Lua Pastebin in OOP for ComputerCraft

--[[ This is a Lua object to handle interacting with the Pastebin API via HTTP.

    To use this in a program do the following (assuming this file is in the CraftOS root directory)
        class = assert(loadfile("pastebin_obj"))
        class()
        Object = Pastebin:new()

    Member functions can now be called by doing Object:function(arg1,arg2,...)
    Member variables can be set and accessed with Object.member_variable

    See http://www.computercraft.info/forums2/index.php?/topic/8393-oop-in-lua/ for more info on the OOP practices
    See http://www.computercraft.info/forums2/index.php?/topic/10450-handling-errors-creating-controlled-errors-creating-a-bsod/
        for information on how to handle errors.

    WHAT THIS THING CAN DO
        Gets a user API key from Pastebin.com so the user can be logged in
        allows you to create pastes (anonymously, and under a username, some arguments require the user to be logged in)
        allows you to get a paste from Pastebin.com as a fs.open() handle
        allows you to get a raw XML list of a users posts off Pastebin.com as a fs.open() handle (must be logged in)
        allows you to get a list of a users posts in table form (must be logged in)
        allows you to delete a paste (must be logged in)
]]

Pastebin = {}
Pastebin.__index = Pastebin

-- Member variables being declared

Pastebin.api_dev_key = ""
Pastebin.api_user_key = ""

-- Member functions

-- Constructor
function Pastebin.new(self, dev_key)
    if not http then
        error("Error constructing Pastebin object. Pastebin requires http API. Set enableAPI_http to 1 in mod_ComputerCraft.cfg")
    end
    local PastebinObject = {}
    setmetatable(PastebinObject, Pastebin)
    self.api_dev_key = dev_key
    return PastebinObject
end

-- This attempts to get an API key for the user and returns true on success, false on failure.
function Pastebin.login(self, user_name, user_password)
    local response = http.post(
        "http://pastebin.com/api/api_login.php",
        "api_dev_key="..textutils.urlEncode(self.api_dev_key).."&"..
        "api_user_name="..textutils.urlEncode(user_name).."&"..
        "api_user_password="..textutils.urlEncode(user_password)
    )
    if response then
        local sResponse = response.readAll()
        response.close()
        self.api_user_key = string.match(sResponse,"[^/]+$")
        return true
    else
        return false
    end
end

-- gets a raw paste off Pastebin, and returns it.
-- Returns a http handle that uses handle.close(), handle.readLine() and handle.readAll() to work with.
-- be sure to close the handle when you're done!
function Pastebin.get_raw(self, sCode)
    local response = http.get("http://pastebin.com/raw.php?i="..textutils.urlEncode(sCode))
    if response then
        -- the response should be saved in a member variable, and a bool returned
        return response
    else
        error("Bad response from Pastebin.com. Unable to get data.")
    end
end

-- same as put(), but paste_code is replaced by a file path.
function Pastebin.put_file(...)

    local args = { ... }
    local self = args[1]
    local sPath = args[2]
    local paste_name = args[3] or ""
    local paste_format = args[4] or "text"
    local paste_private = args[5] or "0"
    local paste_expire_date = args[6] or "N"

    if #args < 2 or #args > 6 then
        error("Invalid number of arguments provided to Pastebin.put()")
    end

    if not fs.exists( sPath ) or fs.isDir( sPath ) then
        error( "No such file" )
    end

    -- Read in the file
    local sName = fs.getName( sPath )
    local file = fs.open( sPath, "r" )
    local sText = file.readAll()
    file.close()

    return self:put(sText,paste_name,paste_format,paste_private,paste_expire_date)

end

-- used to put stuff on pastebin
--[[ argument format is Obj.put(paste_code, paste_name, paste_format, paste_private, paste_expire)
    paste_code is the text of the paste (required)
    paste_name is the name of the paste (optional, use "" to leave blank)
    paste_format is the syntax highlighting, which is "text" by default (see Pastebin.com API documentation for other options)
    paste_private is the privacy code, which is "0" by default (0=public, 1=unlisted, 2=private, if using 2 then you must be logged in before calling this function)
    paste_expire is the expire for the paste (see Pastebin.com API documentation for other options)
    http://pastebin.com/api
    returns the code of the created paste
]]

function Pastebin.put(...)
    local args = { ... }
    local self = args[1]
    local paste_code = args[2]
    local paste_name = args[3] or ""
    local paste_format = args[4] or "text"
    local paste_private = args[5] or "0"
    local paste_expire_date = args[6] or "N"

    if #args < 2 or #args > 6 then
        error("Invalid number of arguments provided to Pastebin.put()")
    end

    if paste_code == "" then
        error("No paste_code provided to Pastebin.put method.")
    end

    local url = "http://pastebin.com/api/api_post.php"

    local params = "api_dev_key="..textutils.urlEncode(self.api_dev_key).."&"..
                    "api_option=paste&"..
                    "api_paste_code="..textutils.urlEncode(paste_code)

    if self.api_user_key ~= "" then
        params = params.."&api_user_key="..textutils.urlEncode(self.api_user_key)
    end

