{{/*
  resolve_gallery_items — Resolves gallery block items into a list of fully-processed
  image props ready for the Preact component. Three source modes:

    1. content.items[]        — explicit per-image dicts (curated)
    2. content.album          — folder under assets/, e.g. "media/albums/gallery"
    3. content.page_resources — auto-discover image resources in the current page bundle

  For each resolved image, produces a dict with:
    {src, srcset, width, height, aspect_ratio, lqip, alt, caption, credit, link, title}

  Metadata waterfall — first non-empty value per field wins:
    1. Frontmatter (items[].caption etc.)
    2. Sidecar file next to the image (.yaml / .yml / .json)
         — tried as "<full-name>.yaml" then "<basename-without-ext>.yaml"
         — looked up in both site assets and the current page bundle
    3. Embedded IPTC/EXIF via Hugo's .Exif.Tags
         — caption from Caption-Abstract / ImageDescription / XPSubject / Description
         — credit from By-line / Artist / Creator
    4. Humanised filename (alt only — captions stay empty when no metadata exists)

  Inputs:
    .content: the block's content dict
    .Page:    current page (used for page-resource lookup + RenderString markdown)

  Returns: dict { items: [...] } or empty if nothing resolves.
*/}}
{{ $page := .Page }}
{{ $content := .content }}
{{ if not (reflect.IsMap $content) }}{{ $content = dict }}{{ end }}

{{ $allowed_exts := slice ".jpg" ".jpeg" ".png" ".webp" ".gif" ".avif" ".svg" }}
{{ $sort_order := lower ($content.sort | default "asc") }}
{{ $limit := $content.limit | default 0 }}

{{/* Build a unified list of {resource?, fallback_url?, meta} entries */}}
{{ $candidates := slice }}

{{/* Source A — explicit items */}}
{{ with $content.items }}
  {{ range . }}
    {{ $src := .src | default "" }}
    {{ if $src }}
      {{ $resolved := partial "functions/resolve_image_resource" (dict "path" $src "Page" $page) }}
      {{ $candidates = $candidates | append (dict
        "resource" $resolved.resource
        "fallback_url" ($resolved.fallback_url | default "")
        "meta" .
      ) }}
    {{ end }}
  {{ end }}
{{ end }}

{{/* Source B — album folder glob */}}
{{ with $content.album }}
  {{ $album := strings.TrimSuffix "/" . }}
  {{ $matches := resources.Match (printf "%s/*" $album) }}
  {{ $sorted := sort $matches "Name" $sort_order }}
  {{ range $sorted }}
    {{ if in $allowed_exts (lower (path.Ext .Name)) }}
      {{ $candidates = $candidates | append (dict
        "resource" .
        "fallback_url" ""
        "meta" dict
      ) }}
    {{ end }}
  {{ end }}
{{ end }}

{{/* Source C — page bundle auto-discovery */}}
{{ if $content.page_resources }}
  {{ with $page }}
    {{ $imgs := .Resources.ByType "image" }}
    {{ $sorted := sort $imgs "Name" $sort_order }}
    {{ range $sorted }}
      {{ if in $allowed_exts (lower (path.Ext .Name)) }}
        {{ $candidates = $candidates | append (dict
          "resource" .
          "fallback_url" ""
          "meta" dict
        ) }}
      {{ end }}
    {{ end }}
  {{ end }}
{{ end }}

{{/* Apply limit */}}
{{ if gt $limit 0 }}
  {{ $candidates = first $limit $candidates }}
{{ end }}

{{/* Process each candidate into final item props */}}
{{ $out := slice }}
{{ range $candidates }}
  {{ $meta := .meta }}
  {{ $resource := .resource }}
  {{ $fallback_url := .fallback_url }}

  {{/* ---- Metadata waterfall ---- */}}
  {{ $alt := index $meta "alt" | default "" }}
  {{ $caption_raw := index $meta "caption" | default "" }}
  {{ $title_raw := index $meta "title" | default "" }}
  {{ $credit_raw := index $meta "credit" | default "" }}
  {{ $link := index $meta "link" | default "" }}

  {{/* Tier 2 — sidecar file lookup. Tries:
        <name>.yaml/.yml/.json (full filename, Lightroom-style convention)
        <basename>.yaml/.yml/.json (filename minus extension)
       in both site assets and the page bundle. */}}
  {{ $sidecar := false }}
  {{ if $resource }}
    {{/* Resource.Name comes back with a leading slash for site assets (e.g.
        "/media/albums/gallery/01.jpg"); strip it so resources.Get treats the
        path as relative to assets/. Page-bundle resource names have no
        leading slash, so TrimPrefix is a no-op for those. */}}
    {{ $name := strings.TrimPrefix "/" $resource.Name }}
    {{ $basename := strings.TrimSuffix (path.Ext $name) $name }}
    {{ $patterns := slice
      (printf "%s.yaml" $name)
      (printf "%s.yml" $name)
      (printf "%s.json" $name)
      (printf "%s.yaml" $basename)
      (printf "%s.yml" $basename)
      (printf "%s.json" $basename)
    }}
    {{ range $pattern := $patterns }}
      {{ if not $sidecar }}
        {{ $candidate := resources.Get $pattern }}
        {{ if not $candidate }}{{ $candidate = resources.GetMatch $pattern }}{{ end }}
        {{ if and (not $candidate) $page }}
          {{ $candidate = $page.Resources.GetMatch $pattern }}
        {{ end }}
        {{ if $candidate }}
          {{ $sidecar = $candidate }}
        {{ end }}
      {{ end }}
    {{ end }}
  {{ end }}

