Cyrene_v2/plugins/channels/weixin_ilink/send.go

package weixin_ilink

import (
	"bytes"
	"context"
	"crypto/aes"
	"crypto/rand"
	"encoding/base64"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"net/http"
	"strconv"
	"time"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/channel/adapter"
)

// item kind constants reuse the iLink item type codes from poll.go, so
// outbound media maps to the same numbers as inbound parsing.

// sendResult is the sendmessage response envelope.
type sendResult struct {
	Ret     int `json:"ret"`
	Errcode int `json:"errcode"`
}

// SendMessage delivers a reply to the channel. Each message is sent to the
// peer resolved from the message (or resp.ReplyTo) using that peer's stored
// context_token, so the platform can associate the reply with the right
// conversation (design/08 §8).
func (a *Adapter) SendMessage(ctx context.Context, resp adapter.UnifiedResponse) error {
	if !a.IsConnected() {
		return adapter.ErrNotConnected
	}
	for _, m := range resp.Messages {
		peer, _ := recipient(m)
		if peer == "" {
			peer = resp.ReplyTo
		}
		if err := a.sendToOne(ctx, peer, m); err != nil {
			return fmt.Errorf("weixin_ilink: send message: %w", err)
		}
	}
	return nil
}

// SendProactive pushes a message that was not triggered by a recent inbound.
// WeChat iLink only allows this inside the 24h window since the user's last
// message (design/08 §3-4): when the user has been silent longer, or has never
// messaged, the push is rejected with ErrProactiveWindow and Capabilities.
// Proactive is only true so callers know the capability exists.
func (a *Adapter) SendProactive(ctx context.Context, msg adapter.UnifiedMessage) error {
	if !a.IsConnected() {
		return adapter.ErrNotConnected
	}
	peer, _ := recipient(msg)
	if peer == "" {
		return ErrNoContextToken
	}

	a.mu.RLock()
	last, seen := a.lastMsgAt[peer]
	window := a.cfg.ProactiveWindow
	a.mu.RUnlock()

	if !seen || a.clock().Sub(last) > window {
		return ErrProactiveWindow
	}
	if a.contextFor(peer) == "" {
		return ErrNoContextToken
	}
	return a.sendToOne(ctx, peer, msg)
}

// sendToOne sends one normalized message to a peer as a native iLink message,
// composing its item_list from any text plus uploaded media.
func (a *Adapter) sendToOne(ctx context.Context, peer string, m adapter.UnifiedMessage) error {
	if peer == "" {
		return ErrNoContextToken
	}
	ctxToken := a.contextFor(peer)
	if ctxToken == "" {
		return ErrNoContextToken
	}

	items := make([]any, 0, 1+len(m.Media))
	if m.Content != "" {
		items = append(items, nativeTextItem(m.Content))
	}
	for _, md := range m.Media {
		item, err := a.buildMediaItem(ctx, md)
		if err != nil {
			return fmt.Errorf("weixin_ilink: build media item for %q: %w", md.Kind, err)
		}
		items = append(items, item)
	}
	if len(items) == 0 {
		return nil
	}
	return a.sendNative(ctx, peer, ctxToken, items)
}

// buildMediaItem encrypts media bytes, uploads them to the CDN and returns the
// native item referencing the uploaded object and its AES key.
func (a *Adapter) buildMediaItem(ctx context.Context, md adapter.Media) (any, error) {
	plaintext := md.Data
	if len(plaintext) == 0 && md.URL != "" {
		data, err := a.fetchBody(ctx, md.URL)
		if err != nil {
			return nil, fmt.Errorf("weixin_ilink: fetch media source: %w", err)
		}
		plaintext = data
	}

	key := make([]byte, aes.BlockSize)
	if _, err := rand.Read(key); err != nil {
		return nil, fmt.Errorf("weixin_ilink: generate aes key: %w", err)
	}
	encrypted, err := aesECBEncrypt(key, plaintext)
	if err != nil {
		return nil, fmt.Errorf("weixin_ilink: encrypt media: %w", err)
	}
	uploadURL, err := a.getUploadURL(ctx)
	if err != nil {
		return nil, fmt.Errorf("weixin_ilink: get upload url: %w", err)
	}
	if err := a.putBytes(ctx, uploadURL, encrypted); err != nil {
		return nil, fmt.Errorf("weixin_ilink: upload media: %w", err)
	}
	return nativeMediaItem(nativeMediaTypeFor(md.Kind), uploadURL, key, md), nil
}

