package mailgun

import (
	"context"
	"errors"
	"testing"

	mailx "code.yun.ink/pkg/mailx"
	"github.com/mailgun/mailgun-go/v4"
)

// mockMG 实现 mgClient 接口，记录 NewMessage 的参数与 Send 调用
type mockMG struct {
	sendErr error

	// NewMessage 捕获
	from, subject, text string
	to                  []string

	// Send 捕获
	msgSent bool
	sentMsg *mailgun.Message
}

func (m *mockMG) NewMessage(from, subject, text string, to ...string) *mailgun.Message {
	m.from, m.subject, m.text = from, subject, text
	m.to = to
	return mailgun.NewMessage(from, subject, text, to...)
}

func (m *mockMG) Send(_ context.Context, msg *mailgun.Message) (string, string, error) {
	m.msgSent = true
	m.sentMsg = msg
	if m.sendErr != nil {
		return "", "", m.sendErr
	}
	return "mock-id", "queued", nil
}

// TestSendSuccess 验证完整发送流程与消息构造参数
func TestSendSuccess(t *testing.T) {
	mock := &mockMG{}
	g := &MailGun{cfg: Config{APIKey: "key", Domain: "mg.example.com", Sender: "noreply@example.com"}, client: mock}

	msg := mailx.NewMessage().
		To("a@example.com", "b@example.com").
		Cc("cc@example.com").
		Bcc("bcc@example.com").
		Subject("hi").
		Text("plain").
		HTML("<b>html</b>").
		ReplyTo("reply@example.com").
		AttachBytes("a.txt", []byte("data")).
		InlineImageBytes("cid1", "a.png", []byte{1}).
		Build()

	if err := g.Send(context.Background(), msg); err != nil {
		t.Fatal(err)
	}
	if !mock.msgSent {
		t.Fatal("message not sent")
	}
	if mock.from != "noreply@example.com" {
		t.Errorf("From = %q", mock.from)
	}
	if mock.subject != "hi" {
		t.Errorf("Subject = %q", mock.subject)
	}
	if mock.text != "plain" {
		t.Errorf("Text = %q", mock.text)
	}
	if len(mock.to) != 2 || mock.to[0] != "a@example.com" || mock.to[1] != "b@example.com" {
		t.Errorf("To = %v", mock.to)
	}
}

// TestSendFromFallback 验证 msg.From 为空时回退 cfg.Sender
func TestSendFromFallback(t *testing.T) {
	mock := &mockMG{}
	g := &MailGun{cfg: Config{APIKey: "key", Domain: "mg.example.com", Sender: "cfg@example.com"}, client: mock}

	msg := mailx.NewMessage().To("a@example.com").Subject("s").Build()
	if err := g.Send(context.Background(), msg); err != nil {
		t.Fatal(err)
	}
	if mock.from != "cfg@example.com" {
		t.Errorf("From = %q, want cfg fallback", mock.from)
	}
}

// TestSendTextFallback 验证 Body 为纯文本时作为 text 传递
func TestSendTextFallback(t *testing.T) {
	mock := &mockMG{}
	g := &MailGun{cfg: Config{APIKey: "key", Domain: "mg.example.com", Sender: "s@example.com"}, client: mock}

	msg := mailx.NewMessage().To("a@example.com").Subject("s").Body("plain body no html").Build()
	if err := g.Send(context.Background(), msg); err != nil {
		t.Fatal(err)
	}
	if mock.text != "plain body no html" {
		t.Errorf("Text = %q, want fallback to Body", mock.text)
	}
}

// TestSendHTMLOnly 验证 Body 为 HTML 时不作为 text 传递
func TestSendHTMLOnly(t *testing.T) {
	mock := &mockMG{}
	g := &MailGun{cfg: Config{APIKey: "key", Domain: "mg.example.com", Sender: "s@example.com"}, client: mock}

	msg := mailx.NewMessage().To("a@example.com").Subject("s").HTML("<b>html</b>").Build()
	if err := g.Send(context.Background(), msg); err != nil {
		t.Fatal(err)
	}
	if mock.text != "" {
		t.Errorf("Text = %q, want empty for html body", mock.text)
	}
}

// TestSendFail 验证发送失败包装为 ErrSendFailed
func TestSendFail(t *testing.T) {
	mock := &mockMG{sendErr: errors.New("mailgun down")}
	g := &MailGun{cfg: Config{APIKey: "key", Domain: "mg.example.com", Sender: "s@example.com"}, client: mock}

	msg := mailx.NewMessage().To("a@example.com").Subject("s").Build()
	err := g.Send(context.Background(), msg)
	if err == nil || !errors.Is(err, mailx.ErrSendFailed) {
		t.Fatalf("err = %v, want ErrSendFailed", err)
	}
}

// TestSendNoSender 验证缺少 Sender 报错
func TestSendNoSender(t *testing.T) {
	g := &MailGun{cfg: Config{APIKey: "key", Domain: "mg.example.com"}, client: &mockMG{}}
	msg := mailx.NewMessage().To("a@example.com").Subject("s").Build()
	err := g.Send(context.Background(), msg)
	if err == nil || !errors.Is(err, mailx.ErrInvalidConfig) {
		t.Fatalf("err = %v, want ErrInvalidConfig", err)
	}
}

// TestSendNoDomain 验证缺少 Domain/APIKey 报错
func TestSendNoDomain(t *testing.T) {
	g := &MailGun{cfg: Config{Sender: "s@example.com"}, client: &mockMG{}}
	msg := mailx.NewMessage().To("a@example.com").Subject("s").Build()
	err := g.Send(context.Background(), msg)
	if err == nil || !errors.Is(err, mailx.ErrInvalidConfig) {
		t.Fatalf("err = %v, want ErrInvalidConfig", err)
	}
}

// TestSendAttachmentErrors 验证附件边界情况
func TestSendAttachmentErrors(t *testing.T) {
	g := &MailGun{cfg: Config{APIKey: "key", Domain: "mg.example.com", Sender: "s@example.com"}, client: &mockMG{}}

	// 附件既无 path 也无 data
	msg := mailx.NewMessage().To("a@example.com").Subject("s").
		AttachBytes("x.txt", []byte{1}).
		Build()
	msg.Attachments[0].Data = nil // 清空 data
	if err := g.Send(context.Background(), msg); err == nil {
		t.Fatal("attachment without path/data should error")
	}

	// 附件路径不存在
	msg = mailx.NewMessage().To("a@example.com").Subject("s").
		Attach("no-such-file.txt").
		Build()
	if err := g.Send(context.Background(), msg); err == nil {
		t.Fatal("missing attachment file should error")
	}

	// 内嵌图片路径不存在
	msg = mailx.NewMessage().To("a@example.com").Subject("s").
		InlineImage("cid1", "no-such-img.png").
		Build()
	if err := g.Send(context.Background(), msg); err == nil {
		t.Fatal("missing inline file should error")
	}
}

// TestGetClient 验证 getClient 惰性复用
func TestGetClient(t *testing.T) {
	g := New(Config{APIKey: "key", Domain: "mg.example.com"})
	c1 := g.getClient()
	c2 := g.getClient()
	if c1 != c2 {
		t.Error("client should be reused")
	}
}