local chest = peripheral.find("chest")
local me = peripheral.find("aemultipart")
local mon = peripheral.find("monitor")
local dataMax = 300
local readsPerSecond = 2
local items = {}

local resolution = "min"
local scale = 60

local endings = {"K","M","B","T","Q","WTF"}

local timer = os.startTimer(1/readsPerSecond)

function linReg(data)
    if #data == 0 then return 0,0 end
    local i
    local x,y,x2,y2,xy = 0,0,0,0,0
    for i=1,#data do
        x = x + i
        y = y + data[i]
        x2 = x2 + i*i
        y2 = y2 + data[i]*data[i]
        xy = xy + i*data[i]
    end
    local a,b = (x*x2-x*xy)/(#data*x2-x*x),(#data*xy-x*y)/(#data*x2-x*x)
    if a ~= a then a = 0 end
    if b ~= b then b = 0 end
    return a,b
end

function buildItemList()
    chest = peripheral.find("chest")
    me = peripheral.find("aemultipart")
    if not chest or not me then
        return
    end
    local list = {}
    local stacks = chest.getAllStacks()
    for k,v in pairs(stacks) do
        local a = v.all()
        local data = {
            current = -1,
            slope = 0,
            name = a.display_name,
            id = a.id,
            dmg = a.dmg,
            count = {}
        }
        if items and items[a.dmg.."~"..a.id] then
            data.count = items[a.dmg.."~"..a.id].count
        end
        if #data.count >= dataMax then table.remove(data.count,1) end
        local value = nil
        local ok = pcall(function() value = me.getItemDetail(a) end)
        if ok then
            data.current = value.basic().qty
        end
        table.insert(data.count,data.current)
        local b,m = linReg(data.count)
        data.slope = m
        list[a.dmg.."~"..a.id] = data
    end
    items = list
end

function round(n)
    if n%2 ~= 0.5 then
        return math.floor(n+0.5)
    end
    return n-0.5
end

function adjustNumber(n)
    if n == 0 then return 0 end
    local d = math.floor(math.log10(math.abs(n)))+1
    local adj = 4
    if d > 4 or d < 2 then adj = 3 end
    n = math.floor(n/math.pow(10,d-adj))*math.pow(10,d-adj)
    if d > 4 then n = (n * math.pow(10,-math.floor((d-1)/3)*3))..(endings[math.floor((d-1)/3)] or "") end
    return n
end

function getScaledSlope(slope)
    return round(slope*readsPerSecond*getScale()*100)/100
end

function getScale()
    return scale
end

function getScaledUnits()
    return resolution
end

function showStats()
    term.redirect(mon)
    local r=1
    local w,h = term.getSize()
    for k,v in pairs(items) do
        term.setCursorPos(1,r)
        if #v.count < dataMax/3 then
            term.setTextColor(colors.gray)
        elseif #v.count < dataMax*2/3 then
            term.setTextColor(colors.lightGray)
        else
            term.setTextColor(colors.white)
        end
        term.clearLine()
        term.write(#v.count.." ")
        term.setCursorPos(5,r)
        if term.isColor() then term.setTextColor(colors.yellow) else term.setTextColor(colors.white) end
        term.write(v.name..": ")
        term.setTextColor(colors.white)
        term.write(adjustNumber(v.current).." ")
        if term.isColor() then term.setTextColor(colors.red) else term.setTextColor(colors.lightGray) end
        term.write("("..adjustNumber(getScaledSlope(v.slope)).." / "..getScaledUnits()..")")
        r = r + 1
    end
    while r <= h do
        term.setCursorPos(1,r)
        term.clearLine()
        r = r + 1
    end
    term.setTextColor(colors.white)
    term.setCursorPos(2,h)
    term.write("^")
    term.setCursorPos(5,h)
    term.write("v")
    if getScaledUnits() == "sec" then term.setTextColor(colors.green) else term.setTextColor(colors.red) end
    term.setCursorPos(w-15,h)
    term.write("sec")
    if getScaledUnits() == "min" then term.setTextColor(colors.green) else term.setTextColor(colors.red) end
    term.setCursorPos(w-9,h)
    term.write("min")
    if getScaledUnits() == "hr" then term.setTextColor(colors.green) else term.setTextColor(colors.red) end
    term.setCursorPos(w-3,h)
    term.write("hr")
end

while true do
    event = {os.pullEvent()}
    if event[1] == "monitor_touch" then
        local x,y = event[3],event[4]
        local w,h = mon.getSize()
        term.setCursorPos(x,y)
        term.write("o")
        if y == h and x >= 1 and x <= 3 then
                --scroll up
        elseif y == h and x >= 4 and x <= 6 then
                --scroll down
        elseif y == h and x >= w-16 and x <= w - 12 then
            resolution = "sec"
            scale = 1
        elseif y == h and x >= w-10 and x <= w - 6 then
            resolution = "min"
            scale = 60
        elseif y == h and x >= w - 4 and x <= w then
            resolution = "hr"
            scale = 3600
        end
    elseif event[1] == "timer" then
        if event[2] == timer then
            buildItemList()
            showStats()
            timer = os.startTimer(1/readsPerSecond)
        end
    end
end