"""Ollama client wrapper with tool-calling chat loop and streaming."""

from __future__ import annotations

import base64
import json
from collections.abc import AsyncIterator, Callable, Iterator
from typing import Any, cast

import ollama
from ollama import Message

from .config import settings
from .tools.registry import ToolRegistry, default_registry

# Maximum successive tool-call rounds before we force a final answer.
# Some models request many tools per round; we keep this bounded but large
# enough to let iterative research complete (e.g. search, then fetch).
MAX_TOOL_ROUNDS = 5

# Upper bound on the cumulative size of tool results sent back to ollama.

# Larger values can cause ollama to spend a very long time processing the
# context between rounds.
MAX_TOOL_CONTEXT_CHARS = 24000

# Type alias matching ollama's expected tools signature.
ToolCallable = Callable[..., Any]


def get_client(host: str | None = None) -> ollama.Client:
    """Return an ``ollama.Client`` configured for the configured host."""
    import httpx

    timeout = httpx.Timeout(
        settings.ollama_timeout,
        connect=10.0,
        read=settings.ollama_timeout,
        write=10.0,
        pool=10.0,
    )
    return ollama.Client(host=host or settings.ollama_host, timeout=timeout)


def list_models(host: str | None = None) -> list[str]:
    """Return the list of locally available model names."""
    client = get_client(host)
    try:
        resp = client.list()
    except Exception:  # noqa: BLE001
        return []
    models: list[str] = []
    for item in resp.get("models", []) if isinstance(resp, dict) else getattr(resp, "models", []):
        name = item.get("model") if isinstance(item, dict) else getattr(item, "model", None)
        if name:
            models.append(str(name))
    return models


def get_model_capabilities(model: str, host: str | None = None) -> set[str]:
    """Return the capability set for a single model via ``ollama.show()``.

    Unknown or unreachable models are treated as having no special capabilities,
    which keeps the UI conservative and avoids sending unsupported parameters.
    """
    try:
        client = get_client(host)
        show_response = client.show(model)
    except Exception:  # noqa: BLE001
        return set()

    caps = getattr(show_response, "capabilities", None)
    if caps is None and isinstance(show_response, dict):
        caps = show_response.get("capabilities")
    if not caps:
        return set()
    return {str(c).lower() for c in caps}


def _is_image_message(message: Message) -> bool:
    """Check whether a message has image attachments."""
    images = getattr(message, "images", None)
    return bool(images)


def _embed_images_in_content(message: Message) -> Message:
    """Convert image bytes attached to a message into base64 markdown links.

    Non-vision models cannot consume the ``images`` field, so we fall back to
    embedding the image as data URIs inside the text content.
    """
    images = getattr(message, "images", None) or []
    if not images:
        return message

    parts: list[str] = []
    for img in images:
        raw = getattr(img, "value", None) or (img if isinstance(img, (bytes, bytearray)) else None)
        if raw is None:
            continue
        encoded = base64.b64encode(bytes(raw)).decode("ascii")
        # Use a generic data URI since ollama already processed the image.
        parts.append(f"![image](data:image/png;base64,{encoded})")

    content = str(getattr(message, "content", "") or "")
    if parts:
        content = content + "\n\n" + "\n\n".join(parts)

    kwargs: dict[str, Any] = {"role": getattr(message, "role", "user"), "content": content}
    for attr in ("name", "tool_calls", "tool_name"):
        value = getattr(message, attr, None)
        if value is not None:
            kwargs[attr] = value
    if getattr(message, "thinking", None):
        kwargs["thinking"] = message.thinking
    return Message(**kwargs)


def _tool_calls(response: Any) -> list[dict[str, Any]]:
    """Extract tool calls from an ollama response in a tolerant manner."""
    msg = getattr(response, "message", None) or (
        response.get("message") if isinstance(response, dict) else None
    )
    return _tool_calls_from_message(msg)


