gistfile1.txt

# based on http://uberblo.gs/2011/06/high-performance-url-shortening-with-redis-backed-nginx
# using code from http://stackoverflow.com/questions/3554315/lua-base-converter
# fixes: use adresses with args, and adresses to way out site. example: /shorten/www.bn.ru/?test=shorten

# "database scheme"
# database 5: id ~> url  (use 0 is not good idea)
# database 1: id ~> hits
# database 2: id ~> [{referer|user_agent}]
# database 3: id ~> hits (when id is not found)
# database 4: id ~> [{referer|user_agent}] (when id is not found)
# database 5: key "count" storing the number of shortened urls; the id is generated by (this number + 1) converted to base 62

server {
  location ~ ^/retrieve$ {
    internal;

    redis2_query select 5;
    redis2_query get "ngx:shrt:$request_uri";
    redis2_pass 127.0.0.1:6379;
  }

  location ~ ^/count$ {
    internal;

    redis2_query select 5;
    redis2_query get "ngx:shrtcount";
    redis2_pass 127.0.0.1:6379;
  }

  location ~ ^/history$ {
    internal;

    redis2_query select 1;
    redis2_query incr "ngx:shrt:$request_uri";

    redis2_query select 2;
    redis2_query rpush "ngx:shrt:$request_uri" "$http_referer|$http_user_agent";
    redis2_pass 127.0.0.1:6379;
  }

  location ~ ^/notfound$ {
    internal;

    redis2_query select 3;
    redis2_query incr "ngx:shrt:$request_uri";

    redis2_query select 4;
    redis2_query rpush "ngx:shrt:$request_uri" "$http_referer|$http_user_agent";

    redis2_pass 127.0.0.1:6379;
  }

  location ~ ^/store$ {
    internal;

    redis2_query select 5;
    set_unescape_uri $id $arg_id;
    set_unescape_uri $url $arg_url;
    redis2_query set "ngx:shrt:$id" $url;

    redis2_query select 5;
    redis2_query incr "ngx:shrtcount";

    redis2_pass 127.0.0.1:6379;
  }

  location ~ ^/shorten/(?<gurl>.*)$ {
    auth_basic "Restricted";
    auth_basic_user_file /etc/nginx/.htpasswd;
    add_header Content-Type text/plain;

    content_by_lua '
          local parser = require "redis.parser";
          local res = ngx.location.capture("/count");
          local results, type = parser.parse_replies(res.body, 2);

          basen = function(n, b)
            n = math.floor(n);
            if not b or b == 10 then return tostring(n) end
            local digits = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
            local t = {};
            local sign = "";
            if n < 0 then
              sign = "-";
              n = -n;
            end
            repeat
              local d = (n % b) + 1;
              n = math.floor(n / b);
              table.insert(t, 1, digits:sub(d, d));
            until n == 0
            return sign .. table.concat(t, "");
          end

          if (results[2][1]) then
            local id = basen(results[2][1] + 1, 62);
          else
            local id = basen(0, 62);
          end
          local in_args = ngx.req.get_uri_args();
          local keys = {};
          for key, val in pairs(in_args) do
            table.insert(keys, key .. "=" .. val);
          end
          table.insert(keys, "from=" .. ngx.var.host);
          local st_args = table.concat(keys, "&");
          ngx.location.capture("/store",
                  { args = { id = "/" .. tostring(id), url = ngx.encode_base64("http://" .. ngx.var.gurl .. "?" .. st_args) } }
          );
          ngx.say("original url: http://" .. ngx.var.gurl .. "?" .. st_args);
          ngx.say(" shorted url: http://" .. ngx.var.host .. "/" .. id);
    ';
  }

  location / {
    content_by_lua '
          local parser = require "redis.parser";
          local res = ngx.location.capture("/retrieve");
          local href, type = parser.parse_reply(res.body);
          if type == parser.ERROR_REPLY or href == nil then
            ngx.location.capture("/notfound");
--          ngx.say("Not found");
            ngx.exit(ngx.HTTP_NOT_FOUND);
          else
            ngx.location.capture("/history");
            ngx.redirect(ngx.decode_base64(href));
          end
    ';
  }

}