import argparse
import json
import re
from pathlib import Path
from typing import Any, Dict, List

from src.config import DECODED_DIR, PROMPTS_DIR
from src.generator import Generator
from src.region_registry import get_region_description


def parse_args() -> argparse.Namespace:
    parser = argparse.ArgumentParser(
        description="Decode localized DAS into natural dialogue."
    )
    parser.add_argument(
        "--input_path",
        type=str,
        required=True,
        help="Path to localized JSON file.",
    )
    parser.add_argument(
        "--output_path",
        type=str,
        default=None,
        help="Path to save decoded output JSON.",
    )
    parser.add_argument(
        "--language",
        type=str,
        required=True,
        help="Target language label, e.g. 'Swahili'.",
    )
    parser.add_argument(
        "--region",
        type=str,
        default="",
        help="Optional target region/community, e.g. 'Kenya - Nairobi'.",
    )
    parser.add_argument(
        "--decode_prompt",
        type=str,
        default=str(PROMPTS_DIR / "das_decode.md"),
        help="Path to DAS decode prompt.",
    )
    parser.add_argument(
        "--model",
        type=str,
        default=None,
        help="Model alias from model_registry.py",
    )
    parser.add_argument(
        "--max_instances",
        type=int,
        default=None,
        help="Optional cap on number of dialogues to process.",
    )
    parser.add_argument(
        "--start_idx",
        type=int,
        default=0,
        help="Optional start index for slicing input data.",
    )
    parser.add_argument(
        "--end_idx",
        type=int,
        default=None,
        help="Optional end index for slicing input data.",
    )
    parser.add_argument(
        "--dont_use_cached",
        action="store_true",
        help="Disable cached prompt responses.",
    )
    return parser.parse_args()


def load_json(path: str) -> Any:
    return json.loads(Path(path).read_text(encoding="utf-8"))


def save_json(path: str, data: Any) -> None:
    output_path = Path(path)
    output_path.parent.mkdir(parents=True, exist_ok=True)
    output_path.write_text(
        json.dumps(data, indent=2, ensure_ascii=False),
        encoding="utf-8",
    )


def normalize_speaker_id(speaker_id: Any) -> str:
    speaker = str(speaker_id)
    if speaker == "1":
        return "A"
    if speaker == "2":
        return "B"
    return speaker


def preprocess_localized_conversation(localized_das: List[Dict[str, Any]]) -> str:
    formatted_turns: List[str] = []

    for idx, turn in enumerate(localized_das, start=1):
        speaker = normalize_speaker_id(turn.get("speaker_id", "A"))
        functions = turn.get("functions", "")

        if isinstance(functions, list):
            functions_str = "; ".join(str(f) for f in functions)
        else:
            functions_str = str(functions)

        formatted_turns.append(f"{idx}: {speaker}.{functions_str}")

    return "\n".join(formatted_turns)


def get_original_dialogue(item: Dict[str, Any]) -> List[str]:
    if "original" in item and isinstance(item["original"], list):
        return item["original"]

    if "conversation" in item and isinstance(item["conversation"], list):
        return item["conversation"]

    if "dialogue" in item and isinstance(item["dialogue"], list):
        return item["dialogue"]

    if "utterances" in item and isinstance(item["utterances"], list):
        return item["utterances"]

    return []


def preprocess_decode_input(
    data: List[Dict[str, Any]],
    language: str,
    region: str,
) -> List[Dict[str, Any]]:
    decode_desc = get_region_description(region, "decode", language) or ""
    processed: List[Dict[str, Any]] = []

    for item in data:
        if "localized_das" not in item:
            raise ValueError("Each input item must contain 'localized_das'.")
        if "localized_context" not in item:
            raise ValueError("Each input item must contain 'localized_context'.")

        if not isinstance(item["localized_das"], list):
            raise ValueError(
                f"localized_das must be a list, got {type(item['localized_das']).__name__}"
            )

        new_item = dict(item)
        new_item["language"] = language
        new_item["region"] = region
        new_item["region_description"] = decode_desc
        new_item["turns"] = preprocess_localized_conversation(item["localized_das"])
        new_item["localized_context"] = item["localized_context"]
        new_item["context"] = item["localized_context"]
        processed.append(new_item)

    return processed


def strip_code_fences(text: str) -> str:
    text = text.strip()
    if text.startswith("```"):
        text = re.sub(r"^```[a-zA-Z0-9_+-]*\n?", "", text)
        text = re.sub(r"\n?```$", "", text)
    return text.strip()


def parse_numbered_dialogue_string(raw: str) -> List[str]:
    raw = strip_code_fences(raw)

