c4mate/c4mate

#!/bin/lua
--
-- c4mate: command line client for the C4 mukas instance (aka Mate-Pad).
--
-- Author: Shy
-- License: CC0

-- Enter your user name here:
USER = nil
HOST = "http://mate.labor.koeln.ccc.de"

function utf8_decode(str)
    -- Replace JSON Unicode escape sequences with chars.
    if str == nil then return "" end
    return string.gsub(str, "\\u(%x%x%x%x)",
        function (s) return utf8.char(tonumber(s, 16)) end)
end

function url_encode(str)
    -- URL-encode string. Used only for usernames.
    -- Todo: make this more sophisticated.
    return string.gsub(str, " ", "%%20")
end

MatePad = {
    CURL_FLAGS = "--silent --show-error --fail --user-agent 'c4mate' --max-redirs 0 --max-filesize 65536",
}
function MatePad:new(HOST, USER)
    local o = {
        HOST = HOST,
        USER = USER,
        COOKIE_JAR,
        balance
    }
    -- Metatable. Make garbage collector delete our temporary cookie jar.
    local m = {
        __index = self,
        __gc = function (f)
            if f.COOKIE_JAR ~= nil then os.remove(f.COOKIE_JAR) end
        end
    }
    return setmetatable(o, m)
end

-- Fetch response from given api endpoint.
function MatePad:fetch(api, data)
    local responce, curl, ok, exit, signal
    -- Set up cookie jar if not yet present.
    if self.COOKIE_JAR == nil then self.COOKIE_JAR = os.tmpname() end

    if data ~= nil then
        local flags = ""
        for k, v in pairs(data) do
            flags = string.format("%s --data-urlencode \"%s=%s\"", flags, k, v)
        end
        curl = io.popen(string.format(
            "curl %s --cookie \"%s\" --cookie-jar \"%s\" %s \"%s/%s\"",
            self.CURL_FLAGS, self.COOKIE_JAR, self.COOKIE_JAR, flags, self.HOST, api))
    else
        curl = io.popen(string.format(
            "curl %s --cookie \"%s\" --cookie-jar \"%s\" \"%s/%s\"",
            self.CURL_FLAGS, self.COOKIE_JAR, self.COOKIE_JAR, self.HOST, api))
    end
    responce = curl:read("a")

    ok, exit, signal = curl:close()
    if not ok then
        if exit == "signal" then
            io.stderr:write("Error: 'curl' received signal "..signal..".\n")
        else
            io.stderr:write("Error: 'curl' returned exit code "..signal..". ")
            if signal == 22 then
                io.stderr:write("Maybe incorrect username?\n")
            else
                io.stderr:write("\n")
            end
        end
    end
    return responce
end

-- Initialize session.
function MatePad:init()
    self.token = self:fetch("api/csrf_token")
    -- Todo: check token.
end

-- Update user balance.
function MatePad:update_balance()
    self.balance = self:fetch("api/user/"..url_encode(self.USER).."/balance?_csrf_token="..self.token)
    return self.balance ~= ""
end

-- Parse history.
function MatePad:parse_log()
    local pipe, ok, exit, signal
    local datefile = os.tmpname()
    local log = {}
    -- sed #1: Insert newlines between log entries.
    -- sed #2: Extract time and write it into datefile. Then extract and print
    -- oldbalance, newbalance, parameter and method. Depending on method, print
    -- either reason or item_name. If any extraction fails we fail with exit
    -- code 1.
    pipe = io.popen(string.format([=[
curl %s --header "Accept: application/json" "%s/api/user/%s/log?type=json" | \
sed -n --sandbox '
    /.*\[\([^]]*\)\].*/{
        s//\1/
        s/} *,/&\n/gp
    }' | \
sed -n '
    h
    s/.*"time" *: *"\([^"]\+\)".*/\1UTC/
    T fail
    w %s
    g
    s/.*"oldbalance" *: *\(-\?[0-9]\+\).*/\1/p
    T fail
    g
    s/.*"newbalance" *: *\(-\?[0-9]\+\).*/\1/p
    T fail
    g
    s/.*"parameter" *: *\([0-9]\+\).*/\1/p
    T fail
    g
    s/.*"method" *: *"\([^"]\+\)".*/\1/p
    T fail
    /set_balance\|transfer/{
        g
        s/.*"reason" *: *\(null\|"\([^"]*\)"\).*/\2/p
        T fail
        b
    }
    g
    s/.*"item_name" *: *\(null\|"\([^"]*\)"\).*/\2/p
    T fail
    b
    :fail
    q 1 ']=], self.CURL_FLAGS, self.HOST, url_encode(self.USER), datefile))

    while true do
        local entry = {}
        local oldbalance = tonumber(pipe:read("l"))
        if oldbalance == nil then break end
        entry.oldbalance = oldbalance
        entry.newbalance = tonumber(pipe:read("l"))
        entry.parameter = tonumber(pipe:read("l"))
        entry.method = pipe:read("l")
        if entry.method == "buy" or entry.method == "recharge" then
            entry.name = utf8_decode(pipe:read("l"))
        else
            -- set_balance, transferTo, transferFrom
            entry.reason = utf8_decode(pipe:read("l"))
        end
        table.insert(log, entry)
    end

