{% macro headBegin(title, description, author, keywords, robots = 'index,follow', charset = 'UTF-8') %}
    <meta charset="{{ charset }}">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    {% if title -%}
    <title>{{ title }}</title>
    {% endif %}
    {%- if description -%}
    <meta name="description" content="{{ description }}">
    {% endif %}
    {%- if author -%}
    <meta name="author" content="{{ author }}">
    {% endif %}
    {%- if keywords -%}
    <meta name="keywords" content="{{ keywords }}">
    {% endif %}
    {%- if robots -%}
    <meta name="robots" content="{{ robots }}">
    {% endif %}
{% endmacro %}

{% macro headOpenGraph(i18n, lang, title, description, url, name, image, imageType = 'image/png', width = 1200, height = 630, pageUrl = '') %}
    <meta property="og:type" content="website">
    <meta property="og:title" content="{{ title }}">
    <meta property="og:description" content="{{ description }}">
    <meta property="og:url" content="{{ pageUrl or url + '/' }}">
    <meta property="og:site_name" content="{{ name }}">
    {% if i18n %}
    <meta property="og:locale" content="{{ i18n.pages[lang].ogLocale }}">
    {%- for locale in i18n.locales %}
      {%- if locale != lang %}
    <meta property="og:locale:alternate" content="{{ i18n.pages[locale].ogLocale }}">
      {%- endif -%}
    {% endfor %}
    {% else %}
    <meta property="og:locale" content="{{ lang }}">
    {% endif %}
    <meta property="og:image" content="{{ url }}{{ image }}">
    <meta property="og:image:type" content="{{ imageType }}">
    <meta property="og:image:width" content="{{ width }}">
    <meta property="og:image:height" content="{{ height }}">
    <meta property="og:image:alt" content="{{ title }}">
{% endmacro %}

{% macro headTwitter(title, description, url, image, imageAlt) %}
    <meta name="twitter:card" content="summary_large_image">
    <meta name="twitter:title" content="{{ title }}">
    <meta name="twitter:description" content="{{ description }}">
    <meta name="twitter:image" content="{{ url }}{{ image }}">
    <meta name="twitter:image:alt" content="{{ imageAlt }}">
{% endmacro %}

{% macro headJsonLdGraph(context = 'https://schema.org') %}
    <script type="application/ld+json">
      {
        "@context": "{{ context }}",
        "@graph": [
{{ caller() }}
        ]
      }
    </script>
{% endmacro %}

{# Emits a schema.org WebPage node inside a JSON-LD graph. #}
{% macro headJsonLdWebPage(id, url, name, description, language, websiteId, aboutId, comma = true) %}
          {
            "@type": "WebPage",
            "@id": "{{ id }}",
            "url": "{{ url }}",
            "name": "{{ name }}",
            "description": "{{ description }}",
            "inLanguage": "{{ language }}",
            "isPartOf": {
              "@id": "{{ websiteId }}"
            },
            "about": {
              "@id": "{{ aboutId }}"
            }
          }{% if comma %},{% endif %}
{% endmacro %}

{# Emits a schema.org WebSite node inside a JSON-LD graph. #}
{% macro headJsonLdWebSite(id, url, name, publisherId, comma = true) %}
          {
            "@type": "WebSite",
            "@id": "{{ id }}",
            "url": "{{ url }}",
            "name": "{{ name }}",
            "publisher": {
              "@id": "{{ publisherId }}"
            }
          }{% if comma %},{% endif %}
{% endmacro %}

{# Emits a schema.org SoftwareApplication or WebApplication node. #}
{% macro headJsonLdApplication(type, id, name, url, description = '', language = '', category = 'EducationalApplication', operatingSystem = 'Web', license = '', authorId = '', publisherId = '', isAccessibleForFree = '', offersPrice = '', comma = true) %}
          {
            "@type": "{{ type }}",
            "@id": "{{ id }}",
            "name": "{{ name }}",
            "url": "{{ url }}"{% if description %},
            "description": "{{ description }}"{% endif %},
            "applicationCategory": "{{ category }}",
            "operatingSystem": "{{ operatingSystem }}"{% if language %},
            "inLanguage": "{{ language }}"{% endif %}{% if isAccessibleForFree %},
            "isAccessibleForFree": {{ isAccessibleForFree }}{% endif %}{% if license %},
            "license": "{{ license }}"{% endif %}{% if offersPrice %},
            "offers": {
              "@type": "Offer",
              "price": {{ offersPrice }}
            }{% endif %}{% if authorId %},
            "author": {
              "@id": "{{ authorId }}"
            }{% endif %}{% if publisherId %},
            "publisher": {
              "@id": "{{ publisherId }}"
            }{% endif %}
          }{% if comma %},{% endif %}
{% endmacro %}

