"""In-process Hugging Face clients for the two translation models.

Stage 1 - `translate`: google/translategemma-12b-it via its official
TranslateGemma chat template.

Stage 2 - `adjust_tone`: google/gemma-4-12B-it via the normal Gemma 4 chat
template, rewriting a draft translation in a character's voice using their
wiki.
"""

from __future__ import annotations

import gc
import re
import sys
from dataclasses import dataclass
from pathlib import Path
from typing import Any

sys.path.insert(0, str(Path(__file__).parent.parent))
import config

try:
    import spaces
except ImportError:  # Local/dev installs do not need the Spaces runtime.
    spaces = None


# Runtime-injected tokens like "Person1" that must survive translation verbatim.
_PLACEHOLDER_RE = re.compile(r"\b([A-Za-z]+)(\d+)\b")

TONE_SYSTEM_TEMPLATE = """\
You are a localization editor for "Riverstone", a narrative mystery mobile game \
told through phone chats. Below is the voice wiki for {name}, a game character.

{wiki}

You will receive one of {name}'s chat lines in English and a draft {language} \
translation. Rewrite the {language} draft so it reads like {name} texting in \
{language}: match the wiki's tone, register, slang level, emoji and punctuation \
habits.

Rules:
- Keep the exact meaning of the English line; never add or drop information.
- Keep placeholder tokens (e.g. Person1), proper names, emoji and special \
symbols exactly as written.
- Use the formality level the wiki implies for {name} (casual characters use \
informal address).
- If the draft already sounds right, return it unchanged.
- Output ONLY the final {language} line - no quotes, no commentary.
"""

TONE_USER_TEMPLATE = """\
{context}English line: {source}
Draft {language} translation: {draft}
Final {language} line:"""

WIKI_MAX_NEW_TOKENS = 1200


@dataclass
class _LoadedModel:
    processor: Any
    model: Any


_MODELS: dict[str, _LoadedModel] = {}
_MODEL_IDS = {
    "translate": config.TRANSLATE_MODEL_ID,
    "tone": config.TONE_MODEL_ID,
}


def _gpu(fn):
    if spaces is None:
        return fn
    return spaces.GPU(
        duration=config.ZERO_GPU_DURATION_S,
        size=config.ZERO_GPU_SIZE,
    )(fn)


def _torch():
    try:
        import torch
    except ImportError as exc:
        raise RuntimeError(
            "Hugging Face inference requires torch. Install the Space/runtime "
            "dependencies from requirements.txt."
        ) from exc
    return torch


def _hf_classes():
    try:
        from transformers import AutoModelForMultimodalLM, AutoProcessor

        return AutoProcessor, AutoModelForMultimodalLM
    except ImportError:
        try:
            from transformers import AutoModelForImageTextToText, AutoProcessor

            return AutoProcessor, AutoModelForImageTextToText
        except ImportError as exc:
            raise RuntimeError(
                "Hugging Face inference requires a recent transformers release "
                "with Gemma multimodal model support."
            ) from exc


def _from_pretrained(model_id: str):
    AutoProcessor, AutoModel = _hf_classes()
    kwargs: dict[str, Any] = {}
    if config.HF_DEVICE_MAP is not None:
        kwargs["device_map"] = config.HF_DEVICE_MAP
    if config.HF_DTYPE is not None:
        kwargs["dtype"] = config.HF_DTYPE
    if config.HF_ATTN_IMPLEMENTATION:
        kwargs["attn_implementation"] = config.HF_ATTN_IMPLEMENTATION

    processor = AutoProcessor.from_pretrained(model_id)
    try:
        model = AutoModel.from_pretrained(model_id, **kwargs)
    except TypeError:
        # Older Transformers used torch_dtype instead of dtype.
        if "dtype" in kwargs:
            kwargs["torch_dtype"] = kwargs.pop("dtype")
        model = AutoModel.from_pretrained(model_id, **kwargs)
    model.eval()
    return _LoadedModel(processor=processor, model=model)


def release_models(except_key: str | None = None) -> None:
    """Free loaded HF models, optionally keeping one active model resident."""
    for key in list(_MODELS):
        if key != except_key:
            del _MODELS[key]
    gc.collect()
    try:
        torch = _torch()
        if torch.cuda.is_available():
            torch.cuda.empty_cache()
    except RuntimeError:
        pass


def warm_models(*keys: str) -> None:
    """Preload selected models, useful from a Space module at startup."""
    for key in keys:
        _get_model(key)


def _get_model(key: str) -> _LoadedModel:
    if key not in _MODEL_IDS:
        raise ValueError(f"Unknown model key: {key}")
    if key not in _MODELS:
        if not config.HF_KEEP_BOTH_MODELS:
            release_models(except_key=key)
        _MODELS[key] = _from_pretrained(_MODEL_IDS[key])
    return _MODELS[key]


def _model_device(model):
    device = getattr(model, "device", None)
    if device is not None:
        return device
    try:
        return next(model.parameters()).device
    except StopIteration:
        return None


def _model_dtype(model):
    try:
        for parameter in model.parameters():
            if parameter.is_floating_point():
                return parameter.dtype
    except StopIteration:
        return None
    return None


def _move_inputs(inputs, model):
    device = _model_device(model)
    dtype = _model_dtype(model)
    if device is None:
        return inputs
    if dtype is not None:
        try:
            return inputs.to(device, dtype=dtype)
        except TypeError:
            pass
    return inputs.to(device)


def _apply_chat_template(processor, messages, *, enable_thinking: bool = False):
    kwargs = {
        "tokenize": True,
        "add_generation_prompt": True,
        "return_dict": True,
        "return_tensors": "pt",
    }
    try:
        return processor.apply_chat_template(
            messages,
            enable_thinking=enable_thinking,
            **kwargs,
        )
    except TypeError:
        return processor.apply_chat_template(messages, **kwargs)


