Add change host method in Co-op game

README.md

@@ -23,15 +23,60 @@ Dependencies:
 - Python 3
 - [uesave-rs](https://github.com/trumank/uesave-rs)
 
+### Migrate server
+
 Command:    
-`python fix-host-save.py <uesave.exe> <save_path> <new_guid> <old_guid>`    
+`python fix_host_save.py <uesave.exe> <save_path> <new_guid> <old_guid>`    
 `<uesave.exe>` - Path to your uesave.exe    
 `<save_path>` - Path to your save folder    
 `<new_guid>` - GUID of the player on the new server    
 `<old_guid>` - GUID of the player from the old server
 
 Example:    
-`python fix-host-save.py "C:\Users\John\.cargo\bin\uesave.exe" "C:\Users\John\Desktop\my_temporary_folder\2E85FD38BAA792EB1D4C09386F3A3CDA" 6E80B1A6000000000000000000000000 00000000000000000000000000000001`
+`python fix_host_save.py "C:\Users\John\.cargo\bin\uesave.exe" "C:\Users\John\Desktop\my_temporary_folder\2E85FD38BAA792EB1D4C09386F3A3CDA" 6E80B1A6000000000000000000000000 00000000000000000000000000000001`
+
+### Change Co-op host
+
+Prepare:
+
+Fill `uesave_path`、`save_path` and `player_list` in *config.json*, for example:
+
+```json
+{
+  "uesave_path": "C:\\Users\\John\\.cargo\\bin\\uesave.exe",
+  "save_path": "C:\\Users\\John\\Desktop\\my_temporary_folder\\2E85FD38BAA792EB1D4C09386F3A3CDA",
+  "player_list": [
+    {
+      "GUID": "6E80B1A6000000000000000000000000",
+      "name": "Arthur"
+    },
+    {
+      "GUID": "F5A892D9000000000000000000000000",
+      "name": "John"
+    },
+    {
+      "GUID": "",
+      "name": ""
+    },
+    {
+      "GUID": "",
+      "name": ""
+    },
+    {
+      "GUID": "",
+      "name": ""
+    },
+    {
+      "GUID": "",
+      "name": ""
+    }
+  ]
+}
+```
+
+Command:
+
+`python change_coop_host.py John`
 
 ## How to migrate a co-op save to a Windows dedicated server
 
@@ -79,6 +124,21 @@ Steps:
 
 If someone wants to make sure this kind of migration works and then create the instructions to do it, I'd accept a PR for them.
 
+## How to change host in Local 4-player Co-op game
+
+Prerequisites:
+
+- Install the dependencies [above](#usage).
+- The original host need to get a standard GUID, by joining a friend's world or building and joining a dedicated server, more details can refer to the tutorial above.
+
+Steps:
+
+1. **Make a backup of your save**
+2. Fill `uesave_path`、`save_path` and `player_list` in *config.json*, `player_list` should include all players who have joined this save, you can add more GUID-name pairs if needed. Note that all GUID are standard GUID, not `00000000000000000000000000000001`.
+3. Run *change_coop_host.py* with a `host` parameter, which can be a GUID or just a nickname for convenience, after that this guy will become the new host.
+4. Send this new save to the new host, and replace *LocalData.sav* from this new save file with that from the original save file of the new host, since *LocalData.sav* saves personal map and tutorial data.
+5. Let the new host starts the game and invites you and other friends.
+
 ## Known bugs
 
