#!/usr/bin/env python3
"""
context.py — System prompt and user message assembly for The Chaos engine.

All functions are standalone — no dependency on GameEngine.
"""

from __future__ import annotations

from .paths import CHAR_PATH, WORLD_PATH, BOOK_PATH
from .prompts import SYSTEM_PROMPT
from . import state


def build_system_prompt() -> str:
    """Assemble the system prompt with current game state."""
    char = state.read_file(CHAR_PATH) or "*No character sheet.*"
    world = state.truncate_world(state.read_file(WORLD_PATH) or "") or "*No world state.*"
    log = state.read_recent_log()
    story = state.read_recent_book()
    return SYSTEM_PROMPT.substitute(
        character=char, world=world, log=log, story=story
    )


def build_prose_prompt() -> str:
    """Assemble the prose-generation prompt with current game state."""
    from .prompts import PROSE_PROMPT
    char = state.read_file(CHAR_PATH) or "*No character sheet.*"
    world = state.truncate_world(state.read_file(WORLD_PATH) or "") or "*No world state.*"
    log = state.read_recent_log()
    story = state.read_recent_book()
    return PROSE_PROMPT.substitute(
        character=char, world=world, log=log, story=story
    )


def build_user_message(
    player_action: str | None = None,
    last_prompt: str | None = None,
    **kwargs: str | None,
) -> str:
    """Build the user message for this turn's LLM call."""
    if kwargs:
        raise TypeError(
            f"build_user_message() got unexpected keyword arguments: "
            f"{set(kwargs)}. Did you mean 'last_prompt' instead of one of these?"
        )
    parts = []

    if last_prompt:
        parts.append(f"## Situation\n{last_prompt}")
    if player_action:
        parts.append(f"## Player's Request\n{player_action}")

    has_existing_story = bool(
        state.read_file(BOOK_PATH).strip()
    ) if not last_prompt else True

    if not player_action and not last_prompt:
        if has_existing_story:
            raise RuntimeError("User action is required for every turn.")
        else:
            parts.append(
                "## Instructions\n"
                "This is a new story. Welcome the player and guide them through the game setup."
            )
    else:
        parts.append(
            "## Instructions\n"
            "Advance the story based on the player's request. "
            "All state is shown above — write the outcome directly."
        )
    return "\n\n".join(parts)