import json
import re
import site
import sys
from itertools import chain
from pathlib import Path

from .text_quality import clean_answer_text, clean_context_text, clean_training_text

TEXT_FIELD_PREFERENCES = (
    "text",
    "content",
    "body",
    "article",
    "document",
    "passage",
    "markdown",
)

DIALOGUE_FIELD_PREFERENCES = (
    "messages",
    "conversation",
    "conversations",
    "dialogue",
    "dialog",
    "turns",
)

PREFERENCE_FIELD_PAIRS = (
    ("chosen", "rejected"),
    ("response_j", "response_k"),
    ("response_0", "response_1"),
)

INSTRUCTION_FIELD_PAIRS = (
    ("instruction", "output"),
    ("prompt", "completion"),
    ("prompt", "response"),
    ("question", "answer"),
    ("question", "response"),
    ("query", "response"),
)

TRANSCRIPT_ROLE_PATTERN = re.compile(r"(?:^|\n\s*\n)(Human|Assistant|System)\s*:\s*", re.IGNORECASE)
ROLE_ALIASES = {
    "assistant": "assistant",
    "bot": "assistant",
    "gpt": "assistant",
    "model": "assistant",
    "assistant_response": "assistant",
    "human": "user",
    "user": "user",
    "prompter": "user",
    "customer": "user",
    "system": "system",
}


def _word_count(text: str) -> int:
    return len(text.split())


def _alpha_ratio(text: str) -> float:
    if not text:
        return 0.0
    alpha_count = sum(character.isalpha() for character in text)
    return alpha_count / len(text)


def _default_record_weight(record_type: str) -> int:
    if record_type == "dialogue_turn":
        return 2
    if record_type == "instruction_answer":
        return 2
    if record_type == "preference_chosen":
        return 3
    if record_type == "preference_rejected":
        return 0
    return 1


def choose_text_field(columns: list[str]) -> str:
    normalized = {column.casefold(): column for column in columns}
    for preferred in TEXT_FIELD_PREFERENCES:
        if preferred in normalized:
            return normalized[preferred]
    raise ValueError("Could not infer a text column. Pass --text-field explicitly.")


def choose_dialogue_field(columns: list[str]) -> str:
    normalized = {column.casefold(): column for column in columns}
    for preferred in DIALOGUE_FIELD_PREFERENCES:
        if preferred in normalized:
            return normalized[preferred]
    raise ValueError("Could not infer a conversation column.")


def choose_preference_fields(columns: list[str]) -> tuple[str, str]:
    normalized = {column.casefold(): column for column in columns}
    for chosen_name, rejected_name in PREFERENCE_FIELD_PAIRS:
        if chosen_name in normalized and rejected_name in normalized:
            return normalized[chosen_name], normalized[rejected_name]
    raise ValueError("Could not infer chosen/rejected preference columns.")


def choose_instruction_fields(columns: list[str]) -> tuple[str, str]:
    normalized = {column.casefold(): column for column in columns}
    for prompt_name, answer_name in INSTRUCTION_FIELD_PAIRS:
        if prompt_name in normalized and answer_name in normalized:
            return normalized[prompt_name], normalized[answer_name]
    raise ValueError("Could not infer instruction/answer columns.")


def _row_identifier(row: dict[str, object]) -> str:
    for candidate in ("id", "_id", "row_id", "uuid", "prompt_id"):
        if candidate in row and str(row[candidate]).strip():
            return str(row[candidate]).strip()
    return ""


def _base_record(
    *,
    dataset: str,
    config: str | None,
    split: str,
    row_id: str,
) -> dict[str, str]:
    return {
        "source": "huggingface",
        "dataset": dataset,
        "config": config or "",
        "split": split,
        "row_id": row_id,
    }


def _row_language(row: dict[str, object]) -> str:
    for candidate in ("lang", "language", "locale"):
        value = row.get(candidate)
        if isinstance(value, str) and value.strip():
            return value.strip()
    return ""


def _normalize_role(raw_role: object) -> str:
    role = str(raw_role or "").strip().casefold()
    return ROLE_ALIASES.get(role, role)


def _message_content(message: dict[str, object]) -> str:
    for field in ("content", "value", "text", "message"):
        value = message.get(field)
        if isinstance(value, str) and value.strip():
            return clean_training_text(value)
    return ""


def _message_role(message: dict[str, object]) -> str:
    for field in ("role", "from", "speaker", "author"):
        value = message.get(field)
        if value is not None:
            normalized = _normalize_role(value)
            if normalized:
                return normalized
    return ""