{# Emits an ItemList node whose items are application summaries. #}
{% macro headJsonLdApplicationList(id, name, apps, publisherId, comma = true) %}
          {
            "@type": "ItemList",
            "@id": "{{ id }}",
            "name": "{{ name }}",
            "numberOfItems": {{ apps | length }},
            "itemListElement": [
              {% for app in apps %}
                {
                  "@type": "ListItem",
                  "position": {{ loop.index }},
                  "item": {
                    "@type": "SoftwareApplication",
                    "@id": "{{ app.href }}#software",
                    "name": "{{ app.label }}",
                    "description": "{{ app.description }}",
                    "url": "{{ app.href }}",
                    "applicationCategory": "EducationalApplication",
                    "operatingSystem": "Web",
                    "publisher": {
                      "@id": "{{ publisherId }}"
                    }
                  }
                }{% if not loop.last %},{% endif %}
              {% endfor %}
            ]
          }{% if comma %},{% endif %}
{% endmacro %}

{# Emits a schema.org Person node inside a JSON-LD graph. #}
{% macro headJsonLdPerson(id, name, comma = true) %}
          {
            "@type": "Person",
            "@id": "{{ id }}",
            "name": "{{ name }}"
          }{% if comma %},{% endif %}
{% endmacro %}

{# Emits a schema.org Organization node with logo and sameAs links. #}
{% macro headJsonLdOrganization(id, name, url, logoUrl, logoWidth, logoHeight, sameAs, comma = true) %}
          {
            "@type": "Organization",
            "@id": "{{ id }}",
            "name": "{{ name }}",
            "url": "{{ url }}",
            "logo": {
              "@type": "ImageObject",
              "url": "{{ logoUrl }}",
              "width": {{ logoWidth }},
              "height": {{ logoHeight }}
            },
            "sameAs": [
              {% for url in sameAs %}
                "{{ url }}"{% if not loop.last %},{% endif %}
              {% endfor %}
            ]
          }{% if comma %},{% endif %}
{% endmacro %}

{% macro headAlternate(i18n, canonical, url, default = '', postfix = '') %}
    {% if canonical %}
    <link rel="canonical" href="{{ url }}/{{ canonical }}/{{ postfix }}">
    {% else %}
    <link rel="canonical" href="{{ url }}/{{ postfix }}">
    {% endif %}
    {% for locale in i18n.locales -%}
      <link rel="alternate" hreflang="{{ i18n.pages[locale].htmlLang }}" href="{{ url }}/{{ locale }}/{{ postfix }}">
    {% endfor -%}
    {% if default %}
    <link rel="alternate" hreflang="x-default" href="{{ url }}/{{ default }}/{{ postfix }}">
    {% else %}
    <link rel="alternate" hreflang="x-default" href="{{ url }}/{{ postfix }}">
    {% endif %}
{% endmacro %}

{% macro headIcon(light, dark, svg, appleTouch, sizes = '16x16 32x32 48x48') %}
    {%- if dark %}
    <meta name="color-scheme" content="light dark">
    <link rel="icon" href="{{ light }}" sizes="{{ sizes }}" type="image/x-icon" media="(prefers-color-scheme: light)" data-appearance-icon data-light-href="{{ light }}" data-dark-href="{{ dark }}">
    <link rel="icon" href="{{ dark }}" sizes="{{ sizes }}" type="image/x-icon" media="(prefers-color-scheme: dark)" data-appearance-icon data-light-href="{{ light }}" data-dark-href="{{ dark }}">
    {% else %}
    <link rel="icon" href="{{ light }}" sizes="{{ sizes }}" type="image/x-icon">
    {% endif %}
    {%- if svg -%}
    <link rel="icon" href="{{ svg }}" sizes="any" type="image/svg+xml">
    {% endif %}
    {%- if appleTouch -%}
    <link rel="apple-touch-icon" href="{{ appleTouch }}">
    {% endif -%}
{% endmacro %}