from __future__ import annotations

from typing import Any

from .config_loader import business_config
from .decision import evaluate_tree
from .retrieval import retrieve_for_scheme
from .session_store import (
    Session,
    looks_like_handoff,
    naive_fill_slots,
    next_slot_prompt,
    store,
)


def create_session() -> Session:
    return store.create()


def handle_message(session_id: str, message: str) -> dict[str, Any]:
    session = store.get(session_id)
    if not session:
        raise KeyError("session_not_found")

    text = (message or "").strip()
    session.messages.append({"role": "user", "content": text})

    if looks_like_handoff(text, business_config.handoff_phrases):
        session.phase = "handoff"
        reply = "已为您标记转人工。请留下称呼与联系方式，销售同事会跟进。（原型：仅记录意图，未接 Chatwoot）"
        return _finish(session, reply, need_handoff=True)

    # fill slots while collecting
    if session.phase in ("collecting", "scheme_ready"):
        session.slots = naive_fill_slots(text, business_config.slots, session.slots)

    nxt = next_slot_prompt(business_config.slots, session.slots)
    if nxt and session.phase == "collecting":
        # first turn with empty slots: greet + first question
        if len(session.messages) == 1 and not any(session.slots.values()):
            # put first user utterance into first slot if they already answered something
            session.slots = naive_fill_slots(text, business_config.slots, session.slots)
            nxt = next_slot_prompt(business_config.slots, session.slots)
        if nxt:
            reply = nxt["prompt"]
            return _finish(session, reply, asking_slot=nxt["id"])

    # all required (+ optional asked or filled) → scheme
    decision = evaluate_tree(business_config.rules, session.slots)
    confidence = float(decision.get("confidence") or 0)
    need_handoff = bool(decision.get("handoff")) or confidence < business_config.handoff_confidence_below
    bundle = list(decision.get("product_bundle") or [])
    retrieval = retrieve_for_scheme(session.slots, bundle)

    scheme = {
        "tech_line": decision.get("tech_line"),
        "product_bundle": bundle,
        "summary": decision.get("summary"),
        "confidence": confidence,
        "rule_id": decision.get("rule_id"),
        "citations": [
            {"id": c.get("id"), "title": c.get("title"), "content": c.get("content")}
            for c in retrieval.chunks
        ],
        "slots": dict(session.slots),
    }
    session.last_scheme = scheme
    session.phase = "handoff" if need_handoff else "scheme_ready"

    lines = [
        business_config.closing_prompt,
        "",
        f"技术路线：{scheme['tech_line']}",
        f"推荐组合：{', '.join(bundle)}",
        f"说明：{scheme['summary']}",
        f"置信度：{confidence:.0%}",
    ]
    if scheme["citations"]:
        lines.append("")
        lines.append("知识依据（原型检索）：")
        for c in scheme["citations"][:3]:
            lines.append(f"- {c['title']}：{c['content']}")
    if need_handoff:
        lines.append("")
        lines.append("系统建议转人工确认后再对外发送方案。回复「转人工」可进入人工流程。")
    else:
        lines.append("")
        lines.append("可继续补充约束，或回复「转人工」交给销售。")

    reply = "\n".join(lines)
    return _finish(session, reply, scheme=scheme, need_handoff=need_handoff)


def _finish(
    session: Session,
    reply: str,
    *,
    asking_slot: str | None = None,
    scheme: dict[str, Any] | None = None,
    need_handoff: bool = False,
) -> dict[str, Any]:
    session.messages.append({"role": "assistant", "content": reply})
    store.touch(session)
    return {
        "session_id": session.id,
        "reply": reply,
        "phase": session.phase,
        "slots": session.slots,
        "asking_slot": asking_slot,
        "scheme": scheme or session.last_scheme,
        "need_handoff": need_handoff,
    }