 ### ~~\[Guild bug\]~~

change_coop_host.py

@@ -0,0 +1,163 @@
+import argparse
+import json
+import os
+from pathlib import Path
+import sys
+
+from fix_host_save import sav_to_json, json_to_sav, clean_up_files
+
+# GUID of current host is 00..01, we need to get his standard GUID.
+def old_host(player_list, player_save_path):
+    all_guid_list = [player['GUID'] for player in player_list]
+    current_guid_list = [save.stem for save in player_save_path.iterdir()]
+    old_host = set(all_guid_list) - set(current_guid_list)
+    return old_host.pop()
+
+# Get new host's standard GUID.
+def new_host(name_or_guid, player_list):
+    for player in player_list:
+        if player['name'] == name_or_guid or player['GUID'] == name_or_guid:
+            return player['GUID']
+    return None
+
+def change_guid(old_guid, new_guid, save_path, uesave_path):
+    # Apply expected formatting for the GUID.
+    new_guid_formatted = '{}-{}-{}-{}-{}'.format(new_guid[:8], new_guid[8:12], new_guid[12:16], new_guid[16:20], new_guid[20:]).lower()
+    old_level_formatted = ''
+    new_level_formatted = ''
+
+    # Player GUIDs in a guild are stored as the decimal representation of their GUID.
+    # Every byte in decimal represents 2 hexidecimal characters of the GUID
+    # 32-bit little endian.
+    for y in range(8, 36, 8):
+        for x in range(y-1, y-9, -2):
+           temp_old = str(int(old_guid[x-1] + old_guid[x], 16))+',\n'
+           temp_new = str(int(new_guid[x-1] + new_guid[x], 16))+',\n'
+           old_level_formatted += temp_old
+           new_level_formatted += temp_new
+
+    old_level_formatted = old_level_formatted.rstrip("\n,")
+    new_level_formatted = new_level_formatted.rstrip("\n,")
+    old_level_formatted = list(map(int, old_level_formatted.split(",\n")))
+    new_level_formatted = list(map(int, new_level_formatted.split(",\n")))
+
+    level_sav_path = save_path + '/Level.sav'
+    old_sav_path = save_path + '/Players/'+ old_guid + '.sav'
+    new_sav_path = save_path + '/Players/' + new_guid + '.sav'
+    level_json_path = level_sav_path + '.json'
+    old_json_path = old_sav_path + '.json'
+
+    # Convert save files to JSON so it is possible to edit them.
+    sav_to_json(uesave_path, level_sav_path)
+    sav_to_json(uesave_path, old_sav_path)
+    print('Converted save files to JSON')
+
+    # Parse our JSON files.
+    with open(old_json_path) as f:
+        old_json = json.load(f)
+    with open(level_json_path) as f:
+        level_json = json.load(f)
+    print('JSON files have been parsed')
+
+    # Replace all instances of the old GUID with the new GUID.
+
+    # Player data replacement.
+    old_json["root"]["properties"]["SaveData"]["Struct"]["value"]["Struct"]["PlayerUId"]["Struct"]["value"]["Guid"] = new_guid_formatted
+    old_json["root"]["properties"]["SaveData"]["Struct"]["value"]["Struct"]["IndividualId"]["Struct"]["value"]["Struct"]["PlayerUId"]["Struct"]["value"]["Guid"] = new_guid_formatted
+    old_instance_id = old_json["root"]["properties"]["SaveData"]["Struct"]["value"]["Struct"]["IndividualId"]["Struct"]["value"]["Struct"]["InstanceId"]["Struct"]["value"]["Guid"]
+
+    # Level data replacement.
+    instance_ids_len = len(level_json["root"]["properties"]["worldSaveData"]["Struct"]["value"]["Struct"]["CharacterSaveParameterMap"]["Map"]["value"])
+    for i in range(instance_ids_len):
+        instance_id = level_json["root"]["properties"]["worldSaveData"]["Struct"]["value"]["Struct"]["CharacterSaveParameterMap"]["Map"]["value"][i]["key"]["Struct"]["Struct"]["InstanceId"]["Struct"]["value"]["Guid"]
+        if instance_id == old_instance_id:
+            level_json["root"]["properties"]["worldSaveData"]["Struct"]["value"]["Struct"]["CharacterSaveParameterMap"]["Map"]["value"][i]["key"]["Struct"]["Struct"]["PlayerUId"]["Struct"]["value"]["Guid"] = new_guid_formatted
+            break
+
+    # Guild data replacement.
+    group_ids_len = len(level_json["root"]["properties"]["worldSaveData"]["Struct"]["value"]["Struct"]["GroupSaveDataMap"]["Map"]["value"])
+    for i in range(group_ids_len):
+        group_id = level_json["root"]["properties"]["worldSaveData"]["Struct"]["value"]["Struct"]["GroupSaveDataMap"]["Map"]["value"][i]
+        if group_id["value"]["Struct"]["Struct"]["GroupType"]["Enum"]["value"] == "EPalGroupType::Guild":
