"""Base LLM provider interface."""

import asyncio
import json
import re
from abc import ABC, abstractmethod
from collections.abc import Awaitable, Callable
from dataclasses import dataclass, field
from datetime import datetime, timezone
from email.utils import parsedate_to_datetime
from typing import Any

from loguru import logger

from nanobot.utils.helpers import image_placeholder_text


@dataclass
class ToolCallRequest:
    """A tool call request from the LLM."""
    id: str
    name: str
    arguments: dict[str, Any]
    extra_content: dict[str, Any] | None = None
    provider_specific_fields: dict[str, Any] | None = None
    function_provider_specific_fields: dict[str, Any] | None = None

    def to_openai_tool_call(self) -> dict[str, Any]:
        """Serialize to an OpenAI-style tool_call payload."""
        tool_call = {
            "id": self.id,
            "type": "function",
            "function": {
                "name": self.name,
                "arguments": json.dumps(self.arguments, ensure_ascii=False),
            },
        }
        if self.extra_content:
            tool_call["extra_content"] = self.extra_content
        if self.provider_specific_fields:
            tool_call["provider_specific_fields"] = self.provider_specific_fields
        if self.function_provider_specific_fields:
            tool_call["function"]["provider_specific_fields"] = self.function_provider_specific_fields
        return tool_call


@dataclass
class LLMResponse:
    """Response from an LLM provider."""
    content: str | None
    tool_calls: list[ToolCallRequest] = field(default_factory=list)
    finish_reason: str = "stop"
    usage: dict[str, int] = field(default_factory=dict)
    retry_after: float | None = None  # Provider supplied retry wait in seconds.
    reasoning_content: str | None = None  # Kimi, DeepSeek-R1, MiMo etc.
    thinking_blocks: list[dict] | None = None  # Anthropic extended thinking
    
    @property
    def has_tool_calls(self) -> bool:
        """Check if response contains tool calls."""
        return len(self.tool_calls) > 0


@dataclass(frozen=True)
class GenerationSettings:
    """Default generation settings."""

    temperature: float = 0.7
    max_tokens: int = 4096
    reasoning_effort: str | None = None


class LLMProvider(ABC):
    """Base class for LLM providers."""

    _CHAT_RETRY_DELAYS = (1, 2, 4)
    _PERSISTENT_MAX_DELAY = 60
    _PERSISTENT_IDENTICAL_ERROR_LIMIT = 10
    _RETRY_HEARTBEAT_CHUNK = 30
    _TRANSIENT_ERROR_MARKERS = (
        "429",
        "rate limit",
        "500",
        "502",
        "503",
        "504",
        "overloaded",
        "timeout",
        "timed out",
        "connection",
        "server error",
        "temporarily unavailable",
    )

    _SENTINEL = object()

    def __init__(self, api_key: str | None = None, api_base: str | None = None):
        self.api_key = api_key
        self.api_base = api_base
        self.generation: GenerationSettings = GenerationSettings()

    @staticmethod
    def _sanitize_empty_content(messages: list[dict[str, Any]]) -> list[dict[str, Any]]:
        """Sanitize message content: fix empty blocks, strip internal _meta fields."""
        result: list[dict[str, Any]] = []
        for msg in messages:
            content = msg.get("content")

            if isinstance(content, str) and not content:
                clean = dict(msg)
                clean["content"] = None if (msg.get("role") == "assistant" and msg.get("tool_calls")) else "(empty)"
                result.append(clean)
                continue

            if isinstance(content, list):
                new_items: list[Any] = []
                changed = False
                for item in content:
                    if (
                        isinstance(item, dict)
                        and item.get("type") in ("text", "input_text", "output_text")
                        and not item.get("text")
                    ):
                        changed = True
                        continue
                    if isinstance(item, dict) and "_meta" in item:
                        new_items.append({k: v for k, v in item.items() if k != "_meta"})
                        changed = True
                    else:
                        new_items.append(item)
                if changed:
                    clean = dict(msg)
                    if new_items:
                        clean["content"] = new_items
                    elif msg.get("role") == "assistant" and msg.get("tool_calls"):
                        clean["content"] = None
                    else:
                        clean["content"] = "(empty)"
                    result.append(clean)
                    continue

