IIS Rewrite with optional query string or adding defaults - mod-rewrite

Question

I am using IIS 8 and just learning about rewrites as I haven't ever written anything that cared about SEO.
I have the following rules that is working assuming the url looks like this: /survey/abc123/email
<rule name="Survey Rule" stopProcessing="true">
<match url="survey/([_0-9a-z-]+)/([_0-9a-z-]+)" />
<action type="Rewrite" url="survey.htm?var1={R:1}&var2={R:2}" />
</rule>
On the survey.htm page I have code that check for existence of var1 & var2 but in this rewrite if I have the url /survey/abc123 it doesn't obviously hit the Survey Rule. I have tried a couple of <conditions> but could find the right one.
I feel there must be a way to say
If {R:1} exists then var1={R:1} else var1=''
If {R:2} exists then var2={R:2} else var1=''
Ideally some type if loop. Is there any way to do this in a rewrite to that no matter how many / there are after survey, whether 0 or 10 it will always it the survey page?
I have looked at the rewrite map but I am not sure that solves this issue.
Edit
Possible urls that I would like to be rewritten:
/survey/abc123/
/survey.htm?var1=abc123
/survey/abc123/email/
/survey.htm?var1=abc123&var2=email
/survey/abc123/email/bob/
/survey.htm?var1=abc123&var2=email&var3=bob
/survey/abc123/email/bob/someOtherVar
/survey.htm?var1=abc123&var2=email&var3=bob&var4=someOtherVar
/result/1/
/result.htm?var1=1
/result/1/test#example.com
/result.htm?var1=1&var2=test#example.com
I would like the first item after the slash to be the page name and then each item after turned into the "query_string". I hope this makes a little more sense.

Answer 1

Short answer
You can't have exactly what you want with IIS rewrite only. And by what you want, i mean dynamically handling it with a loop.
Long answer
(1) With IIS rewrite only, this is the closest possible solution to your problem:
<rule name="Survey/Result Loop Rule" stopProcessing="true">
<match url="^(survey|result)/([^/]+)/(.*)$" />
<action type="Rewrite" url="/{R:1}/{R:3}?{R:2}={R:2}" appendQueryString="true" />
</rule>
<rule name="Survey/Result Default Rule" stopProcessing="true">
<match url="^(survey|result)/$" />
<action type="Rewrite" url="/{R:1}.htm" appendQueryString="true" />
</rule>
It will simulate a loop as long as the url contains parameters as subfolders, for both /survey/ and /result/. Then, it finally rewrites it to .htm page with query string appened. This is not possible to dynamicly generate query names such as var1 var2 etc by incrementing a number (at least, if a solution exists, it would be very tricky and heavy, because the rewrite engine is not made for this). In this example, both query names and values are the same, such as ?abc123=abc123&email=email.
(2) The cleanest way for this would be to delegate the job to the script:
<rule name="Survey/Result Default Rule" stopProcessing="true">
<match url="^(survey|result)/(.*)$" />
<action type="Rewrite" url="/{R:1}.htm?params={R:2}" />
</rule>
This rule rewrites, for instance, /survey/XXX/YYY/ZZZ/ to /survey.htm?params=XXX/YYY/ZZZ/. Since the job is delegated to the script, your htm files need to implement something like this (in pseudo code):
params = query_get('params');
// remove trailing slash in params if present
parameters = explode("/", query_get('params'))
for (i = 0; i < count(parameters); i++)
var{i+1} = parameters[i]
// var1 = parameters[0]
// var2 = parameters[1]
// var3 = parameters[2]
// and so on...
I think you get the idea.