sethmc student.lua

local modem = peripheral.find("modem")
if not modem then error("No modem found. Please attach a wireless modem.") end

modem.open(1) -- Use channel 1 for all communications

local function encrypt(text)
    local result = ""
    for i = 1, #text do
        result = result .. string.char((string.byte(text, i) + 5) % 256)
    end
    return result
end

local function decrypt(text)
    local result = ""
    for i = 1, #text do
        result = result .. string.char((string.byte(text, i) - 5) % 256)
    end
    return result
end

local function saveUsername(username)
    local file = fs.open(".userdata", "w")
    file.write(encrypt(username))
    file.close()
end

local function loadUsername()
    if fs.exists(".userdata") then
        local file = fs.open(".userdata", "r")
        local encryptedUsername = file.readAll()
        file.close()
        return decrypt(encryptedUsername)
    end
    return nil
end

local function sendRequest(request, expectedType)
    modem.transmit(1, 1, request)
    local timer = os.startTimer(5)
    while true do
        local event, param1, _, _, message = os.pullEvent()
        if event == "modem_message" and type(message) == "table" then
            if expectedType then
                if message.type == expectedType then return message end
                if message.type == "error" then return message end
            else
                if message.type then return message end
            end
        elseif event == "timer" and param1 == timer then
            return nil
        end
    end
end

local function createAccount()
    print("Enter new student ID:")
    local newId = read()
    print("Enter password:")
    local password = read("*")
    local response = sendRequest({type = "create_account", studentId = newId, password = password}, "account_response")
    if response and response.success then
        print(response.message)
        saveUsername(newId)
        return newId
    else
        print(response and response.message or "Failed to create account")
        return nil
    end
end

local function login(savedUsername)
    local username = savedUsername
    if not username then
        print("Enter your student ID:")
        username = read()
    else
        print("Logged in as: " .. username)
    end
    print("Enter your password:")
    local password = read("*")
    local response = sendRequest({type = "login", studentId = username, password = password}, "login_response")
    if response and response.success then
        print(response.message)
        saveUsername(username)
        return username, password
    else
        print(response and response.message or "Login failed")
        return nil, nil
    end
end

local function showNews()
    local response = sendRequest({type = "get_news"})
    if response and response.type == "news" then
        print("\nNews:")
        print(response.content)
    else
        print("Failed to retrieve news")
    end
end



local function checkBalance(studentId, password)
    local response = sendRequest({type = "get_balance", studentId = studentId, password = password})
    if response and response.type == "balance_response" then
        print("\nYour balance: " .. response.balance .. " Eddies")
    else
        print("Failed to retrieve balance")
    end
end

local function transferMoney(studentId, password)
    print("Enter recipient's student ID:")
    local recipientId = read()

    -- Verify recipient exists
    local response = sendRequest({type = "verify_student", recipientId = recipientId})
    if not response or not response.exists then
        print("Recipient does not exist.")
        return
    end

    print("Enter amount to transfer:")
    local amount = tonumber(read())
    if not amount or amount <= 0 then
        print("Invalid amount.")
        return
    end

    -- Verify sufficient funds
    local balanceResponse = sendRequest({type = "get_balance", studentId = studentId, password = password})
    if not balanceResponse or not balanceResponse.balance then
        print("Failed to retrieve balance.")
        return
    end

    local balance = tonumber(balanceResponse.balance)
    if balance < amount then
        print("Insufficient funds.")
        return
    end

    -- Send transfer request
    local transferResponse = sendRequest({
        type = "transfer_money",
        studentId = studentId,
        password = password,
        recipientId = recipientId,
        amount = amount
    })

    if transferResponse and transferResponse.success then
        print("Transfer successful. New balance: " .. transferResponse.newBalance)
    else
        print("Transfer failed: " .. (transferResponse and transferResponse.message or "Unknown error"))
    end
end

local function composeEmail(studentId, password, recipientId, subject, body)
    if not recipientId then
        print("Enter Recipient ID:")
        recipientId = read()
    end
    if not subject then
        print("Enter Subject:")
        subject = read()
    end
    if not body then
        print("Enter Body:")
        body = read()
    end

    local response = sendRequest({
        type = "send_email",
        studentId = studentId,
        password = password,
        recipientId = recipientId,
        subject = subject,
        body = body
    })

    if response and response.success then
        print("Email sent successfully!")
    else
        print("Failed to send email: " .. (response and response.message or "Unknown error"))
    end
end

local function deleteEmail(studentId, password, index)
    local response = sendRequest({
        type = "delete_email",
        studentId = studentId,
        password = password,
        emailIndex = index
    })
    if response and response.success then
        print("Email deleted.")
        return true
    else
        print("Failed to delete email: " .. (response and response.message or "Unknown error"))
        return false
    end
end

local function readEmail(studentId, password, email, index)
    print("\n--- Email ---")
    print("From: " .. email.sender)
    print("Date: " .. os.date("%Y-%m-%d %H:%M", email.timestamp / 1000)) -- approximate conversion if needed, or just display raw
    print("Subject: " .. email.subject)
    print("----------------")
    print(email.body)
    print("----------------")

    while true do
        print("\n1. Reply")
        print("2. Forward")
        print("3. Delete")
        print("4. Back to Inbox")
        local choice = read()

