/*
Copyright 2018 The Kubernetes Authors All rights reserved.

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package lua

import (
	"fmt"
	"path/filepath"

	"github.com/yuin/gopher-lua"

	hapi "k8s.io/helm/pkg/hapi/chart"
)

// LoadScripts is a depth-first script loader for Lua scripts
//
// It walks the chart and all dependencies, loading the ext/lua/chart.lua
// script for each chart.
//
// If a script fails to load, loading immediately ceases and the error is returned.
func LoadScripts(vm *lua.LState, chart *hapi.Chart) error {
	// We go depth first so that the top level chart gets the final word.
	// That is, the top level chart should be able to modify objects that the
	// child charts set.
	for _, child := range chart.Dependencies {
		LoadScripts(vm, child)
	}
	// For now, we only load a `chart.lua`, since that is how other Lua impls
	// do it (e.g. single entrypoint, not multi).
	for _, script := range chart.Ext {
		target := filepath.Join("ext", "lua", "chart.lua")
		if script.Name == target {
			if err := vm.DoString(string(script.Data)); err != nil {
				return fmt.Errorf("failed to execute Lua for %s: %s", chart.Metadata.Name, err)
			}
		}
	}
	return nil
}