package mail

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"testing"

	"gorm.io/gorm"

	"ws_usernode/internal/model"
)

// flakyMailer 前 n 次发送失败，之后成功；用于验证重试。
type flakyMailer struct {
	failures int
	calls    int
}

var errFlaky = errors.New("mail: smtp down")

func (m *flakyMailer) Send(_ context.Context, _, _, _ string) error {
	m.calls++
	if m.calls <= m.failures {
		return errFlaky
	}
	return nil
}

// recordingMailer 记录直发调用次数。
type recordingMailer struct{ calls int }

func (m *recordingMailer) Send(context.Context, string, string, string) error {
	m.calls++
	return nil
}

func testQueued(t *testing.T, base Mailer) (*QueuedMailer, *gorm.DB) {
	t.Helper()
	db, err := model.Open("sqlite", ":memory:", false)
	if err != nil {
		t.Fatalf("open test db: %v", err)
	}
	if err := db.AutoMigrate(&model.MailLog{}); err != nil {
		t.Fatalf("migrate mail_logs: %v", err)
	}
	log := slog.New(slog.NewTextHandler(io.Discard, nil))
	return NewQueuedMailer(base, db, log), db
}

func TestQueuedMailerSendSuccess(t *testing.T) {
	rec := &recordingMailer{}
	q, db := testQueued(t, rec)
	if err := q.Send(context.Background(), "a@example.com", "主题", "正文"); err != nil {
		t.Fatalf("send: %v", err)
	}
	if rec.calls != 1 {
		t.Fatalf("base send calls = %d, want 1", rec.calls)
	}
	var n int64
	if err := db.Model(&model.MailLog{}).Where("status = ?", StatusSent).Count(&n).Error; err != nil {
		t.Fatalf("count sent: %v", err)
	}
	if n != 1 {
		t.Fatalf("sent = %d, want 1", n)
	}
}

func TestQueuedMailerFailureQueuedAndRetry(t *testing.T) {
	base := &flakyMailer{failures: 2}
	q, db := testQueued(t, base)

	// 第一次发送失败：Send 仍返回 nil（不阻断业务），落 failed 记录
	if err := q.Send(context.Background(), "b@example.com", "s", "body"); err != nil {
		t.Fatalf("send returned error: %v", err)
	}
	if base.calls != 1 {
		t.Fatalf("base calls = %d, want 1", base.calls)
	}
	var row model.MailLog
	if err := db.First(&row, "status = ?", StatusFailed).Error; err != nil {
		t.Fatalf("failed row: %v", err)
	}
	if row.RetryCount != 1 || row.Error != errFlaky.Error() {
		t.Fatalf("failed row = %+v", row)
	}

	// Retry 1：仍失败 → retry_count=2；Retry 2：成功 → sent
	if err := q.Retry(context.Background(), 5); err != nil {
		t.Fatalf("retry: %v", err)
	}
	if base.calls != 2 {
		t.Fatalf("calls after retry1 = %d, want 2", base.calls)
	}
	if err := q.Retry(context.Background(), 5); err != nil {
		t.Fatalf("retry2: %v", err)
	}
	if base.calls != 3 {
		t.Fatalf("calls after retry2 = %d, want 3", base.calls)
	}
	var n int64
	if err := db.Model(&model.MailLog{}).Where("status = ?", StatusSent).Count(&n).Error; err != nil {
		t.Fatalf("count sent: %v", err)
	}
	if n != 1 {
		t.Fatalf("sent = %d, want 1", n)
	}
}

func TestQueuedMailerRetryHitsMax(t *testing.T) {
	base := &flakyMailer{failures: 100} // 永远失败
	q, db := testQueued(t, base)
	if err := q.Send(context.Background(), "c@example.com", "s", "body"); err != nil {
		t.Fatalf("send: %v", err)
	}
	// 达到上限后 Retry 不再挑选（retry_count 不再增长）
	for i := 0; i < 10; i++ {
		if err := q.Retry(context.Background(), MaxRetries); err != nil {
			t.Fatalf("retry: %v", err)
		}
	}
	var row model.MailLog
	if err := db.First(&row, "status = ?", StatusFailed).Error; err != nil {
		t.Fatalf("failed row: %v", err)
	}
	if row.RetryCount > MaxRetries {
		t.Fatalf("retry_count = %d, want <= %d", row.RetryCount, MaxRetries)
	}
}