package infra

import (
	"context"
	"database/sql"
	"fmt"
	"sync"
	"sync/atomic"
	"testing"
	"time"

	_ "github.com/mattn/go-sqlite3"
)

// openTestDB opens an in-memory SQLite database for testing.
// MaxOpenConns is set to 1 to ensure all goroutines share the same connection
// (required for in-memory SQLite which is per-connection otherwise).
func openTestDB(t *testing.T) *sql.DB {
	t.Helper()
	db, err := sql.Open("sqlite3", ":memory:?_journal_mode=WAL")
	if err != nil {
		t.Fatalf("open test db: %v", err)
	}
	db.SetMaxOpenConns(1)
	t.Cleanup(func() { db.Close() })
	return db
}

func TestJobQueueCreate(t *testing.T) {
	t.Run("test_queue_create", func(t *testing.T) {
		db := openTestDB(t)
		q, err := JobQueueCreate(db, "jobs")
		if err != nil {
			t.Fatalf("JobQueueCreate: %v", err)
		}
		if q == nil {
			t.Fatal("expected non-nil JobQueue")
		}
		if q.TableName != "jobs" {
			t.Errorf("TableName = %q, want %q", q.TableName, "jobs")
		}

		// Verify table exists by inserting a row directly.
		_, err = db.Exec(`INSERT INTO jobs (id, type, scheduled_at) VALUES ('x', 'test', ?)`,
			time.Now().UTC().Format(time.RFC3339))
		if err != nil {
			t.Fatalf("table not created: %v", err)
		}
	})

	t.Run("test_queue_create_default_table_name", func(t *testing.T) {
		db := openTestDB(t)
		q, err := JobQueueCreate(db, "")
		if err != nil {
			t.Fatalf("JobQueueCreate with empty name: %v", err)
		}
		if q.TableName != "jobs" {
			t.Errorf("TableName = %q, want %q", q.TableName, "jobs")
		}
	})

	t.Run("test_queue_create_nil_db", func(t *testing.T) {
		_, err := JobQueueCreate(nil, "jobs")
		if err == nil {
			t.Fatal("expected error for nil db")
		}
	})
}

func TestJobEnqueueDequeue(t *testing.T) {
	t.Run("enqueue_dequeue_atomicidad", func(t *testing.T) {
		db := openTestDB(t)
		q, err := JobQueueCreate(db, "jobs")
		if err != nil {
			t.Fatalf("create: %v", err)
		}

		id, err := JobEnqueue(q, "send_email", `{"to":"a@b.com"}`)
		if err != nil {
			t.Fatalf("enqueue: %v", err)
		}
		if id == "" {
			t.Fatal("expected non-empty job ID")
		}

		job, err := JobDequeue(q, nil)
		if err != nil {
			t.Fatalf("dequeue: %v", err)
		}
		if job == nil {
			t.Fatal("expected a job, got nil")
		}
		if job.ID != id {
			t.Errorf("job ID = %q, want %q", job.ID, id)
		}
		if job.Type != "send_email" {
			t.Errorf("job Type = %q, want %q", job.Type, "send_email")
		}
		if job.Status != JobStatusRunning {
			t.Errorf("job Status = %q, want %q", job.Status, JobStatusRunning)
		}

		// Second dequeue should return nil (job is now running, not pending).
		job2, err := JobDequeue(q, nil)
		if err != nil {
			t.Fatalf("second dequeue: %v", err)
		}
		if job2 != nil {
			t.Errorf("expected nil second dequeue, got job %q", job2.ID)
		}
	})

	t.Run("dequeue_empty_queue_returns_nil", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		job, err := JobDequeue(q, nil)
		if err != nil {
			t.Fatalf("dequeue empty: %v", err)
		}
		if job != nil {
			t.Errorf("expected nil, got job %q", job.ID)
		}
	})

	t.Run("dequeue_priority_order", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		_, _ = JobEnqueue(q, "low", "{}", WithPriority(0))
		_, _ = JobEnqueue(q, "high", "{}", WithPriority(10))
		_, _ = JobEnqueue(q, "mid", "{}", WithPriority(5))

		job, _ := JobDequeue(q, nil)
		if job == nil || job.Type != "high" {
			t.Errorf("expected high-priority job first, got %v", job)
		}
	})

	t.Run("dequeue_jobtype_filter", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		_, _ = JobEnqueue(q, "email", "{}")
		_, _ = JobEnqueue(q, "sms", "{}")

