feat: 批量导出所有聊天为 JSON + 提取共享 helper 模块 (#77)

* Add export_all_chats.py: batch export all WeChat chats to JSON

Mirrors export_chat.py functionality to export every chat in the
decrypted WeChat database at once. Output format is byte-for-byte
identical to export_chat.py.

Usage: python3 export_all_chats.py [output_dir]

- Reads all sessions from decrypted/session/session.db
- Uses the same content extraction pipeline as export_chat.py:
  _resolve_sender, _extract_content, _msg_type_str, sticker/video/system
- Outputs group_<display>.json or single_<display>.json with same schema
- Progress reporting every 100 exports with summary at end

* refactor: 将 7 个重复 helper 函数提取到 chat_export_helpers.py

根据 PR #77 review 反馈，将 export_chat.py 和 export_all_chats.py 中
逐字复制的消息格式化函数提取到共享模块 chat_export_helpers.py。

提取的函数:
  MSG_TYPE_MAP, _msg_type_str, _resolve_sender,
  _decode_sticker_desc, _format_sticker_message,
  _format_system_message, _format_video_message, _extract_content

两个导出脚本现在从 chat_export_helpers import 所需函数，
消除代码漂移风险。

chat_export_helpers.py

@@ -0,0 +1,138 @@
+"""聊天导出共享工具函数。
+
+本模块包含 export_chat.py 和 export_all_chats.py 共用的消息格式化函数。
+统一维护，避免两处代码漂移。
+"""
+
+import base64
+
+import mcp_server
+
+
+MSG_TYPE_MAP = {
+    1: "text",
+    3: "image",
+    34: "voice",
+    42: "contact_card",
+    43: "video",
+    47: "sticker",
+    48: "location",
+    49: "link_or_file",
+    50: "call",
+    10000: "system",
+    10002: "recall",
+}
+
+
+def _msg_type_str(local_type):
+    base, _ = mcp_server._split_msg_type(local_type)
+    return MSG_TYPE_MAP.get(base, f"type_{local_type}")
+
+
+def _resolve_sender(row, ctx, names, id_to_username):
+    """Resolve the sender of a message.
+
+    Returns "me" for the logged-in user, or the sender's display name otherwise
+    (the contact's name in 1-on-1 chats, the member's name in groups). Empty
+    string for unattributable messages (e.g. system notifications).
+    """
+    local_id, local_type, create_time, real_sender_id, content, ct = row
+    decoded = mcp_server._decompress_content(content, ct)
+    sender_from_content, _ = mcp_server._format_message_text(
+        local_id, local_type, decoded, ctx["is_group"], ctx["username"], ctx["display_name"], names
+    )
+    label = mcp_server._resolve_sender_label(
+        real_sender_id,
+        sender_from_content,
+        ctx["is_group"],
+        ctx["username"],
+        ctx["display_name"],
+        names,
+        id_to_username,
+    )
+    return label or ""
+
+
+def _decode_sticker_desc(b64_desc):
+    """WeChat encodes sticker labels as base64 protobuf: repeated (lang, text) pairs.
+    Returns the 'default' language label (usually Chinese), or None.