def _tool_calls_from_message(msg: Any) -> list[dict[str, Any]]:
    """Extract tool calls from a message object/dict."""
    if msg is None:
        return []
    calls = getattr(msg, "tool_calls", None) if not isinstance(msg, dict) else msg.get("tool_calls")
    if not calls:
        return []
    out: list[dict[str, Any]] = []
    for c in calls:
        if isinstance(c, dict):
            fn = c.get("function", {})
            name = fn.get("name") or c.get("name", "")
            args = fn.get("arguments") or c.get("arguments", {})
            out.append({"name": name, "arguments": args})
        else:
            fn = getattr(c, "function", None)
            if fn is not None:
                name = getattr(fn, "name", "")
                args = getattr(fn, "arguments", {})
            else:
                name = getattr(c, "name", "")
                args = getattr(c, "arguments", {})
            out.append({"name": name, "arguments": args})
    return out


def _assistant_message(response: Any) -> Message:
    """Convert a non-streaming response into a Message for re-submission."""
    msg = getattr(response, "message", None) or (
        response.get("message") if isinstance(response, dict) else None
    )
    if isinstance(msg, dict):
        return Message(**msg)
    if msg is not None:
        return cast(Message, msg)
    return Message(role="assistant", content="")


def chat_with_tools(
    messages: list[Message],
    model: str,
    *,
    think: bool | str | None = None,
    registry: ToolRegistry | None = None,
    host: str | None = None,
    capabilities: set[str] | None = None,
) -> Iterator[dict[str, Any]]:
    """Run a multi-round tool-calling chat and yield progress events.

    Events are dicts with a ``type`` key:

    - ``{"type": "tool_start", "name": str, "arguments": dict}``
    - ``{"type": "tool_end", "name": str, "result": str}``
    - ``{"type": "delta", "content": str}``
    - ``{"type": "thinking", "content": str}``
    - ``{"type": "done"}``
    - ``{"type": "error", "message": str}``

    The final assistant message is streamed token-by-token via ``delta`` events.
    """
    import logging

    logger = logging.getLogger("ollama_web.llm")

    caps = capabilities or set()
    raw_client = get_client(host)
    reg = registry or default_registry()
    tools: list[ToolCallable] = [cast(Any, t) for t in reg.ollama_tools]
    effective_tools = tools if "tools" in caps else []
    effective_think = think if "thinking" in caps else None

    # Non-vision models cannot use the ``images`` field; embed them as base64.
    if "vision" not in caps:
        messages = [_embed_images_in_content(m) if _is_image_message(m) else m for m in messages]

    cumulative_tool_chars = 0

    rounds = 0
    while rounds < MAX_TOOL_ROUNDS:
        rounds += 1
        logger.info(
            "tool round %d/%d start messages=%d model=%s cumulative_tool_chars=%d",
            rounds,
            MAX_TOOL_ROUNDS,
            len(messages),
            model,
            cumulative_tool_chars,
        )
        try:
            resp = cast(Any, raw_client).chat(
                model=model,
                messages=messages,
                tools=effective_tools,
                think=effective_think,
                stream=False,
            )
        except Exception as exc:  # noqa: BLE001
            logger.warning("ollama chat call failed: %s", exc)
            yield {"type": "error", "message": str(exc)}
            return

        calls = _tool_calls(resp)
        if not calls:
            # No tool calls: stream the final answer for UI effect.
            content = _assistant_content(resp)
            thinking = _assistant_thinking(resp)
            if thinking:
                yield {"type": "thinking", "content": thinking}
            if content:
                yield {"type": "delta", "content": content}
            yield {"type": "done"}
            return

