dir2config: switch to includes instead of ad-hoc defaults

cmd/dkl-dir2config/assemble.go

@@ -0,0 +1,138 @@
+package main
+
+import (
+	"bytes"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+
+	"gopkg.in/yaml.v2"
+)
+
+func mergeIn(tgt, add map[any]any) {
+mergeLoop:
+	for k, v := range add {
+		switch v := v.(type) {
+		case map[any]any:
+			if tgtV, ok := tgt[k]; ok {
+				switch tgtV := tgtV.(type) {
+				case map[any]any:
+					mergeIn(tgtV, v)
+					continue mergeLoop
+				}
+			}
+		}
+
+		tgt[k] = v
+	}
+}
+
+func assemble(path string) (yamlBytes []byte, err error) {
+	obj := map[any]any{}
+
+	if Debug {
+		log.Printf("assemble %q", path)
+	}
+
+	err = eachFragment(path, searchList, func(r io.Reader) (err error) {
+		m := map[any]any{}
+		err = yaml.NewDecoder(r).Decode(&m)
+		if err != nil {
+			return
+		}
+
+		mergeIn(obj, m)
+		return
+	})
+	if err != nil {
+		err = fmt.Errorf("failed to assemble %q: %w", path, err)
+		return
+	}
+
+	yamlBytes, err = yaml.Marshal(obj)
+	if err != nil {
+		return
+	}
+
+	if Debug {
+		log.Printf("assemble %q result:\n%s", path, yamlBytes)
+	}
+
+	return
+}
+
+func eachFragment(path string, searchList []FS, walk func(io.Reader) error) (err error) {
+	var r io.ReadCloser
+
+	for len(searchList) != 0 {
+		fs := searchList[0]
+
+		r, err = fs.Open(path + ".yaml")
+		if os.IsNotExist(err) {
+			searchList = searchList[1:]
+			continue
+		}
+
+		if err != nil {
+			return
+		}
+
+		// found and open
+		break
+	}
+
+	if r == nil {
+		err = fmt.Errorf("%s: %w", path, os.ErrNotExist)
+		return
+	}
+
+	ba, err := io.ReadAll(r)
+	r.Close()
+
+	if err != nil {
+		return
+	}
+
+	if Debug {
+		log.Print("fragment:\n", string(ba))
+	}
+
+	in := bytes.NewBuffer(ba)
+
+	for {
+		var line string
+		line, err = in.ReadString('\n')
+		if err == io.EOF {
+			break
+		}
+		if err != nil {
+			return
+		}
+
+		line = strings.TrimSpace(line)
+		if len(line) == 0 {
+			continue
+		}
+
+		includePath, found := strings.CutPrefix(line, "#!include ")
+		if !found {
+			continue // or break?
+		}
+
+		includePath = strings.TrimSpace(includePath)
+		if Debug {
+			log.Print("#!include ", includePath)
+		}
+		err = eachFragment(includePath, searchList, walk)
+		if err != nil {
+			err = fmt.Errorf("include %q: %w", includePath, err)
+			return
+		}
+	}
+
+	in = bytes.NewBuffer(ba)
+	err = walk(in)
+	return
+}