Content Aware Headers and Footers?

Question

Using Latex

I need to set my headers and footers on a page by page by basis pending the contents of the page. For example if the page contains

(A) then the header and footer needs to say Apple

If the page contains

(B) then the header and footer needs to say Bravo

Hierarchy for example is (B) is more important than (A). If (B) and (A) are on the same page it needs to always say Bravo on the pages where both are there. If it is just (A) on the page Apple is fine.

Is there an easy way to do this in my style/headers? If not, what path should I be looking down?

Example Code for how it should look like

\documentclass[12pt]{article}
\usepackage{blindtext}
\usepackage{fancyhdr}
\pagestyle{fancy}

\begin{document}
    \setlength{\headheight}{1in}
    \fancyhf{}
    \fancyhead[C]{\bfseries{\Large BRAVO}}
    \fancyfoot[C]{\thepage \\ \bfseries{\Large BRAVO}}
    (A)\Blindtext[1]

    (B)\Blindtext[1]

    (A)\Blindtext[1]

    (A)\Blindtext[1]
    \fancyhead[C]{\bfseries{\Large APPLE}}
    \fancyfoot[C]{\thepage \\ \bfseries{\Large APPLE}}
    (A)\Blindtext[1]
    (A)\Blindtext[1]
    (A)\Blindtext[1]
    (A)\Blindtext[1]
\end{document}

Answer 1

This gives the output you described. But I do have some doubts that it is really what you are after.

\documentclass[12pt, a4paper]{article}
\usepackage{blindtext}
\usepackage{fancyhdr}
\pagestyle{fancy}
\fancyhf{}
\fancyhead[C]{\leftmark}
\fancyfoot[C]{\thepage --\leftmark}   
\usepackage{afterpage} 
\begin{document}
\markboth{Apple}{Apple}%Initialize to Apple
(A)\Blindtext[1]

(B)\markboth{Bravo}{Bravo}\afterpage{\markboth{Apple}{Apple}}\Blindtext[1]

(A)\Blindtext[1]

(A)\Blindtext[1]
(A)\Blindtext[1]
(A)\Blindtext[1]
(A)\Blindtext[1]
(A)\Blindtext[1]
\end{document}

Answer 2

I went ahead and it did it slightly different since I didn't want to use marks etex or etoolbox. It leaves the main code a bit more clean IMO. I'm pretty sure the function could be cleaned up significantly, but for now I think this will work for me.

\documentclass[12pt]{article}
\usepackage{blindtext}
\usepackage{fancyhdr}

\pagestyle{fancy}
\usepackage{xstring}

\newcommand{\pageclass}{}

\makeatletter
    \newcounter{pagerank}
    \newcounter{thispage}
    \setcounter{thispage}{0}
    \newcounter{rank}
    \newcommand\setClass[1]{
        \setcounter{rank}{0}
        \IfStrEq{#1}{A}{
            \setcounter{rank}{1}
        }{
        \IfStrEq{#1}{B}{
            \setcounter{rank}{2}
        }{
        \IfStrEq{#1}{C}{
            \setcounter{rank}{3}
        }{}}}
        \ifnum \value{page}=\value{thispage}\else
            \setcounter{thispage}{\value{page}}
            \setcounter{pagerank}{\value{rank}}
        \fi
        \ifnum \value{rank}>\value{pagerank}
            \setcounter{pagerank}{\value{rank}}
        \fi     
        \ifnum \value{pagerank}=1
            \def\pageclass{Alpha}
        \else \ifnum \value{pagerank}=2
            \def\pageclass{Beta}
        \else \ifnum \value{pagerank}=3
            \def\pageclass{Charlie}
        \fi \fi \fi
        \fancyhead[C]{\bfseries{\Large \pageclass}}
        \fancyfoot[C]{\thepage \\ \bfseries{\Large \pageclass}}
        (#1)
    }
\makeatother

\begin{document}
    \setlength{\headheight}{1in}
    \fancyhf{}
    \setClass{A}Lorem Ipsum Dolor Sit Alum\\
    \setClass{B}
    \Blindtext[1]
    \setClass{A}
    \Blindtext[1]
    \setClass{A}
    \Blindtext[1]
    \setClass{A}
    \Blindtext[1]
    \setClass{A}
    \Blindtext[1]
    \setClass{A}
    \Blindtext[1]
    \setClass{A}
    \Blindtext[1]
    \setClass{B}
    \Blindtext[1]
    \setClass{C}
    \Blindtext[1]
\end{document}