package worker

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"strings"
	"sync"
	"testing"
	"time"

	"moku-backend/internal/jobs"
)

func TestRunnerProcessesRegisteredJob(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	store := &fakeJobStore{
		job: &jobs.Job{
			ID:      "job-1",
			Kind:    jobs.KindBootstrapStructureMaterialize,
			Payload: []byte(`{"installationId":"installation-1"}`),
		},
		cancel: cancel,
	}
	runner := NewRunner(store, slog.New(slog.NewTextHandler(io.Discard, nil)), 0)

	handlerCalled := false
	runner.Register(jobs.KindBootstrapStructureMaterialize, func(ctx context.Context, job jobs.Job) error {
		handlerCalled = true
		if job.ID != "job-1" {
			t.Fatalf("expected job id job-1, got %s", job.ID)
		}
		return nil
	})

	if err := runner.Run(ctx); err != nil {
		t.Fatalf("runner returned error: %v", err)
	}

	if !handlerCalled {
		t.Fatal("expected handler to be called")
	}
	if len(store.succeeded) != 1 || store.succeeded[0] != "job-1" {
		t.Fatalf("expected job to be marked succeeded once, got %#v", store.succeeded)
	}
	if len(store.failed) != 0 {
		t.Fatalf("expected no failed jobs, got %#v", store.failed)
	}
}

func TestRunnerMarksFailedWhenHandlerErrors(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	store := &fakeJobStore{
		job: &jobs.Job{
			ID:   "job-2",
			Kind: jobs.KindBootstrapStructureMaterialize,
		},
		cancel: cancel,
	}
	runner := NewRunner(store, slog.New(slog.NewTextHandler(io.Discard, nil)), 0)
	runner.Register(jobs.KindBootstrapStructureMaterialize, func(ctx context.Context, job jobs.Job) error {
		return errors.New("boom")
	})

	if err := runner.Run(ctx); err != nil {
		t.Fatalf("runner returned error: %v", err)
	}

	if len(store.succeeded) != 0 {
		t.Fatalf("expected no succeeded jobs, got %#v", store.succeeded)
	}
	if len(store.failed) != 1 {
		t.Fatalf("expected one failed job, got %#v", store.failed)
	}
	if store.failed[0].jobID != "job-2" {
		t.Fatalf("expected failed job id job-2, got %#v", store.failed[0])
	}
	if !strings.Contains(store.failed[0].failure, "boom") {
		t.Fatalf("expected failure to mention handler error, got %#v", store.failed[0])
	}
}

func TestRunnerMarksFailedWhenHandlerMissing(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	store := &fakeJobStore{
		job: &jobs.Job{
			ID:   "job-3",
			Kind: "unknown.kind",
		},
		cancel: cancel,
	}
	runner := NewRunner(store, slog.New(slog.NewTextHandler(io.Discard, nil)), 0)

	if err := runner.Run(ctx); err != nil {
		t.Fatalf("runner returned error: %v", err)
	}

	if len(store.failed) != 1 {
		t.Fatalf("expected one failed job, got %#v", store.failed)
	}
	if !strings.Contains(store.failed[0].failure, "no handler registered") {
		t.Fatalf("expected missing handler failure, got %#v", store.failed[0])
	}
}

func TestRunnerRetriesClaimErrors(t *testing.T) {
	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	store := &fakeJobStore{
		claimErrors: []error{errors.New("relation \"background_jobs\" does not exist")},
		job: &jobs.Job{
			ID:   "job-4",
			Kind: jobs.KindBootstrapStructureMaterialize,
		},
		cancel: cancel,
	}
	runner := NewRunner(store, slog.New(slog.NewTextHandler(io.Discard, nil)), time.Millisecond)

	handlerCalled := false
	runner.Register(jobs.KindBootstrapStructureMaterialize, func(ctx context.Context, job jobs.Job) error {
		handlerCalled = true
		return nil
	})

	if err := runner.Run(ctx); err != nil {
		t.Fatalf("runner returned error: %v", err)
	}

	if !handlerCalled {
		t.Fatal("expected handler to be called after claim retry")
	}
	if store.claimAttempts < 2 {
		t.Fatalf("expected at least two claim attempts, got %d", store.claimAttempts)
	}
	if len(store.succeeded) != 1 || store.succeeded[0] != "job-4" {
		t.Fatalf("expected job to be marked succeeded once, got %#v", store.succeeded)
	}
	if len(store.failed) != 0 {
		t.Fatalf("expected no failed jobs, got %#v", store.failed)
	}
}

type fakeJobStore struct {
	mu            sync.Mutex
	job           *jobs.Job
	claimed       bool
	claimErrors   []error
	claimAttempts int
	succeeded     []string
	failed        []fakeFailure
	cancel        context.CancelFunc
}

type fakeFailure struct {
	jobID   string
	failure string
}

func (store *fakeJobStore) ClaimNext(ctx context.Context) (*jobs.Job, error) {
	store.mu.Lock()
	defer store.mu.Unlock()
	store.claimAttempts++

	if len(store.claimErrors) > 0 {
		err := store.claimErrors[0]
		store.claimErrors = store.claimErrors[1:]
		return nil, err
	}

	if store.claimed || store.job == nil {
		return nil, nil
	}

	store.claimed = true
	job := *store.job
	return &job, nil
}

func (store *fakeJobStore) MarkSucceeded(ctx context.Context, jobID string) error {
	store.mu.Lock()
	store.succeeded = append(store.succeeded, jobID)
	store.mu.Unlock()

	if store.cancel != nil {
		store.cancel()
	}

	return nil
}

func (store *fakeJobStore) MarkFailed(ctx context.Context, jobID, failure string) error {
	store.mu.Lock()
	store.failed = append(store.failed, fakeFailure{jobID: jobID, failure: failure})
	store.mu.Unlock()

	if store.cancel != nil {
		store.cancel()
	}

	return nil
}