update replacement

index.ts

-import { Adapter, Bot, Context, Filter } from 'koishi';
+import { Bot, Context, Filter, segment } from 'koishi';
 import _ from 'lodash';
 import { RegisterSchema, SchemaProperty } from 'schemastery-gen';
 
@@ -95,6 +95,36 @@ export class SendTarget {
     return ctx.intersect(this.getFilter());
   }
 
+  private runForEachSegemnt(segments: segment[], action: (s: segment) => void) {
+    for (const s of segments) {
+      action(s);
+      if (s.children?.length) {
+        this.runForEachSegemnt(s.children, action);
+      }
+    }
+  }
+
+  replaceContent(content: string, fromKey: string, toKey: string) {
+    const segments = segment.parse(content);
+    this.runForEachSegemnt(segments, (s) => {
+      const { attrs } = s;
+      if (!attrs || s.type !== 'image') {
+        return;
+      }
+      if (attrs.url?.startsWith('base64')) {
+        const { url } = attrs;
+        attrs.file = url;
+        delete attrs.url;
+      }
+      if (attrs[fromKey]?.startsWith('http')) {
+        const { [fromKey]: url } = attrs;
+        attrs[toKey] = url;
+        delete attrs[fromKey];
+      }
+    });
+    return segments.map((s) => s.toString()).join('');
+  }
+
   async send(bots: Bot[], content: string) {
     const bot = this.getBot(bots);
     if (!bot) {
@@ -103,9 +133,8 @@ export class SendTarget {
     let privateContent = content;
     let channelContent = content;
     if (this.isOneBotBot(bot)) {
-      content = content.replace(/,url=base64/g, ',file=base64');
-      privateContent = content.replace(/,url=http/g, ',file=http'); // private should be file
-      channelContent = content.replace(/,file=http/g, ',url=http'); // channel should be url
+      privateContent = this.replaceContent(content, 'url', 'file'); // private should be file
+      channelContent = this.replaceContent(content, 'file', 'url'); // channel should be url
     }
     return _.flatten(
       await Promise.all([

tests/sample.spec.ts

-import { Session } from 'koishi';
-import { SendTarget } from '..';
+import { segment, Session } from 'koishi';
+import { SendTarget } from '../index';
 
 describe('Target def.', () => {
   const def = new SendTarget({
@@ -81,4 +81,22 @@ describe('Target def.', () => {
       } as Session),
     ).toBe(true);
   });
+
+  it('should replace content', () => {
+    const target = new SendTarget({});
+    const imageBase64 = segment('image', { url: 'base64://foo' });
+    const imageBase64Replaced = segment.parse(
+      target.replaceContent(imageBase64.toString(), 'url', 'url'),
+    )[0];
+    const imageUrl = segment('image', {
+      file: 'http://example.com/1.png',
+    });
+    const imageUrlReplaced = segment.parse(
+      target.replaceContent(imageUrl.toString(), 'file', 'url'),
+    )[0];
+    expect(imageBase64Replaced.attrs?.url).toBeUndefined();
+    expect(imageBase64Replaced.attrs?.file).toBe('base64://foo');
+    expect(imageUrlReplaced.attrs?.url).toBe('http://example.com/1.png');
+    expect(imageUrlReplaced.attrs?.file).toBeUndefined();
+  });
 });