#s04: Hooks — 挂在循环上，不写进循环里

def agent_loop(messages):
    while True:
        # ... LLM call ...
        for block in response.content:
            if block.type == "tool_use":
                log_to_file(block)          # 加一行
                check_permission(block)     # 加一行
                notify_slack(block)         # 又加一行
                output = execute(block)
                auto_git_add(block)         # 再加一行
                # ... 很快循环就认不出来了

HOOKS = {
    "UserPromptSubmit": [],
    "PreToolUse": [],
    "PostToolUse": [],
    "Stop": [],
}

def register_hook(event: str, callback):
    HOOKS[event].append(callback)

def trigger_hooks(event: str, *args):
    for callback in HOOKS[event]:
        result = callback(*args)
        if result is not None:   # 返回值 ≠ None → hook 说"停"
            return result
    return None

def context_inject_hook(query: str) -> str | None:
    """Inject current working directory info into every prompt."""
    print(f"\033[90m[HOOK] UserPromptSubmit: working in {WORKDIR}\033[0m")
    return None   # return None = no modification, let prompt through

register_hook("UserPromptSubmit", context_inject_hook)

query = input("s04 >> ")
trigger_hooks("UserPromptSubmit", query)   # ← 进入 LLM 之前
history.append({"role": "user", "content": query})
agent_loop(history)

# PreToolUse: 权限检查（s03 的逻辑，从循环移到 hook）
def permission_hook(block):
    if block.name == "bash":
        for pattern in DENY_LIST:
            if pattern in block.input.get("command", ""):
                return "Permission denied by deny list"
    if block.name in ("write_file", "edit_file"):
        path = block.input.get("path", "")
        if not (WORKDIR / path).resolve().is_relative_to(WORKDIR):
            choice = input("   Allow? [y/N] ").strip().lower()
            if choice not in ("y", "yes"):
                return "Permission denied by user"
    return None

# PreToolUse: 日志
def log_hook(block):
    print(f"[HOOK] {block.name}(...)")

# PostToolUse: 大文件提醒
def large_output_hook(block, output):
    if len(str(output)) > 100000:
        print(f"[HOOK] ⚠ Large output from {block.name}")

register_hook("PreToolUse", permission_hook)
register_hook("PreToolUse", log_hook)
register_hook("PostToolUse", large_output_hook)

def summary_hook(messages: list) -> str | None:
    """Print a summary when the loop is about to stop."""
    tool_count = sum(1 for m in messages
                     for b in (m.get("content") if isinstance(m.get("content"), list) else [])
                     if isinstance(b, dict) and b.get("type") == "tool_result")
    print(f"\033[90m[HOOK] Stop: session used {tool_count} tool calls\033[0m")
    return None   # return None = allow stop, return string = force continuation

register_hook("Stop", summary_hook)

if response.stop_reason != "tool_use":
    force = trigger_hooks("Stop", messages)   # ← 退出之前
    if force:
        # hook returned a message → inject it and continue
        messages.append({"role": "user", "content": force})
        continue
    return

for block in response.content:
    if block.type != "tool_use":
        continue

    # s03: if not check_permission(block): ...
    # s04: hook 替代硬编码
    blocked = trigger_hooks("PreToolUse", block)
    if blocked:
        results.append({"type": "tool_result", "tool_use_id": block.id,
                        "content": str(blocked)})
        continue

    handler = TOOL_HANDLERS.get(block.name)
    output = handler(**block.input) if handler else f"Unknown: {block.name}"

    trigger_hooks("PostToolUse", block, output)

    results.append({"type": "tool_result", "tool_use_id": block.id,
                    "content": output})