+
+    Limitation: treats the length byte as a single octet rather than a real protobuf
+    varint — labels >127 bytes would be misread. In practice sticker descriptions are
+    short (<30 chars), so this is adequate. Also sensitive to the bytes b"default"
+    appearing inside a preceding value; no such cases observed.
+    """
+    try:
+        raw = base64.b64decode(b64_desc)
+    except Exception:
+        return None
+    # Find the 'default' marker; text follows as: \x12 <varint len> <utf-8>
+    i = raw.find(b"default")
+    if i < 0 or i + 7 >= len(raw) or raw[i + 7] != 0x12:
+        return None
+    try:
+        text_len = raw[i + 8]
+        text_bytes = raw[i + 9 : i + 9 + text_len]
+        return text_bytes.decode("utf-8") or None
+    except (IndexError, UnicodeDecodeError):
+        return None
+
+
+def _format_sticker_message(content):
+    root = mcp_server._parse_xml_root(content) if content else None
+    if root is None:
+        return "[表情]"
+    emoji = root.find(".//emoji")
+    if emoji is None:
+        return "[表情]"
+    desc = emoji.get("desc") or ""
+    label = _decode_sticker_desc(desc) if desc else None
+    return f"[表情] {label}" if label else "[表情]"
+
+
+def _format_system_message(content):
+    if not content:
+        return "[系统消息]"
+    if "<sysmsg" not in content:
+        return content
+    root = mcp_server._parse_xml_root(content)
+    if root is None:
+        return content
+    inner = root.findtext(".//content")
+    return inner.strip() if inner else content
+
+
+def _format_video_message(content):
+    root = mcp_server._parse_xml_root(content) if content else None
+    if root is None:
+        return "[视频]"
+    video = root.find(".//videomsg")
+    if video is None:
+        return "[视频]"
+    playlength = video.get("playlength")
+    return f"[视频] {playlength}秒" if playlength else "[视频]"
+
+
+def _extract_content(local_id, local_type, content, ct, chat_username, chat_display_name):
+    content = mcp_server._decompress_content(content, ct)
+    if content is None:
+        return None
+
+    base, _ = mcp_server._split_msg_type(local_type)
+    if base == 1:
+        return content or ""
+    if base == 43:
+        return _format_video_message(content)
+    if base == 47:
+        return _format_sticker_message(content)
+    if base == 49:
+        return mcp_server._format_app_message_text(
+            content, local_type, False, chat_username, chat_display_name, {}
+        )
+    if base == 50:
+        return mcp_server._format_voip_message_text(content)
+    if base == 10000:
+        return _format_system_message(content)
+    if base == 10002:
+        return "[撤回消息]"
+    return None

