{{- /*
  -- Returns the image used when the page is shared on social networks
  -- (Open Graph, Twitter cards) and in the structured data, as a dict:
  --   - image: the processed image resource
  --   - isDefault: true if the default image of the site is used
  --
  -- The image is chosen in this order:
  -- 1. the first image of the "images" front matter parameter
  -- 2. a page resource named *feature*, *cover* or *thumbnail*
  -- 3. the first image displayed in the page content
  -- 4. the first image of the "images" site parameter
  --
  -- The image is converted to JPEG (WebP is not supported everywhere) and
  -- resized to 1200 px wide max, without cropping: the social networks crop
  -- it to their own aspect ratio.
  */ -}}
{{- $formats := slice "jpeg" "png" "webp" "gif" "bmp" "tiff" -}}
{{- $images := slice -}}
{{- range .Resources.ByType "image" -}}
  {{- if in $formats .MediaType.SubType -}}
    {{- $images = $images | append . -}}
  {{- end -}}
{{- end -}}

{{- $source := false -}}
{{- $isDefault := false -}}

{{- /* 1. The "images" front matter parameter */ -}}
{{- range $name := .Params.images -}}
  {{- if not $source -}}
    {{- range $images -}}
      {{- if and (not $source) (eq .Name $name) -}}{{- $source = . -}}{{- end -}}
    {{- end -}}
  {{- end -}}
{{- end -}}

{{- /* 2. A page resource named *feature*, *cover* or *thumbnail* */ -}}
{{- if not $source -}}
  {{- range $images -}}
    {{- if and (not $source) (findRE `(?i)(feature|cover|thumbnail)` .Name) -}}{{- $source = . -}}{{- end -}}
  {{- end -}}
{{- end -}}

{{- /* 3. The first image displayed in the page content */ -}}
{{- if and (not $source) $images -}}
  {{- /*
    -- The images are compared by name (without extension) since the image
    -- render hook serves processed variants (name_hu_<hash>.webp). Do not use
    -- .RelPermalink here: it would publish all the images of the page.
    */ -}}
  {{- range findRESubmatch `<img[^>]*\ssrc="([^"]+)"` .Content -}}
    {{- $name := index . 1 | path.Base | replaceRE `_hu_[0-9a-f]+\.\w+$` "" | replaceRE `\.\w+$` "" -}}
    {{- if not $source -}}
      {{- range $images -}}
        {{- if and (not $source) (eq (replaceRE `\.\w+$` "" (path.Base .Name)) $name) -}}{{- $source = . -}}{{- end -}}
      {{- end -}}
    {{- end -}}
  {{- end -}}
{{- end -}}

{{- /* 4. The default image of the site */ -}}
{{- if not $source -}}
  {{- with index site.Params.images 0 -}}
    {{- with resources.Get (strings.TrimPrefix "/" .) -}}
      {{- $source = . -}}
      {{- $isDefault = true -}}
    {{- end -}}
  {{- end -}}
{{- end -}}

{{- $result := dict -}}
{{- with $source -}}
  {{- $image := . -}}
  {{- if gt .Width 1200 -}}
    {{- $image = .Resize "1200x jpg q85" -}}
  {{- else -}}
    {{- $image = .Process "jpg q85" -}}
  {{- end -}}
  {{- $result = dict "image" $image "isDefault" $isDefault -}}
{{- end -}}
{{- return $result -}}