        # Append the assistant message that requested tool calls.
        messages.append(_assistant_message(resp))

        # Execute each requested tool and append tool-role messages.
        tool_results: list[tuple[str, str]] = []
        for call in calls:
            name = call.get("name", "")
            args = call.get("arguments", {})
            yield {"type": "tool_start", "name": name, "arguments": args}
            result = reg.execute(name, args if isinstance(args, dict) else json.dumps(args))
            result = _trim_tool_result(result, settings.max_tool_result_chars)
            yield {"type": "tool_end", "name": name, "result": result}
            tool_results.append((name, result))

        if sum(len(r) for _, r in tool_results) > MAX_TOOL_CONTEXT_CHARS:
            budget = MAX_TOOL_CONTEXT_CHARS - len(tool_results) * 200
            max_per_tool = budget // max(1, len(tool_results))
            logger.warning(
                "tool results too large (%d chars), truncating to %d chars per tool",
                sum(len(r) for _, r in tool_results),
                max_per_tool,
            )
            tool_results = [(n, _trim_tool_result(r, max_per_tool)) for n, r in tool_results]

        cumulative_tool_chars += sum(len(r) for _, r in tool_results)
        for name, result in tool_results:
            messages.append(Message(role="tool", tool_name=name, content=result))

    # Exceeded tool rounds: ask for a final answer without tools.
    logger.info(
        (
            "max tool rounds exceeded, requesting final answer without tools "
            "(cumulative_tool_chars=%d)"
        ),
        cumulative_tool_chars,
    )
    yield {
        "type": "status",
        "message": "ツール呼び出し上限に達しました。これまでの調査結果を整理中…",
    }
    messages.append(
        Message(
            role="user",
            content=(
                "ツール呼び出しの上限に達しました。これまでの検索結果と会話を元に、"
                "ユーザーが求めた回答を最終的にまとめてください。"
            ),
        )
    )
    try:
        resp = cast(Any, raw_client).chat(
            model=model,
            messages=messages,
            tools=effective_tools,
            think=effective_think,
            stream=False,
        )
    except Exception as exc:  # noqa: BLE001
        logger.warning("final ollama chat call failed: %s", exc)
        yield {"type": "error", "message": str(exc)}
        return
    content = _assistant_content(resp)
    thinking = _assistant_thinking(resp)
    if thinking:
        yield {"type": "thinking", "content": thinking}
    if content:
        yield {"type": "delta", "content": content}
    yield {"type": "done"}


def _trim_tool_result(result: str, limit: int) -> str:
    """Truncate ``result`` to ``limit`` chars while keeping it readable."""
    if len(result) <= limit:
        return result
    # Prefer cutting at a paragraph boundary.
    cutoff = result[:limit].rsplit("\n\n", 1)[0]
    if len(cutoff) < limit * 0.5:
        # No good paragraph boundary; cut at a space instead.
        cutoff = result[:limit].rsplit(" ", 1)[0]
    return cutoff + "\n\n…[tool result truncated]"


def stream_chat_with_tools(
    messages: list[Message],
    model: str,
    *,
    think: bool | str | None = None,
    registry: ToolRegistry | None = None,
    host: str | None = None,
    capabilities: set[str] | None = None,
) -> Iterator[dict[str, Any]]:
    """Run a tool-calling chat loop and yield real streaming events from ollama.

    The final assistant answer is streamed token-by-token. Tool and thinking
    events are emitted inline so the UI can render them inside the assistant
    message.
    """
    import logging
    import time

    logger = logging.getLogger("ollama_web.llm")

    caps = capabilities or set()
    raw_client = get_client(host)
    reg = registry or default_registry()
    tools: list[ToolCallable] = [cast(Any, t) for t in reg.ollama_tools]
    effective_tools = tools if "tools" in caps else []
    effective_think = think if "thinking" in caps else None

