computer-playbook/roles/srv-web-7-7-inj-compose/templates/location.lua.j2

lua_need_request_body on;

header_filter_by_lua_block {
    local ct = ngx.header.content_type or ""
    if ct:lower():find("^text/html") then
        ngx.ctx.is_html = true
    else
        ngx.ctx.is_html = false
    end
}

body_filter_by_lua_block {
    -- only apply further processing if this is an HTML response
    if not ngx.ctx.is_html then
        return
    end

    -- initialize or reuse the buffer
    ngx.ctx.buf = ngx.ctx.buf or {}
    local chunk, eof = ngx.arg[1], ngx.arg[2]

    if chunk ~= "" then
        table.insert(ngx.ctx.buf, chunk)
    end

    if not eof then
        -- drop intermediate chunks; we’ll emit only on eof
        ngx.arg[1] = nil
        return
    end

    -- on eof: concatenate all buffered chunks
    local whole = table.concat(ngx.ctx.buf)
    ngx.ctx.buf = nil  -- clear buffer
{#    whole = string.gsub(whole, "</body>", "<!-- injected text2 -->\n</body>")
    ngx.arg[1] = whole #}

    -- build a list of head-injection snippets
    local head_snippets = {}

{# Deactivated 'logout' temporary due to chunk size. Needs an CDN. #}
    {% for head_feature in ['css', 'matomo', 'port-ui-desktop', 'javascript' ] %}
    {% if applications | get_app_conf(application_id, 'features.' ~ head_feature, false) | bool %}
    head_snippets[#head_snippets + 1] = [=[
        {%- include "roles/srv-web-7-7-inj-" ~ head_feature ~ "/templates/head_sub.j2" -%}
    ]=]
    {% endif %}
    {% endfor %}

    -- inject all collected snippets right before </head>
    local head_payload = table.concat(head_snippets, "\n") .. "</head>"
    whole = string.gsub(whole, "</head>", head_payload)

    {% if applications | get_app_conf(application_id, 'features.matomo', false) | bool %}
    -- build Matomo noscript snippet for the body
    local body_matomo = [=[
        {%- include 'roles/srv-web-7-7-inj-matomo/templates/body_sub.j2' -%}
    ]=]
    -- inject it right before </body>
    whole = string.gsub(whole, "</body>", body_matomo)
    {% endif %}

    -- finally send the modified HTML out
    ngx.arg[1] = whole
}