refactor: generate Alloy config from nix attribute set

1 files changed, 129 insertions, 0 deletions

diff --git a/nixos/shared/alloy-nix-config/alloy_nix_config.go b/nixos/shared/alloy-nix-config/alloy_nix_config.go
new file mode 100644
index 0000000..4b6eb63
--- /dev/null
+++ b/nixos/shared/alloy-nix-config/alloy_nix_config.go
@@ -0,0 +1,129 @@
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"maps"
+	"os"
+	"slices"
+	"strconv"
+	"strings"
+)
+
+func main() {
+	if len(os.Args) != 3 {
+		fmt.Fprintf(os.Stderr, "usage: %s <json_path> <out_path>\n", os.Args[0])
+		os.Exit(1)
+	}
+
+	jsonPath := os.Args[1]
+	outPath := os.Args[2]
+
+	jsonData, err := os.ReadFile(jsonPath)
+	if err != nil {
+		fmt.Fprintf(os.Stderr, "error reading file %s: %v\n", jsonPath, err)
+		os.Exit(1)
+	}
+
+	// It would be nice to preserve the order of blocks ... except that we can't
+	// because Nix already doesn't preserve the order of attribute sets.
+	var config map[string]any
+	if err := json.Unmarshal(jsonData, &config); err != nil {
+		fmt.Fprintf(os.Stderr, "error parsing JSON: %v\n", err)
+		os.Exit(1)
+	}
+
+	result := formatConfig(config)
+
+	if err := os.WriteFile(outPath, []byte(result), 0644); err != nil {
+		fmt.Fprintf(os.Stderr, "error writing file %s: %v\n", outPath, err)
+		os.Exit(1)
+	}
+}
+
+func formatConfig(config map[string]any) string {
+	var s strings.Builder
+
+	for _, blockName := range slices.Sorted(maps.Keys(config)) {
+		labels := config[blockName]
+
+		if labelsMap, ok := labels.(map[string]any); ok {
+			for label, block := range labelsMap {
+				if blockMap, ok := block.(map[string]any); ok {
+					s.WriteString(formatBlock(blockName, label, blockMap, 0))
+				}
+			}
+		}
+	}
+
+	return s.String()
+}
+
+func formatBlock(blockName string, label string, block map[string]any, indent int) string {
+	var s strings.Builder
+
+	s.WriteString(strings.Repeat("  ", indent))
+	s.WriteString(blockName)
+	if label != "" {
+		s.WriteString(fmt.Sprintf(` %s`, strconv.Quote(label)))
+	}
+	s.WriteString(" {\n")
+
+	var blocks []any
+	if blocksValue, exists := block["blocks"]; exists {
+		if blocksList, ok := blocksValue.([]any); ok {
+			blocks = blocksList
+		}
+		delete(block, "blocks")
+	}
+
+	for _, key := range slices.Sorted(maps.Keys(block)) {
+		s.WriteString(strings.Repeat("  ", indent+1))
+		s.WriteString(fmt.Sprintf("%s = %s\n", key, formatValue(block[key])))
+	}
+
+	for _, blockItem := range blocks {
+		if blockMap, ok := blockItem.(map[string]any); ok {
+			var name string
+			if nameValue, exists := blockMap["name"]; exists {
+				if nameStr, ok := nameValue.(string); ok {
+					name = nameStr
+				}
+				delete(blockMap, "name")
+			}
+
+			s.WriteString(formatBlock(name, "", blockMap, indent+1))
+		}
+	}
+
+	s.WriteString(strings.Repeat("  ", indent))
+	s.WriteString("}\n")
+
+	return s.String()
+}
+
+func formatValue(value any) string {
+	switch v := value.(type) {
+	case string:
+		return strconv.Quote(v)
+	case map[string]any:
+		if ref, exists := v["$ref"]; exists {
+			if refStr, ok := ref.(string); ok {
+				return refStr
+			}
+		}
+		var parts []string
+		for _, name := range slices.Sorted(maps.Keys(v)) {
+			parts = append(parts, fmt.Sprintf("%s=%s,", name, formatValue(v[name])))
+		}
+		return "{" + strings.Join(parts, " ") + "}"
+	case []any:
+		var parts []string
+		for _, item := range v {
+			parts = append(parts, formatValue(item))
+		}
+		return "[" + strings.Join(parts, ", ") + "]"
+	default:
+		return fmt.Sprintf("%v", v)
+	}
+}