PF re-plan in Diff after detecting a replace

pkg/pf/tfbridge/provider_diff.go

@@ -19,6 +19,7 @@ import (
 	"fmt"
 	"sort"
 
+	"github.com/hashicorp/terraform-plugin-go/tfprotov6"
 	"github.com/hashicorp/terraform-plugin-go/tftypes"
 	"github.com/pulumi/pulumi/sdk/v3/go/common/resource"
 	"github.com/pulumi/pulumi/sdk/v3/go/common/resource/plugin"
@@ -29,58 +30,38 @@ import (
 	"github.com/pulumi/pulumi-terraform-bridge/v3/unstable/propertyvalue"
 )
 
-// Diff checks what impacts a hypothetical update will have on the resource's properties. Receives checkedInputs from
-// Check and the prior state. The implementation here calls PlanResourceChange Terraform method. Essentially:
-//
-//	Diff(priorState, checkedInputs):
-//	    proposedNewState = priorState.applyChanges(checkedInputs)
-//	    plannedState = PlanResourceChange(priorState, proposedNewState)
-//	    priorState.Diff(plannedState)
-func (p *provider) DiffWithContext(
-	ctx context.Context,
-	urn resource.URN,
-	id resource.ID,
-	priorStateMap resource.PropertyMap,
-	checkedInputs resource.PropertyMap,
-	allowUnknowns bool,
-	ignoreChanges []string,
-) (plugin.DiffResult, error) {
-	ctx = p.initLogging(ctx, p.logSink, urn)
-	rh, err := p.resourceHandle(ctx, urn)
-	if err != nil {
-		return plugin.DiffResult{}, err
-	}
-
-	priorStateMap, err = transformFromState(ctx, rh, priorStateMap)
+func (p *provider) getPlanAndPriorState(
+	ctx context.Context, priorStateMap resource.PropertyMap, rh resourceHandle,
+	checkedInputs resource.PropertyMap, ignoreChanges []string,
+) (*tfprotov6.PlanResourceChangeResponse, *upgradedResourceState, error) {
+	priorStateMap, err := transformFromState(ctx, rh, priorStateMap)
 	if err != nil {
-		return plugin.DiffResult{}, err
+		return nil, nil, err
 	}
 
 	checkedInputs, err = propertyvalue.ApplyIgnoreChanges(priorStateMap, checkedInputs, ignoreChanges)
 	if err != nil {
-		return plugin.DiffResult{}, fmt.Errorf("failed to apply ignore changes: %w", err)
+		return nil, nil, fmt.Errorf("failed to apply ignore changes: %w", err)
 	}
 
 	rawPriorState, err := parseResourceState(&rh, priorStateMap)
 	if err != nil {
-		return plugin.DiffResult{}, err
+		return nil, nil, err
 	}
 
 	priorState, err := p.UpgradeResourceState(ctx, &rh, rawPriorState)
 	if err != nil {
-		return plugin.DiffResult{}, err
+		return nil, nil, err
 	}
 
-	tfType := rh.schema.Type(ctx).(tftypes.Object)
-
 	checkedInputsValue, err := convert.EncodePropertyMap(rh.encoder, checkedInputs)
 	if err != nil {
-		return plugin.DiffResult{}, err
+		return nil, nil, err
 	}
 
 	planResp, err := p.plan(ctx, rh.terraformResourceName, rh.schema, priorState, checkedInputsValue)
 	if err != nil {
-		return plugin.DiffResult{}, err
+		return nil, nil, err
 	}
 
 	// NOTE: this currently ignores planRep.PlanedPrivate but it is unclear if it should signal differences between
@@ -89,9 +70,42 @@ func (p *provider) DiffWithContext(
 	// to surface private state differences to the user from the Diff method.
 
 	if err := p.processDiagnostics(planResp.Diagnostics); err != nil {
+		return nil, nil, err
+	}
+
+	return planResp, priorState, nil
+}
+
+// Diff checks what impacts a hypothetical update will have on the resource's properties. Receives checkedInputs from
+// Check and the prior state. The implementation here calls PlanResourceChange Terraform method. Essentially:
+//
+//	Diff(priorState, checkedInputs):
+//	    proposedNewState = priorState.applyChanges(checkedInputs)
+//	    plannedState = PlanResourceChange(priorState, proposedNewState)
+//	    priorState.Diff(plannedState)
+func (p *provider) DiffWithContext(
+	ctx context.Context,
+	urn resource.URN,
+	id resource.ID,
+	priorStateMap resource.PropertyMap,
+	checkedInputs resource.PropertyMap,
+	allowUnknowns bool,
+	ignoreChanges []string,
+) (plugin.DiffResult, error) {
+	ctx = p.initLogging(ctx, p.logSink, urn)
+	rh, err := p.resourceHandle(ctx, urn)
+	if err != nil {
 		return plugin.DiffResult{}, err
 	}
 
+	planResp, priorState, err := p.getPlanAndPriorState(
+		ctx, priorStateMap, rh, checkedInputs, ignoreChanges)
+	if err != nil {
+		return plugin.DiffResult{}, err
+	}
+
+	tfType := rh.schema.Type(ctx).(tftypes.Object)
+
 	// TODO[pulumi/pulumi-terraform-bridge#751] ignoreChanges support
 	plannedStateValue, err := planResp.PlannedState.Unmarshal(tfType)
 	if err != nil {
@@ -135,6 +149,13 @@ func (p *provider) DiffWithContext(
 	}
 
 	if providerOpts.enableAccurateBridgePreview {
+		if len(planResp.RequiresReplace) > 0 {
+			// If we have a replace, we need to recompute the plan with a nil prior
+			// in order to correctly mark computed properties for recomputation.
+			//nolint:lll
+			// https://github.com/opentofu/opentofu/blob/864aa9d1d629090cfc4ddf9fdd344d34dee9793e/internal/tofu/node_resource_abstract_instance.go#L1054
+			// TODO plan again with nil prior
+		}
 		pluginDetailedDiff, err := calculateDetailedDiff(ctx, &rh, priorState, plannedStateValue, checkedInputs)
 		if err != nil {
 			return plugin.DiffResult{}, err