"""Select file-backed conversation prompts from semantic routing results."""

from __future__ import annotations

from collections.abc import Sequence
from dataclasses import dataclass
from pathlib import Path
from typing import TYPE_CHECKING, Any

from app.core.exceptions import AppException

if TYPE_CHECKING:
    from app.models.entities import ConversationMessage


PROMPT_DIRECTORY = Path(__file__).resolve().parents[1] / "prompts"
DEFAULT_PROMPT_KEY = "product_manager"


@dataclass(frozen=True)
class PromptDefinition:
    name: str
    filename: str


PROMPT_CATALOG = {
    DEFAULT_PROMPT_KEY: PromptDefinition("开品产品经理", "开品产品经理-美妆护肤-角色Prompt.md"),
    "selection_insight": PromptDefinition("选品洞察", "01-选品洞察.md"),
    "project_review": PromptDefinition("立项评审", "02-立项评审.md"),
    "cost_pricing": PromptDefinition("成本定价", "03-成本定价.md"),
    "compliance_risk": PromptDefinition("合规风控", "04-合规风控.md"),
    "listing_selling_points": PromptDefinition("上架卖点", "05-上架卖点.md"),
}
SPECIALIST_PROMPT_KEYS = frozenset(PROMPT_CATALOG) - {DEFAULT_PROMPT_KEY}


def _read_prompt(relative_path: str) -> str:
    """Read only application-owned paths; model output never becomes a path."""

    try:
        content = (PROMPT_DIRECTORY / relative_path).read_text(encoding="utf-8-sig").strip()
    except (OSError, UnicodeError) as exc:
        raise AppException("会话 Prompt 文件无法读取，请检查部署文件", code=500, status_code=500) from exc
    if not content:
        raise AppException("会话 Prompt 文件不能为空", code=500, status_code=500)
    return content


def semantic_system_prompt() -> str:
    return _read_prompt("semantic_router.md")


def previous_prompt_key(messages: Sequence[ConversationMessage]) -> str:
    """Recover the last completed turn's route, including after a restart."""

    for message in reversed(messages):
        if message.role != "assistant":
            continue
        semantic = (message.structured_data or {}).get("semantic")
        if isinstance(semantic, dict):
            key = semantic.get("prompt_key")
            if isinstance(key, str) and key in PROMPT_CATALOG:
                return key
        # A newer legacy turn must not revive a stale specialist from earlier turns.
        return DEFAULT_PROMPT_KEY
    return DEFAULT_PROMPT_KEY


def semantic_history(
    history: Sequence[dict[str, str]],
    messages: Sequence[ConversationMessage],
) -> list[dict[str, str]]:
    return [
        {
            "role": "system",
            "content": (
                f"上一轮已使用的主题 prompt_key={previous_prompt_key(messages)}。"
                "本条是应用路由元数据。用户补充材料或无新主题地继续追问时可选择 inherit；"
                "用户明确提出新任务时必须重新选择主题。"
            ),
        },
        *history,
    ]


def resolve_prompt_selection(
    semantics: dict[str, Any],
    messages: Sequence[ConversationMessage],
) -> dict[str, Any]:
    """Resolve inheritance and reject unsupported keys before reading any file."""

    result = dict(semantics)
    requested = result.get("prompt_key")
    if requested == "inherit":
        key = previous_prompt_key(messages)
        source = "inherited"
    elif isinstance(requested, str) and requested in PROMPT_CATALOG:
        key = requested
        source = "semantic"
    else:
        key = DEFAULT_PROMPT_KEY
        source = "fallback"
    definition = PROMPT_CATALOG[key]
    result.update(
        prompt_key=key,
        prompt_name=definition.name,
        prompt_file=definition.filename,
        prompt_route_source=source,
    )
    return result


def reply_system_messages(semantics: dict[str, Any]) -> list[dict[str, str]]:
    requested = semantics.get("prompt_key")
    key = requested if isinstance(requested, str) and requested in PROMPT_CATALOG else DEFAULT_PROMPT_KEY
    base = PROMPT_CATALOG[DEFAULT_PROMPT_KEY]
    messages = [
        {"role": "system", "content": _read_prompt(f"product_development/{base.filename}")},
    ]
    if key != DEFAULT_PROMPT_KEY:
        expert = PROMPT_CATALOG[key]
        messages.append(
            {"role": "system", "content": _read_prompt(f"product_development/{expert.filename}")},
        )
    messages.append(
        {
            "role": "system",
            "content": (f"本轮主任务：{PROMPT_CATALOG[key].name}。\n" + _read_prompt("conversation_runtime.md")),
        },
    )
    return messages