    if paste_name ~= "" then
        params = params.."&api_paste_name="..textutils.urlEncode(paste_name)
    end

    params = params.."&api_paste_format="..textutils.urlEncode(paste_format)

    if paste_private == "0" then
        -- do nothing
    elseif paste_private == "1" then
        params = params.."&api_paste_private="..textutils.urlEncode(paste_private)
    elseif paste_private == "2" then
        if self.api_user_key ~= "" then
            params = params.."&api_paste_private="..textutils.urlEncode(paste_private)
        else
            error("User must be logged in before they can create a private paste.")
        end
    else
        error("Invalid value provided to Pastebin.put(). paste_private can be the string 0, 1, or 2.")
    end

    if paste_expire_date ~= "N" and paste_expire_date ~= "10M" and paste_expire_date ~= "1H" and paste_expire_date ~= "1D" and paste_expire_date ~= "1W" and paste_expire_date ~= "2W" and paste_expire_date ~= "1M" then
        error("Invalid argument provided to Pastebin.put(). paste_expire date can be N, 10M, 1H, 1D, 1W, 2W, or 1M.")
    else
        params = params.."&api_paste_expire="..textutils.urlEncode(paste_expire_date)
    end

    local response = http.post(url,params)
    if response then
        local sResponse = response.readAll()
        response.close()
        return string.match(sResponse,"[^/]+$")
    else
        error("Bad response from Pastebin. Unable to put data on server.")
    end

end

-- fetches and returns the list of posts for the logged in user. Returns a http handle that uses handle.close(), handle.readLine() and handle.readAll() to work with.
-- be sure to close the handle when you're done!
function Pastebin.list_raw(self,results_limit)
    if self.api_user_key == "" then
        error("User must be logged in before attempting to retrieve list of pastes.")
    end

    local sLimit = results_limit or "50"
    if sLimit ~= "50" then
        if tonumber(sLimit) < 1 or tonumber(sLimit) > 1000 then
            error("Invalid argument provided to Pastebin.list(). results_limit must be a string integer between 1 and 1000.")
        end
    end

    local params = "api_dev_key="..textutils.urlEncode(self.api_dev_key).."&api_user_key="..textutils.urlEncode(self.api_user_key).."&api_option=list&api_results_limit="..textutils.urlEncode(sLimit)

    local response = http.post("http://pastebin.com/api/api_post.php",params)
    if response then
        -- the response should be saved in a member variable, and a bool returned.
        return response
    else
        error("Bad response from Pastebin. Unable to retirieve list.")
    end
end

--gets a list of a users posts, and returns it in a 2-dimensional table.
function Pastebin.list_table(self, results_limit)
    local tResult = {}
    local raw_list = self:list_raw(results_limit)
    local index = 0
    local sLine = raw_list.readLine()
    while sLine do
        tResult[index] = {}
        tResult[index]["paste_key"] = string.sub(raw_list.readLine(),12,-13)
        tResult[index]["paste_date"] = string.sub(raw_list.readLine(),13,-14)
        tResult[index]["paste_title"] = string.sub(raw_list.readLine(),14,-15)
        tResult[index]["paste_size"] = string.sub(raw_list.readLine(),13,-14)
        tResult[index]["paste_expire_date"] = string.sub(raw_list.readLine(),20,-21)
        tResult[index]["paste_private"] = string.sub(raw_list.readLine(),16,-17)
        tResult[index]["paste_format_long"] = string.sub(raw_list.readLine(),20,-21)
        tResult[index]["paste_format_short"] = string.sub(raw_list.readLine(),21,-22)
        tResult[index]["paste_url"] = string.sub(raw_list.readLine(),12,-13)
        tResult[index]["paste_hits"] = string.sub(raw_list.readLine(),13,-14)
        sLine = raw_list.readLine()
        sLine = raw_list.readLine()
        index = index + 1
    end
    raw_list.close()
    return tResult
end

-- deletes a paste off Pastebin.com (must be logged in)
function Pastebin.delete(self,code)

    if self.api_user_key == "" then
        print("User must be logged in before attempting to delete a paste.")
    end

    local url = "http://pastebin.com/api/api_post.php"
    local params =  "api_dev_key="..textutils.urlEncode(self.api_dev_key)..
                    "&api_user_key="..textutils.urlEncode(self.api_user_key)..
                    "&api_paste_key="..textutils.urlEncode(code)..
                    "&api_option=delete"

    local response = http.post(url,params)
    if response then
        local sResponse = response.readAll()
        response.close()
        if sResponse == "Paste Removed" then
            return true
        else
            error("Unable to remove paste. Pastebin says \""..sResponse.."\"")
        end
    else
        error("Bad resposne from Pastebin. Unable to delete paste")
    end

end

-- allows you to download a paste into a file.
function Pastebin.get_file(self,sCode,sPath)
    if fs.exists(sPath) then
        error("File already exists")
    end
    local response = self:get_raw(sCode)
    if response then
        local sResponse = response.readAll()
        response.close()
        local file = fs.open(sPath,"w")
        file.write(sResponse)
        file.close()
        return true
    else
        error("Failed to paste "..sPath)
    end
end