export_all_chats.py

@@ -0,0 +1,159 @@
+#!/usr/bin/env python3
+"""批量导出所有微信聊天记录为 JSON 文件。
+
+此脚本将导出所有会话的聊天记录，输出格式与 export_chat.py 完全一致。
+支持导出到指定目录，默认输出到 ./exported_chats 目录。
+
+用法:
+    python3 export_all_chats.py [output_dir]
+
+示例:
+    python3 export_all_chats.py /path/to/output
+"""
+
+import argparse
+import json
+import os
+import re
+import sqlite3
+import sys
+from contextlib import closing
+from datetime import datetime
+
+import mcp_server
+from chat_export_helpers import _extract_content, _msg_type_str, _resolve_sender
+
+
+def export_one(username, output_dir, names):
+    """
+    导出单个会话。
+
+    返回: (成功标志, 消息数, 错误信息)
+    """
+    ctx = mcp_server._resolve_chat_context(username)
+    if ctx is None:
+        return False, 0, f"Cannot resolve: {username}"
+
+    display_name = ctx["display_name"]
+    message_tables = ctx["message_tables"]
+
+    if not message_tables:
+        return False, 0, "no tables"
+
+    all_rows = []
+    for table_info in message_tables:
+        db_path = table_info["db_path"]
+        table_name = table_info["table_name"]
+        try:
+            with closing(sqlite3.connect(db_path)) as conn:
+                id_to_username = mcp_server._load_name2id_maps(conn)
+                rows = mcp_server._query_messages(
+                    conn, table_name, limit=None, oldest_first=True
+                )
+                for row in rows:
+                    all_rows.append((row, id_to_username))
+        except Exception as e:
+            return False, 0, f"DB query error: {e}"
+
+    all_rows.sort(key=lambda pair: pair[0][2] or 0)
+
+    messages = []
+    for row, id_to_username in all_rows:
+        local_id, local_type, create_time, real_sender_id, content, ct = row
+        sender = _resolve_sender(row, ctx, names, id_to_username)
+        type_str = _msg_type_str(local_type)
+        rendered = _extract_content(local_id, local_type, content, ct, username, display_name)
+
+        msg = {"local_id": local_id, "timestamp": create_time, "sender": sender}
+        if type_str != "text":
+            msg["type"] = type_str
+        if rendered is not None:
+            msg["content"] = rendered
+        messages.append(msg)
+
+    if not messages:
+        return False, 0, "empty"
+
+    output = {
+        "chat": display_name,
+        "username": username,
+        "exported_at": datetime.now().strftime("%Y-%m-%d %H:%M:%S"),
+        "messages": messages,
+    }
+    if ctx["is_group"]:
+        output["is_group"] = True
+
+    prefix = "group" if ctx["is_group"] else "single"
+    safe = re.sub(r'[\\/:*?"<>|]', "_", f"{prefix}_{display_name}")
+    out_path = os.path.join(output_dir, f"{safe}.json")
+    with open(out_path, "w", encoding="utf-8") as f:
+        json.dump(output, f, ensure_ascii=False, indent=2)
+
+    return True, len(messages), None
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="批量导出所有微信聊天记录为 JSON 文件",
+        formatter_class=argparse.RawDescriptionHelpFormatter,
+        epilog="""
+示例:
+    python3 export_all_chats.py /path/to/output
+        """,
+    )
+    parser.add_argument(
+        "output_dir",
+        nargs="?",
+        default=None,
+        help="输出目录路径 (默认: ./exported_chats)",
+    )
+    args = parser.parse_args()
+
+    script_dir = os.path.dirname(os.path.abspath(__file__))
+    output_dir = args.output_dir or os.path.join(script_dir, "exported_chats")
+
+    if not os.path.exists(mcp_server.DECRYPTED_DIR):
+        print(f"错误: 解密目录不存在: {mcp_server.DECRYPTED_DIR}", file=sys.stderr)
+        sys.exit(1)
+    os.makedirs(output_dir, exist_ok=True)
+
+    session_db = os.path.join(mcp_server.DECRYPTED_DIR, "session", "session.db")
+    try:
+        with closing(sqlite3.connect(session_db)) as conn:
+            sessions = [u for u, _ in conn.execute("SELECT username, type FROM SessionTable")]
+    except sqlite3.Error as e:
+        print(f"会话数据库查询失败: {e}", file=sys.stderr)
+        sys.exit(1)
+
+    names = mcp_server.get_contact_names()
+
+    print(f"会话总数: {len(sessions)}")
+    print(f"联系人映射: {len(names)}")
+    print(f"输出目录: {output_dir}")
+    print("=" * 60)
+
+    ok, skip, err, total = 0, 0, 0, 0
+    for i, username in enumerate(sessions, 1):
+        display = names.get(username, username)
+        success, count, reason = export_one(username, output_dir, names)
+        if success:
+            ok += 1
+            total += count
+            if i <= 10 or i % 100 == 0:
+                print(f"[{i}/{len(sessions)}] {display} - {count} 条消息")
+        else:
+            if "no tables" in str(reason) or "empty" in str(reason):
+                skip += 1
+                if i <= 10 or i % 50 == 0:
+                    print(f"[{i}/{len(sessions)}] {display} - 跳过({reason})")
+            else:
+                err += 1
+                print(f"[{i}/{len(sessions)}] {display} - 失败: {reason}")
+
+    print()
+    print("=" * 60)
+    print(f"完成! 成功={ok} 跳过={skip} 失败={err} 总消息={total}")
+
+
+if __name__ == "__main__":
+    main()

export_chat.py

@@ -41,136 +41,11 @@ from contextlib import closing
 from datetime import datetime
 
