Fix bug in almostontop that truncated long prompts

Add collection of cursor line immediately after the previous command
completes and use this when calculating the number of lines required to
move the screen in order to display only the latest prompt.

prompt_fresh_setup

@@ -27,9 +27,11 @@ prompt_fresh_setup() {
   if [ $almostontop -eq 1 ]; then
     # Hook to clear the screen then prints the prompt with previous command at
     # the top of the screen.
-    add-zsh-hook preexec fresh_almostontop
+    add-zsh-hook precmd fresh_almostontop_precmd
+    add-zsh-hook preexec fresh_almostontop_preexec
   else
-    add-zsh-hook -d preexec fresh_almostontop
+    add-zsh-hook -d preexec fresh_almostontop_preexec
+    add-zsh-hook -d precmd fresh_almostontop_precmd
   fi
 
   [ $recompile -eq 1 ] && prompt_cleanup
@@ -128,7 +130,22 @@ fresh_line_one() {
   print -P "$time_stamp $directory$git$py$docker$result"
 }
 
-fresh_almostontop() {
+# Executed before each prompt.
+fresh_almostontop_precmd() {
+  # TODO: store the cursor position for use in fresh_almostontop_preexec
+  # CSI ESC[6n gets the cursor position in the form ESC[<row>;<column>R
+  printf "\033[6n"
+  # Discard prefix delimited by [
+  read -s -d [
+  # Store the <row> delimited by ; in fresh_precmd_row
+  read -s -d \; fresh_precmd_row
+  # Discard suffix delimted by R otherwise it is output to the tty
+  read -s -d R
+  # printf "$fresh_precmd_row\n"
+}
+
+# Executed just after a command has been read and is about to be executed.
+fresh_almostontop_preexec() {
   # CSI ESC[6n gets the cursor position in the form ESC[<row>;<column>R
   printf "\033[6n"
   # Discard prefix delimited by [
@@ -141,14 +158,16 @@ fresh_almostontop() {
   # CSI ESC[<num>B moves the cursor down <num> lines
   let "down = $LINES - $row"
   printf "\033[${down}B"
+  # Calculate the number of lines in the prompt
+  let "prompt_lines = ($row - $fresh_precmd_row) + 2"
   # Print new lines to push the old command out of view
-  let "new = $row - 3"
+  let "new = $row - $prompt_lines"
   for (( i = 0; i < $new; i++ )); do
     printf "\n"
   done
   # Move the cursor to the line below the prompt
   # CSI ESC[<num>A moves the cursor up <num> lines
-  let "up = $LINES - 3"
+  let "up = $LINES - $prompt_lines"
   printf "\033[${up}A"
 }