#!/usr/bin/tclsh
package require http
package require Tk

set top "XKic"

proc charArtimetric {char operator} {
    set asciiValue [scan $char %c]
    if {$operator == "+"} {
        if {$asciiValue == "z"} { return [list "A" 1] }
        if {$asciiValue == "Z"} { return [list "a" 1] }
    }
    if {$operator == "-"} {
        if {$asciiValue == "a"} { return [list "Z" 1] }
        if {$asciiValue == "A"} { return [list "z" 1] }
    }
    return [list [format %c [expr $asciiValue $operator 1]] 0]
}

proc stringArtimetric {str operator n} {
    set rReverse ""
    for {set carry 0; set i [expr [string length $str] - 1]} {$i >= 0} {incr i -1} {
        set c [string index $str $i]
        for {set h 0} {$h < [expr 1 + $carry]} {incr h} {
            set rc [charArtimetric $c $operator]
            set c [lindex $rc 0]
        }
        append rReverse $c
        if [lindex $rc 1] {
            set $carry 1
        } else {
            for {set h [expr $i - 1]} {$h >= 0} {incr h -1} {
                append rReverse [string index $str $h]
            }
            break
        }
    }
    set r [string reverse $rReverse]
    return $r
}

proc get0x0page {page} {
    set baseUrl "http://0x0.st/"
    set extensionList [list ".txt" ".log"]

    .output delete 1.0 end

    foreach extension $extensionList {
        set url ""
        append url $baseUrl $page $extension

        .controls.url configure -text $url
        set response [http::geturl $url]

        if {[http::ncode $response] == 200} {
            .output insert end [http::data $response]
            return
        }
    }

    .output insert end "**Missing page**"
}

proc previous {} {
    set ::top [stringArtimetric $::top - 1]
    get0x0page $::top
}

proc next {} {
    set ::top [stringArtimetric $::top + 1]
    get0x0page $::top
}

wm title . "0x0.st peeper"

text .output
pack .output -expand 1 -fill both

frame .controls
pack .controls -side bottom
button .controls.previous -text "Previous" -command previous
button .controls.next     -text "Next"     -command next
label .controls.url
pack .controls.previous -side left
pack .controls.next -side left
pack .controls.url -side right


get0x0page $::top