def _generate_text(
    key: str,
    messages: list[dict],
    *,
    max_new_tokens: int,
    enable_thinking: bool = False,
    **generation_kwargs,
) -> str:
    loaded = _get_model(key)
    torch = _torch()
    inputs = _apply_chat_template(
        loaded.processor,
        messages,
        enable_thinking=enable_thinking,
    )
    inputs = _move_inputs(inputs, loaded.model)
    input_len = inputs["input_ids"].shape[-1]

    with torch.inference_mode():
        output = loaded.model.generate(
            **inputs,
            max_new_tokens=max_new_tokens,
            **generation_kwargs,
        )

    generated = output[0][input_len:]
    decoded = loaded.processor.decode(generated, skip_special_tokens=False)
    return _parse_response(loaded.processor, decoded)


def _parse_response(processor, decoded: str) -> str:
    if hasattr(processor, "parse_response"):
        try:
            parsed = processor.parse_response(decoded)
            if isinstance(parsed, str):
                return parsed.strip()
            if isinstance(parsed, dict):
                for key in ("content", "text", "response", "answer"):
                    value = parsed.get(key)
                    if isinstance(value, str):
                        return value.strip()
        except Exception:
            pass

    text = decoded
    text = re.sub(r"<\|channel\>thought.*?<channel\|>", "", text, flags=re.DOTALL)
    text = re.sub(r"<[^>]+>", "", text)
    return text.strip()


def restore_placeholders(source: str, translated: str) -> str:
    """Undo model damage to PersonN-style tokens (e.g. 'Person 1' -> 'Person1')."""
    result = translated
    for word, num in _PLACEHOLDER_RE.findall(source):
        token = f"{word}{num}"
        if token in result:
            continue
        spaced = re.compile(rf"\b{re.escape(word)}\s+{num}\b", re.IGNORECASE)
        result = spaced.sub(token, result)
    return result


def _translate_text(text: str) -> str:
    messages = [
        {
            "role": "user",
            "content": [
                {
                    "type": "text",
                    "source_lang_code": config.SOURCE_LANG_CODE,
                    "target_lang_code": config.TARGET_LANG_CODE,
                    "text": text,
                }
            ],
        }
    ]
    reply = _generate_text(
        "translate",
        messages,
        max_new_tokens=config.TRANSLATE_MAX_NEW_TOKENS,
        do_sample=False,
    )
    return restore_placeholders(text, reply)


def _adjust_tone_text(
    source: str,
    draft: str,
    wiki: str,
    char_name: str,
    context_lines: list[str] | None = None,
) -> str:
    """Rewrite a draft translation in the character's voice via Gemma 4."""
    context = ""
    if context_lines:
        joined = "\n".join(f"  {line}" for line in context_lines)
        context = f"Preceding lines in this chat (English, for context only):\n{joined}\n\n"
    messages = [
        {
            "role": "system",
            "content": TONE_SYSTEM_TEMPLATE.format(
                name=char_name, wiki=wiki, language=config.TARGET_LANG_NAME
            ),
        },
        {
            "role": "user",
            "content": TONE_USER_TEMPLATE.format(
                context=context,
                source=source,
                draft=draft,
                language=config.TARGET_LANG_NAME,
            ),
        },
    ]
    reply = _generate_text(
        "tone",
        messages,
        max_new_tokens=config.TONE_MAX_NEW_TOKENS,
        enable_thinking=False,
        **config.TONE_GENERATION_KWARGS,
    )
    reply = reply.strip().strip('"').strip()
    return restore_placeholders(source, reply) if reply else draft


@_gpu
def translate(text: str) -> str:
    """Translate one string with TranslateGemma (greedy)."""
    return _translate_text(text)


@_gpu
def adjust_tone(
    source: str,
    draft: str,
    wiki: str,
    char_name: str,
    context_lines: list[str] | None = None,
) -> str:
    """Rewrite a draft translation in the character's voice via Gemma 4."""
    return _adjust_tone_text(source, draft, wiki, char_name, context_lines)


@_gpu
def translate_and_tone_items(
    items: list[dict],
    cache: dict,
    wiki: str | None,
    char_name: str | None,
    context_window: int = 2,
) -> tuple[list[dict], dict, dict]:
    """Translate and tone a full review record in one GPU allocation."""
    cache = dict(cache)
    translated = 0
    toned = 0

    for item in items:
        if item.get("mt") is not None:
            continue
        source = item["source"]
        cached = cache.get(source)
        if cached is not None:
            item["mt"] = cached
        else:
            item["mt"] = _translate_text(source)
            cache[source] = item["mt"]
            translated += 1

    if wiki and char_name:
        sources = [item["source"] for item in items]
        for i, item in enumerate(items):
            if item.get("kind") != "dialogue" or item.get("toned") is not None:
                continue
            if item.get("mt") is None:
                continue
            context = sources[max(0, i - context_window) : i]
            item["toned"] = _adjust_tone_text(
                item["source"], item["mt"], wiki, char_name, context
            )
            toned += 1

    return items, cache, {"translated": translated, "toned": toned}


@_gpu
def update_character_wiki(system_prompt: str, user_msg: str) -> str:
    """Update a character wiki via the same in-process Gemma runtime as tone pass."""
    messages = [
        {"role": "system", "content": system_prompt},
        {"role": "user", "content": user_msg},
    ]
    return _generate_text(
        "tone",
        messages,
        max_new_tokens=WIKI_MAX_NEW_TOKENS,
        enable_thinking=False,
        **config.TONE_GENERATION_KWARGS,
    ).strip()


if getattr(config, "HF_PRELOAD_MODELS", ()):
    warm_models(*config.HF_PRELOAD_MODELS)