vcl 4.1;

import xkey;
import std;

backend default {
    .host = "app.internal";
    .port = "8080";
}

acl purge {
    "0.0.0.0"/0;  // Allow all IP addresses
    "::0"/0;      // Allow all IPv6 addresses
}

sub vcl_recv {
    # Remove empty query string parameters
    # e.g.: www.example.com/index.html?
    if (req.url ~ "\?$") {
        set req.url = regsub(req.url, "\?$", "");
    }

    # Remove port number from host header
    set req.http.Host = regsub(req.http.Host, ":[0-9]+", "");

    # Sorts query string parameters alphabetically for cache normalization purposes
    set req.url = std.querysort(req.url);

    # Remove the proxy header to mitigate the httpoxy vulnerability
    # See https://httpoxy.org/
    unset req.http.proxy;

    # Add X-Forwarded-Proto header when using https
    if (!req.http.X-Forwarded-Proto) {
        if(std.port(server.ip) == 443 || std.port(server.ip) == 8443) {
            set req.http.X-Forwarded-Proto = "https";
        } else {
            set req.http.X-Forwarded-Proto = "http";
        }
    }

    # Set the X-Forwarded-Host header to the proxy host
    set req.http.X-Forwarded-Host = "proxy-app.internal";

    # Purge logic to remove objects from the cache.
    if (req.method == "PURGE") {
        if (client.ip !~ purge) {
            return (synth(403, "Forbidden"));
        }

        if (req.http.xkey) {
            set req.http.n-gone = xkey.softpurge(req.http.xkey);
            return (synth(200, "Invalidated " + req.http.n-gone + " objects"));
        }
        return(synth(200, "Purged"));
    }

    # Only handle relevant HTTP request methods
    if (
        req.method != "GET" &&
        req.method != "HEAD" &&
        req.method != "PUT" &&
        req.method != "POST" &&
        req.method != "PATCH" &&
        req.method != "TRACE" &&
        req.method != "OPTIONS" &&
        req.method != "DELETE"
    ) {
        return (pipe);
    }

    # Remove tracking query string parameters used by analytics tools
    if (req.url ~ "(\?|&)(utm_source|utm_medium|utm_campaign|utm_content|gclid|cx|ie|cof|siteurl)=") {
        set req.url = regsuball(req.url, "&(utm_source|utm_medium|utm_campaign|utm_content|gclid|cx|ie|cof|siteurl)=([A-z0-9_\-\.%25]+)", "");
        set req.url = regsuball(req.url, "\?(utm_source|utm_medium|utm_campaign|utm_content|gclid|cx|ie|cof|siteurl)=([A-z0-9_\-\.%25]+)", "?");
        set req.url = regsub(req.url, "\?&", "?");
        set req.url = regsub(req.url, "\?$", "");
    }

    # Only cache GET and HEAD requests
    if (req.method != "GET" && req.method != "HEAD") {
        set req.http.X-Cacheable = "NO:REQUEST-METHOD";
        return(pass);
    }

    # Mark static files with the X-Static-File header, and remove any cookies
    # X-Static-File is also used in vcl_backend_response to identify static files
    if (req.url ~ "^[^?]*\.(7z|avi|bmp|bz2|css|csv|doc|docx|eot|flac|flv|gif|gz|ico|jpeg|jpg|js|less|mka|mkv|mov|mp3|mp4|mpeg|mpg|odt|ogg|ogm|opus|otf|pdf|png|ppt|pptx|rar|rtf|svg|svgz|swf|tar|tbz|tgz|ttf|txt|txz|wav|webm|webp|woff|woff2|xls|xlsx|xml|xz|zip)(\?.*)?$") {
        set req.http.X-Static-File = "true";
        unset req.http.Cookie;
        return(hash);
    }

