From 012d68923c5575f043bd55faf5158f3a0218f948 Mon Sep 17 00:00:00 2001
From: Mitchell Hashimoto <mitchell.hashimoto@gmail.com>
Date: Wed, 4 Feb 2015 11:30:53 -0500
Subject: [PATCH] terraform: Eval

---
 terraform/eval.go                 | 17 ++++++++++++
 terraform/eval_context_builtin.go | 46 ++++++++++++++++++++++++++++---
 terraform/eval_test.go            | 45 ++++++++++++++++++++++++++++++
 terraform/graph.go                |  6 +---
 terraform/resource.go             |  9 ++++++
 5 files changed, 114 insertions(+), 9 deletions(-)

diff --git a/terraform/eval.go b/terraform/eval.go
index eb1fe5a60..150820842 100644
--- a/terraform/eval.go
+++ b/terraform/eval.go
@@ -22,3 +22,20 @@ type EvalNode interface {
 type GraphNodeEvalable interface {
 	EvalTree() EvalNode
 }
+
+// Eval evaluates the given EvalNode with the given context, properly
+// evaluating all args in the correct order.
+func Eval(n EvalNode, ctx EvalContext) (interface{}, error) {
+	argNodes, _ := n.Args()
+	args := make([]interface{}, len(argNodes))
+	for i, n := range argNodes {
+		v, err := Eval(n, ctx)
+		if err != nil {
+			return nil, err
+		}
+
+		args[i] = v
+	}
+
+	return n.Eval(ctx, args)
+}
diff --git a/terraform/eval_context_builtin.go b/terraform/eval_context_builtin.go
index 05b77c08d..d74b490b7 100644
--- a/terraform/eval_context_builtin.go
+++ b/terraform/eval_context_builtin.go
@@ -5,12 +5,14 @@ import (
 	"sync"
 
 	"github.com/hashicorp/terraform/config"
+	"github.com/hashicorp/terraform/config/lang/ast"
 )
 
 // BuiltinEvalContext is an EvalContext implementation that is used by
 // Terraform by default.
 type BuiltinEvalContext struct {
-	Providers map[string]ResourceProviderFactory
+	Providers      map[string]ResourceProviderFactory
+	ComputeMissing bool
 
 	providers map[string]ResourceProvider
 	once      sync.Once
@@ -37,9 +39,45 @@ func (ctx *BuiltinEvalContext) Provider(n string) ResourceProvider {
 }
 
 func (ctx *BuiltinEvalContext) Interpolate(
-	config *config.RawConfig) (*ResourceConfig, error) {
-	// TODO: Actual interpolation, for now we just return it as-is
-	return NewResourceConfig(config), nil
+	cfg *config.RawConfig) (*ResourceConfig, error) {
+	vs := make(map[string]ast.Variable)
+
+	// If we don't have a config, use the blank config
+	if cfg == nil {
+		goto INTERPOLATE_RESULT
+	}
+
+	for n, rawV := range cfg.Variables {
+		switch rawV.(type) {
+		case *config.ModuleVariable:
+			if ctx.ComputeMissing {
+				vs[n] = ast.Variable{
+					Value: config.UnknownVariableValue,
+					Type:  ast.TypeString,
+				}
+			}
+		case *config.ResourceVariable:
+			if ctx.ComputeMissing {
+				vs[n] = ast.Variable{
+					Value: config.UnknownVariableValue,
+					Type:  ast.TypeString,
+				}
+			}
+		default:
+			return nil, fmt.Errorf(
+				"unknown interpolation type: %#v", rawV)
+		}
+	}
+
+	// Do the interpolation
+	if err := cfg.Interpolate(vs); err != nil {
+		return nil, err
+	}
+
+INTERPOLATE_RESULT:
+	result := NewResourceConfig(cfg)
+	result.interpolateForce()
+	return result, nil
 }
 
 func (ctx *BuiltinEvalContext) init() {
diff --git a/terraform/eval_test.go b/terraform/eval_test.go
index e89f2641b..47154ef2c 100644
--- a/terraform/eval_test.go
+++ b/terraform/eval_test.go
@@ -7,3 +7,48 @@ import (
 func TestMockEvalContext_impl(t *testing.T) {
 	var _ EvalContext = new(MockEvalContext)
 }
+
+func TestEval(t *testing.T) {
+	n := &testEvalAdd{
+		Items: []EvalNode{
+			&EvalLiteral{Value: 10},
+			&EvalLiteral{Value: 32},
+		},
+	}
+
+	result, err := Eval(n, nil)
+	if err != nil {
+		t.Fatalf("err: %s", err)
+	}
+
+	if result != 42 {
+		t.Fatalf("bad: %#v", result)
+	}
+}
+
+type testEvalAdd struct {
+	Items []EvalNode
+}
+
+func (n *testEvalAdd) Args() ([]EvalNode, []EvalType) {
+	types := make([]EvalType, len(n.Items))
+	for i, _ := range n.Items {
+		types[i] = EvalTypeInvalid
+	}
+
+	return n.Items, types
+}
+
+func (n *testEvalAdd) Eval(
+	ctx EvalContext, args []interface{}) (interface{}, error) {
+	result := 0
+	for _, arg := range args {
+		result += arg.(int)
+	}
+
+	return result, nil
+}
+
+func (n *testEvalAdd) Type() EvalType {
+	return EvalTypeInvalid
+}
diff --git a/terraform/graph.go b/terraform/graph.go
index e59ec87b0..d0e68648c 100644
--- a/terraform/graph.go
+++ b/terraform/graph.go
@@ -18,7 +18,7 @@ var RootModulePath = []string{RootModuleName}
 type Graph struct {
 	// Graph is the actual DAG. This is embedded so you can call the DAG
 	// methods directly.
-	*dag.Graph
+	dag.AcyclicGraph
 
 	// Path is the path in the module tree that this Graph represents.
 	// The root is represented by a single element list containing
@@ -112,10 +112,6 @@ func (g *Graph) Dependable(n string) dag.Vertex {
 }
 
 func (g *Graph) init() {
-	if g.Graph == nil {
-		g.Graph = new(dag.Graph)
-	}
-
 	if g.dependableMap == nil {
 		g.dependableMap = make(map[string]dag.Vertex)
 	}
diff --git a/terraform/resource.go b/terraform/resource.go
index cbcd7814d..931d1b323 100644
--- a/terraform/resource.go
+++ b/terraform/resource.go
@@ -226,3 +226,12 @@ func (c *ResourceConfig) interpolate(
 	c.Config = c.raw.Config()
 	return nil
 }
+
+// interpolateForce is a temporary thing. We want to get rid of interpolate
+// above and likewise this, but it can only be done after the f-ast-graph
+// refactor is complete.
+func (c *ResourceConfig) interpolateForce() {
+	c.ComputedKeys = c.raw.UnknownKeys()
+	c.Raw = c.raw.Raw
+	c.Config = c.raw.Config()
+}