"""
会话 transcript 与 Redis 历史条目的纯映射（无 I/O）。

仅由 ConversationService 使用：对齐 ChatOrchestrator 经 save_message 写入 Redis 的字段形状，
不属于 Agent 层 —— 多 Agent 模块只消费已就绪的 history，不负责从 DB 重建。
"""

from __future__ import annotations

from datetime import timezone
from typing import Any, Dict, List

from app.features.conversation.models import Segment


def _voice_session_id_from_audio_url(audio_url: str | None) -> str | None:
    if not audio_url:
        return None
    prefix = "audio-segment:"
    if not audio_url.startswith(prefix):
        return None
    payload = audio_url[len(prefix) :]
    voice_session_id_raw, sep, _ = payload.rpartition(":")
    if sep and voice_session_id_raw:
        return voice_session_id_raw
    return None


def _segment_timestamp_iso(seg: Segment) -> str | None:
    if not seg.created_at:
        return None
    dt = seg.created_at
    if dt.tzinfo is None:
        dt = dt.replace(tzinfo=timezone.utc)
    return dt.isoformat()


def segments_to_redis_history(segments: List[Segment]) -> List[Dict[str, Any]]:
    """Segment 行 → Redis conversation history 项（与 ChatOrchestrator 写入格式一致）。"""
    history: List[Dict[str, Any]] = []
    for seg in segments:
        ts = _segment_timestamp_iso(seg)
        is_voice = bool(seg.audio_url)
        human: Dict[str, Any] = {
            "role": "human",
            "content": seg.transcript_text or "",
            "messageType": "audio" if is_voice else "text",
            "timestamp": ts,
        }
        vsid = _voice_session_id_from_audio_url(seg.audio_url)
        if vsid:
            human["voiceSessionId"] = vsid
        history.append(human)
        if seg.agent_response and seg.agent_response.strip():
            history.append(
                {
                    "role": "ai",
                    "content": seg.agent_response.strip(),
                    "messageType": "text",
                    "timestamp": ts,
                }
            )
    return history