term.header.v

pub fn header(otext, divider string) string {
    cols, _ := get_terminal_size()
    mut text := otext
    if text.len > 0 {
        text = ' $text '
    }
    // clip the text if it is too long
    text = if cols > text.len + 1 + 2*divider.len { text } else { text[0..cols-(1+2*divider.len)] }
    // make the text align with the terminal size:
    if (text.len % 2) != (cols % 2 ) {
        text += divider
    }
    filler := divider.repeat( (cols - text.len) / (2*divider.len) )
    return filler + text + filler
}

fn test_header(){
    divider := term.h_divider('-')
    term_width := divider.len

    empty_header := term.header('', '-')
    short_header := term.header('reasonable header', '-')
    very_long_header := term.header(['abc'].repeat(500).join(' '), '-')

    eprintln( empty_header )
    eprintln( short_header )
    eprintln(term.header('another longer header', '-+-'))
    eprintln(term.header('another longer header', '-'))
    eprintln(term.header('short','-'))
    eprintln(term.header('12345','-'))
    eprintln(term.header('1234','-'))
    eprintln(term.header('123','-'))
    eprintln(term.header('12','-'))
    eprintln(term.header('1','-'))
    eprintln( very_long_header )
    eprintln(term.header('','-'))

    assert term_width == empty_header.len
    assert term_width == short_header.len
    assert term_width == very_long_header.len
}

Produces:

--------------------------------------------------------------------------------
------------------------------ reasonable header -------------------------------
-+--+--+--+--+--+--+--+--+- another longer header -+--+--+--+--+--+--+--+--+--+-
---------------------------- another longer header -----------------------------
------------------------------------ short -------------------------------------
------------------------------------ 12345 -------------------------------------
------------------------------------- 1234 -------------------------------------
------------------------------------- 123 --------------------------------------
-------------------------------------- 12 --------------------------------------
-------------------------------------- 1 ---------------------------------------
- abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc --
--------------------------------------------------------------------------------

pub fn header(text, divider string) string {
    cols, _ := get_terminal_size()
    text_limit := if cols > text.len + 1 + 2*divider.len {
        text.len
    } else {
        cols-(1+2*divider.len)
    }
    text_limit_alligned := if (text_limit % 2) != (cols % 2 ) {
        text_limit + 1
    } else {
        text_limit
    }
    text_start := (cols - text_limit_alligned)/2
    filler_line := divider.repeat( 1 + cols / divider.len )[0..cols]
    result := if text.len == 0 {
        filler_line
    } else {
        filler_line[0..text_start-1] + ' ' + text[0..(text_limit)] + ' ' + filler_line[text_start+text_limit+1..cols]
    }
    return result
}

This one produces:

--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
------------------------------ reasonable header -------------------------------
_-/\_-/\_-/\_-/\_-/\_-/\_-/\ another longer header \_-/\_-/\_-/\_-/\_-/\_-/\_-/\
---------------------------- another longer header -----------------------------
------------------------------------ short -------------------------------------
------------------------------------ 12345 -------------------------------------
------------------------------------- 1234 -------------------------------------
------------------------------------- 123 --------------------------------------
-------------------------------------- 12 --------------------------------------
-------------------------------------- 1 ---------------------------------------
 abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc abc a -
 abcd abcd abcd abcd abcd abcd abcd abcd abcd abcd abcd abcd abcd abcd abcd ab -
--------------------------------------------------------------------------------