg)
+				}
+			}
+			flag = ""
+			continue
+		}
+
+		flag = arg
+	}
+
+	if flag != "" {
+		updates[flag[2:]] = true
+		flag = ""
+	}
+
+	return updates, nil
+}
+
+func normalizeArgs(args []string) []string {
+	var norm []string
+
+	for _, arg := range args {
+		if !strings.HasPrefix(arg, "--") {
+			norm = append(norm, arg)
+		} else {
+			norm = append(norm, strings.SplitN(arg, "=", 2)...)
+		}
+	}
+
+	return norm
+}
+
+func parseArg(arg string) any {
+	if arg == "true" {
+		return true
+	}
+	if arg == "false" {
+		return false
+	}
+	if num, err := strconv.Atoi(arg); err == nil {
+		return num
+	}
+	return arg
+}
+
+func isFlag(arg string) bool {
+	return strings.HasPrefix(arg, "--")
+}