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

set baseUrl "http://0x0.st/"
set seed "XG8y"
set extensionListPlain [list ".txt" ".log" ".cpp" ".c" ".py" ".ini" ".json" ".yaml" ".tcl"]
set extensionListImage [list ".png" ".jpg" ".jpeg"]

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

proc stringFiniteArtimetric {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 [charFiniteArtimetric $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} {
    proc loggedGeturl {url} {
        puts -nonewline "Getting $url..."
        flush stdout
        .controls.url configure -text $url
        set r [http::geturl $url -timeout 1000]
        puts "done"

        return $r
    }

    .output.output_text delete 1.0 end

    foreach extension $::extensionListPlain {
        set url "$::baseUrl$page$extension"

        set response [loggedGeturl $url]

        if {[http::ncode $response] == 200} {
            puts "Page found."
            .output.output_text insert end [http::data $response]
            return 1
        }
    }

    foreach extension $::extensionListImage {
        set url "$::baseUrl$page$extension"

        set response [loggedGeturl $url]

        if {[http::ncode $response] == 200} {
            set image_data [http::data $response]
            set file_name "out$extension"
            set file_id [open $file_name "wb"]
            puts $file_id $image_data
            close $file_id
            .output.output_image delete all
            .output.output_image create image 0 0 -anchor nw -image [image create photo -file $file_name]
            return 1
        }
    }

    .output.output_text insert end "**Missing page**"
    return 0
}

proc previous {} {
    set ::seed [stringFiniteArtimetric $::seed - 1]
    return [get0x0page $::seed]
}

proc next {} {
    set ::seed [stringFiniteArtimetric $::seed + 1]
    return [get0x0page $::seed]
}

proc backward {} {
    while {![previous]} {}
}

proc forward {} {
    while {![next]} { }
}

proc resizeFont {i} {
    set font_size [lindex [split [.output.output_text cget -font] " "] 1]

    if {($i && $font_size >= 100) || (!$i && $font_size  <= 0)} {
        return
    }

    set font_size [expr $font_size + $i]
    .output.output_text configure -font "TkFixedFont $font_size"
}

wm title . "0x0.st peeper"

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

text .output.output_text -font "TkFixedFont 8"
bind .output.output_text <Control-Button-4> {resizeFont  1}
bind .output.output_text <Control-Button-5> {resizeFont -1}
pack .output.output_text -fill both -expand 1 -side left
canvas .output.output_image
pack .output.output_image -fill both -expand 1 -side left

scrollbar .output.output_scroll -orient vertical -command ".output yview"
pack .output.output_scroll -side right -fill y

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


get0x0page $::seed