easy-shell

local args = {...}

local exStr = [[shell.run("/usr/bin/easy-shell execute")]]

local function loadStartup()
    local lines = {}
    if fs.exists("/startup") then
        local handle = io.open("/startup", "r")
        if handle then
            for line in handle:lines() do
                table.insert(lines, line)
            end
            handle:close()
        end
    end
    return lines
end

local function writeStartup(contents)
    local handle = io.open("/startup", "w")
    if handle then
        for i, line in ipairs(contents) do
            handle:write(line.."\n")
        end
        handle:close()
    else
        error("Could not write startup file!")
    end
end

if #args >= 1 then
    if args[1] == "execute" then
        shell.setPath(shell.path()..":/usr/bin")

        local loadAPI = os.loadAPI

        os.loadAPI = function(path)
            if fs.exists(path) then
                return loadAPI(path)
            elseif fs.exists(fs.combine("/usr/apis", path)) then
                return loadAPI(fs.combine("/usr/apis", path))
            end
        end
    elseif args[1] == "install" then
        if tonumber(string.sub(os.version(), 9)) and tonumber(string.sub(os.version(), 9)) > 1.7 and fs.isDir("/startup") then
            --In CraftOS 1.8+, simply add a file to the startup folder.
            local handle = io.open("/startup/easy-shell.lua")
            if handle then
                handle:write(exStr)
                handle:close()
            else
                error("Could not write file!")
            end
        else
            --otherwise, attempt to cleanly add a line to the startup file.
            local contents = loadStartup()
            local changed = false
            if fs.exists("/startup") then
                local exists = false

                for i = 1, #contents do
                    if contents[i] == exStr then
                        exists = true
                        break
                    end
                end

                if not exists then
                    table.insert(contents, 1, exStr)
                    changed = true
                end
            else
                contents[1] = exStr
                changed = true
            end
            if changed then
                writeStartup(contents)
            end
        end
        shell.run("usr/bin/easy-shell execute")
    elseif args[1] == "remove" then
        if tonumber(string.sub(os.version(), 9)) and tonumber(string.sub(os.version(), 9)) > 1.7 and fs.exists("/startup/easy-shell.lua") then
            --in 1.8+, we just have to delete the file we added.
            fs.delete("/startup/easy-shell.lua")
        else
            local contents = loadStartup()
            for i = #contents, 1, -1 do
                 if contents[i] == exStr then
                    table.remove(contents, i)
                end
            end
            writeStartup(contents)
        end
    end
end