            if isinstance(content, dict):
                clean = dict(msg)
                clean["content"] = [content]
                result.append(clean)
                continue

            result.append(msg)
        return result

    @staticmethod
    def _sanitize_request_messages(
        messages: list[dict[str, Any]],
        allowed_keys: frozenset[str],
    ) -> list[dict[str, Any]]:
        """Keep only provider-safe message keys and normalize assistant content."""
        sanitized = []
        for msg in messages:
            clean = {k: v for k, v in msg.items() if k in allowed_keys}
            if clean.get("role") == "assistant" and "content" not in clean:
                clean["content"] = None
            sanitized.append(clean)
        return sanitized

    @abstractmethod
    async def chat(
        self,
        messages: list[dict[str, Any]],
        tools: list[dict[str, Any]] | None = None,
        model: str | None = None,
        max_tokens: int = 4096,
        temperature: float = 0.7,
        reasoning_effort: str | None = None,
        tool_choice: str | dict[str, Any] | None = None,
    ) -> LLMResponse:
        """
        Send a chat completion request.
        
        Args:
            messages: List of message dicts with 'role' and 'content'.
            tools: Optional list of tool definitions.
            model: Model identifier (provider-specific).
            max_tokens: Maximum tokens in response.
            temperature: Sampling temperature.
            tool_choice: Tool selection strategy ("auto", "required", or specific tool dict).
        
        Returns:
            LLMResponse with content and/or tool calls.
        """
        pass

    @classmethod
    def _is_transient_error(cls, content: str | None) -> bool:
        err = (content or "").lower()
        return any(marker in err for marker in cls._TRANSIENT_ERROR_MARKERS)

    @staticmethod
    def _strip_image_content(messages: list[dict[str, Any]]) -> list[dict[str, Any]] | None:
        """Replace image_url blocks with text placeholder. Returns None if no images found."""
        found = False
        result = []
        for msg in messages:
            content = msg.get("content")
            if isinstance(content, list):
                new_content = []
                for b in content:
                    if isinstance(b, dict) and b.get("type") == "image_url":
                        path = (b.get("_meta") or {}).get("path", "")
                        placeholder = image_placeholder_text(path, empty="[image omitted]")
                        new_content.append({"type": "text", "text": placeholder})
                        found = True
                    else:
                        new_content.append(b)
                result.append({**msg, "content": new_content})
            else:
                result.append(msg)
        return result if found else None

    async def _safe_chat(self, **kwargs: Any) -> LLMResponse:
        """Call chat() and convert unexpected exceptions to error responses."""
        try:
            return await self.chat(**kwargs)
        except asyncio.CancelledError:
            raise
        except Exception as exc:
            return LLMResponse(content=f"Error calling LLM: {exc}", finish_reason="error")

    async def chat_stream(
        self,
        messages: list[dict[str, Any]],
        tools: list[dict[str, Any]] | None = None,
        model: str | None = None,
        max_tokens: int = 4096,
        temperature: float = 0.7,
        reasoning_effort: str | None = None,
        tool_choice: str | dict[str, Any] | None = None,
        on_content_delta: Callable[[str], Awaitable[None]] | None = None,
    ) -> LLMResponse:
        """Stream a chat completion, calling *on_content_delta* for each text chunk.

        Returns the same ``LLMResponse`` as :meth:`chat`.  The default
        implementation falls back to a non-streaming call and delivers the
        full content as a single delta.  Providers that support native
        streaming should override this method.
        """
        response = await self.chat(
            messages=messages, tools=tools, model=model,
            max_tokens=max_tokens, temperature=temperature,
            reasoning_effort=reasoning_effort, tool_choice=tool_choice,
        )
        if on_content_delta and response.content:
            await on_content_delta(response.content)
        return response

    async def _safe_chat_stream(self, **kwargs: Any) -> LLMResponse:
        """Call chat_stream() and convert unexpected exceptions to error responses."""
        try:
            return await self.chat_stream(**kwargs)
        except asyncio.CancelledError:
            raise
        except Exception as exc:
            return LLMResponse(content=f"Error calling LLM: {exc}", finish_reason="error")