+           group_raw_data =  group_id["value"]["Struct"]["Struct"]["RawData"]["Array"]["value"]["Base"]["Byte"]["Byte"]
+           raw_data_len = len(group_raw_data)
+           for i in range(raw_data_len-15):
+               if group_raw_data[i:i+16] == old_level_formatted:
+                  group_raw_data[i:i+16] = new_level_formatted
+    print('Changes have been made')
+
+    # Dump modified data to JSON.
+    with open(old_json_path, 'w') as f:
+        json.dump(old_json, f, indent=2)
+    with open(level_json_path, 'w') as f:
+        json.dump(level_json, f, indent=2)
+    print('JSON files have been exported')
+
+    # Convert our JSON files to save files.
+    json_to_sav(uesave_path, level_json_path)
+    json_to_sav(uesave_path, old_json_path)
+    print('Converted JSON files back to save files')
+
+    # Clean up miscellaneous GVAS and JSON files which are no longer needed.
+    clean_up_files(level_sav_path)
+    clean_up_files(old_sav_path)
+    print('Miscellaneous files removed')
+
+    # We must rename the patched save file from the old GUID to the new GUID for the server to recognize it.
+    if os.path.exists(new_sav_path):
+        os.remove(new_sav_path)
+    os.rename(old_sav_path, new_sav_path)
+    print(f'Changed GUID {old_guid} -> {new_guid}')
+
+
+def main():
+    parser = argparse.ArgumentParser(description='Change host in local 4-player co-op game.')
+    parser.add_argument('host', help='GUID or name of new co-op host')
+    args = parser.parse_args()
+
+    # Warn the user about potential data loss.
+    print('WARNING: Running this script WILL change your save files and could \
+potentially corrupt your data. It is HIGHLY recommended that you make a backup \
+of your save folder before continuing. Press enter if you would like to continue.')
+    input('> ')
+
+    config_path = Path(__file__).parent / 'config.json'
+    with open(config_path, 'r') as file:
+        config = json.load(file)
+
+    uesave_path = config['uesave_path']
+    save_path = config['save_path']
+    player_list = config['player_list']
+    player_list = [player for player in player_list if player['GUID'] != '']
+    print(f'uesave_path: {uesave_path}')
+    print(f'save_path: {save_path}')
+    print(f'player_list: {player_list}')
+
+    # uesave_path must point directly to the executable, not just the path it is located in.
+    if not os.path.exists(uesave_path) or not os.path.isfile(uesave_path):
+        print('ERROR: Your given <uesave_path> of "' + uesave_path + '" is invalid. It must point directly to the executable. For example: C:\\Users\\Bob\\.cargo\\bin\\uesave.exe')
+        exit(1)
+
+    # save_path must exist in order to use it.
+    if not os.path.exists(save_path):
+        print('ERROR: Your given <save_path> of "' + save_path + '" does not exist. Did you enter the correct path to your save folder?')
+        exit(1)
+
+    # player_list must have at least 2 players.
+    if len(player_list) < 2:
+        print('ERROR: You must have at least 2 players in your <players> list, add more players to your config.json file.')
+        exit(1)
+
+    # host must be a valid GUID or name.
+    if args.host not in [player['GUID'] for player in player_list] and args.host not in [player['name'] for player in player_list]:
+        print('ERROR: Your given <host> of "' + args.host + '" is not a valid GUID or name. Please refer to your config.json file.')
+        exit(1)
+
+    old_host_guid = old_host(player_list, Path(save_path)/'Players')
+    new_host_guid = new_host(args.host, player_list)
+    change_guid('00000000000000000000000000000001', old_host_guid, save_path, uesave_path)
+    change_guid(new_host_guid, '00000000000000000000000000000001', save_path, uesave_path)
+    print('Host change has been applied! Have fun!')
+
+if __name__ == '__main__':
+    main()

config.json

@@ -0,0 +1,30 @@
+{
+  "uesave_path": "",
+  "save_path": "",
+  "player_list": [
+    {
+      "GUID": "",
+      "name": ""
+    },
+    {
+      "GUID": "",
+      "name": ""
+    },
+    {
+      "GUID": "",
+      "name": ""
+    },
+    {
+      "GUID": "",
+      "name": ""
+    },
+    {
+      "GUID": "",
+      "name": ""
+    },
+    {
+      "GUID": "",
+      "name": ""
+    }
+  ]
+}