Enable ads

Author: coatless

_extensions/coatless-quarto/adsense/_extension.yml

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+title: Adsense
+author: James Balamuta
+version: 2.0.0
+quarto-required: ">=1.3.0"
+contributes:
+  filters:
+    - adsense.lua
+

_extensions/coatless-quarto/adsense/adsense.lua

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+----
+--- Setup variables for default initialization
+
+-- Check to see if we've already defined the adsense Unit
+-- Note: This should only trigger _once_
+local isAdsenseUnitMissing = true
+
+-- Check to see if we should show ads on the given page
+local enableAds = true
+
+----
+--- Process initialization
+
+-- Check if variable is present and not just the empty string
+local function isVariableEmpty(s)
+  return s == nil or s == ''
+end
+
+local function isVariablePopulated(s)
+  return not isVariableEmpty(s)
+end
+
+-- Check if a value is true or false, including string representations
+local function isBoolean(value)
+  if type(value) == "boolean" then
+    return true
+  elseif type(value) == "string" then
+    local lowercaseValue = value:lower()
+    return lowercaseValue == "true" or lowercaseValue == "false"
+  else
+    return false
+  end
+end
+
+-- Coerce a "true" or "false" string to `true`/`false`.
+local function stringToBoolean(str)
+  return str == "true" and true or false
+end
+
+-- Ad unit HTML
+local function adsense_html(publisher_id)
+  local html_text = '<script async'..
+  ' src="https://pagead2.googlesyndication.com/pagead/js/adsbygoogle.js?client=' .. publisher_id .. '"' ..
+  ' crossorigin="anonymous">' ..
+  '</script>'
+
+  return html_text
+end
+
+
+-- Retrieve publisher and setup ad unit
+function Meta(m)
+
+  -- Detect HTML format (excluding epub which won't handle fa)
+  if not quarto.doc.is_format("html:js") then
+    quarto.log.error("The `adsense` extensions works only on HTML powered Quarto projects.")
+  end 
+
+  -- Check for configuration
+  local adsense_meta = m.adsense
+  if isVariableEmpty(adsense_meta) then
+    quarto.log.error(
+      "The Quarto project is missing the `adsense` key in either" ..
+       "\n - the document header,\n - `_quarto.yml`, or\n - `_metadata.yml`."
+    )
+  end
+
+  -- Retrieve enable-ads from meta
+  if isVariablePopulated(adsense_meta['enable-ads']) then
+    enableAds = pandoc.utils.stringify(adsense_meta['enable-ads'])
+
+    if not isBoolean(enableAds) then
+      quarto.log.error("The `enable-ads` must be either `true` or `false`, not `" .. enableAds .. "`." ..
+      "\nPlease fix by correcting the value supplied to `enable-ads` in the current document.")
+    end
+
+    -- Apply conversion from string to boolean
+    enableAds = stringToBoolean(enableAds)
+
+    -- If ads should be disabled; exit here to avoid running into a publisher-id unset error.
+    if enableAds == false then
+      return m
+    end 
+  end
+
+  -- Retrieve publisherID from meta
+  local publisher_id = nil
+  if isVariablePopulated(adsense_meta['publisher-id']) then
+    publisher_id = pandoc.utils.stringify(adsense_meta['publisher-id'])
+  else 
+    quarto.log.error(
+      "The `publisher-id` is not set. Please set the `publisher-id` by either:" ..
+      "\n - the value in the current document," .. 
+      "\n - the projects `_quarto.yml`, or" ..
+      "\n - `_metadata.yml` for the directory.\n")
+  end 
+
+  if enableAds and isAdsenseUnitMissing then
+    -- Avoid re-running insertion
+    isAdsenseUnitMissing = false
+    -- Customize the ad unit script tag
+    local adsense_customized_adunit_html = adsense_html(publisher_id)
+    -- Inject the customized unit into the HTML document's header section 
+    -- using Quarto's API.
+    quarto.doc.include_text("in-header", adsense_customized_adunit_html)
+  end
+
+  return m
+end