    async def chat_stream_with_retry(
        self,
        messages: list[dict[str, Any]],
        tools: list[dict[str, Any]] | None = None,
        model: str | None = None,
        max_tokens: object = _SENTINEL,
        temperature: object = _SENTINEL,
        reasoning_effort: object = _SENTINEL,
        tool_choice: str | dict[str, Any] | None = None,
        on_content_delta: Callable[[str], Awaitable[None]] | None = None,
        retry_mode: str = "standard",
        on_retry_wait: Callable[[str], Awaitable[None]] | None = None,
    ) -> LLMResponse:
        """Call chat_stream() with retry on transient provider failures."""
        if max_tokens is self._SENTINEL:
            max_tokens = self.generation.max_tokens
        if temperature is self._SENTINEL:
            temperature = self.generation.temperature
        if reasoning_effort is self._SENTINEL:
            reasoning_effort = self.generation.reasoning_effort

        kw: dict[str, Any] = dict(
            messages=messages, tools=tools, model=model,
            max_tokens=max_tokens, temperature=temperature,
            reasoning_effort=reasoning_effort, tool_choice=tool_choice,
            on_content_delta=on_content_delta,
        )
        return await self._run_with_retry(
            self._safe_chat_stream,
            kw,
            messages,
            retry_mode=retry_mode,
            on_retry_wait=on_retry_wait,
        )

    async def chat_with_retry(
        self,
        messages: list[dict[str, Any]],
        tools: list[dict[str, Any]] | None = None,
        model: str | None = None,
        max_tokens: object = _SENTINEL,
        temperature: object = _SENTINEL,
        reasoning_effort: object = _SENTINEL,
        tool_choice: str | dict[str, Any] | None = None,
        retry_mode: str = "standard",
        on_retry_wait: Callable[[str], Awaitable[None]] | None = None,
    ) -> LLMResponse:
        """Call chat() with retry on transient provider failures.

        Parameters default to ``self.generation`` when not explicitly passed,
        so callers no longer need to thread temperature / max_tokens /
        reasoning_effort through every layer.
        """
        if max_tokens is self._SENTINEL:
            max_tokens = self.generation.max_tokens
        if temperature is self._SENTINEL:
            temperature = self.generation.temperature
        if reasoning_effort is self._SENTINEL:
            reasoning_effort = self.generation.reasoning_effort

        kw: dict[str, Any] = dict(
            messages=messages, tools=tools, model=model,
            max_tokens=max_tokens, temperature=temperature,
            reasoning_effort=reasoning_effort, tool_choice=tool_choice,
        )
        return await self._run_with_retry(
            self._safe_chat,
            kw,
            messages,
            retry_mode=retry_mode,
            on_retry_wait=on_retry_wait,
        )

    @classmethod
    def _extract_retry_after(cls, content: str | None) -> float | None:
        text = (content or "").lower()
        patterns = (
            r"retry after\s+(\d+(?:\.\d+)?)\s*(ms|milliseconds|s|sec|secs|seconds|m|min|minutes)?",
            r"try again in\s+(\d+(?:\.\d+)?)\s*(ms|milliseconds|s|sec|secs|seconds|m|min|minutes)",
            r"wait\s+(\d+(?:\.\d+)?)\s*(ms|milliseconds|s|sec|secs|seconds|m|min|minutes)\s*before retry",
            r"retry[_-]?after[\"'\s:=]+(\d+(?:\.\d+)?)",
        )
        for idx, pattern in enumerate(patterns):
            match = re.search(pattern, text)
            if not match:
                continue
            value = float(match.group(1))
            unit = match.group(2) if idx < 3 else "s"
            return cls._to_retry_seconds(value, unit)
        return None

    @classmethod
    def _to_retry_seconds(cls, value: float, unit: str | None = None) -> float:
        normalized_unit = (unit or "s").lower()
        if normalized_unit in {"ms", "milliseconds"}:
            return max(0.1, value / 1000.0)
        if normalized_unit in {"m", "min", "minutes"}:
            return max(0.1, value * 60.0)
        return max(0.1, value)