    # Non-vision models cannot use the ``images`` field; embed them as base64.
    if "vision" not in caps:
        messages = [_embed_images_in_content(m) if _is_image_message(m) else m for m in messages]

    cumulative_tool_chars = 0

    rounds = 0
    while rounds < MAX_TOOL_ROUNDS:
        rounds += 1
        full_message: dict[str, Any] = {"role": "assistant", "content": "", "thinking": ""}
        tool_calls: list[dict[str, Any]] = []
        logger.info(
            "tool round %d/%d start messages=%d model=%s cumulative_tool_chars=%d",
            rounds,
            MAX_TOOL_ROUNDS,
            len(messages),
            model,
            cumulative_tool_chars,
        )
        t0 = time.time()
        try:
            stream = cast(Any, raw_client).chat(
                model=model,
                messages=messages,
                tools=effective_tools,
                think=effective_think,
                stream=True,
            )
        except Exception as exc:  # noqa: BLE001
            logger.warning("ollama chat call failed in %.2fs: %s", time.time() - t0, exc)
            yield {"type": "error", "message": str(exc)}
            return

        chunk_count = 0
        for chunk in stream:
            chunk_count += 1
            thinking = _assistant_thinking(chunk)
            if thinking:
                full_message.setdefault("thinking", "")
                full_message["thinking"] += thinking
                yield {"type": "thinking", "content": thinking}
            content = _assistant_content(chunk)
            if content:
                full_message["content"] += content
                yield {"type": "delta", "content": content}

            calls = _tool_calls_from_message(getattr(chunk, "message", None))
            for c in calls:
                # Avoid duplicates from repeated chunks containing the same call.
                if c not in tool_calls:
                    tool_calls.append(c)

        logger.info(
            "ollama stream finished round=%d chunks=%d elapsed=%.2fs",
            rounds,
            chunk_count,
            time.time() - t0,
        )

        # Reconstruct the assistant message including any tool_calls so the
        # next round can see them.
        if tool_calls:
            full_message["tool_calls"] = tool_calls
        msg = _assistant_message_chunk(full_message)
        if msg is not None:
            messages.append(msg)

        if not tool_calls:
            yield {"type": "done"}
            return

        logger.info("executing %d tool call(s) round=%d", len(tool_calls), rounds)
        tool_results: list[tuple[str, str]] = []
        total_result_len = 0
        for call in tool_calls:
            name = call.get("name", "")
            args = call.get("arguments", {})
            yield {"type": "tool_start", "name": name, "arguments": args}
            t1 = time.time()
            try:
                result = reg.execute(
                    name, args if isinstance(args, dict) else json.dumps(args)
                )
            except Exception as exc:  # noqa: BLE001
                logger.warning("tool %s execution failed in %.2fs: %s", name, time.time() - t1, exc)
                result = f"Tool execution failed: {exc}"
            # Always truncate per-tool result immediately so it does not bloat
            # the context even before we reach the cumulative limit.
            result = _trim_tool_result(result, settings.max_tool_result_chars)
            logger.info(
                "tool %s executed len=%d elapsed=%.2fs",
                name,
                len(result),
                time.time() - t1,
            )
            yield {"type": "tool_end", "name": name, "result": result}
            tool_results.append((name, result))
            total_result_len += len(result)

        # If the accumulated tool results are still too large, truncate each
        # one more aggressively to keep ollama's context processing fast.
        if total_result_len > MAX_TOOL_CONTEXT_CHARS:
            budget = MAX_TOOL_CONTEXT_CHARS - len(tool_results) * 200  # reserve footer per tool
            max_per_tool = budget // max(1, len(tool_results))
            logger.warning(
                "tool results too large (%d chars), truncating to %d chars per tool",
                total_result_len,
                max_per_tool,
            )
            trimmed_results: list[tuple[str, str]] = []
            for name, result in tool_results:
                trimmed_results.append((name, _trim_tool_result(result, max_per_tool)))
            tool_results = trimmed_results

        cumulative_tool_chars += sum(len(r) for _, r in tool_results)
        for name, result in tool_results:
            messages.append(Message(role="tool", tool_name=name, content=result))

