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package builder
import (
"encoding/json"
"fmt"
"os"
"path/filepath"
"regexp"
"sort"
"strings"
)
// componentRe matches <!-- component:tag-name { ...json... } -->
// Props JSON is optional.
var componentRe = regexp.MustCompile(
`<!--\s*component:([a-z][a-z0-9-]*)\s*(\{[^}]*\})?\s*-->`)
// customElementRe matches opening tags for custom elements (name must contain a hyphen).
var customElementRe = regexp.MustCompile(`<([a-z][a-z0-9]*(?:-[a-z0-9]+)+)[\s/>]`)
// ProcessComponents replaces HTML comment component directives with custom element tags.
//
// <!-- component:my-counter {"start": 5, "label": "Count"} -->
// → <my-counter start="5" label="Count"></my-counter>
func ProcessComponents(html string) string {
return componentRe.ReplaceAllStringFunc(html, func(match string) string {
subs := componentRe.FindStringSubmatch(match)
if len(subs) < 2 {
return match
}
tagName := subs[1]
attrs := ""
if len(subs) > 2 && subs[2] != "" {
var props map[string]any
if err := json.Unmarshal([]byte(subs[2]), &props); err == nil {
attrs = propsToAttrs(props)
}
}
if attrs != "" {
return fmt.Sprintf(`<%s %s></%s>`, tagName, attrs, tagName)
}
return fmt.Sprintf(`<%s></%s>`, tagName, tagName)
})
}
// propsToAttrs converts a JSON props map to an HTML attribute string.
// Keys are emitted in sorted order for deterministic output.
func propsToAttrs(props map[string]any) string {
keys := make([]string, 0, len(props))
for k := range props {
keys = append(keys, k)
}
sort.Strings(keys)
var parts []string
for _, k := range keys {
v := props[k]
switch val := v.(type) {
case string:
parts = append(parts, fmt.Sprintf(`%s="%s"`, k, strings.ReplaceAll(val, `"`, `"`)))
case bool:
if val {
parts = append(parts, k) // boolean attribute, no value
}
case float64:
if val == float64(int64(val)) {
parts = append(parts, fmt.Sprintf(`%s="%d"`, k, int64(val)))
} else {
parts = append(parts, fmt.Sprintf(`%s="%g"`, k, val))
}
default:
// Complex value → JSON-encode into single-quoted attribute.
b, _ := json.Marshal(v)
parts = append(parts, fmt.Sprintf(`%s='%s'`, k, string(b)))
}
}
return strings.Join(parts, " ")
}
// FindComponentScripts scans HTML for used custom elements and returns
// /components/<name>.js paths for any that exist on disk.
func FindComponentScripts(html, componentsDir string) []string {
matches := customElementRe.FindAllStringSubmatch(html, -1)
seen := make(map[string]bool)
var scripts []string
for _, m := range matches {
if len(m) < 2 || seen[m[1]] {
continue
}
seen[m[1]] = true
jsPath := filepath.Join(componentsDir, m[1]+".js")
if _, err := os.Stat(jsPath); err == nil {
scripts = append(scripts, "/components/"+m[1]+".js")
}
}
return scripts
}
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