    @classmethod
    def _extract_retry_after_from_headers(cls, headers: Any) -> float | None:
        if not headers:
            return None
        retry_after: Any = None
        if hasattr(headers, "get"):
            retry_after = headers.get("retry-after") or headers.get("Retry-After")
        if retry_after is None and isinstance(headers, dict):
            for key, value in headers.items():
                if isinstance(key, str) and key.lower() == "retry-after":
                    retry_after = value
                    break
        if retry_after is None:
            return None
        retry_after_text = str(retry_after).strip()
        if not retry_after_text:
            return None
        if re.fullmatch(r"\d+(?:\.\d+)?", retry_after_text):
            return cls._to_retry_seconds(float(retry_after_text), "s")
        try:
            retry_at = parsedate_to_datetime(retry_after_text)
        except Exception:
            return None
        if retry_at.tzinfo is None:
            retry_at = retry_at.replace(tzinfo=timezone.utc)
        remaining = (retry_at - datetime.now(retry_at.tzinfo)).total_seconds()
        return max(0.1, remaining)

    async def _sleep_with_heartbeat(
        self,
        delay: float,
        *,
        attempt: int,
        persistent: bool,
        on_retry_wait: Callable[[str], Awaitable[None]] | None = None,
    ) -> None:
        remaining = max(0.0, delay)
        while remaining > 0:
            if on_retry_wait:
                kind = "persistent retry" if persistent else "retry"
                await on_retry_wait(
                    f"Model request failed, {kind} in {max(1, int(round(remaining)))}s "
                    f"(attempt {attempt})."
                )
            chunk = min(remaining, self._RETRY_HEARTBEAT_CHUNK)
            await asyncio.sleep(chunk)
            remaining -= chunk

    async def _run_with_retry(
        self,
        call: Callable[..., Awaitable[LLMResponse]],
        kw: dict[str, Any],
        original_messages: list[dict[str, Any]],
        *,
        retry_mode: str,
        on_retry_wait: Callable[[str], Awaitable[None]] | None,
    ) -> LLMResponse:
        attempt = 0
        delays = list(self._CHAT_RETRY_DELAYS)
        persistent = retry_mode == "persistent"
        last_response: LLMResponse | None = None
        last_error_key: str | None = None
        identical_error_count = 0
        while True:
            attempt += 1
            response = await call(**kw)
            if response.finish_reason != "error":
                return response
            last_response = response
            error_key = ((response.content or "").strip().lower() or None)
            if error_key and error_key == last_error_key:
                identical_error_count += 1
            else:
                last_error_key = error_key
                identical_error_count = 1 if error_key else 0

            if not self._is_transient_error(response.content):
                stripped = self._strip_image_content(original_messages)
                if stripped is not None and stripped != kw["messages"]:
                    logger.warning(
                        "Non-transient LLM error with image content, retrying without images"
                    )
                    retry_kw = dict(kw)
                    retry_kw["messages"] = stripped
                    return await call(**retry_kw)
                return response

            if persistent and identical_error_count >= self._PERSISTENT_IDENTICAL_ERROR_LIMIT:
                logger.warning(
                    "Stopping persistent retry after {} identical transient errors: {}",
                    identical_error_count,
                    (response.content or "")[:120].lower(),
                )
                return response

            if not persistent and attempt > len(delays):
                break

            base_delay = delays[min(attempt - 1, len(delays) - 1)]
            delay = response.retry_after or self._extract_retry_after(response.content) or base_delay
            if persistent:
                delay = min(delay, self._PERSISTENT_MAX_DELAY)

            logger.warning(
                "LLM transient error (attempt {}{}), retrying in {}s: {}",
                attempt,
                "+" if persistent and attempt > len(delays) else f"/{len(delays)}",
                int(round(delay)),
                (response.content or "")[:120].lower(),
            )
            await self._sleep_with_heartbeat(
                delay,
                attempt=attempt,
                persistent=persistent,
                on_retry_wait=on_retry_wait,
            )

        return last_response if last_response is not None else await call(**kw)

    @abstractmethod
    def get_default_model(self) -> str:
        """Get the default model for this provider."""
        pass