-- get make_package so we can overwrite it
local make_package = dofile("rom/modules/main/cc/require.lua").make

-- make some upvalues
-- tProgramStack is from the OG shell; keeps track of the stack of running programs
local tProgramStack = {}
local userPaths_mt = {
    __index=userPaths,
    __newindex=function() error("Use customPackage.addPackagePath() to add to the userPaths list.", 2) end,
    __metatable="Dude, what are you trying to do?"
}
-- make a global variable we can access from any program
_G.customPackage = {
    userPaths = setmetatable({}, userPaths_mt)
}
--
customPackage.addPackagePath = function(path)
    if not fs.isDir(path) then
        error(path.." is not a directory",2)
    end
    if path:sub(1,1) ~= "/" then
        error(path.." is not absolute (Make sure there's a leading slash)",2)
    end
    -- add trailing slash if there isn't one
    rawset(customPackage.userPaths, #customPackage.userPaths + 1, (path:sub(-1,-1) == "/") and path or path.."/")
end

local function createShellEnv(dir)
    local env = { shell = shell, multishell = multishell }
    env.require, env.package = make_package(env, dir)
    return env
end

function shell.execute(command, ...)
    local sPath = shell.resolveProgram(command)
    if sPath ~= nil then
        tProgramStack[#tProgramStack + 1] = sPath
        if multishell then
            local sTitle = fs.getName(sPath)
            if sTitle:sub(-4) == ".lua" then
                sTitle = sTitle:sub(1, -5)
            end
            multishell.setTitle(multishell.getCurrent(), sTitle)
        end

        local sDir = fs.getDir(sPath)
        local env = createShellEnv(sDir)
        env.arg = { [0] = command, ... }
        for _, path in ipairs(customPackage.userPaths) do
            env.package.path = path.."?;"..path.."?.lua;"..path.."?/init.lua;"..env.package.path
        end
        local result = os.run(env, sPath, ...)

        tProgramStack[#tProgramStack] = nil
        if multishell then
            if #tProgramStack > 0 then
                local sTitle = fs.getName(tProgramStack[#tProgramStack])
                if sTitle:sub(-4) == ".lua" then
                    sTitle = sTitle:sub(1, -5)
                end
                multishell.setTitle(multishell.getCurrent(), sTitle)
            else
                multishell.setTitle(multishell.getCurrent(), "shell")
            end
        end
        return result
    else
        printError("No such program")
        return false
    end
end