package module

import (
	"github.com/hashicorp/terraform/config"
)

// Tree represents the module import tree of configurations.
//
// This Tree structure can be used to get (download) new modules, load
// all the modules without getting, flatten the tree into something
// Terraform can use, etc.
type Tree struct {
	Config   *config.Config
	Children []*Tree
}

// GetMode is an enum that describes how modules are loaded.
//
// GetModeLoad says that modules will not be downloaded or updated, they will
// only be loaded from the storage.
//
// GetModeGet says that modules can be initially downloaded if they don't
// exist, but otherwise to just load from the current version in storage.
//
// GetModeUpdate says that modules should be checked for updates and
// downloaded prior to loading. If there are no updates, we load the version
// from disk, otherwise we download first and then load.
type GetMode byte

const (
	GetModeNone GetMode = iota
	GetModeGet
	GetModeUpdate
)

// Flatten takes the entire module tree and flattens it into a single
// namespace in *config.Config with no module imports.
//
// Validate is called here implicitly, since it is important that semantic
// checks pass before flattening the configuration. Otherwise, encapsulation
// breaks in horrible ways and the errors that come out the other side
// will be surprising.
func (t *Tree) Flatten() (*config.Config, error) {
	return nil, nil
}

// Modules returns the list of modules that this tree imports.
func (t *Tree) Modules() []*Module {
	return nil
}

// Load loads the configuration of the entire tree.
//
// The parameters are used to tell the tree where to find modules and
// whether it can download/update modules along the way.
//
// Various semantic-like checks are made along the way of loading since
// module trees inherently require the configuration to be in a reasonably
// sane state: no circular dependencies, proper module sources, etc. A full
// suite of validations can be done by running Validate (after loading).
func (t *Tree) Load(s Storage, mode GetMode) error {
	return nil
}

// Validate does semantic checks on the entire tree of configurations.
//
// This will call the respective config.Config.Validate() functions as well
// as verifying things such as parameters/outputs between the various modules.
func (t *Tree) Validate() error {
	return nil
}