from typing import Optional, List
import time
import cohere
from settings import (
    COHERE_API_KEY, COHERE_API_URL, COHERE_MODEL_PRIMARY, COHERE_EMBED_MODEL,
    MODEL_SETTINGS, USE_OPEN_FALLBACKS
)

# Optional open-model fallback (only used if USE_OPEN_FALLBACKS=True)
try:
    from local_llm import LocalLLM
    _HAS_LOCAL = True
except Exception:
    _HAS_LOCAL = False

_client: Optional[cohere.Client] = None

def _co_client() -> Optional[cohere.Client]:
    global _client
    if _client is not None:
        return _client
    if not COHERE_API_KEY:
        return None
    # NOTE: The Cohere Python SDK auto-selects API base; you can pass a custom base if provided.
    if COHERE_API_URL:
        _client = cohere.Client(api_key=COHERE_API_KEY, base_url=COHERE_API_URL, timeout=MODEL_SETTINGS.get("timeout_s", 45))
    else:
        _client = cohere.Client(api_key=COHERE_API_KEY, timeout=MODEL_SETTINGS.get("timeout_s", 45))
    return _client

def _retry(fn, attempts=3, backoff=0.8):
    last = None
    for i in range(attempts):
        try:
            return fn()
        except Exception as e:
            last = e
            time.sleep(backoff * (2 ** i))
    raise last if last else RuntimeError("Unknown error")

def cohere_chat(prompt: str) -> Optional[str]:
    cli = _co_client()
    if not cli:
        return None
    def _call():
        resp = cli.chat(
            model=COHERE_MODEL_PRIMARY,
            message=prompt,
            temperature=MODEL_SETTINGS["temperature"],
            max_tokens=MODEL_SETTINGS["max_new_tokens"],
        )
        # SDK shape may provide .text, .reply, or generations
        if hasattr(resp, "text") and resp.text:
            return resp.text
        if hasattr(resp, "reply") and resp.reply:
            return resp.reply
        if hasattr(resp, "generations") and resp.generations:
            return resp.generations[0].text
        return None
    try:
        return _retry(_call, attempts=3)
    except Exception:
        return None

def open_fallback_chat(prompt: str) -> Optional[str]:
    if not USE_OPEN_FALLBACKS or not _HAS_LOCAL:
        return None
    try:
        return LocalLLM().chat(prompt)
    except Exception:
        return None

def cohere_embed(texts: List[str]) -> List[List[float]]:
    cli = _co_client()
    if not cli or not texts:
        return []
    def _call():
        resp = cli.embed(texts=texts, model=COHERE_EMBED_MODEL)
        # Newer SDK: resp.embeddings; older: resp.data
        return getattr(resp, "embeddings", None) or getattr(resp, "data", []) or []
    try:
        return _retry(_call, attempts=3)
    except Exception:
        return []

def generate_narrative(scenario_text: str, structured_sections_md: str, rag_snippets: List[str]) -> str:
    grounding = "\n\n".join([f"[RAG {i+1}]\n{t}" for i, t in enumerate(rag_snippets or [])])
    prompt = f"""You are a Canadian healthcare operations copilot.
Follow the scenario's requested deliverables exactly. Use the structured computations provided (already calculated deterministically) and the RAG snippets for grounding.

# Scenario
{scenario_text}

# Deterministic Results (already computed)
{structured_sections_md}

# Grounding (Canadian sources, snippets)
{grounding}

Write a concise, decision-ready report tailored to provincial operations leaders.
Do not invent numbers. If data are missing, say so clearly.
"""
    out = cohere_chat(prompt)
    if out: return out
    out = open_fallback_chat(prompt)
    if out: return out
    return "Unable to generate narrative at this time."