vim9script

def GetMatch(b: string, l: string): list<any>
    var s = b
    while stridx(l, s) == -1
        s = strpart(s, 1)
        if strlen(s) == 0
            return [0, ""]
        endif
    endwhile
    const idx = stridx(l, s)
    const slen = strlen(s)
    return [slen, b .. strpart(l, idx + slen)]
enddef

export def WholeLineCompl(f: bool, b: string): any
    if f
        return 0
    endif
    return getline(0, '$')
        ->sort()
        ->uniq()
        ->map( (_, v) => GetMatch(b, v) )
        ->sort( (x, y) => y[0] - x[0] )
        ->map( (_, v) => v[1] )
enddef

setlocal completefunc=WholeLineCompl