package engine

import (
	"context"
	"log/slog"
	"os"
	"sync"
	"testing"
	"time"

	"tangled.org/core/spindle/config"
	"tangled.org/core/spindle/models"
)

type slottedEngine struct {
	*mockEngine
	slots *SemaphoreSlotter
}

func (e *slottedEngine) AcquireWorkflowSlot(ctx context.Context, wid models.WorkflowId, wf *models.Workflow, mode AcquireMode) (WorkflowSlot, error) {
	return e.slots.AcquireWorkflowSlot(ctx, wid, wf, mode)
}

func TestQueuedWorkflowHasNoLogFileUntilItHoldsASlot(t *testing.T) {
	testDB := newTestDB(t)
	logDir := t.TempDir()
	started := make(chan models.WorkflowId, 2)
	release := make(chan struct{})
	eng := &slottedEngine{mockEngine: &mockEngine{}, slots: NewSemaphoreSlotter(1)}
	eng.runStepFunc = func(_ context.Context, wid models.WorkflowId, _ int, _ models.WorkflowLogger) error {
		started <- wid
		<-release
		return nil
	}

	pipelineId := models.PipelineId("slot-log")
	step := []models.Step{mockStep{name: "step"}}
	pipeline := &models.Pipeline{Workflows: map[models.Engine][]models.Workflow{
		eng: {{Name: "a", Steps: step}, {Name: "b", Steps: step}},
	}}
	cfg := &config.Config{Server: config.Server{LogDir: logDir}}

	var wg sync.WaitGroup
	wg.Go(func() {
		StartWorkflows(slog.New(slog.NewTextHandler(os.Stderr, nil)), nil, cfg, nil, nil, testDB, nil, nil, nil, context.Background(), pipeline, pipelineId)
	})

	holder := <-started
	waiting := "a"
	if holder.Name == "a" {
		waiting = "b"
	}
	// nothing signals the waiter parked on the slot, this is just a wait
	time.Sleep(300 * time.Millisecond)
	if _, err := os.Stat(models.LogFilePath(logDir, models.WorkflowId{PipelineId: pipelineId, Name: waiting})); err == nil {
		t.Errorf("workflow %q is waiting for a slot and already has a log file open", waiting)
	}
	close(release)
	wg.Wait()
}