from abc import ABC, abstractmethod
from config import get_settings


class BaseLLM(ABC):
    @abstractmethod
    def generate(self, prompt: str, system: str = "") -> str:
        ...

    @abstractmethod
    def stream(self, prompt: str, system: str = ""):
        ...


# ── Gemini provider ────────────────────────────────────────────────────────────

class GeminiLLM(BaseLLM):
    def __init__(self, api_key: str, model: str):
        from google import genai
        self.client = genai.Client(api_key=api_key)
        self.model = model

    def generate(self, prompt: str, system: str = "") -> str:
        full_prompt = f"{system}\n\n{prompt}" if system else prompt
        response = self.client.models.generate_content(
            model=self.model,
            contents=full_prompt,
        )
        return response.text

    def stream(self, prompt: str, system: str = ""):
        full_prompt = f"{system}\n\n{prompt}" if system else prompt
        for chunk in self.client.models.generate_content_stream(
            model=self.model,
            contents=full_prompt,
        ):
            if chunk.text:
                yield chunk.text


# ── Groq provider (free tier, no daily quota issues) ──────────────────────────

class GroqLLM(BaseLLM):
    """
    Uses Groq's free API — no per-day quota, just a per-minute rate limit
    that is far more generous than Gemini's free tier.

    Sign up at https://console.groq.com and set GROQ_API_KEY in your .env.
    Recommended model: llama-3.3-70b-versatile (free)
    """

    def __init__(self, api_key: str, model: str):
        from groq import Groq
        self.client = Groq(api_key=api_key)
        self.model = model

    def _messages(self, prompt: str, system: str) -> list[dict]:
        messages = []
        if system:
            messages.append({"role": "system", "content": system})
        messages.append({"role": "user", "content": prompt})
        return messages

    def generate(self, prompt: str, system: str = "") -> str:
        response = self.client.chat.completions.create(
            model=self.model,
            messages=self._messages(prompt, system),
        )
        return response.choices[0].message.content

    def stream(self, prompt: str, system: str = ""):
        stream = self.client.chat.completions.create(
            model=self.model,
            messages=self._messages(prompt, system),
            stream=True,
        )
        for chunk in stream:
            delta = chunk.choices[0].delta.content
            if delta:
                yield delta


# ── Factory ───────────────────────────────────────────────────────────────────

def get_llm_client() -> BaseLLM:
    settings = get_settings()

    if settings.llm_provider == "gemini":
        return GeminiLLM(settings.gemini_api_key, settings.llm_model)

    if settings.llm_provider == "groq":
        return GroqLLM(settings.groq_api_key, settings.groq_model)

    raise ValueError(
        f"Unsupported LLM_PROVIDER '{settings.llm_provider}'. "
        "Valid options: 'gemini', 'groq'"
    )


# ── Prompt templates ──────────────────────────────────────────────────────────

def build_prompt(query: str, context: str, task_type: str) -> str:
    templates = {
        "qa": (
            "You are a codebase assistant. Use the context below to answer the question.\n\n"
            "Context:\n{context}\n\nQuestion: {query}\n\nAnswer clearly, citing file names when relevant."
        ),
        "bug_finding": (
            "Analyze the following code for potential bugs, security issues, or bad practices.\n\n"
            "Code:\n{context}\n\n"
            "Return a JSON list of objects with keys: line, issue, severity, suggestion."
        ),
        "docstring": (
            "Write a clear, concise docstring for the following function. "
            "Follow standard conventions for its language.\n\nFunction:\n{query}"
        ),
        "file_creation": (
            "Generate complete, production-ready code for the following request.\n\n"
            "Request: {query}\n\nRelevant existing code for context:\n{context}\n\n"
            "Return only the code, no explanations."
        ),
    }
    template = templates.get(task_type, templates["qa"])
    return template.format(query=query, context=context)


def count_tokens(text: str) -> int:
    import tiktoken
    encoder = tiktoken.get_encoding("cl100k_base")
    return len(encoder.encode(text))