Feat v0.3.2 workflow engine (#16)

Co-authored-by: Jeffrey Smith <jasafpro@gmail.com> Co-committed-by: Jeffrey Smith <jasafpro@gmail.com>
2026-03-27 21:37:44 +00:00
parent 01ee9e668b
commit ab28e4b784
13 changed files with 1652 additions and 24 deletions
--- a/server/workflow/engine.go
+++ b/server/workflow/engine.go
@@ -0,0 +1,282 @@
+package workflow
+
+import (
+	"context"
+	"encoding/json"
+	"fmt"
+	"log"
+	"time"
+
+	"switchboard-core/events"
+	"switchboard-core/models"
+	"switchboard-core/sandbox"
+	"switchboard-core/store"
+
+	"github.com/google/uuid"
+)
+
+// MaxConsecutiveAutomated is the cycle guard limit for automated stages.
+const MaxConsecutiveAutomated = 10
+
+// Engine orchestrates workflow instance lifecycle.
+type Engine struct {
+	stores store.Stores
+	bus    *events.Bus
+	runner *sandbox.Runner
+}
+
+// NewEngine creates a workflow engine.
+func NewEngine(stores store.Stores, bus *events.Bus, runner *sandbox.Runner) *Engine {
+	return &Engine{stores: stores, bus: bus, runner: runner}
+}
+
+// Start creates a new workflow instance and kicks off the first stage.
+func (e *Engine) Start(ctx context.Context, workflowID string, initialData json.RawMessage, userID string) (*models.WorkflowInstance, error) {
+	wf, err := e.stores.Workflows.GetByID(ctx, workflowID)
+	if err != nil {
+		return nil, fmt.Errorf("workflow not found: %w", err)
+	}
+	if !wf.IsActive {
+		return nil, fmt.Errorf("workflow %q is not active", wf.Name)
+	}
+
+	ver, err := e.stores.Workflows.GetLatestVersion(ctx, workflowID)
+	if err != nil {
+		return nil, fmt.Errorf("no published version: %w", err)
+	}
+
+	var stages []models.WorkflowStage
+	if err := json.Unmarshal(ver.Snapshot, &stages); err != nil {
+		return nil, fmt.Errorf("corrupt version snapshot: %w", err)
+	}
+	if len(stages) == 0 {
+		return nil, fmt.Errorf("workflow has no stages")
+	}
+
+	inst := &models.WorkflowInstance{
+		WorkflowID:      workflowID,
+		WorkflowVersion: ver.VersionNumber,
+		CurrentStage:    stages[0].Name,
+		StageData:       initialData,
+		Status:          models.InstanceStatusActive,
+		StartedBy:       userID,
+		Metadata:        json.RawMessage(`{}`),
+	}
+
+	if wf.EntryMode == "public_link" {
+		tok := uuid.New().String()
+		inst.EntryToken = &tok
+	}
+
+	if err := e.stores.Workflows.CreateInstance(ctx, inst); err != nil {
+		return nil, fmt.Errorf("create instance: %w", err)
+	}
+
+	// Create initial assignment if first stage has a team
+	if stages[0].AssignmentTeamID != nil {
+		a := &models.WorkflowAssignment{
+			InstanceID: inst.ID,
+			Stage:      stages[0].Name,
+			TeamID:     *stages[0].AssignmentTeamID,
+		}
+		if err := e.stores.Workflows.CreateAssignment(ctx, a); err != nil {
+			log.Printf("[workflow-engine] create initial assignment: %v", err)
+		}
+	}
+
+	e.emit(ctx, "workflow.started", inst.ID, map[string]any{
+		"workflow_id": workflowID,
+		"instance_id": inst.ID,
+		"started_by":  userID,
+	})
+
+	// If first stage is automated, process it
+	if stages[0].StageMode == models.StageModeAutomated {
+		if err := e.processAutomatedStage(ctx, inst, stages, 0); err != nil {
+			log.Printf("[workflow-engine] automated stage error on start: %v", err)
+		}
+		// Re-read instance after automated processing
+		inst, _ = e.stores.Workflows.GetInstance(ctx, inst.ID)
+	}
+
+	return inst, nil
+}
+
+// Advance moves an instance to the next stage.
