// SPDX-Licence-Identifier: EUPL-1.2
package main

import (
	"strconv"
	"strings"
)

var canonicalSlotOrder = []string{"H", "L", "C", "R", "F"}
var reservedCustomElementTags = map[string]struct{}{
	"annotation-xml":   {},
	"color-profile":    {},
	"font-face":        {},
	"font-face-src":    {},
	"font-face-uri":    {},
	"font-face-format": {},
	"font-face-name":   {},
	"missing-glyph":    {},
}

// cmd/wasm/components.go: isValidCustomElementTag reports whether tag is a safe
// custom element name.
// It mirrors the codegen package validation without importing the heavier
// template and logging dependencies into the WASM-linked path.
func isValidCustomElementTag(tag string) bool {
	if tag == "" || !strings.Contains(tag, "-") {
		return false
	}
	if tag[0] < 'a' || tag[0] > 'z' {
		return false
	}
	if _, reserved := reservedCustomElementTags[tag]; reserved {
		return false
	}

	for i := range len(tag) {
		ch := tag[i]
		switch {
		case ch >= 'a' && ch <= 'z':
		case ch >= '0' && ch <= '9':
		case ch == '-' || ch == '.' || ch == '_':
		default:
			return false
		}
	}

	return true
}

// cmd/wasm/components.go: tagToClassName converts a kebab-case tag into a
// PascalCase class name.
// Example: tagToClassName("nav-bar") returns NavBar.
func tagToClassName(tag string) string {
	var b strings.Builder
	for part := range strings.SplitSeq(tag, "-") {
		if len(part) == 0 {
			continue
		}
		b.WriteString(strings.ToUpper(part[:1]))
		b.WriteString(part[1:])
	}
	return b.String()
}

// cmd/wasm/components.go: jsStringLiteral returns a quoted JavaScript string literal.
func jsStringLiteral(s string) string {
	return strconv.Quote(s)
}

// cmd/wasm/components.go: customElementClassSource returns a JavaScript class
// expression that mirrors the codegen bundle's closed-shadow custom element
// behaviour.
func customElementClassSource(tag, slot string) string {
	className := tagToClassName(tag)
	return "class " + className + " extends HTMLElement {" +
		"#shadow;" +
		"constructor(){super();this.#shadow=this.attachShadow({mode:\"closed\"});}" +
		"connectedCallback(){this.#shadow.textContent=\"\";const slot=this.getAttribute(\"data-slot\")||" + jsStringLiteral(slot) + ";" +
		"this.dispatchEvent(new CustomEvent(\"wc-ready\",{detail:{tag:" + jsStringLiteral(tag) + ",slot},bubbles:true,composed:true}));}" +
		"render(html){const tpl=document.createElement(\"template\");tpl.insertAdjacentHTML(\"afterbegin\",html);" +
		"this.#shadow.textContent=\"\";this.#shadow.appendChild(tpl.content.cloneNode(true));}" +
		"}"
}