    -- Check pipe exit status.
    ok, exit, signal = pipe:close()
    if not ok then -- sed error
        io.stderr:write("Sorry, there was an error while parsing the API response.\n")
        -- An empty log will throw no further exceptions.
        log = {}
    elseif log == {} then -- curl error
        io.stderr:write("Sorry, there was an error while connecting the API.\n")
    end

    -- Convert timestamps to local time.
    local timestamps = io.popen("date -f "..datefile.." +'%_c'")
    for i = 1, #log do
        log[i].time = timestamps:read("l")
    end

    -- Check date exit code.
    ok, exit, signal = timestamps:close()
    os.remove(datefile)
    if not ok then
        io.stderr:write(string.format(
            "Warning: 'date' exited with non-zero exit code (%s/%s).\n",
            exit, signal))
    end
    return log
end

-- Print given history.
function MatePad:print_log(log)
    local event
    for i = #log, 1, -1 do
        event = log[i]
        if event.method == "buy" or event.method == "recharge" then
            print(string.format(
                "[%s] Bought %s (#%d)",
                event.time, event.name, event.parameter
            ))
        elseif event.method == "set_balance" then
            print(string.format(
                "[%s] Set balance from %.2f € to %.2f €",
                event.time, event.oldbalance/100, event.newbalance/100
            ))
        elseif event.method == "transferTo" then
            print(string.format(
                "[%s] Transferred %.2f € to #%d (%s)",
                event.time, (event.oldbalance - event.newbalance)/100,
                event.parameter, event.reason
            ))
        elseif event.method == "transferFrom" then
            print(string.format(
                "[%s] Received %.2f € from #%d (%s)",
                event.time, (event.newbalance - event.oldbalance)/100,
                event.parameter, event.reason
            ))
        else
            print("Warning: unknown event \""..event.method.."\".")
        end
    end
end

-- Get available items.
function MatePad:get_roster()
    local pipe, ok, exit, signal
    local roster = {}
    -- sed #1: Extract items section and insert newlines between entries.
    -- sed #2: Extract and print id, name and price. If any extraction fails we
    -- fail with exit code 1.
    pipe = io.popen(string.format([=[
curl %s --header "Accept: application/json" "%s/api/items" | \
sed -n --sandbox '
    /.*"items": *\[\( *{.*}\)*\].*/{
        s//\1/
        s/} *,/&\n/gp
    }' | \
sed -n --sandbox '
    h
    s/.*"id" *: *\([0-9]\+\).*/\1/p
    T fail
    g
    s/.*"name" *: *"\([^"]*\)".*/\1/p
    T fail
    g
    s/.*"price" *: *\(-\?[0-9]\+\).*/\1/p
    T fail
    b
    :fail
    q 1 ']=], self.CURL_FLAGS, self.HOST))

    while true do
        local item = {}
        item.id = tonumber(pipe:read("l"))
        if item.id == nil then break end
        item.name = utf8_decode(pipe:read("l"))
        item.price = tonumber(pipe:read("l"))
        table.insert(roster, item)
    end

    ok, exit, signal = pipe:close()
    if not ok then -- sed error
        io.stderr:write("Sorry, there was an error while parsing the API response.\n")
        -- Empty table will throw no exceptions.
        return {}
    elseif roster == nil then -- curl error
        io.stderr:write("Sorry, there was an error while connecting the API.\n")
        return {}
    end
    return roster
end

-- Buy given item.
function MatePad:buy(id)
    return self:fetch(string.format(
        "api/user/%s/buy/%d?_csrf_token=%s",
        url_encode(self.USER), id, self.token))
end

-- Set new balance (in cents).
function MatePad:set_balance(amount)
    return self:fetch(string.format(
        "api/user/%s/balance?_csrf_token=%s",
        url_encode(self.USER), self.token),
        {newbalance = amount})
end

-- Transfer credits to given user.
function MatePad:give(amount, recipient, reason)
    return self:fetch(string.format(
        "api/user/%s/transfer?_csrf_token=%s",
        url_encode(self.USER), self.token),
        {
            recipient = recipient,
            amount = amount,
            reason = reason or ""
        })
end

