// Package aliyun 提供阿里云邮件推送（DirectMail）通道。
package aliyun

import (
	"context"
	"fmt"
	"strings"
	"sync"
	"time"

	mailx "code.yun.ink/pkg/mailx"
	openapi "github.com/alibabacloud-go/darabonba-openapi/v2/client"
	dm20151123 "github.com/alibabacloud-go/dm-20151123/v2/client"
	util "github.com/alibabacloud-go/tea-utils/v2/service"
	"github.com/alibabacloud-go/tea/tea"
)

// defaultTimeout 单次 API 调用的默认超时
const defaultTimeout = 30 * time.Second

// Config 阿里云邮件推送通道配置
type Config struct {
	AccessKeyID     string // AccessKey ID
	AccessKeySecret string // AccessKey Secret
	Endpoint        string // Endpoint，默认 dm.aliyuncs.com
	AccountName     string // 发信地址（必填）
	ReplyAddress    string // 默认回复地址（可选）
	Timeout         time.Duration // 单次 API 调用的超时，默认 30s
}

// dmMailer 阿里云 DM 客户端的最小接口（便于测试注入 mock）
type dmMailer interface {
	SingleSendMailWithOptions(request *dm20151123.SingleSendMailRequest, runtime *util.RuntimeOptions) (*dm20151123.SingleSendMailResponse, error)
	SenderStatisticsDetailByParamWithOptions(request *dm20151123.SenderStatisticsDetailByParamRequest, runtime *util.RuntimeOptions) (*dm20151123.SenderStatisticsDetailByParamResponse, error)
}

// Aliyun 阿里云发送通道
type Aliyun struct {
	cfg Config

	initOnce sync.Once
	client   dmMailer
	initErr  error
}

// New 创建阿里云通道
func New(cfg Config) *Aliyun {
	if cfg.Endpoint == "" {
		cfg.Endpoint = "dm.aliyuncs.com"
	}
	return &Aliyun{cfg: cfg}
}

// Name 返回通道名称
func (a *Aliyun) Name() string { return "aliyun" }

// Send 发送一封邮件
func (a *Aliyun) Send(ctx context.Context, msg *mailx.Message) error {
	logger := mailx.LoggerFromContext(ctx)

	if len(msg.To) > 100 {
		return fmt.Errorf("%w: aliyun up to 100 recipients allowed", mailx.ErrInvalidMessage)
	}
	if a.cfg.AccountName == "" {
		return fmt.Errorf("%w: aliyun AccountName is required", mailx.ErrInvalidConfig)
	}
	if len(msg.Inline) > 0 {
		return fmt.Errorf("%w: aliyun SingleSendMail does not support inline images", mailx.ErrInvalidConfig)
	}

	client, err := a.newClient()
	if err != nil {
		return fmt.Errorf("mailx/aliyun: create client: %w", err)
	}

	// 阿里云 DirectMail 的 HtmlBody 必填；纯文本也需以 HTML 形式传递
	htmlBody := msg.Body
	if htmlBody == "" {
		htmlBody = mailx.EscapeHTML(msg.TextBody)
	}
	req := &dm20151123.SingleSendMailRequest{
		AccountName: tea.String(a.cfg.AccountName),
		ToAddress:   tea.String(strings.Join(msg.To, ",")),
		Subject:     tea.String(msg.Subject),
		HtmlBody:    tea.String(htmlBody),
		AddressType: tea.Int32(0), // 0：随机账号；1：发信地址
	}

	replyTo := msg.ReplyTo
	if replyTo == "" {
		replyTo = a.cfg.ReplyAddress
	}
	if replyTo != "" {
		req.ReplyToAddress = tea.Bool(false)
		req.ReplyAddress = tea.String(replyTo)
	} else {
		req.ReplyToAddress = tea.Bool(true)
	}

	// 将 ctx 的 deadline 折算为超时，同时应用配置超时
	runtime := a.runtimeOptions(ctx)
	if _, err := client.SingleSendMailWithOptions(req, runtime); err != nil {
		logger.Errorf(ctx, "mailx/aliyun: send failed: %v", err)
		return fmt.Errorf("%w: %v", mailx.ErrSendFailed, err)
	}
	logger.Infof(ctx, "mailx/aliyun: sent to %v subject=%q", msg.To, msg.Subject)
	return nil
}