		// Only dequeue "sms" jobs.
		job, err := JobDequeue(q, []string{"sms"})
		if err != nil {
			t.Fatalf("dequeue with filter: %v", err)
		}
		if job == nil || job.Type != "sms" {
			t.Errorf("expected sms job, got %v", job)
		}
	})

	t.Run("dequeue_scheduled_in_future_waits", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		future := time.Now().Add(1 * time.Hour)
		_, _ = JobEnqueue(q, "future", "{}", WithScheduledAt(future))

		job, err := JobDequeue(q, nil)
		if err != nil {
			t.Fatalf("dequeue future: %v", err)
		}
		if job != nil {
			t.Errorf("expected nil (future job not yet due), got job %q", job.ID)
		}
	})
}

func TestJobCompleteAndFail(t *testing.T) {
	t.Run("complete_fail_transitions", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		id, _ := JobEnqueue(q, "work", "{}", WithMaxAttempts(3))
		job, _ := JobDequeue(q, nil)
		if job == nil {
			t.Fatal("expected job")
		}

		// Complete it.
		if err := JobComplete(q, id, `{"ok":true}`); err != nil {
			t.Fatalf("complete: %v", err)
		}

		// Verify status in DB.
		var status string
		_ = db.QueryRow(`SELECT status FROM jobs WHERE id = ?`, id).Scan(&status)
		if status != "completed" {
			t.Errorf("status = %q, want completed", status)
		}
	})

	t.Run("fail_increments_attempts", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		id, _ := JobEnqueue(q, "work", "{}", WithMaxAttempts(3))
		_, _ = JobDequeue(q, nil)

		// First failure → status = failed (attempts=1 < max=3).
		if err := JobFail(q, id, "oops"); err != nil {
			t.Fatalf("fail: %v", err)
		}
		var status string
		var attempts int
		_ = db.QueryRow(`SELECT status, attempts FROM jobs WHERE id = ?`, id).Scan(&status, &attempts)
		if status != "failed" {
			t.Errorf("status = %q, want failed", status)
		}
		if attempts != 1 {
			t.Errorf("attempts = %d, want 1", attempts)
		}
	})

	t.Run("fail_transitions_to_dead", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		id, _ := JobEnqueue(q, "work", "{}", WithMaxAttempts(2))

		// Fail twice → dead.
		for i := 0; i < 2; i++ {
			// Re-set to pending so we can dequeue again (simulate retry logic).
			if i > 0 {
				_, _ = db.Exec(`UPDATE jobs SET status = 'pending' WHERE id = ?`, id)
			}
			_, _ = JobDequeue(q, nil)
			_ = JobFail(q, id, fmt.Sprintf("error %d", i+1))
		}

		var status string
		_ = db.QueryRow(`SELECT status FROM jobs WHERE id = ?`, id).Scan(&status)
		if status != "dead" {
			t.Errorf("status = %q, want dead after max_attempts reached", status)
		}
	})
}

func TestJobStatusSummaryFn(t *testing.T) {
	t.Run("job_status_summary_format", func(t *testing.T) {
		counts := map[string]int{
			"pending":   5,
			"running":   2,
			"completed": 10,
			"failed":    1,
			"dead":      0,
		}
		got := JobStatusSummary(counts)
		want := "pending: 5, running: 2, completed: 10, failed: 1, dead: 0"
		if got != want {
			t.Errorf("got %q, want %q", got, want)
		}
	})

	t.Run("job_status_summary_empty_map", func(t *testing.T) {
		got := JobStatusSummary(map[string]int{})
		want := "pending: 0, running: 0, completed: 0, failed: 0, dead: 0"
		if got != want {
			t.Errorf("got %q, want %q", got, want)
		}
	})
}

func TestJobWorkerGracefulShutdown(t *testing.T) {
	t.Run("worker_graceful_shutdown", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		ctx, cancel := context.WithCancel(context.Background())

		done := make(chan struct{})
		go func() {
			defer close(done)
			_ = JobWorker(ctx, q, func(j Job) error {
				return nil
			}, WithPollInterval(10*time.Millisecond))
		}()