  {{ if $sidecar }}
    {{ $data := transform.Unmarshal $sidecar }}
    {{ if reflect.IsMap $data }}
      {{ if not $caption_raw }}{{ $caption_raw = index $data "caption" | default "" }}{{ end }}
      {{ if not $title_raw }}{{ $title_raw = index $data "title" | default "" }}{{ end }}
      {{ if not $credit_raw }}{{ $credit_raw = index $data "credit" | default "" }}{{ end }}
      {{ if not $alt }}{{ $alt = index $data "alt" | default "" }}{{ end }}
      {{ if not $link }}{{ $link = index $data "link" | default "" }}{{ end }}
    {{ end }}
  {{ end }}

  {{/* Tier 3 — embedded IPTC/EXIF. Lightroom/Capture One JPEG exports carry
       Caption-Abstract + By-line + Copyright; this picks them up automatically. */}}
  {{ $exif_tags := dict }}
  {{ if $resource }}
    {{ $exif_try := try $resource.Exif }}
    {{ if and (not $exif_try.Err) $exif_try.Value }}
      {{ $exif_tags = $exif_try.Value.Tags | default dict }}
    {{ end }}
  {{ end }}

  {{ if $exif_tags }}
    {{ if not $caption_raw }}
      {{ range $key := (slice "Caption-Abstract" "ImageDescription" "XPSubject" "Description") }}
        {{ if not $caption_raw }}
          {{ $v := index $exif_tags $key }}
          {{ if $v }}{{ $caption_raw = printf "%v" $v }}{{ end }}
        {{ end }}
      {{ end }}
    {{ end }}
    {{ if not $credit_raw }}
      {{ range $key := (slice "By-line" "Artist" "Creator") }}
        {{ if not $credit_raw }}
          {{ $v := index $exif_tags $key }}
          {{ if $v }}{{ $credit_raw = printf "%v" $v }}{{ end }}
        {{ end }}
      {{ end }}
    {{ end }}
  {{ end }}

  {{/* ---- Inline-Markdown render of text fields (RenderString display:inline) ---- */}}
  {{ $caption := $caption_raw }}
  {{ if and $caption_raw $page }}
    {{ $caption = $page.RenderString (dict "display" "inline") $caption_raw }}
  {{ end }}
  {{ $title := $title_raw }}
  {{ if and $title_raw $page }}
    {{ $title = $page.RenderString (dict "display" "inline") $title_raw }}
  {{ end }}
  {{ $credit := $credit_raw }}
  {{ if and $credit_raw $page }}
    {{ $credit = $page.RenderString (dict "display" "inline") $credit_raw }}
  {{ end }}

  {{ $entry := dict
    "alt" $alt
    "caption" $caption
    "credit" $credit
    "link" $link
    "title" $title
  }}

  {{ if $resource }}
    {{ $canProcess := and (reflect.IsImageResourceProcessable $resource) (ne $resource.MediaType.SubType "gif") }}
    {{ if $canProcess }}
      {{ $responsive := partial "functions/process_responsive_image.html" (dict
        "image" $resource
        "mode" "fit"
        "sizes" (slice 480 768 1024 1366 1920)
      ) }}
      {{ $entry = merge $entry (dict
        "src" $responsive.fallback.RelPermalink
        "srcset" $responsive.srcset
        "width" $responsive.fallback.Width
        "height" $responsive.fallback.Height
        "aspect_ratio" (div (float $resource.Width) (float $resource.Height))
      ) }}

      {{/* LQIP — 20px wide WebP, inlined as base64 for instant placeholder paint */}}
      {{ $lqip_res := $resource.Resize "20x webp q30" }}
      {{ $lqip_b64 := $lqip_res.Content | base64Encode }}
      {{ $entry = merge $entry (dict "lqip" (printf "data:image/webp;base64,%s" $lqip_b64)) }}
    {{ else }}
      {{/* SVG / GIF — pass through unprocessed */}}
      {{ $entry = merge $entry (dict
        "src" $resource.RelPermalink
        "width" $resource.Width
        "height" $resource.Height
        "aspect_ratio" (cond (gt $resource.Height 0) (div (float $resource.Width) (float $resource.Height)) 1.0)
      ) }}
    {{ end }}

    {{/* Tier 4 — alt fallback: plainified caption → humanised filename. Caption
        itself stays empty when no metadata source has supplied one. */}}
    {{ if not $entry.alt }}
      {{ $fallback_alt := "" }}
      {{ with $caption_raw }}
        {{ $fallback_alt = plainify (printf "%s" $entry.caption) }}
      {{ end }}
      {{ if not $fallback_alt }}
        {{ $base := path.Base $resource.Name }}
        {{ $name := strings.TrimSuffix (path.Ext $base) $base }}
        {{ $name = replace $name "-" " " }}
        {{ $name = replace $name "_" " " }}
        {{ $fallback_alt = humanize $name }}
      {{ end }}
      {{ $entry = merge $entry (dict "alt" $fallback_alt) }}
    {{ end }}
  {{ else if $fallback_url }}
    {{ $entry = merge $entry (dict "src" $fallback_url) }}
  {{ end }}

  {{ if $entry.src }}
    {{ $out = $out | append $entry }}
  {{ end }}
{{ end }}

{{ return dict "items" $out }}