    # Exceeded tool rounds: ask for a final answer without tools.
    logger.info(
        (
            "max tool rounds exceeded, requesting final answer without tools "
            "(cumulative_tool_chars=%d)"
        ),
        cumulative_tool_chars,
    )
    yield {
        "type": "status",
        "message": "ツール呼び出し上限に達しました。これまでの調査結果を整理中…",
    }
    messages.append(
        Message(
            role="user",
            content=(
                "ツール呼び出しの上限に達しました。これまでの検索結果と会話を元に、"
                "ユーザーが求めた回答を最終的にまとめてください。"
            ),
        )
    )
    t0 = time.time()
    try:
        stream = cast(Any, raw_client).chat(
            model=model,
            messages=messages,
            tools=effective_tools,
            think=effective_think,
            stream=True,
        )
    except Exception as exc:  # noqa: BLE001
        logger.warning("final ollama chat call failed in %.2fs: %s", time.time() - t0, exc)
        yield {"type": "error", "message": str(exc)}
        return

    logger.info("streaming final answer")
    for chunk in stream:
        thinking = _assistant_thinking(chunk)
        if thinking:
            yield {"type": "thinking", "content": thinking}
        content = _assistant_content(chunk)
        if content:
            yield {"type": "delta", "content": content}
    logger.info("final answer stream finished elapsed=%.2fs", time.time() - t0)
    yield {"type": "done"}


async def astream_chat_with_tools(
    messages: list[Message],
    model: str,
    *,
    think: bool | str | None = None,
    registry: ToolRegistry | None = None,
    host: str | None = None,
    capabilities: set[str] | None = None,
) -> AsyncIterator[dict[str, Any]]:
    """Async wrapper that yields events from ``stream_chat_with_tools``."""
    import anyio

    gen = stream_chat_with_tools(
        messages, model, think=think, registry=registry, host=host, capabilities=capabilities
    )

    def _next() -> dict[str, Any] | None:
        try:
            return next(gen)
        except StopIteration:
            return None

    while True:
        event = await anyio.to_thread.run_sync(_next, abandon_on_cancel=True)
        if event is None:
            break
        yield event


def _assistant_content(response: Any) -> str:
    msg = getattr(response, "message", None) or (
        response.get("message") if isinstance(response, dict) else None
    )
    if msg is None:
        return ""
    if isinstance(msg, dict):
        return str(msg.get("content", "") or "")
    return str(getattr(msg, "content", "") or "")


def _assistant_thinking(response: Any) -> str:
    msg = getattr(response, "message", None) or (
        response.get("message") if isinstance(response, dict) else None
    )
    if msg is None:
        return ""
    if isinstance(msg, dict):
        return str(msg.get("thinking", "") or "")
    return str(getattr(msg, "thinking", "") or "")


def _chunk_text(text: str, size: int) -> Iterator[str]:
    """Yield successive chunks of ``text`` up to ``size`` characters."""
    for i in range(0, len(text), size):
        yield text[i : i + size]


def _assistant_message_chunk(full_message: dict[str, Any]) -> Message | None:
    """Build an assistant ``Message`` from the accumulated streamed message.

    ``tool_calls`` are expected to be already accumulated into ``full_message``.
    If the message is empty, ``None`` is returned.
    """
    content = full_message.get("content", "")
    thinking = full_message.get("thinking", "")
    calls = full_message.get("tool_calls", [])

    if not content and not thinking and not calls:
        return None

    kwargs: dict[str, Any] = {"role": "assistant", "content": content}
    if thinking:
        kwargs["thinking"] = thinking
    if calls:
        # Convert plain dicts into ollama ToolCall objects.
        tc_list: list[Message.ToolCall] = []
        for c in calls:
            name = c.get("name", "")
            args = c.get("arguments", {})
            tc_list.append(
                Message.ToolCall(
                    function=Message.ToolCall.Function(name=name, arguments=args)
                )
            )
        kwargs["tool_calls"] = tc_list
    return Message(**kwargs)