From 1b5dfa043bda8b9ca0ace2fb3927e35137948062 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 28 May 2014 13:56:43 -0700
Subject: [PATCH] terraform: some files laying out an API

---
 terraform/diff.go              | 16 +++++++++++++
 terraform/resource_provider.go |  4 ++++
 terraform/state.go             | 20 ++++++++++++++++
 terraform/terraform.go         | 43 ++++++++++++++++++++++++++++++++++
 4 files changed, 83 insertions(+)
 create mode 100644 terraform/diff.go
 create mode 100644 terraform/state.go
 create mode 100644 terraform/terraform.go

diff --git a/terraform/diff.go b/terraform/diff.go
new file mode 100644
index 000000000..725800d2f
--- /dev/null
+++ b/terraform/diff.go
@@ -0,0 +1,16 @@
+package terraform
+
+// Diff tracks the differences between resources to apply.
+type Diff struct {
+	resources map[string]map[string]*resourceDiff
+}
+
+// resourceDiff is the diff of a single attribute of a resource.
+//
+// This tracks the old value, the new value, and whether the change of this
+// value actually requires an entirely new resource.
+type resourceDiff struct {
+	Old         string
+	New         string
+	RequiresNew bool
+}
diff --git a/terraform/resource_provider.go b/terraform/resource_provider.go
index 2440d9c36..365764794 100644
--- a/terraform/resource_provider.go
+++ b/terraform/resource_provider.go
@@ -19,3 +19,7 @@ type ResourceProvider interface {
 type ResourceType struct {
 	Name string
 }
+
+// ResourceProviderFactory is a function type that creates a new instance
+// of a resource provider.
+type ResourceProviderFactory func() (ResourceProvider, error)
diff --git a/terraform/state.go b/terraform/state.go
new file mode 100644
index 000000000..812b1133e
--- /dev/null
+++ b/terraform/state.go
@@ -0,0 +1,20 @@
+package terraform
+
+// State keeps track of a snapshot state-of-the-world that Terraform
+// can use to keep track of what real world resources it is actually
+// managing.
+type State struct {
+	resources map[string]resourceState
+}
+
+// resourceState is the state of a single resource.
+//
+// The ID is required and is some opaque string used to recognize
+// the realized resource.
+//
+// Extra is arbitrary extra metadata that the resource provider returns
+// that is sent back into the resource provider when it is needed.
+type resourceState struct {
+	ID    string
+	Extra map[string]interface{}
+}
diff --git a/terraform/terraform.go b/terraform/terraform.go
new file mode 100644
index 000000000..f1cd66b2c
--- /dev/null
+++ b/terraform/terraform.go
@@ -0,0 +1,43 @@
+package terraform
+
+import (
+	"github.com/hashicorp/terraform/config"
+)
+
+// Terraform is the primary structure that is used to interact with
+// Terraform from code, and can perform operations such as returning
+// all resources, a resource tree, a specific resource, etc.
+type Terraform struct {
+	config    *config.Config
+	providers []ResourceProvider
+}
+
+// Config is the configuration that must be given to instantiate
+// a Terraform structure.
+type Config struct {
+	Config    *config.Config
+	Providers map[string]ResourceProviderFactory
+	Variables map[string]string
+}
+
+// New creates a new Terraform structure, initializes resource providers
+// for the given configuration, etc.
+//
+// Semantic checks of the entire configuration structure are done at this
+// time, as well as richer checks such as verifying that the resource providers
+// can be properly initialized, can be configured, etc.
+func New(c *Config) (*Terraform, error) {
+	return nil, nil
+}
+
+func (t *Terraform) Apply(*State, *Diff) (*State, error) {
+	return nil, nil
+}
+
+func (t *Terraform) Diff(*State) (*Diff, error) {
+	return nil, nil
+}
+
+func (t *Terraform) Refresh(*State) (*State, error) {
+	return nil, nil
+}