[Tex/LaTex] Custom enumerate margin with enumitem

Question

I'd like to tell to enumitem to customize the enumerate environment so that, with the following code, I'd get the result pictured below ('a' labels for 1.(a) and 2.(a) should be aligned). How can I do?

Update: The important point is that I'd like the text to be aligned with the previous paragraph (except for the first line) and that each new level of enumeration should add a leftmargin.

I produced the example below using \parshape and some dirty hacks with \hspace{\parindent}: this is why the first (a) label ["1.(a)"] is not properly aligned with the second (a) label ["2.(a)"].

\documentclass{article}
\usepackage{enumitem}
\begin{document}

Text text text text Text text text text Text text text text Text text
text text Text text text text Text text text text Text text text text
Text text text text Text text text text Text text text text Text text
text text Text text text text Text text text text 

\begin{enumerate}
\item Text text text text Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text Text text text text Text text text text Text text text text Text
text text text Text text text text Text text text text
\begin{enumerate}
\item Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text Text text text text Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text
\item Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text Text text text text Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text
\end{enumerate}
\item \begin{enumerate}
  \item Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text Text text text text Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text
\item Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text Text text text text Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text
\end{enumerate}
\item Text text text text Text text text text Text text text text Text
text text text Text text text text Text text text text Text text text
text Text text text text Text text text text Text text text text Text
text text text Text text text text Text text text text
\end{enumerate}
\end{document}

Answer 1

Here is a solution to your problem, I think. This is quite an awful looking format. The tricky part is getting the indent of the first item of an embedded second level list. This bit of hackery (appropriately called \trickindent) is due to egreg.

\documentclass{article}
\usepackage{enumitem}
\usepackage{kantlipsum}
\setlist[enumerate]{nosep,itemindent=3.5em}
\newcommand{\trickindent}{%
  \let\normalitem\item
  \def\item{%
    \itemindent=0pt
    \normalitem
    \itemindent=3.5em
    \let\item\normalitem}%
}
\begin{document}
\begin{enumerate}
\item\kant*[1]
\begin{enumerate}
\item\kant*[4]
\end{enumerate}
\item\begin{enumerate}[before=\trickindent]
  \item\kant*[2]
  \item\kant*[3]
\end{enumerate}
\end{enumerate}
\end{document}