def _parse_dialogue_messages(raw_messages: object) -> list[dict[str, str]]:
    if not isinstance(raw_messages, list):
        return []

    parsed: list[dict[str, str]] = []
    for message in raw_messages:
        if not isinstance(message, dict):
            continue
        role = _message_role(message)
        content = _message_content(message)
        if role not in {"system", "user", "assistant"} or not content:
            continue
        parsed.append({"role": role, "content": content})
    return parsed


def _parse_transcript_messages(raw_text: object) -> list[dict[str, str]]:
    if not isinstance(raw_text, str):
        return []

    text = raw_text.strip()
    if not text:
        return []

    matches = list(TRANSCRIPT_ROLE_PATTERN.finditer(text))
    if not matches:
        return []

    parsed: list[dict[str, str]] = []
    for index, match in enumerate(matches):
        role = _normalize_role(match.group(1))
        start = match.end()
        end = matches[index + 1].start() if index + 1 < len(matches) else len(text)
        content = clean_training_text(text[start:end].strip())
        if role in {"system", "user", "assistant"} and content:
            parsed.append({"role": role, "content": content})
    return parsed


def _render_prompt(messages: list[dict[str, str]]) -> str:
    lines = []
    for message in messages:
        content = clean_context_text(message["content"])
        if content:
            lines.append(content)
    return "\n".join(lines).strip()


def _compose_training_text(context: str, answer: str) -> str:
    context = clean_context_text(context)
    answer = clean_answer_text(answer)
    return f"<reason> {context} <answer> {answer}".strip()


def _compose_instruction_context(row: dict[str, object], prompt_field: str) -> str:
    parts: list[str] = []
    prompt = clean_context_text(str(row.get(prompt_field, "")).strip())
    extra_input = clean_context_text(str(row.get("input", "")).strip())
    if prompt:
        parts.append(prompt)
    if extra_input:
        parts.append(extra_input)
    return "\n".join(parts).strip()


def _extract_prompt_answer(
    row: dict[str, object],
    *,
    field_name: str,
) -> tuple[str, str]:
    dialogue_messages = _parse_dialogue_messages(row.get(field_name))
    if dialogue_messages and dialogue_messages[-1]["role"] == "assistant":
        prompt = _render_prompt(dialogue_messages[:-1])
        answer = dialogue_messages[-1]["content"]
        if prompt and answer:
            return prompt, answer

    messages = _parse_transcript_messages(row.get(field_name))
    if messages:
        if messages[-1]["role"] == "assistant":
            prompt = _render_prompt(messages[:-1])
            answer = messages[-1]["content"]
            if prompt and answer:
                return prompt, answer

    prompt = clean_training_text(str(row.get("prompt", row.get("question", ""))).strip())
    answer = clean_answer_text(str(row.get(field_name, "")).strip())
    return prompt, answer


def _ordered_preference_fields(
    row: dict[str, object],
    *,
    left_field: str,
    right_field: str,
) -> tuple[str, str]:
    if {left_field, right_field} != {"response_0", "response_1"}:
        return left_field, right_field

    for selector in ("safer_response_id", "better_response_id"):
        value = row.get(selector)
        try:
            preferred = int(value)
        except (TypeError, ValueError):
            continue
        if preferred == 0:
            return "response_0", "response_1"
        if preferred == 1:
            return "response_1", "response_0"
    return left_field, right_field


def _passes_quality_gate(
    record: dict[str, str],
    *,
    min_words: int,
    max_words: int,
    min_alpha_ratio: float,
    allowed_languages: set[str],
) -> bool:
    candidate = str(record.get("answer") or record.get("text") or "").strip()
    if not candidate:
        return False

    word_count = _word_count(candidate)
    if min_words > 0 and word_count < min_words:
        return False
    if max_words > 0 and word_count > max_words:
        return False

    alpha_ratio = _alpha_ratio(candidate)
    if min_alpha_ratio > 0.0 and alpha_ratio < min_alpha_ratio:
        return False

    if allowed_languages:
        language = str(record.get("language", "")).strip().casefold()
        if not language or language not in allowed_languages:
            return False

    record["quality_word_count"] = str(word_count)
    record["quality_alpha_ratio"] = f"{alpha_ratio:.4f}"
    return True


def to_json_record(
    *,
    dataset: str,
    config: str | None,
    split: str,
    text_field: str,
    row: dict[str, object],
) -> dict[str, str]:
    text = clean_training_text(str(row.get(text_field, "")).strip())
    if not text:
        raise ValueError("Row is missing usable text.")