// sendNative posts a composed sendmessage payload.
func (a *Adapter) sendNative(ctx context.Context, peer, ctxToken string, items []any) error {
	body, err := json.Marshal(map[string]any{
		"msg": map[string]any{
			"to_user_id":    peer,
			"client_id":     newClientID(),
			"message_type":  2, // bot message
			"message_state": 2, // FINISH
			"context_token": ctxToken,
			"item_list":     items,
		},
	})
	if err != nil {
		return fmt.Errorf("weixin_ilink: encode sendmessage: %w", err)
	}
	var out sendResult
	if err := a.doJSON(ctx, http.MethodPost, a.apiURL("/ilink/bot/sendmessage"),
		bytes.NewReader(body), &out); err != nil {
		return fmt.Errorf("weixin_ilink: sendmessage: %w", err)
	}
	if out.Errcode == errSessionExpired {
		return ErrSessionExpired
	}
	if out.Ret != 0 {
		return fmt.Errorf("weixin_ilink: sendmessage ret=%d", out.Ret)
	}
	return nil
}

// getUploadURL requests a pre-signed CDN upload URL. The response field names
// vary across server versions, so several candidates are tried.
func (a *Adapter) getUploadURL(ctx context.Context) (string, error) {
	body, err := json.Marshal(map[string]any{})
	if err != nil {
		return "", fmt.Errorf("weixin_ilink: encode getuploadurl: %w", err)
	}
	var raw map[string]any
	if err := a.doJSON(ctx, http.MethodPost, a.apiURL("/ilink/bot/getuploadurl"),
		bytes.NewReader(body), &raw); err != nil {
		return "", fmt.Errorf("weixin_ilink: getuploadurl: %w", err)
	}
	u := firstString(raw, "upload_url", "url", "uploadUrl", "cdn_url")
	if u == "" {
		return "", fmt.Errorf("weixin_ilink: getuploadurl returned no url")
	}
	return u, nil
}

// putBytes uploads encrypted media bytes to a pre-signed CDN URL.
func (a *Adapter) putBytes(ctx context.Context, uploadURL string, data []byte) error {
	req, err := http.NewRequestWithContext(ctx, http.MethodPut, uploadURL, bytes.NewReader(data))
	if err != nil {
		return fmt.Errorf("weixin_ilink: build upload: %w", err)
	}
	req.Header.Set("Content-Type", "application/octet-stream")
	resp, err := a.httpClient.Do(req)
	if err != nil {
		return fmt.Errorf("weixin_ilink: upload media: %w", err)
	}
	defer resp.Body.Close()
	if resp.StatusCode < 200 || resp.StatusCode >= 300 {
		return fmt.Errorf("weixin_ilink: upload media: status %d", resp.StatusCode)
	}
	return nil
}

// nativeTextItem builds a text item_list entry.
func nativeTextItem(text string) map[string]any {
	return map[string]any{
		"type":      itemText,
		"text_item": map[string]any{"text": text},
	}
}

// nativeMediaItem builds a media item_list entry that references the uploaded
// object. Both cdn_ref and url are set because the exact field is not public.
func nativeMediaItem(kind int, ref string, key []byte, md adapter.Media) map[string]any {
	item := map[string]any{
		"type":      kind,
		"cdn_ref":   ref,
		"url":       ref,
		"aes_key":   base64.StdEncoding.EncodeToString(key),
		"file_name": md.Name,
		"size":      md.Size,
	}
	if md.MIMEType != "" {
		item["mime"] = md.MIMEType
	}
	return item
}

// nativeMediaTypeFor maps a normalized MediaKind to the iLink item type code.
func nativeMediaTypeFor(kind adapter.MediaKind) int {
	switch kind {
	case adapter.MediaImage:
		return itemImage
	case adapter.MediaVoice:
		return itemVoice
	case adapter.MediaVideo:
		return itemVideo
	default:
		return itemFile
	}
}

// newClientID returns a random hex client id used to de-duplicate sends. On an
// (unlikely) crypto/rand failure it falls back to a time-based value.
func newClientID() string {
	var b [12]byte
	if _, err := rand.Read(b[:]); err == nil {
		return hex.EncodeToString(b[:])
	}
	return "c-" + strconv.FormatInt(time.Now().UnixNano(), 36)
}