From 7f0be4c18c5420538e5c79291cb9a035e87402d6 Mon Sep 17 00:00:00 2001
From: Hidde Beydals <hidde@hhh.computer>
Date: Fri, 13 Dec 2024 14:10:27 +0100
Subject: [PATCH] feat(directives): add `compose-output` directive

Signed-off-by: Hidde Beydals <hidde@hhh.computer>
---
 internal/directives/output_composer.go        | 73 +++++++++++++++++++
 .../directives/schemas/compose-output.json    |  6 ++
 internal/directives/zz_config_types.go        |  2 +
 ui/src/gen/directives/compose-output.json     |  6 ++
 4 files changed, 87 insertions(+)
 create mode 100644 internal/directives/output_composer.go
 create mode 100644 internal/directives/schemas/compose-output.json
 create mode 100644 ui/src/gen/directives/compose-output.json

diff --git a/internal/directives/output_composer.go b/internal/directives/output_composer.go
new file mode 100644
index 000000000..1ef9c6f4f
--- /dev/null
+++ b/internal/directives/output_composer.go
@@ -0,0 +1,73 @@
+package directives
+
+import (
+	"context"
+	"fmt"
+
+	"github.com/xeipuuv/gojsonschema"
+
+	kargoapi "github.com/akuity/kargo/api/v1alpha1"
+)
+
+func init() {
+	builtins.RegisterPromotionStepRunner(newOutputComposer(), nil)
+}
+
+// outputComposer is an implementation of the PromotionStepRunner interface
+// that allows composing outputs from previous steps into new outputs.
+//
+// It works based on the PromotionStepContext.Config field allowing to an
+// arbitrary number of key-value pairs to be exported as outputs.
+// Because the values are allowed to be expressions and can contain
+// references to outputs from previous steps, this allows for remapping
+// the outputs of previous steps to new keys, or even combining them
+// into new structures.
+type outputComposer struct {
+	schemaLoader gojsonschema.JSONLoader
+}
+
+// newOutputComposer returns an implementation of the PromotionStepRunner
+// interface that composes output from previous steps into new output.
+func newOutputComposer() PromotionStepRunner {
+	r := &outputComposer{}
+	r.schemaLoader = getConfigSchemaLoader(r.Name())
+	return r
+}
+
+// Name implements the PromotionStepRunner interface.
+func (c *outputComposer) Name() string {
+	return "compose-output"
+}
+
+// RunPromotionStep implements the PromotionStepRunner interface.
+func (c *outputComposer) RunPromotionStep(
+	_ context.Context,
+	stepCtx *PromotionStepContext,
+) (PromotionStepResult, error) {
+	// Validate the configuration against the JSON Schema.
+	if err := validate(c.schemaLoader, gojsonschema.NewGoLoader(stepCtx.Config), c.Name()); err != nil {
+		return PromotionStepResult{Status: kargoapi.PromotionPhaseErrored}, err
+	}
+
+	// Convert the configuration into a typed object.
+	cfg, err := ConfigToStruct[ComposeOutput](stepCtx.Config)
+	if err != nil {
+		return PromotionStepResult{Status: kargoapi.PromotionPhaseErrored},
+			fmt.Errorf("could not convert config into %s config: %w", c.Name(), err)
+	}
+
+	return c.runPromotionStep(cfg)
+}
+
+func (c *outputComposer) runPromotionStep(
+	cfg ComposeOutput,
+) (PromotionStepResult, error) {
+	var output = make(map[string]any, len(cfg))
+	for k, v := range cfg {
+		output[k] = v
+	}
+	return PromotionStepResult{
+		Status: kargoapi.PromotionPhaseSucceeded,
+		Output: output,
+	}, nil
+}
diff --git a/internal/directives/schemas/compose-output.json b/internal/directives/schemas/compose-output.json
new file mode 100644
index 000000000..76421df1d
--- /dev/null
+++ b/internal/directives/schemas/compose-output.json
@@ -0,0 +1,6 @@
+{
+  "$schema": "https://json-schema.org/draft/2020-12/schema",
+  "title": "ComposeOutput",
+  "type": "object",
+  "minProperties": 1
+}
diff --git a/internal/directives/zz_config_types.go b/internal/directives/zz_config_types.go
index e09b38c60..c1d89150b 100644
--- a/internal/directives/zz_config_types.go
+++ b/internal/directives/zz_config_types.go
@@ -4,6 +4,8 @@ package directives
 
 type CommonDefs interface{}
 
+type ComposeOutput map[string]interface{}
+
 type ArgoCDUpdateConfig struct {
 	Apps       []ArgoCDAppUpdate `json:"apps"`
 	FromOrigin *AppFromOrigin    `json:"fromOrigin,omitempty"`
diff --git a/ui/src/gen/directives/compose-output.json b/ui/src/gen/directives/compose-output.json
new file mode 100644
index 000000000..b168b74f6
--- /dev/null
+++ b/ui/src/gen/directives/compose-output.json
@@ -0,0 +1,6 @@
+{
+ "$schema": "https://json-schema.org/draft/2020-12/schema",
+ "title": "ComposeOutput",
+ "type": "object",
+ "minProperties": 1
+}
\ No newline at end of file