 import mcp_server
-
+from chat_export_helpers import (
-
+    _extract_content,
-MSG_TYPE_MAP = {
+    _msg_type_str,
-    1: "text",
+    _resolve_sender,
-    3: "image",
-    34: "voice",
-    42: "contact_card",
-    43: "video",
-    47: "sticker",
-    48: "location",
-    49: "link_or_file",
-    50: "call",
-    10000: "system",
-    10002: "recall",
-}
-
-
-def _msg_type_str(local_type):
-    base, _ = mcp_server._split_msg_type(local_type)
-    return MSG_TYPE_MAP.get(base, f"type_{local_type}")
-
-
-def _resolve_sender(row, ctx, names, id_to_username):
-    """Resolve the sender of a message.
-
-    Returns "me" for the logged-in user, or the sender's display name otherwise
-    (the contact's name in 1-on-1 chats, the member's name in groups). Empty
-    string for unattributable messages (e.g. system notifications).
-    """
-    local_id, local_type, create_time, real_sender_id, content, ct = row
-    decoded = mcp_server._decompress_content(content, ct)
-    sender_from_content, _ = mcp_server._format_message_text(
-        local_id, local_type, decoded, ctx["is_group"], ctx["username"], ctx["display_name"], names
 )
-    label = mcp_server._resolve_sender_label(
-        real_sender_id,
-        sender_from_content,
-        ctx["is_group"],
-        ctx["username"],
-        ctx["display_name"],
-        names,
-        id_to_username,
-    )
-    return label or ""
-
-
-def _decode_sticker_desc(b64_desc):
-    """WeChat encodes sticker labels as base64 protobuf: repeated (lang, text) pairs.
-    Returns the 'default' language label (usually Chinese), or None.
-
-    Limitation: treats the length byte as a single octet rather than a real protobuf
-    varint — labels >127 bytes would be misread. In practice sticker descriptions are
-    short (<30 chars), so this is adequate. Also sensitive to the bytes b"default"
-    appearing inside a preceding value; no such cases observed.
-    """
-    import base64
-    try:
-        raw = base64.b64decode(b64_desc)
-    except Exception:
-        return None
-    # Find the 'default' marker; text follows as: \x12 <varint len> <utf-8>
-    i = raw.find(b"default")
-    if i < 0 or i + 7 >= len(raw) or raw[i + 7] != 0x12:
-        return None
-    try:
-        text_len = raw[i + 8]
-        text_bytes = raw[i + 9 : i + 9 + text_len]
-        return text_bytes.decode("utf-8") or None
-    except (IndexError, UnicodeDecodeError):
-        return None
-
-
-def _format_sticker_message(content):
-    root = mcp_server._parse_xml_root(content) if content else None
-    if root is None:
-        return "[表情]"
-    emoji = root.find(".//emoji")
-    if emoji is None:
-        return "[表情]"
-    desc = emoji.get("desc") or ""
-    label = _decode_sticker_desc(desc) if desc else None
-    return f"[表情] {label}" if label else "[表情]"
-
-
-def _format_system_message(content):
-    if not content:
-        return "[系统消息]"
-    if "<sysmsg" not in content:
-        return content
-    root = mcp_server._parse_xml_root(content)
-    if root is None:
-        return content
-    inner = root.findtext(".//content")
-    return inner.strip() if inner else content
-
-
-def _format_video_message(content):
-    root = mcp_server._parse_xml_root(content) if content else None
-    if root is None:
-        return "[视频]"
-    video = root.find(".//videomsg")
-    if video is None:
-        return "[视频]"
-    playlength = video.get("playlength")
-    return f"[视频] {playlength}秒" if playlength else "[视频]"
-
-
-def _extract_content(local_id, local_type, content, ct, chat_username, chat_display_name):
-    content = mcp_server._decompress_content(content, ct)
-    if content is None:
-        return None
-
-    base, _ = mcp_server._split_msg_type(local_type)
-    if base == 1:
-        return content or ""
-    if base == 43:
-        return _format_video_message(content)
-    if base == 47:
-        return _format_sticker_message(content)
-    if base == 49:
-        return mcp_server._format_app_message_text(
-            content, local_type, False, chat_username, chat_display_name, {}
-        )
-    if base == 50:
-        return mcp_server._format_voip_message_text(content)
-    if base == 10000:
-        return _format_system_message(content)
-    if base == 10002:
-        return "[撤回消息]"
-    return None
 
 
 def export_chat(chat_name, output_path):