		// Let the worker poll a couple of times.
		time.Sleep(50 * time.Millisecond)
		cancel()

		select {
		case <-done:
			// OK — worker exited cleanly.
		case <-time.After(2 * time.Second):
			t.Fatal("worker did not stop within timeout after context cancellation")
		}
	})

	t.Run("worker_processes_jobs", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		var processed atomic.Int32
		for i := 0; i < 3; i++ {
			_, _ = JobEnqueue(q, "task", `{}`)
		}

		ctx, cancel := context.WithCancel(context.Background())
		go func() {
			_ = JobWorker(ctx, q, func(j Job) error {
				processed.Add(1)
				return nil
			}, WithPollInterval(10*time.Millisecond))
		}()

		// Wait for all 3 to be processed (with timeout).
		deadline := time.Now().Add(2 * time.Second)
		for time.Now().Before(deadline) {
			if processed.Load() >= 3 {
				break
			}
			time.Sleep(10 * time.Millisecond)
		}
		cancel()

		if n := processed.Load(); n < 3 {
			t.Errorf("processed %d jobs, want 3", n)
		}
	})
}

func TestJobConcurrency(t *testing.T) {
	t.Run("concurrency_multiples_goroutines_dequeue", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		const numJobs = 50
		for i := 0; i < numJobs; i++ {
			_, _ = JobEnqueue(q, "task", fmt.Sprintf(`{"i":%d}`, i))
		}

		var processed atomic.Int32
		var wg sync.WaitGroup

		ctx, cancel := context.WithCancel(context.Background())
		const numWorkers = 5
		for i := 0; i < numWorkers; i++ {
			wg.Add(1)
			go func() {
				defer wg.Done()
				_ = JobWorker(ctx, q, func(j Job) error {
					processed.Add(1)
					return nil
				}, WithPollInterval(5*time.Millisecond))
			}()
		}

		// Wait until all jobs are processed.
		deadline := time.Now().Add(5 * time.Second)
		for time.Now().Before(deadline) {
			if processed.Load() >= numJobs {
				break
			}
			time.Sleep(10 * time.Millisecond)
		}
		cancel()
		wg.Wait()

		if n := processed.Load(); n != numJobs {
			t.Errorf("processed %d, want %d (no double-processing with concurrent workers)", n, numJobs)
		}
	})
}

func TestJobCleanupFn(t *testing.T) {
	t.Run("job_cleanup_removes_old_terminal_jobs", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		id, _ := JobEnqueue(q, "work", "{}")
		_, _ = JobDequeue(q, nil)
		_ = JobComplete(q, id, "")

		// Make the job look old (set created_at in the past, always UTC to match JobCleanup).
		past := time.Now().UTC().Add(-25 * time.Hour).Format(time.RFC3339)
		_, _ = db.Exec(`UPDATE jobs SET created_at = ? WHERE id = ?`, past, id)

		n, err := JobCleanup(q, 24*time.Hour)
		if err != nil {
			t.Fatalf("cleanup: %v", err)
		}
		if n != 1 {
			t.Errorf("deleted %d rows, want 1", n)
		}

		// Job should be gone.
		var count int
		_ = db.QueryRow(`SELECT COUNT(*) FROM jobs WHERE id = ?`, id).Scan(&count)
		if count != 0 {
			t.Errorf("job still in DB after cleanup")
		}
	})

	t.Run("job_cleanup_keeps_recent_jobs", func(t *testing.T) {
		db := openTestDB(t)
		q, _ := JobQueueCreate(db, "jobs")

		id, _ := JobEnqueue(q, "work", "{}")
		_, _ = JobDequeue(q, nil)
		_ = JobComplete(q, id, "")

		// Job was just created — should not be cleaned up.
		n, err := JobCleanup(q, 24*time.Hour)
		if err != nil {
			t.Fatalf("cleanup: %v", err)
		}
		if n != 0 {
			t.Errorf("deleted %d rows, want 0 (job is recent)", n)
		}
	})
}