init.lua

print("Bens ESP8266 starting up!")
cfg={}
cfg.ssid="neu"
cfg.pwd="secretsharing"
print(cfg.ssid)
wifi.ap.config(cfg)
wifi.setmode(wifi.SOFTAP) --access point, broadcasts like a rounter
                          -- cfg = config settings for this
n = 100;  --Number of people needed to come together.  
          --Make this high so it's obvious it needs to be set
rem = 100;--Remaining entries needed.
calctable = {}  --Table for Neville's Algorithm
values = {}  --Table of points
bc = wifi.ap.getip()
print(bc) --192.158.4.1
srv=net.createServer(net.TCP)      --TCP Server on port 80
srv:listen(80,function(conn) 
    conn:on("receive",function(conn,payload) 
    print(payload)           --print each request over serial
    if (string.find(payload,"GET") == 1) then
     if (string.find(payload,"GET / HTTP") == 1) then --homepag
     if rem == 0 then
     conn:send("<h1>SUCCESS. SECRET: "..calctable[n-1][1].."</h1>")  --in case we're done!
     end
          conn:send("<h1> Hello, Agent.  "..rem.." more codes needed.</h1>") 
          conn:send("<form action='addvalue' method='post'>X-Value: <input type='text' name='xval'><br>Y-Value: <input type='text' name='yval'><br><input type='submit' value='Submit'></form>")
          conn:send([[<a href="/reset">RESET, NEW SECRET</a>]])        
     elseif (string.find(payload,"GET /reset HTTP") == 1) then --form to set new n/reset
          conn:send("<h1>Note: THIS WILL DELETE ALL PREVIOUSLY ENTERED POINTS</h1>")
          conn:send("<form action='setn' method='post'>New N needed: <input type='text' name='newn'><br><input type='submit' value='Submit'></form>"
     end
    end
    if (string.find(payload,"POST /setn HTTP") == 1) then --setting new n
    npos = string.find(payload,"newn=")
    numstr = string.sub(payload, npos+5, string.len(payload))
    n = tonumber(numstr)      --set n
    rem = n                   --set remaining = n, no points yet
    conn:send("<h1>Done.</h1>")
    conn:send([[<a href="/">Go Back</a>]])
    elseif (string.find(payload,"POST /addvalue HTTP") == 1) then --new point
         conn:send("<h1>Done.</h1>")
         conn:send([[<a href="/">Go Back</a>]])
         xpos = string.find(payload,"xval=") --these lines parse each coord
         ypos = string.find(payload,"yval=")
         xstr = string.sub(payload, xpos+5, ypos-2) --this makes sure we get all digits
         ystr = string.sub(payload, ypos+5, string.len(payload))
         print("xstr: "..xstr.." and ystr: "..ystr) --debug
         values[2*(n-rem)] = tonumber(xstr) --add the parsed values to our stack
         values[2*(n-rem) + 1] = tonumber(ystr)
         rem = rem - 1
         if rem == 0 then --in case we're done!
         calctable[0] = {}
         for i = 1,n do
         calctable[0][i] = values[2*(i-1) + 1] --send y values to caltable[0][1->n]
         print('i= '..i)
         print('vslue = '..values[2*(i-1) + 1])
         end
         for i = 1,(n-1) do -- Neville's algorithm, cycle through each column, index 0 to n-1
         calctable[i] = {} --make 2D
               for k = 1,n-i do --"triangle": further we go out, fewer rows calculated
                   calctable[i][k] = (values[2*(k+i-1)]*calctable[i-1][k] - values[2*(k-1)]*calctable[i-1][k+1])/(values[2*(k+i-1)] - values[2*(k-1)])  -- This implementation is a mess but it is working.  I should have indexed everything starting at 0, but oh well.  denom = (x[k+i] - x[k])
               end
         end
         conn:send("<h1>SUCCESS. SECRET: "..calctable[n-1][1].."</h1>") --Woohoo!

         end
    end

    end) 
end)