Customising the page number in ToC using titletoc

Question

I am using titletoc to customise the ToC. Right now there are three things I cannot solve (I guess, due to the fact that page number is typeset in a fixed-width box):

1. The titlerule doesn't fill till the page number.
2. If page number is too large, it exceeds into the right margin.
3. If the title is too long, it bumps into the page number.

Here is an illustration:

I have fixed the first issue with

\makeatletter
\renewcommand{\@pnumwidth}{0pt{}}
\makeatother

but the new problem appears

Full MWE:

\documentclass{book}

\usepackage[showframe]{geometry}
\usepackage{titletoc}
\makeatletter
\renewcommand{\@pnumwidth}{0pt{}}
\makeatother
\titlecontents{chapter}
    [1cm]
    {\vspace{1cm}\filright}
    {\large\sffamily\bfseries\contentslabel[\thecontentslabel.]{1cm}}
    {\hspace{-1cm}}
    {\titlerule*[3pt]{.}\sffamily\bfseries\large\contentspage}

\begin{document}

    \tableofcontents

    \chapter{one}

    Sample text

    \cleardoublepage

    \addtocounter{page}{1000}

    \chapter{two}

    \chapter{a long long long long long long long long long long long long long  title}

\end{document}

Answer 1

This is the best I could obtain with the tools from titletoc. It solves points 2 and 3.

\documentclass{book}

\usepackage[showframe]{geometry}
\usepackage{titletoc}
\contentsmargin{1cm}
\titlecontents{chapter}
    [0.6cm]
    {\vspace{1cm}\filright\large\sffamily\bfseries}
    {\contentslabel[\thecontentslabel.]{1.3em}}
    {\hspace{-1cm}}
    {{\mdseries\hspace{0.4em}\titlerule*[6pt]{.}}\contentspage}

\begin{document}

    \tableofcontents

    \chapter{one}

    Sample text

    \cleardoublepage

    \addtocounter{page}{1000}

    \chapter{two}

    \chapter{a long long long long long long long long long long long long long long title}

\end{document}