feat: add 'update_description' action

Author: jippi

cmd/shared.go

@@ -95,7 +95,7 @@ func ProcessMR(ctx context.Context, client scm.Client, cfg *config.Config, event
 
 	slogctx.Info(ctx, "Applying actions")
 
-	if err := runActions(ctx, client, update, actions); err != nil {
+	if err := runActions(ctx, evalContext, client, update, actions); err != nil {
 		return err
 	}
 
@@ -120,10 +120,10 @@ func updateMergeRequest(ctx context.Context, client scm.Client, update *scm.Upda
 	return err
 }
 
-func runActions(ctx context.Context, client scm.Client, update *scm.UpdateMergeRequestOptions, actions []config.Action) error {
+func runActions(ctx context.Context, evalContext scm.EvalContext, client scm.Client, update *scm.UpdateMergeRequestOptions, actions []config.Action) error {
 	for _, action := range actions {
 		for _, task := range action.Then {
-			if err := client.ApplyStep(ctx, update, task); err != nil {
+			if err := client.ApplyStep(ctx, evalContext, update, task); err != nil {
 				return err
 			}
 		}

docs/configuration.md

@@ -38,13 +38,14 @@ The list of operations to take if the [`#!css action.if`](#actions.if) returned
 
 This key controls what kind of action that should be taken.
 
+- `#!yaml approve` to approve the Merge Request.
 - `#!yaml close` to close the Merge Request.
-- `#!yaml reopen` to reopen the Merge Request.
+- `#!yaml comment` to add a comment to the Merge Request
 - `#!yaml lock_discussion` to prevent further discussions on the Merge Request.
-- `#!yaml unlock_discussion` to allow discussions on the Merge Request.
-- `#!yaml approve` to approve the Merge Request.
+- `#!yaml reopen` to reopen the Merge Request.
 - `#!yaml unapprove` to approve the Merge Request.
-- `#!yaml comment` to add a comment to the Merge Request
+- `#!yaml unlock_discussion` to allow discussions on the Merge Request.
+- `#!yaml update_description` to update the Merge Request description
 
       *Additional fields:*
 
@@ -78,6 +79,18 @@ This key controls what kind of action that should be taken.
         label: example
       ```
 
+- `#!yaml update_description` updates the Merge Request Description
+
+      *Additional fields:*
+
+      - (required) `#!css replace` A list of key/value pairs to replace in the description. The `key` is the raw string to replace in the Merge Request description. The `value` is an Expr Lang expression returning a `string` that `key` will be replaced with - all Script Attributes and Script Functions are available within the script.
+
+      ```{.yaml title="update_description example"}
+      - action: update_description
+        replace:
+          "${{CI_MERGE_REQUEST_IID}}": "merge_request.iid"
+      ```
+
 ## `label[]` {#label data-toc-label="label"}
 
 !!! question "What are labels?"