// newClient 惰性创建并复用阿里云 SDK 客户端（线程安全）。
// 若已通过测试或其他方式注入 client，则直接返回注入的客户端。
func (a *Aliyun) newClient() (dmMailer, error) {
	if a.client != nil {
		return a.client, a.initErr
	}
	a.initOnce.Do(func() {
		config := &openapi.Config{
			AccessKeyId:     tea.String(a.cfg.AccessKeyID),
			AccessKeySecret: tea.String(a.cfg.AccessKeySecret),
			Endpoint:        tea.String(a.cfg.Endpoint),
		}
		c, err := dm20151123.NewClient(config)
		if err != nil {
			a.initErr = fmt.Errorf("mailx/aliyun: create client: %w", err)
			return
		}
		a.client = c
	})
	return a.client, a.initErr
}

// runtimeOptions 根据配置与 ctx 计算超时，返回 RuntimeOptions
func (a *Aliyun) runtimeOptions(ctx context.Context) *util.RuntimeOptions {
	timeout := a.cfg.Timeout
	if timeout <= 0 {
		timeout = defaultTimeout
	}
	if dl, ok := ctx.Deadline(); ok {
		if remain := time.Until(dl); remain > 0 && remain < timeout {
			timeout = remain
		}
	}
	ro := &util.RuntimeOptions{}
	if timeout > 0 {
		ms := int(timeout / time.Millisecond)
		ro.SetConnectTimeout(ms)
		ro.SetReadTimeout(ms)
	}
	return ro
}

// SyncStatus 同步发送状态（阿里云特有能力，非 Sender 接口的一部分）
func (a *Aliyun) SyncStatus(ctx context.Context) ([]mailx.EmailSendRecord, error) {
	logger := mailx.LoggerFromContext(ctx)

	client, err := a.newClient()
	if err != nil {
		return nil, fmt.Errorf("mailx/aliyun: create client: %w", err)
	}
	runtime := a.runtimeOptions(ctx)

	var records []mailx.EmailSendRecord
	start := ""
	// 分页拉取最近一天的数据
	for {
		req := &dm20151123.SenderStatisticsDetailByParamRequest{
			StartTime: tea.String(time.Now().AddDate(0, 0, -1).Format("2006-01-02 15:04")),
			EndTime:   tea.String(time.Now().Format("2006-01-02 15:04")),
			Length:    tea.Int32(100),
		}
		if start != "" {
			req.NextStart = tea.String(start)
		}

		resp, err := client.SenderStatisticsDetailByParamWithOptions(req, runtime)
		if err != nil {
			logger.Errorf(ctx, "mailx/aliyun: sync status failed: %v", err)
			return nil, fmt.Errorf("mailx/aliyun: sync status: %w", err)
		}
		if resp == nil || resp.Body == nil || resp.Body.Data == nil {
			break
		}

		for _, d := range resp.Body.Data.MailDetail {
			t, _ := time.ParseInLocation("2006-01-02T15:04Z", tea.StringValue(d.LastUpdateTime), time.Local)
			records = append(records, mailx.EmailSendRecord{
				AccountName:  tea.StringValue(d.AccountName),
				UpdateTime:   t.UnixMilli(),
				ToUser:       tea.StringValue(d.ToAddress),
				Subject:      tea.StringValue(d.Subject),
				ErrorMessage: tea.StringValue(d.Message),
				Status:       mapSendStatus(tea.Int32Value(d.Status)),
			})
		}

		if resp.Body.NextStart == nil || *resp.Body.NextStart == "" {
			break
		}
		start = *resp.Body.NextStart
	}
	return records, nil
}

// mapSendStatus 阿里云状态码映射为统一状态
func mapSendStatus(code int32) mailx.EmailSendStatus {
	switch code {
	case 0:
		return mailx.EmailSendStatusSuccess
	case 2:
		return mailx.EmailSendStatusInvalidAddress
	case 3:
		return mailx.EmailSendStatusSpam
	case 4:
		return mailx.EmailSendStatusFailed
	default:
		return mailx.EmailSendStatusUnknown
	}
}