-- Process help and username options.
if arg[1] == "-h" or
   arg[1] == "--help" then
    -- Usage.
    print([=[
Usage: c4mate [-u <user>] [ <query> | -b <id> | -l | +/-<amount> | -g <amount> <user> [<reason>]]
Display current balance:
    c4mate
Find and buy item (interactive):
    c4mate <query>
Buy by item id (non-interactive):
    c4mate -b|--buy <id>
Show log:
    c4mate -l|--log
Add or subtract credits:
    c4mate <difference>
Give credits:
    c4mate -g <amount> <user> [<reason>]]=])
    os.exit(0)
end

-- Parse -u flag (which may be given multiple times).
while arg[1] == "-u" do
    table.remove(arg, 1)
    USER = arg[1]
    table.remove(arg, 1)
end

-- Set up username.
if USER == nil then
    USER = os.getenv("USER")
    if USER == nil then
        io.stderr:write("Error: no username given and $USER environment variable empty!\n")
        os.exit(1)
    end
end
pad = MatePad:new(HOST, USER)

if arg[1] == nil then
    -- Print balance.
    pad:init()
    if pad:update_balance() then
        print(string.format(
            "Balance of user %s: %.2f €", pad.USER, pad.balance/100))
    end

elseif arg[1] == "-l" or
       arg[1] == "--log" then
    -- Print log.
    pad:print_log(pad:parse_log())

elseif arg[1] == "-g" or
       arg[1] == "--give" then
    -- Give.
    local amount = tonumber(arg[2])
    local recipient = arg[3]
    local reason = table.concat(arg, " ", 4)
    if amount == nil or recipient == nil then
        print("Error: could not parse amount and/or recipient.")
        print("Usage: c4mate --give <amount> <user> [<reason>]")
        return
    end

    pad:init()
    local ok = pad:give(amount, recipient, reason)

    if ok == "OK" then
        pad:update_balance()
        print(string.format(
            "%.2f € transferred from %s to %s.\nNew balance of user %s: %.2f €",
            amount, pad.USER, recipient, pad.USER, pad.balance/100))
    else
        print("Sorry, there was an error. ("..ok..")")
    end

elseif arg[1] == "-b" or arg[1] == "--buy" then
    local id = tonumber(arg[2])
    if id == nil then
        print("Usage: c4mate --buy <id>")
        return
    end

    pad:init()
    if pad:buy(id) == "OK" then
        pad:update_balance()
        print(string.format(
            "Bought #%s. New balance: %.2f €.",
            id, pad.balance/100))
    else
        print("Error while attempting to buy product #"..id..".")
    end

elseif tonumber(arg[1]) ~= nil then
    -- Add to (or subtract from) balance.
    pad:init()
    if pad:update_balance() then
        new = math.tointeger(pad.balance + tonumber(arg[1])*100)
        if pad:set_balance(new) == "OK" then
            pad:update_balance()
            print(string.format(
                "New balance of user %s: %.2f €", pad.USER, pad.balance/100))
        else
            print("Sorry, something went wrong. (Unexpected reply from API.)")
        end
    end

else
    -- Find and buy item.
    local roster, query, input, ok
    roster = pad:get_roster()
    query = string.lower(table.concat(arg, " "))
    local menu = {}

    for i = 1, #roster do
        local item = roster[i]
        if string.match(string.lower(item.name), query) then
            table.insert(menu, item)
        end
    end
    if #menu == 0 then
        print("Sorry, no matching item found.")
    else
        print("Press [y] to accept, [n] for next or anything else to cancel:")
    end

    -- Sort menu by id.
    table.sort(menu, function (e1, e2) return e1.id < e2.id end)

    -- Check if we can invoke stty.
    is_tty = os.execute("tty -s") == true

    for i, item in ipairs(menu) do
        io.stdout:write(string.format("[%d/%d] Buy %s (#%d) for %.2f €? ",
            i, #menu, item.name, item.id, item.price/100))

        -- Turn off canonical mode, so we can read a char without the user
        -- having to press enter.
        if is_tty then os.execute("stty -icanon") end
        ok, input = pcall(io.read, 1)
        if is_tty then os.execute("stty icanon") end

        if not ok then break end -- ^C
        if input == "y" then
            pad:init()
            if pad:buy(item.id) == "OK" then
                pad:update_balance()
                print(string.format(
                    "\nBought %s. New balance: %.2f €.",
                    item.name, pad.balance/100))
            end
            break
        elseif input == "n" then print() -- force newline
        elseif input ~= "\n" then
            print("\nCancelled.")
            break
        end
    end
end