    # Split on numbered turns like "1: ...", "2. ..."
    matches = list(re.finditer(r"(?m)^\s*(\d+)[\:\.]\s*", raw))
    if not matches:
        lines = [line.strip() for line in raw.splitlines() if line.strip()]
        return lines

    turns: List[str] = []
    for idx, match in enumerate(matches):
        start = match.end()
        end = matches[idx + 1].start() if idx + 1 < len(matches) else len(raw)
        turn_text = raw[start:end].strip()
        if turn_text:
            turns.append(turn_text)

    return turns


def normalize_generated_conversation(generated_conversation: Any) -> List[str]:
    # Case 1: expected list of objects with text
    if isinstance(generated_conversation, list):
        text_only_dialogue: List[str] = []

        for turn in generated_conversation:
            if isinstance(turn, dict) and "text" in turn:
                text_only_dialogue.append(str(turn["text"]).strip())
            elif isinstance(turn, str):
                text_only_dialogue.append(turn.strip())
            else:
                raise ValueError(
                    f"Unsupported generated_conversation list item: {turn}"
                )

        return text_only_dialogue

    # Case 2: model returned one big numbered string
    if isinstance(generated_conversation, str):
        return parse_numbered_dialogue_string(generated_conversation)

    raise ValueError(
        f"Unsupported generated_conversation type: {type(generated_conversation).__name__}"
    )


def merge_decoded_responses(
    base_data: List[Dict[str, Any]],
    responses: List[str],
    language: str,
) -> List[Dict[str, Any]]:
    merged: List[Dict[str, Any]] = []
    decoded_key = f"decoded_{language.strip().lower().replace(' ', '_')}"

    for item, response_text in zip(base_data, responses):
        if response_text is None:
            print(f"[Decode] Skipping item with failed generation")
            continue

        response_json = Generator.parse_json_response(response_text)

        if "generated_conversation" not in response_json:
            raise ValueError(
                f"Missing 'generated_conversation' in model response:\n{response_text}"
            )

        generated_conversation = response_json["generated_conversation"]
        text_only_dialogue = normalize_generated_conversation(generated_conversation)

        output_item: Dict[str, Any] = {}

        if "dialogue_id" in item:
            output_item["dialogue_id"] = item["dialogue_id"]
        elif "id" in item:
            output_item["dialogue_id"] = item["id"]

        output_item["original"] = get_original_dialogue(item)
        output_item[decoded_key] = text_only_dialogue

        merged.append(output_item)

    return merged


def default_output_path(input_path: str, language: str, region: str) -> str:
    stem = Path(input_path).stem
    suffix_parts = [language.strip().lower().replace(" ", "_")]

    if region.strip():
        suffix_parts.append(region.strip().lower().replace(" ", "_").replace("/", "_"))

    suffix = "_".join(suffix_parts)
    return str(DECODED_DIR / f"{stem}_{suffix}_decoded.json")


def main() -> None:
    args = parse_args()

    raw_data = load_json(args.input_path)
    if not isinstance(raw_data, list):
        raise ValueError("Input JSON must be a list of dialogue objects.")

    sliced_data = raw_data[args.start_idx:args.end_idx]
    if args.max_instances is not None:
        sliced_data = sliced_data[: args.max_instances]

    output_path = args.output_path or default_output_path(
        args.input_path,
        args.language,
        args.region,
    )

    generator = Generator(
        model_alias=args.model,
        use_cache=not args.dont_use_cached,
    )

    processed_data = preprocess_decode_input(
        data=sliced_data,
        language=args.language,
        region=args.region,
    )

    print(f"[Decode] Building decoded dialogue for {len(processed_data)} items...")
    decode_prompts, decode_response_format = generator.build_prompts(
        args.decode_prompt,
        processed_data,
    )

    decode_responses = generator.prompt(
        prompts=decode_prompts,
        response_format=decode_response_format,
        dont_use_cached=args.dont_use_cached,
        skip_failures=True,
    )

    final_data = merge_decoded_responses(
        processed_data,
        decode_responses,
        args.language,
    )

    save_json(output_path, final_data)
    print(f"Saved decoded data to: {output_path}")
    generator.print_usage_summary(stage="Decode")


if __name__ == "__main__":
    main()