package dynblock
import (
"fmt"
"github.com/hashicorp/hcl2/hcl"
"github.com/zclconf/go-cty/cty"
)
// expandBody wraps another hcl.Body and expands any "dynamic" blocks found
// inside whenever Content or PartialContent is called.
type expandBody struct {
original hcl.Body
forEachCtx *hcl.EvalContext
iteration *iteration // non-nil if we're nested inside another "dynamic" block
// These are used with PartialContent to produce a "remaining items"
// body to return. They are nil on all bodies fresh out of the transformer.
//
// Note that this is re-implemented here rather than delegating to the
// existing support required by the underlying body because we need to
// retain access to the entire original body on subsequent decode operations
// so we can retain any "dynamic" blocks for types we didn't take consume
// on the first pass.
hiddenAttrs map[string]struct{}
hiddenBlocks map[string]hcl.BlockHeaderSchema
}
func (b *expandBody) Content(schema *hcl.BodySchema) (*hcl.BodyContent, hcl.Diagnostics) {
extSchema := b.extendSchema(schema)
rawContent, diags := b.original.Content(extSchema)
blocks, blockDiags := b.expandBlocks(schema, rawContent.Blocks, false)
diags = append(diags, blockDiags...)
attrs := b.prepareAttributes(rawContent.Attributes)
content := &hcl.BodyContent{
Attributes: attrs,
Blocks: blocks,
MissingItemRange: b.original.MissingItemRange(),
}
return content, diags
}
func (b *expandBody) PartialContent(schema *hcl.BodySchema) (*hcl.BodyContent, hcl.Body, hcl.Diagnostics) {
extSchema := b.extendSchema(schema)
rawContent, _, diags := b.original.PartialContent(extSchema)
// We discard the "remain" argument above because we're going to construct
// our own remain that also takes into account remaining "dynamic" blocks.
blocks, blockDiags := b.expandBlocks(schema, rawContent.Blocks, true)
diags = append(diags, blockDiags...)
attrs := b.prepareAttributes(rawContent.Attributes)
content := &hcl.BodyContent{
Attributes: attrs,
Blocks: blocks,
MissingItemRange: b.original.MissingItemRange(),
}
remain := &expandBody{
original: b.original,
forEachCtx: b.forEachCtx,
iteration: b.iteration,
hiddenAttrs: make(map[string]struct{}),
hiddenBlocks: make(map[string]hcl.BlockHeaderSchema),
}
for name := range b.hiddenAttrs {
remain.hiddenAttrs[name] = struct{}{}
}
for typeName, blockS := range b.hiddenBlocks {
remain.hiddenBlocks[typeName] = blockS
}
for _, attrS := range schema.Attributes {
remain.hiddenAttrs[attrS.Name] = struct{}{}
}
for _, blockS := range schema.Blocks {
remain.hiddenBlocks[blockS.Type] = blockS
}
return content, remain, diags
}
func (b *expandBody) extendSchema(schema *hcl.BodySchema) *hcl.BodySchema {
// We augment the requested schema to also include our special "dynamic"
// block type, since then we'll get instances of it interleaved with
// all of the literal child blocks we must also include.
extSchema := &hcl.BodySchema{
Attributes: schema.Attributes,
Blocks: make([]hcl.BlockHeaderSchema, len(schema.Blocks), len(schema.Blocks)+len(b.hiddenBlocks)+1),
}
copy(extSchema.Blocks, schema.Blocks)
extSchema.Blocks = append(extSchema.Blocks, dynamicBlockHeaderSchema)
// If we have any hiddenBlocks then we also need to register those here
// so that a call to "Content" on the underlying body won't fail.
// (We'll filter these out again once we process the result of either
// Content or PartialContent.)
for _, blockS := range b.hiddenBlocks {
extSchema.Blocks = append(extSchema.Blocks, blockS)
}
// If we have any hiddenAttrs then we also need to register these, for
// the same reason as we deal with hiddenBlocks above.
if len(b.hiddenAttrs) != 0 {
newAttrs := make([]hcl.AttributeSchema, len(schema.Attributes), len(schema.Attributes)+len(b.hiddenAttrs))
copy(newAttrs, extSchema.Attributes)
for name := range b.hiddenAttrs {
newAttrs = append(newAttrs, hcl.AttributeSchema{
Name: name,
Required: false,
})
}
extSchema.Attributes = newAttrs
}
return extSchema
}
func (b *expandBody) prepareAttributes(rawAttrs hcl.Attributes) hcl.Attributes {
if len(b.hiddenAttrs) == 0 && b.iteration == nil {
// Easy path: just pass through the attrs from the original body verbatim
return rawAttrs
}
// Otherwise we have some work to do: we must filter out any attributes
// that are hidden (since a previous PartialContent call already saw these)
// and wrap the expressions of the inner attributes so that they will
// have access to our iteration variables.
