v0.30.1 configuration engine as wasm

cmd/lwconf/main.go

@@ -0,0 +1,90 @@
+//go:build js && wasm
+
+// Command lwconf is the configuration engine as WebAssembly, for the website.
+// It sets globalThis.lwconf, whose calls take strings and return a JSON object:
+// {"value": ...}, or {"error": "..."} for a call refused. Pipelines travel in
+// compose's JSON form; off the host a preset's directory path ends in '/'.
+package main
+
+import (
+	"encoding/json"
+	"fmt"
+	"slices"
+	"strings"
+	"syscall/js"
+
+	"github.com/lixenwraith/logwisp/internal/compose"
+)
+
+// calls are lwconf's, by name, with the string arguments each takes
+var calls = map[string]struct {
+	args []string
+	call func(args []string) (any, error)
+}{
+	"schema": {nil, func([]string) (any, error) { return compose.NewSchema(), nil }},
+	"preset": {[]string{"name", "values"}, func(a []string) (any, error) {
+		var values map[string]string
+		if err := json.Unmarshal([]byte(a[1]), &values); err != nil {
+			return nil, fmt.Errorf("values: %w", err)
+		}
+		return pipelines(compose.FromPreset(a[0], values, nil))
+	}},
+	"parse": {[]string{"line"}, func(a []string) (any, error) {
+		return pipelines(compose.FromCommandLine(a[0], nil))
+	}},
+	"validate": {[]string{"pipelines"}, func(a []string) (any, error) {
+		c, err := compose.FromJSON([]byte(a[0]))
+		if err == nil {
+			err = c.Validate()
+		}
+		return pipelines(c, err)
+	}},
+	"emit": {[]string{"pipelines", "form"}, func(a []string) (any, error) {
+		c, err := compose.FromJSON([]byte(a[0]))
+		if err != nil {
+			return nil, err
+		}
+		forms := compose.Forms()
+		if i := slices.IndexFunc(forms, func(f compose.Form) bool { return f.Name == a[1] }); i >= 0 {
+			return forms[i].Write(c)
+		}
+		return nil, fmt.Errorf("no form %q", a[1])
+	}},
+}
+
+// pipelines is a composition's value: its pipelines settled, ids given
+func pipelines(c *compose.Composition, err error) (any, error) {
+	if err != nil {
+		return nil, err
+	}
+	data, err := c.JSON()
+	return json.RawMessage(data), err
+}
+
+func main() {
+	api := map[string]any{}
+	for name := range calls {
+		api[name] = js.FuncOf(func(_ js.Value, args []js.Value) any { return answer(name, args) })
+	}
+	js.Global().Set("lwconf", js.ValueOf(api))
+	select {} // the page calls in until it closes
+}
+
+// answer is a call's JSON for the page: its value, or why it was refused
+func answer(name string, args []js.Value) string {
+	c := calls[name]
+	value, err := any(nil), fmt.Errorf("usage: lwconf.%s(%s), each a string", name, strings.Join(c.args, ", "))
+	if len(args) == len(c.args) && !slices.ContainsFunc(args, func(v js.Value) bool { return v.Type() != js.TypeString }) {
+		strs := make([]string, len(args))
+		for i, arg := range args {
+			strs[i] = arg.String()
+		}
+		value, err = c.call(strs)
+	}
+	out := map[string]any{"value": value}
+	if err != nil {
+		out = map[string]any{"error": err.Error()}
+	}
+	data, _ := json.Marshal(out)
+	return string(data)
+}