documentclass[11pt]{book}
usepackage[top=3cm,bottom=3cm,left=3.2cm,right=3.2cm,headsep=10pt,letterpaper]{geometry}
usepackage[demo]{graphicx}
usepackage{lipsum}
usepackage{xcolor}
definecolor{mybluei}{RGB}{52,177,201}
definecolor{myblueii}{RGB}{63,200,244}
definecolor{myblueiii}{RGB}{199,234,253}
definecolor{ultramarine}{RGB}{0,45,97}
usepackage{tikz}
usetikzlibrary{shadows.blur}
usetikzlibrary{shapes.symbols}
usepackage{etoolbox,fancyhdr}

%======================================================================================
%   CHAPTER HEADINGS
%======================================================================================
usepackage[explicit,calcwidth]{titlesec}

makeatletter
newcommand{thechapterimage}{}%
newcommand{chapterimage}[1]{renewcommand{thechapterimage}{#1}}%
def@makechapterhead#1{%
{parindent z@ raggedright normalfont
ifnum c@secnumdepth >m@ne
if@mainmatter
begin{tikzpicture}[remember picture,overlay]
node at (current page.north west)
{begin{tikzpicture}[remember picture,overlay]
node[anchor=north west,inner sep=0pt] at (.2,0) {includegraphics[width=paperwidth]{thechapterimage}};
draw[anchor=west] (Gm@lmargin+2.5cm,-4.79cm) node {  %
{begin{tikzpicture}
    node[draw=none,shade,
      top color=mybluei,
      bottom color=mybluei,
      rounded corners=6pt,
      blur shadow={shadow blur steps=6}
      ]{color{white}fontsize{50}{120}itshapermfamilychaptertitlenamehspace{2pt} selectfontthechapter};
end{tikzpicture}}
  };
end{tikzpicture}};
end{tikzpicture}
else
begin{tikzpicture}[remember picture,overlay]
node at (current page.north west)
{begin{tikzpicture}[remember picture,overlay]
node[anchor=north west,inner sep=0pt] at (.2,0) {includegraphics[width=paperwidth]{thechapterimage}};
draw[anchor=west] (Gm@lmargin+1cm,-4.62cm) node {  %
    parbox[b]{70pt}{colorbox{mybluei}{%
        parbox[b][60pt][t]{44pt}{centering%
          color{white}%
          {itshapermfamilysmallchaptertitlename}%
          vfill{fontsize{50}{120}selectfontthechapter}%
        }%
      }%
    }hspace{15pt}%
    parbox[b]{dimexprtextwidth-150pt}{%
      raggedrightscshape#1vskip6pt%
    }%
  };
end{tikzpicture}};
end{tikzpicture}
fifiparvspace*{120p@}stepcounter{chapshift}}}
makeatother

newcommandChapterFont{usefont{T1}{qhv}{b}{n}selectfonthuge}
newcommandSectionFont{usefont{T1}{qhv}{b}{n}selectfont}
titleformat{section}
  {normalfontSectionFontcolor{myblueii}}
  {colorbox{mybluei}{%
    parbox[c][16pt][c]{40pt}{%
      centeringtextcolor{white}{SectionFontLargethesection}%
      }%
    }%
  }
  {1em}
  {#1}
  [vspace{-1.2baselineskip}%
    color{myblueii}hspace*{dimexpr40pt+2fboxseprelax}%
    rule{dimexprtextwidth-40pt-2fboxseprelax}{1pt}%
  ]

%======================================================================================
%   CHAPTER THUMB
%======================================================================================
usetikzlibrary{calc}
pagestyle{plain}
newcounter{chapshift}
addtocounter{chapshift}{-1}
newcommandBoxColor{%
  ultramarine}

%======================================================================================
%   PAGE HEADERS
%======================================================================================
defsubsectiontitle{}
renewcommand{sectionmark}[1]{markright{sffamilynormalsize#1}{}}
renewcommand{subsectionmark}[1]{defsubsectiontitle{#1}}
pagestyle{fancy}
renewcommand{headrule}{{color{myblueii}%
hrule widthheadwidth heightheadrulewidth depthheadrulewidth}}
renewcommand{chaptermark}[1]{markboth{normalsizebfseries  #1}{}}
renewcommand{sectionmark}[1]{markright{sffamilynormalsize#1}{}}
fancyhf{} fancyhead[LE,RO]{normalsizecolorbox{myblueii}{color{white}sffamilybfseriesstrutquadthepagequad}}
fancyhead[LO]{textcolor{mybluei} rightmark%
begin{tikzpicture}[overlay,remember picture]
  node[fill=BoxColor,inner sep=0pt,rectangle,text width=1cm,
    text height=4cm,align=center,anchor=north east]
  at ($ (current page.north east) + (-0cm,-2*thechapshift cm) $)
  {rotatebox{90}{parbox{4cm}{%
   centeringtextcolor{white}{bfseriesscshaperightmark \ sffamilysubsectiontitle}}}};
  end{tikzpicture}}
fancyhead[RE]{Testing Book%
  begin{tikzpicture}[overlay,remember picture]
  node[fill=BoxColor,inner sep=0pt,rectangle,text width=1cm,
    text height=4cm,align=center,anchor=north west]
  at ($ (current page.north west) + (-0cm,-2*thechapshift cm) $)
  {rotatebox{90}{parbox{4cm}{%
    centeringtextcolor{white}{bfseriesscshaperightmark \ sffamilysubsectiontitle}}}};
  end{tikzpicture}}
renewcommand{headrulewidth}{.5pt}
addtolength{headheight}{2.5pt}
newcommand{footrulecolor}[1]{patchcmd{footrule}{hrule}{color{#1}hrule}{}{}}
renewcommand{headrulewidth}{.5pt}
addtolength{headheight}{2.5pt}
renewcommand{footrulewidth}{.5pt}

fancypagestyle{plain}{%
  fancyhf{}
  renewcommand{headrulewidth}{0pt}
  renewcommand{footrulewidth}{0pt}
}

makeatletter
renewcommand{cleardoublepage}{
clearpageifoddc@pageelse
hbox{}
vspace*{fill}
thispagestyle{empty}
newpage
fi}
makeatother

begin{document}
chapterimage{bishade}
chapter{Testing}
section{Test One}
lipsum[1-2]
section{Test Two}
lipsum[1-2]
chapter{Testing Three}
section{Test Four}
lipsum[1-2]
section{Test Two}
lipsum[1]
newpage
section{Test Two}
lipsum[1]

end{document}