        if choice == "1" then
            composeEmail(studentId, password, email.sender, "Re: " .. email.subject)
        elseif choice == "2" then
            print("Enter recipient to forward to:")
            local fwdRecipient = read()
            composeEmail(studentId, password, fwdRecipient, "Fwd: " .. email.subject, email.body)
        elseif choice == "3" then
            if deleteEmail(studentId, password, index) then
                return -- Go back to inbox refresh
            end
        elseif choice == "4" then
            return
        end
    end
end

local function showInbox(studentId, password)
    while true do
        local response = sendRequest({type = "get_inbox", studentId = studentId, password = password})
        if response and response.type == "inbox_response" then
            local emails = response.emails
            if #emails == 0 then
                print("\nInbox is empty")
                print("1. Compose")
                print("2. Back")
                local choice = read()
                if choice == "1" then composeEmail(studentId, password)
                elseif choice == "2" then break end
            else
                print("\n--- Inbox ---")
                for i, email in ipairs(emails) do
                    print(string.format("%d. [%s] %s", i, email.sender, email.subject))
                end
                print("\n1. Read Email")
                print("2. Compose")
                print("3. Back")
                local choice = read()
                if choice == "1" then
                    print("Enter email number:")
                    local idx = tonumber(read())
                    if idx and emails[idx] then
                        readEmail(studentId, password, emails[idx], idx)
                    else
                        print("Invalid email number")
                    end
                elseif choice == "2" then
                    composeEmail(studentId, password)
                elseif choice == "3" then
                    break
                end
            end
        else
            print("Failed to retrieve inbox")
            break
        end
    end
end

local function showPhonebook()
    local response = sendRequest({type = "get_phonebook"}, "phonebook_response")
    if not response or not response.students then
        print("Failed to retrieve phonebook")
        return
    end

    local students = response.students
    if #students == 0 then
        print("\nPhonebook is empty")
        print("Press any key to continue...")
        read()
        return
    end

    local _, screenHeight = term.getSize()
    local itemsPerPage = screenHeight - 6 -- Leave room for header and footer
    if itemsPerPage < 5 then itemsPerPage = 5 end

    local currentPage = 1
    local totalPages = math.ceil(#students / itemsPerPage)

    while true do
        term.clear()
        term.setCursorPos(1, 1)
        print("=== Phonebook ===")
        print("Page " .. currentPage .. " of " .. totalPages .. " (" .. #students .. " students)")
        print("")

        local startIdx = (currentPage - 1) * itemsPerPage + 1
        local endIdx = math.min(startIdx + itemsPerPage - 1, #students)

        for i = startIdx, endIdx do
            print("  " .. students[i])
        end

        print("")
        local navOptions = ""
        if currentPage > 1 then navOptions = navOptions .. "[P]rev " end
        if currentPage < totalPages then navOptions = navOptions .. "[N]ext " end
        navOptions = navOptions .. "[B]ack"
        print(navOptions)

        local choice = read():lower()
        if choice == "p" and currentPage > 1 then
            currentPage = currentPage - 1
        elseif choice == "n" and currentPage < totalPages then
            currentPage = currentPage + 1
        elseif choice == "b" then
            break
        end
    end
end

local function showEconomy()
    local response = sendRequest({type = "get_economy"}, "economy_response")
    if not response then
        print("Failed to retrieve economy data")
        return
    end

    term.clear()
    term.setCursorPos(1, 1)
    print("=== Economy Stats ===")
    print("")
    print("GDP (Total Eddies): " .. (response.gdp or 0))
    print("")
    print("--- Top 5 Richest ---")

    if response.top5 and #response.top5 > 0 then
        for i, entry in ipairs(response.top5) do
            print(i .. ". " .. entry.name .. " - " .. entry.balance .. " Eddies")
        end
    else
        print("  No data available")
    end

    print("")
    print("Press any key to continue...")
    read()
end

-- Main program
-- GPS Background Task
local function gpsSender()
    local studentId = loadUsername() -- Initial load
    while true do
        -- Update ID in case of login change
        studentId = loadUsername()

        if studentId then
            local x, y, z = gps.locate(5) -- 5 second timeout
            if x and y and z then
                modem.transmit(1, 1, {
                    type = "track_location",
                    studentId = studentId,
                    x = math.floor(x),
                    y = math.floor(y),
                    z = math.floor(z)
                })
            end
        end

        sleep(30) -- Send every 30 seconds
    end
end

-- Main Application wrapper
local function mainApp()
    while true do
        local studentId = loadUsername()
        local password
        if not studentId then
            print("\n1. Create Account")
            print("2. Login")
            print("3. Exit")
            local choice = read()
            if choice == "1" then
                studentId = createAccount()
            elseif choice == "2" then
                studentId, password = login()
            elseif choice == "3" then
                break
            end
        else
            studentId, password = login(studentId)
        end

        if studentId and password then
            while true do
                print("\n1. Show News")
                print("2. Check Balance")
                print("3. Transfer Money")
                print("4. Email")
                print("5. Phonebook")
                print("6. Economy")
                print("7. Logout")
                local choice = read()
                if choice == "1" then
                    showNews()
                elseif choice == "2" then
                    checkBalance(studentId, password)
                elseif choice == "3" then
                    transferMoney(studentId, password)
                elseif choice == "4" then
                    showInbox(studentId, password)
                elseif choice == "5" then
                    showPhonebook()
                elseif choice == "6" then
                    showEconomy()
                elseif choice == "7" then
                    break
                end
            end
        end
    end
end

-- Run both in parallel
parallel.waitForAny(mainApp, gpsSender)