    # No caching of special URLs, logged in users and some plugins
    if (
        req.http.Cookie ~ "wordpress_(?!test_)[a-zA-Z0-9_]+|wp-postpass|comment_author_[a-zA-Z0-9_]+|woocommerce_cart_hash|woocommerce_items_in_cart|wp_woocommerce_session_[a-zA-Z0-9]+|wordpress_logged_in_|comment_author|PHPSESSID" ||
        req.http.Authorization ||
        req.url ~ "add_to_cart" ||
        req.url ~ "edd_action" ||
        req.url ~ "nocache" ||
        req.url ~ "^/addons" ||
        req.url ~ "^/bb-admin" ||
        req.url ~ "^/bb-login.php" ||
        req.url ~ "^/bb-reset-password.php" ||
        req.url ~ "^/cart" ||
        req.url ~ "^/checkout" ||
        req.url ~ "^/control.php" ||
        req.url ~ "^/login" ||
        req.url ~ "^/logout" ||
        req.url ~ "^/lost-password" ||
        req.url ~ "^/my-account" ||
        req.url ~ "^/product" ||
        req.url ~ "^/register" ||
        req.url ~ "^/register.php" ||
        req.url ~ "^/server-status" ||
        req.url ~ "^/signin" ||
        req.url ~ "^/signup" ||
        req.url ~ "^/stats" ||
        req.url ~ "^/wc-api" ||
        req.url ~ "^/wp-admin" ||
        req.url ~ "^/wp-comments-post.php" ||
        req.url ~ "^/wp-cron.php" ||
        req.url ~ "^/wp-login.php" ||
        req.url ~ "^/wp-activate.php" ||
        req.url ~ "^/wp-mail.php" ||
        req.url ~ "^/wp-login.php" ||
        req.url ~ "^\?add-to-cart=" ||
        req.url ~ "^\?wc-api=" ||
        req.url ~ "^/preview=" ||
        req.url ~ "^/\.well-known/acme-challenge/"
    ) {
        set req.http.X-Cacheable = "NO:Logged in/Got Sessions";

        if (req.http.X-Requested-With == "XMLHttpRequest") {
            set req.http.X-Cacheable = "NO:Ajax";
        }

        return(pass);
    }

    # Remove any cookies left
    unset req.http.Cookie;

    return(hash);
}

sub vcl_hash {
    if (req.http.X-Forwarded-Proto) {
        # Create cache variations depending on the request protocol
        hash_data(req.http.X-Forwarded-Proto);
    }
}

sub vcl_backend_response {
    # Inject URL & Host header into the object for asynchronous banning purposes
    set beresp.http.x-url = bereq.url;
    set beresp.http.x-host = bereq.http.host;

    # If we dont get a Cache-Control header from the backend
    # we default to 1h cache for all objects
    if (!beresp.http.Cache-Control) {
        set beresp.ttl = 1h;
        set beresp.http.X-Cacheable = "YES:Forced";
    }

    # If the file is marked as static we cache it for 1 day
    if (bereq.http.X-Static-File == "true") {
        unset beresp.http.Set-Cookie;
        set beresp.http.X-Cacheable = "YES:Forced";
        set beresp.ttl = 1d;
    }

    if (beresp.http.Set-Cookie) {
        set beresp.http.X-Cacheable = "NO:Got Cookies";
    } elseif (beresp.http.Cache-Control ~ "private") {
        set beresp.http.X-Cacheable = "NO:Cache-Control=private";
    }

    # The cached document should be "tagged" using the values returned by the x-graphql-keys header
    if (beresp.http.x-graphql-keys) {
        set beresp.http.xkey = beresp.http.x-graphql-keys;
    }
}

sub vcl_deliver {
    # Debug header
    if (req.http.X-Cacheable) {
        set resp.http.X-Cacheable = req.http.X-Cacheable;
    } elseif (obj.uncacheable) {
        if(!resp.http.X-Cacheable) {
            set resp.http.X-Cacheable = "NO:UNCACHEABLE";
        }
    } elseif (!resp.http.X-Cacheable) {
        set resp.http.X-Cacheable = "YES";
    }

    set resp.http.X-Cache-Hits = obj.hits;

    if (obj.hits > 0) {
        set resp.http.X-Cache = "HIT";
    } else {
        set resp.http.X-Cache = "MISS";
    }

    # Cleanup of headers
    unset resp.http.x-url;
    unset resp.http.x-host;
    unset resp.http.via;
    unset resp.http.x-varnish;
}