defmodule Outerfaces.Odd.Plugs.OddCDNRoflHTMLPlug do
@moduledoc """
Provides HTML transformation functions for rewriting [OUTERFACES_ODD_CDN] and
[OUTERFACES_ODD_SPA] tokens in HTML src/href attributes.
This module always emits rev-pinned URLs in the canonical format:
- CDN: `/__rev//cdn/`
- SPA: `/__rev//spa/`
## Examples
# Unified proxy mode (cdn_origin = ""):
html = ""
transform_html_cdn_tokens(html, conn, "") #=> ""
# Direct CDN mode (cdn_origin = "http://localhost:60032"):
html = ""
transform_html_cdn_tokens(html, conn, "http://localhost:60032") #=> ""
# SPA tokens (always relative):
html = ""
transform_html_cdn_tokens(html, conn, "") #=> ""
"""
alias Outerfaces.Rev
# Regex patterns for matching tokens in HTML attributes
# Matches: src="[OUTERFACES_ODD_CDN]/path" or href='[OUTERFACES_ODD_CDN]/path'
@odd_cdn_attr_regex ~r/((?:src|href)=["'])([^"']*)\[OUTERFACES_(?:ODD|LOCAL)_CDN\]\/([^"']*)(["'])/i
@odd_spa_attr_regex ~r/((?:src|href)=["'])([^"']*)\[OUTERFACES_ODD_SPA\]\/([^"']*)(["'])/i
# Regex for injecting rev meta tag (finds or tag)
@head_close_regex ~r{}i
@body_open_regex ~r{]*>}i
@doc """
Transforms HTML content by rewriting ODD_CDN and ODD_SPA tokens in src/href attributes
and injecting a rev meta tag.
## Parameters
- `html_content` - The HTML content to transform
- `conn` - The Plug.Conn struct (used to get rev)
- `cdn_origin` - Origin for CDN assets:
- Unified proxy mode: "" (empty string, emits relative URLs)
- Direct CDN mode: "http://localhost:60032" (full origin)
## Returns
Transformed HTML string with:
- All [OUTERFACES_ODD_CDN] and [OUTERFACES_ODD_SPA] tokens replaced
- Rev meta tag injected in
"""
@spec transform_html_cdn_tokens(String.t(), Plug.Conn.t(), String.t()) :: String.t()
def transform_html_cdn_tokens(html_content, conn, cdn_origin \\ "") do
# Short-circuit if no tokens present (performance optimization)
if String.contains?(html_content, "[OUTERFACES_") do
html_content
|> replace_odd_cdn_tokens(conn, cdn_origin)
|> replace_odd_spa_tokens(conn)
|> inject_rev_meta_tag(conn)
else
html_content
end
end
# Private Functions
@spec replace_odd_cdn_tokens(String.t(), Plug.Conn.t(), String.t()) :: String.t()
defp replace_odd_cdn_tokens(html_content, conn, cdn_origin) do
rev = get_rev(conn)
# Emit canonical rev-pinned URLs: /__rev//cdn/
Regex.replace(@odd_cdn_attr_regex, html_content, fn _match, attr_start, prefix, path, quote ->
"#{attr_start}#{prefix}#{cdn_origin}/__rev/#{rev}/cdn/#{path}#{quote}"
end)
end
@spec replace_odd_spa_tokens(String.t(), Plug.Conn.t()) :: String.t()
defp replace_odd_spa_tokens(html_content, conn) do
# ODD_SPA is always rev-pinned
rev = get_rev(conn)
Regex.replace(@odd_spa_attr_regex, html_content, fn _match, attr_start, prefix, path, quote ->
"#{attr_start}#{prefix}/__rev/#{rev}/spa/#{path}#{quote}"
end)
end
@spec inject_rev_meta_tag(String.t(), Plug.Conn.t()) :: String.t()
defp inject_rev_meta_tag(html_content, conn) do
rev = get_rev(conn)
meta_tag = " \n"
cond do
Regex.match?(@head_close_regex, html_content) ->
# Inject before
Regex.replace(@head_close_regex, html_content, "#{meta_tag}", global: false)
Regex.match?(@body_open_regex, html_content) ->
# No found, inject after
Regex.replace(
@body_open_regex,
html_content,
fn match ->
"#{match}\n#{meta_tag}"
end,
global: false
)
true ->
# No or found, prepend to content
meta_tag <> html_content
end
end
@spec get_rev(Plug.Conn.t()) :: String.t()
defp get_rev(conn) do
Map.get(conn.assigns, :outerfaces_rev) || Rev.current_rev()
end
end