"""客服转人工的最小必要上下文构造。

摘要完全由已持久化的会话消息和受控运行结果确定性生成，不调用模型，也不读取账户、画像或
长期记忆。其目的只是让管理员理解转接缘由，而不是向用户承诺已受理或已完成处理。
"""

from collections.abc import Sequence
from dataclasses import dataclass
from decimal import Decimal
from typing import Any

from app.core.contracts import SourceReference
from app.core.conversation_privacy import sanitize_customer_service_message
from app.model.conversation import ConversationMessage

MAX_SUMMARY_MESSAGES = 6
MAX_SUMMARY_MESSAGE_CHARACTERS = 280


@dataclass(frozen=True)
class CustomerServiceHandoverContext:
    """写入工单、审计与 Outbox 的统一、安全转接上下文。"""

    reason_detail: str
    conversation_summary: str
    source_references: list[dict[str, Any]]
    event_metadata: dict[str, Any]


def _safe_content(content: str) -> str:
    """二次脱敏和单条截断，确保历史会话也不会把凭据扩散到工单。"""
    sanitized = sanitize_customer_service_message(content).strip()
    if len(sanitized) > MAX_SUMMARY_MESSAGE_CHARACTERS:
        return f"{sanitized[:MAX_SUMMARY_MESSAGE_CHARACTERS - 6]}[截断]"
    return sanitized


def build_customer_service_handover_context(
    *, reason_code: str, clarification_round: int, confidence: Decimal | None,
    source_references: Sequence[SourceReference],
    messages: Sequence[ConversationMessage],
) -> CustomerServiceHandoverContext:
    """构造管理员可读但不包含原始敏感凭据的转人工背景。"""
    safe_references = [reference.model_dump(mode="json") for reference in source_references]
    safe_messages = tuple(messages[-MAX_SUMMARY_MESSAGES:])
    summary_lines = [
        f"转接原因：{reason_code}",
        f"已进行澄清轮次：{clarification_round}",
        f"已核验知识来源数：{len(safe_references)}",
        "最近会话（已脱敏）：",
    ]
    if confidence is not None:
        summary_lines.insert(2, f"意图置信度：{confidence}")
    for message in safe_messages:
        role = "用户" if message.role == "user" else "助手"
        summary_lines.append(f"{role}：{_safe_content(message.content)}")
    conversation_summary = "\n".join(summary_lines)
    reason_detail = (
        f"系统自动转接；原因={reason_code}；澄清轮次={clarification_round}；"
        f"知识来源数={len(safe_references)}"
    )
    return CustomerServiceHandoverContext(
        reason_detail=reason_detail,
        conversation_summary=conversation_summary,
        source_references=safe_references,
        event_metadata={
            "reason_code": reason_code,
            "clarification_round": clarification_round,
            "confidence": str(confidence) if confidence is not None else None,
            "source_references": safe_references,
            "conversation_summary": conversation_summary,
        },
    )