+func (e *Engine) Advance(ctx context.Context, instanceID string, stageData json.RawMessage, userID string) (*models.WorkflowInstance, error) {
+	return e.advanceInternal(ctx, instanceID, stageData, userID, 0)
+}
+
+func (e *Engine) advanceInternal(ctx context.Context, instanceID string, stageData json.RawMessage, userID string, autoDepth int) (*models.WorkflowInstance, error) {
+	inst, err := e.stores.Workflows.GetInstance(ctx, instanceID)
+	if err != nil {
+		return nil, fmt.Errorf("instance not found: %w", err)
+	}
+	if inst.Status != models.InstanceStatusActive {
+		return nil, fmt.Errorf("instance is %s, not active", inst.Status)
+	}
+
+	ver, err := e.stores.Workflows.GetVersion(ctx, inst.WorkflowID, inst.WorkflowVersion)
+	if err != nil {
+		return nil, fmt.Errorf("version not found: %w", err)
+	}
+
+	var stages []models.WorkflowStage
+	if err := json.Unmarshal(ver.Snapshot, &stages); err != nil {
+		return nil, fmt.Errorf("corrupt snapshot: %w", err)
+	}
+
+	// Find current stage ordinal
+	currentOrdinal := -1
+	for _, s := range stages {
+		if s.Name == inst.CurrentStage {
+			currentOrdinal = s.Ordinal
+			break
+		}
+	}
+	if currentOrdinal < 0 {
+		return nil, fmt.Errorf("current stage %q not found in snapshot", inst.CurrentStage)
+	}
+	currentStage := stages[currentOrdinal]
+
+	// Merge stage data
+	merged := mergeJSON(inst.StageData, stageData)
+
+	// Resolve next stage
+	nextOrdinal, err := ResolveNextStage(stages, currentOrdinal, merged)
+	if err != nil {
+		return nil, fmt.Errorf("resolve next stage: %w", err)
+	}
+
+	// Terminal — complete the instance
+	if nextOrdinal >= len(stages) {
+		if err := e.stores.Workflows.CompleteInstance(ctx, instanceID); err != nil {
+			return nil, fmt.Errorf("complete: %w", err)
+		}
+		e.emit(ctx, "workflow.completed", instanceID, map[string]any{
+			"instance_id": instanceID,
+		})
+		return e.stores.Workflows.GetInstance(ctx, instanceID)
+	}
+
+	nextStage := stages[nextOrdinal]
+
+	// Advance in store
+	if err := e.stores.Workflows.AdvanceStage(ctx, instanceID, nextStage.Name, merged); err != nil {
+		return nil, fmt.Errorf("advance store: %w", err)
+	}
+
+	// Cancel old assignments for the previous stage
+	oldAssignments, _ := e.stores.Workflows.ListAssignmentsByInstance(ctx, instanceID)
+	for _, a := range oldAssignments {
+		if a.Stage == currentStage.Name && (a.Status == models.AssignmentStatusUnassigned || a.Status == models.AssignmentStatusClaimed) {
+			e.stores.Workflows.CancelAssignment(ctx, a.ID)
+		}
+	}
+
+	// Create new assignment if next stage has a team
+	if nextStage.AssignmentTeamID != nil {
+		a := &models.WorkflowAssignment{
+			InstanceID: instanceID,
+			Stage:      nextStage.Name,
+			TeamID:     *nextStage.AssignmentTeamID,
+		}
+		if err := e.stores.Workflows.CreateAssignment(ctx, a); err != nil {
+			log.Printf("[workflow-engine] create assignment: %v", err)
+		} else {
+			e.emit(ctx, "workflow.assigned", a.TeamID, map[string]any{
+				"instance_id":   instanceID,
+				"stage":         nextStage.Name,
+				"assignment_id": a.ID,
+				"team_id":       a.TeamID,
+			})
+		}
+	}
+
+	e.emit(ctx, "workflow.advanced", instanceID, map[string]any{
+		"instance_id":    instanceID,
+		"previous_stage": currentStage.Name,
+		"current_stage":  nextStage.Name,
+	})
+
+	// If next stage is automated, process it
+	if nextStage.StageMode == models.StageModeAutomated {
+		if err := e.processAutomatedStage(ctx, inst, stages, autoDepth+1); err != nil {
+			log.Printf("[workflow-engine] automated stage error: %v", err)
+		}
+	}
+
+	return e.stores.Workflows.GetInstance(ctx, instanceID)
+}
+
+// Cancel terminates an active instance and all its open assignments.
+func (e *Engine) Cancel(ctx context.Context, instanceID string, userID string) error {
+	inst, err := e.stores.Workflows.GetInstance(ctx, instanceID)
+	if err != nil {
+		return fmt.Errorf("instance not found: %w", err)
+	}
+	if inst.Status != models.InstanceStatusActive {
+		return fmt.Errorf("instance is %s, not active", inst.Status)
+	}
+
+	if err := e.stores.Workflows.CancelInstance(ctx, instanceID); err != nil {
+		return fmt.Errorf("cancel: %w", err)
+	}
+
+	// Cancel all open assignments
+	assignments, _ := e.stores.Workflows.ListAssignmentsByInstance(ctx, instanceID)
+	for _, a := range assignments {
+		if a.Status == models.AssignmentStatusUnassigned || a.Status == models.AssignmentStatusClaimed {
+			e.stores.Workflows.CancelAssignment(ctx, a.ID)
+		}
+	}
+
+	e.emit(ctx, "workflow.cancelled", instanceID, map[string]any{
+		"instance_id": instanceID,
+		"cancelled_by": userID,
+	})
+
+	return nil
+}
+
+// emit publishes an event on the bus.
+func (e *Engine) emit(_ context.Context, label, room string, payload map[string]any) {
+	if e.bus == nil {
+		return
+	}
+	e.bus.Publish(events.Event{
+		Label:   label,
+		Room:    room,
+		Payload: events.MustJSON(payload),
+		Ts:      time.Now().UnixMilli(),
+	})
+}
+
+// mergeJSON merges b into a (shallow). Returns a if b is empty.
+func mergeJSON(a, b json.RawMessage) json.RawMessage {
+	if len(b) == 0 || string(b) == "{}" || string(b) == "null" {
+		if len(a) == 0 {
+			return json.RawMessage(`{}`)
+		}
+		return a
+	}
+	if len(a) == 0 || string(a) == "{}" || string(a) == "null" {
+		return b
+	}
+
+	var ma, mb map[string]json.RawMessage
+	if json.Unmarshal(a, &ma) != nil {
+		return b
+	}
+	if json.Unmarshal(b, &mb) != nil {
+		return a
+	}
+	for k, v := range mb {
+		ma[k] = v
+	}
+	merged, err := json.Marshal(ma)
+	if err != nil {
+		return b
+	}
+	return merged
+}