attrs := make(hcl.Attributes, len(rawAttrs))
for name, rawAttr := range rawAttrs {
if _, hidden := b.hiddenAttrs[name]; hidden {
continue
}
if b.iteration != nil {
attr := *rawAttr // shallow copy so we can mutate it
attr.Expr = exprWrap{
Expression: attr.Expr,
i: b.iteration,
}
attrs[name] = &attr
} else {
// If we have no active iteration then no wrapping is required.
attrs[name] = rawAttr
}
}
return attrs
}
func (b *expandBody) expandBlocks(schema *hcl.BodySchema, rawBlocks hcl.Blocks, partial bool) (hcl.Blocks, hcl.Diagnostics) {
var blocks hcl.Blocks
var diags hcl.Diagnostics
for _, rawBlock := range rawBlocks {
switch rawBlock.Type {
case "dynamic":
realBlockType := rawBlock.Labels[0]
if _, hidden := b.hiddenBlocks[realBlockType]; hidden {
continue
}
var blockS *hcl.BlockHeaderSchema
for _, candidate := range schema.Blocks {
if candidate.Type == realBlockType {
blockS = &candidate
break
}
}
if blockS == nil {
// Not a block type that the caller requested.
if !partial {
diags = append(diags, &hcl.Diagnostic{
Severity: hcl.DiagError,
Summary: "Unsupported block type",
Detail: fmt.Sprintf("Blocks of type %q are not expected here.", realBlockType),
Subject: &rawBlock.LabelRanges[0],
})
}
continue
}
spec, specDiags := b.decodeSpec(blockS, rawBlock)
diags = append(diags, specDiags...)
if specDiags.HasErrors() {
continue
}
if spec.forEachVal.IsKnown() {
for it := spec.forEachVal.ElementIterator(); it.Next(); {
key, value := it.Element()
i := b.iteration.MakeChild(spec.iteratorName, key, value)
block, blockDiags := spec.newBlock(i, b.forEachCtx)
diags = append(diags, blockDiags...)
if block != nil {
// Attach our new iteration context so that attributes
// and other nested blocks can refer to our iterator.
block.Body = b.expandChild(block.Body, i)
blocks = append(blocks, block)
}
}
} else {
// If our top-level iteration value isn't known then we're forced
// to compromise since HCL doesn't have any concept of an
// "unknown block". In this case then, we'll produce a single
// dynamic block with the iterator values set to DynamicVal,
// which at least makes the potential for a block visible
// in our result, even though it's not represented in a fully-accurate
// way.
i := b.iteration.MakeChild(spec.iteratorName, cty.DynamicVal, cty.DynamicVal)
block, blockDiags := spec.newBlock(i, b.forEachCtx)
diags = append(diags, blockDiags...)
if block != nil {
block.Body = b.expandChild(block.Body, i)
// We additionally force all of the leaf attribute values
// in the result to be unknown so the calling application
// can, if necessary, use that as a heuristic to detect
// when a single nested block might be standing in for
// multiple blocks yet to be expanded. This retains the
// structure of the generated body but forces all of its
// leaf attribute values to be unknown.
block.Body = unknownBody{block.Body}
blocks = append(blocks, block)
}
}
default:
if _, hidden := b.hiddenBlocks[rawBlock.Type]; !hidden {
// A static block doesn't create a new iteration context, but
// it does need to inherit _our own_ iteration context in
// case it contains expressions that refer to our inherited
// iterators, or nested "dynamic" blocks.
expandedBlock := *rawBlock // shallow copy
expandedBlock.Body = b.expandChild(rawBlock.Body, b.iteration)
blocks = append(blocks, &expandedBlock)
}
}
}
return blocks, diags
}
func (b *expandBody) expandChild(child hcl.Body, i *iteration) hcl.Body {
chiCtx := i.EvalContext(b.forEachCtx)
ret := Expand(child, chiCtx)
ret.(*expandBody).iteration = i
return ret
}
func (b *expandBody) JustAttributes() (hcl.Attributes, hcl.Diagnostics) {
// blocks aren't allowed in JustAttributes mode and this body can
// only produce blocks, so we'll just pass straight through to our
// underlying body here.
return b.original.JustAttributes()
}
func (b *expandBody) MissingItemRange() hcl.Range {
return b.original.MissingItemRange()
}