    record_type = "text"
    return {
        **_base_record(
            dataset=dataset,
            config=config,
            split=split,
            row_id=_row_identifier(row),
        ),
        "record_type": record_type,
        "language": _row_language(row),
        "text_field": text_field,
        "text": text,
        "word_count": _word_count(text),
        "weight": _default_record_weight(record_type),
    }


def dialogue_to_json_records(
    *,
    dataset: str,
    config: str | None,
    split: str,
    conversation_field: str,
    row: dict[str, object],
) -> list[dict[str, str]]:
    messages = _parse_dialogue_messages(row.get(conversation_field))
    if not messages:
        raise ValueError("Row does not contain usable dialogue turns.")

    row_id = _row_identifier(row)
    records: list[dict[str, str]] = []
    history: list[dict[str, str]] = []
    row_language = _row_language(row)
    system_text = clean_training_text(str(row.get("system", "")).strip())
    if system_text:
        history.append({"role": "system", "content": system_text})
    assistant_turn_index = 0
    for message in messages:
        if message["role"] != "assistant":
            history.append(message)
            continue
        prompt = _render_prompt(history)
        if not prompt:
            continue
        assistant_turn_index += 1
        records.append(
            {
                **_base_record(
                    dataset=dataset,
                    config=config,
                    split=split,
                    row_id=row_id,
                ),
                "record_type": "dialogue_turn",
                "language": row_language,
                "conversation_field": conversation_field,
                "turn_index": str(assistant_turn_index),
                "context": prompt,
                "answer": clean_answer_text(message["content"]),
                "text": _compose_training_text(prompt, message["content"]),
                "word_count": _word_count(clean_answer_text(message["content"])),
                "weight": _default_record_weight("dialogue_turn"),
            }
        )
        history.append(message)

    if not records:
        raise ValueError("Dialogue row did not yield any assistant training turns.")
    return records


def preference_to_json_records(
    *,
    dataset: str,
    config: str | None,
    split: str,
    chosen_field: str,
    rejected_field: str,
    row: dict[str, object],
    preference_target: str = "both",
) -> list[dict[str, str]]:
    row_id = _row_identifier(row)
    pair_id = row_id or f"{chosen_field}:{rejected_field}"
    records: list[dict[str, str]] = []
    row_language = _row_language(row)
    chosen_field, rejected_field = _ordered_preference_fields(
        row,
        left_field=chosen_field,
        right_field=rejected_field,
    )

    field_specs = [
        (chosen_field, "preference_chosen"),
        (rejected_field, "preference_rejected"),
    ]
    if preference_target == "chosen":
        field_specs = [(chosen_field, "preference_chosen")]
    elif preference_target == "rejected":
        field_specs = [(rejected_field, "preference_rejected")]
    elif preference_target != "both":
        raise ValueError("preference_target must be one of: both, chosen, rejected.")

    for field_name, record_type in field_specs:
        prompt, answer = _extract_prompt_answer(row, field_name=field_name)
        if not prompt or not answer:
            continue
        records.append(
            {
                **_base_record(
                    dataset=dataset,
                    config=config,
                    split=split,
                    row_id=row_id,
                ),
                "record_type": record_type,
                "language": row_language,
                "pair_id": pair_id,
                "text_field": field_name,
                "context": prompt,
                "answer": clean_answer_text(answer),
                "text": _compose_training_text(prompt, answer),
                "word_count": _word_count(clean_answer_text(answer)),
                "weight": _default_record_weight(record_type),
            }
        )

    if not records:
        raise ValueError("Preference row did not yield usable chosen/rejected transcripts.")
    return records


def instruction_to_json_records(
    *,
    dataset: str,
    config: str | None,
    split: str,
    prompt_field: str,
    answer_field: str,
    row: dict[str, object],
) -> list[dict[str, str]]:
    context = _compose_instruction_context(row, prompt_field)
    answer = clean_answer_text(str(row.get(answer_field, "")).strip())
    if not context or not answer:
        raise ValueError("Instruction row did not contain usable prompt and answer text.")
    record_type = "instruction_answer"
    return [
        {
            **_base_record(
                dataset=dataset,
                config=config,
                split=split,
                row_id=_row_identifier(row),
            ),
            "record_type": record_type,
            "language": _row_language(row),
            "context": context,
            "answer": answer,
            "text": _compose_training_text(context, answer),
            "word_count": _word_count(answer),
            "weight": _default_record_weight(record_type),
        }
    ]