docs/gitlab/script-functions.md

@@ -20,6 +20,22 @@ merge_request.state_is("merged")
 merge_request.state_is("opened", "locked")
 ```
 
+### `merge_request.state_is_not(string...) -> boolean` {: #merge_request.state_is data-toc-label="state_is"}
+
+Check if the `merge_request` state is NOT any of the provided states
+
+**Valid options**:
+
+- `closed` - In closed state
+- `locked` - Discussion has been locked
+- `merged` - Merge request has been merged
+- `opened` - Opened merge request
+
+```css
+merge_request.state_is_not("merged")
+merge_request.state_is_not("opened", "locked")
+```
+
 ### `merge_request.has_user_activity_within(duration|string...) -> boolean` {: #merge_request.has_user_activity_within data-toc-label="has_user_activity_within"}
 
 !!! info "This function *EXCLUDE* changes made by `scm-engine` and other bots, use [`merge_request.has_no_activity_within`](#merge_request.has_no_activity_within) if you want to include those"

pkg/scm/github/client_actioner.go

@@ -12,7 +12,7 @@ import (
 	slogctx "github.com/veqryn/slog-context"
 )
 
-func (c *Client) ApplyStep(ctx context.Context, update *scm.UpdateMergeRequestOptions, step scm.EvaluationActionStep) error {
+func (c *Client) ApplyStep(ctx context.Context, evalContext scm.EvalContext, update *scm.UpdateMergeRequestOptions, step scm.EvaluationActionStep) error {
 	owner, repo := ownerAndRepo(ctx)
 
 	action, ok := step["action"]

pkg/scm/github/context.go

@@ -84,3 +84,7 @@ func (c *Context) IsValid() bool {
 func (c *Context) SetWebhookEvent(in any) {
 	c.WebhookEvent = in
 }
+
+func (c *Context) GetDescription() string {
+	return c.PullRequest.Body
+}

pkg/scm/gitlab/client.go

@@ -56,12 +56,7 @@ func (client *Client) MergeRequests() scm.MergeRequestClient {
 
 // EvalContext creates a new evaluation context for GitLab specific usage
 func (client *Client) EvalContext(ctx context.Context) (scm.EvalContext, error) {
-	res, err := NewContext(ctx, graphqlBaseURL(client.wrapped.BaseURL()), state.Token(ctx))
-	if err != nil {
-		return nil, err
-	}
-
-	return res, nil
+	return NewContext(ctx, graphqlBaseURL(client.wrapped.BaseURL()), state.Token(ctx))
 }
 
 // Start pipeline

pkg/scm/gitlab/client_actioner.go

@@ -5,14 +5,18 @@ import (
 	"errors"
 	"fmt"
 	"log/slog"
+	"reflect"
+	"strings"
 
+	"github.com/expr-lang/expr"
 	"github.com/jippi/scm-engine/pkg/scm"
 	"github.com/jippi/scm-engine/pkg/state"
+	"github.com/jippi/scm-engine/pkg/stdlib"
 	slogctx "github.com/veqryn/slog-context"
 	"github.com/xanzy/go-gitlab"
 )
 
-func (c *Client) ApplyStep(ctx context.Context, update *scm.UpdateMergeRequestOptions, step scm.EvaluationActionStep) error {
+func (c *Client) ApplyStep(ctx context.Context, evalContext scm.EvalContext, update *scm.UpdateMergeRequestOptions, step scm.EvaluationActionStep) error {
 	action, ok := step["action"]
 	if !ok {
 		return errors.New("step is missing an 'action' key")
@@ -24,6 +28,69 @@ func (c *Client) ApplyStep(ctx context.Context, update *scm.UpdateMergeRequestOp
 	}
 
 	switch actionString {
+	case "update_description":
+		// Use the raw MR description
+		body := evalContext.GetDescription()
+
+		// Unless something else already updated the description in the Update struct
+		if update.Description != nil {
+			body = *update.Description
+		}
+
+		replacements, ok := step["replace"]
+		if !ok {
+			return errors.New("step field 'replace' is required, but missing")
+		}
+
+		replacementSlice, ok := replacements.(map[string]any)
+		if !ok {
+			return fmt.Errorf(`step field 'replace' must be a dictionary with string key and string values ("key": "value"), got: %T`, replacements)
+		}
+
+		replacedAnything := false
+
+		for key, script := range replacementSlice {
+			// If the replacement key do not exist; we can skip the replacement logic entirely!
+			if !strings.Contains(body, key) {
+				continue
+			}
+
+			replacedAnything = true
+
+			// Build the ExprLang VM program
+			// TODO(jippi): make this something generic/shared somewhere more central so we keep settings in sync
+			opts := []expr.Option{}
+			opts = append(opts, expr.AsKind(reflect.TypeFor[string]().Kind()))
+			opts = append(opts, expr.Env(evalContext))
+			opts = append(opts, stdlib.FunctionRenamer)
+			opts = append(opts, stdlib.Functions...)
+
+			program, err := expr.Compile(fmt.Sprintf("%s", script), opts...)
+			if err != nil {
+				return fmt.Errorf("could not evaluate value for 'replace' key '%s': %w", key, err)
+			}
+
+			output, err := expr.Run(program, evalContext)
+			if err != nil {
+				return err
+			}
+
+			switch val := output.(type) {
+			case string:
+				body = strings.ReplaceAll(body, key, val)
+
+			default:
+				return fmt.Errorf("'replace' value for key '%s' did not return a string: %w", key, err)
+			}
+		}
+
+		// Don't update the body if there were no replacements
+		if !replacedAnything {
+			return nil
+		}
+
+		update.Description = &body
+
 	case "add_label":
 		name, ok := step["name"]
 		if !ok {

pkg/scm/gitlab/context.go

@@ -93,3 +93,11 @@ func (c *Context) IsValid() bool {
 func (c *Context) SetWebhookEvent(in any) {
 	c.WebhookEvent = in
 }
+
+func (c *Context) GetDescription() string {
+	if c.MergeRequest.Description == nil {
+		return ""
+	}
+
+	return *c.MergeRequest.Description
+}

pkg/scm/gitlab/context_merge_request.go

@@ -36,6 +36,20 @@ func (e ContextMergeRequest) StateIs(anyOf ...string) bool {
 	return false
 }
 
+func (e ContextMergeRequest) StateIsNot(anyOf ...string) bool {
+	for _, state := range anyOf {
+		if !MergeRequestState(state).IsValid() {
+			panic(fmt.Errorf("unknown state value: %q", state))
+		}
+
+		if state == e.State {
+			return false
+		}
+	}
+
+	return true
+}
+
 // has_no_activity_within
 func (e ContextMergeRequest) HasNoActivityWithin(input any) bool {
 	return !e.HasAnyActivityWithin(input)

pkg/scm/interfaces.go

@@ -9,7 +9,7 @@ type Client interface {
 	Labels() LabelClient
 	MergeRequests() MergeRequestClient
 	EvalContext(ctx context.Context) (EvalContext, error)
-	ApplyStep(ctx context.Context, update *UpdateMergeRequestOptions, step EvaluationActionStep) error
+	ApplyStep(ctx context.Context, evalContext EvalContext, update *UpdateMergeRequestOptions, step EvaluationActionStep) error
 	Start(ctx context.Context) error
 	Stop(ctx context.Context, err error) error
 }
@@ -29,6 +29,7 @@ type MergeRequestClient interface {
 type EvalContext interface {
 	IsValid() bool
 	SetWebhookEvent(in any)
+	GetDescription() string
 }
 
 type EvalContextualizer struct{}

pkg/scm/types.go

@@ -155,12 +155,12 @@ type EvaluationResult struct {
 	Matched bool
 }
 
-type EvaluationActionStep map[string]any
+type EvaluationActionStep = map[string]any
 
 type EvaluationActionResult struct {
-	Name string `yaml:"name"`
-	If   string `yaml:"if"`
-	Then []EvaluationActionStep
+	Name string                 `yaml:"name"`
+	If   string                 `yaml:"if"`
+	Then []EvaluationActionStep `yaml:"then"`
 }
 
 func (local EvaluationResult) IsEqual(ctx context.Context, remote *Label) bool {