Problem with some 縮約形


I just came across some of the "contracted forms" used in conversations, which
I'm not really familiar with. May you help me decoding the ones that I found
impossible to understand and to translate them into the more "common" form?

I will explain it better, for example in this sentence: "あしたいちんち、どっか出掛けよっか。",
I do understand that どっか is どこか and that 出掛けよっか is 出掛けようか, but I cannot figure
out what いちんち means.

I also found: "何すんの", which I believe corresponds to "何するの", but I'm not
really sure about it.

The last one that I cannot understand is 買ってこよっか, as in: "何か飲むもんでも、買ってこよっか".

Thank you in advance.




> あしたいちんち >>> 明日一日 【あしたいちにち】
>
> どっか >>> どこか
>
> 出掛けよっか >>> 出掛けようか 【でかけようか】
>
> 何すんの >>> 何するの 【なにするの】
>
> 飲むもんでも >>> 飲【の】む物【もの】でも
>
> 買ってこよっか >>> 買【か】ってこようか

The first one いちんち is somewhat rare but there are other words like it which
can have similar contractions when certain vowel+consonant combinations occur.

For example おれのうち becoming おれんち.