def _expand_row_records(
    *,
    dataset: str,
    config: str | None,
    split: str,
    row: dict[str, object],
    text_field: str | None,
    preference_target: str,
) -> list[dict[str, str]]:
    if text_field is not None:
        explicit_value = row.get(text_field)
        if isinstance(explicit_value, list):
            return dialogue_to_json_records(
                dataset=dataset,
                config=config,
                split=split,
                conversation_field=text_field,
                row=row,
            )
        return [
            to_json_record(
                dataset=dataset,
                config=config,
                split=split,
                text_field=text_field,
                row=row,
            )
        ]

    columns = list(row)
    try:
        chosen_field, rejected_field = choose_preference_fields(columns)
        return preference_to_json_records(
            dataset=dataset,
            config=config,
            split=split,
            chosen_field=chosen_field,
            rejected_field=rejected_field,
            row=row,
            preference_target=preference_target,
        )
    except ValueError:
        pass

    try:
        prompt_field, answer_field = choose_instruction_fields(columns)
        return instruction_to_json_records(
            dataset=dataset,
            config=config,
            split=split,
            prompt_field=prompt_field,
            answer_field=answer_field,
            row=row,
        )
    except ValueError:
        pass

    try:
        conversation_field = choose_dialogue_field(columns)
        if isinstance(row.get(conversation_field), list):
            return dialogue_to_json_records(
                dataset=dataset,
                config=config,
                split=split,
                conversation_field=conversation_field,
                row=row,
            )
    except ValueError:
        pass

    inferred_text_field = choose_text_field(columns)
    return [
        to_json_record(
            dataset=dataset,
            config=config,
            split=split,
            text_field=inferred_text_field,
            row=row,
        )
    ]


def import_hf_dataset(
    *,
    dataset: str,
    output_path: str | Path,
    config: str | None = None,
    split: str = "train",
    text_field: str | None = None,
    limit: int = 1000,
    streaming: bool = True,
    preference_target: str = "chosen",
    min_words: int = 0,
    max_words: int = 0,
    min_alpha_ratio: float = 0.0,
    allowed_languages: tuple[str, ...] = (),
) -> dict[str, object]:
    try:
        from datasets import load_dataset
    except ModuleNotFoundError:
        user_site = site.getusersitepackages()
        if user_site and user_site not in sys.path:
            sys.path.append(user_site)
        from datasets import load_dataset

    dataset_kwargs: dict[str, object] = {
        "split": split,
        "streaming": streaming,
    }
    if config:
        dataset_kwargs["name"] = config

    hf_dataset = load_dataset(dataset, **dataset_kwargs)
    iterator = iter(hf_dataset)

    first_row: dict[str, object] | None = None
    if text_field is None:
        first_row = dict(next(iterator))
        iterator = chain([first_row], iterator)

    output = Path(output_path)
    output.parent.mkdir(parents=True, exist_ok=True)

    written = 0
    record_types: set[str] = set()
    normalized_languages = {language.casefold() for language in allowed_languages if language.strip()}
    with output.open("w", encoding="utf-8") as handle:
        for row in iterator:
            if written >= limit:
                break
            normalized_row = dict(row)
            try:
                records = _expand_row_records(
                    dataset=dataset,
                    config=config,
                    split=split,
                    row=normalized_row,
                    text_field=text_field,
                    preference_target=preference_target,
                )
            except ValueError:
                continue

            for record in records:
                if written >= limit:
                    break
                if not _passes_quality_gate(
                    record,
                    min_words=min_words,
                    max_words=max_words,
                    min_alpha_ratio=min_alpha_ratio,
                    allowed_languages=normalized_languages,
                ):
                    continue
                record_types.add(record.get("record_type", "text"))
                handle.write(json.dumps(record, ensure_ascii=False) + "\n")
                written += 1

    inferred_mode = "mixed" if len(record_types) > 1 else (next(iter(record_types)) if record_types else "unknown")
    return {
        "dataset": dataset,
        "config": config or "",
        "split": split,
        "text_field": text_field or "",
        "output_path": str(output.resolve()),
        "records_written": written,
        "record_types": sorted(record_types),
        "mode": inferred_mode,
        "preference_target": preference_target,
        "streaming": streaming,
        "min_words": min_words,
        "max_words": max_words,
        "min_alpha_ratio": min_alpha_ratio,
        "allowed_languages": sorted(normalized_languages),
    }