#!/usr/bin/env python3
import json
import argparse
import random
from collections.abc import Sequence
from pathlib import Path
from typing import TypedDict


class AlpacaEntry(TypedDict):
    input: str
    output: str
    instruction: str | None


class Args(argparse.Namespace):
    def __init__(self) -> None:
        super().__init__()
        self.file1: str = ""
        self.file2: str = ""
        self.output: str = ""
        self.shuffle: bool = False
        self.seed: int | None = None
        self.omit_instruction: bool = False


def load_file(file_path: str) -> Sequence[AlpacaEntry]:
    """Load and validate a file in JSON or JSONL format."""
    path = Path(file_path)
    is_jsonl = path.suffix.lower() in (".jsonl", ".ljson")

    with open(file_path, "r", encoding="utf-8") as f:
        if is_jsonl:
            data: list[AlpacaEntry] = []
            for line in f:
                line = line.strip()
                if line:  # Skip empty lines
                    entry: AlpacaEntry = json.loads(line)
                    data.append(entry)
        else:
            data = json.load(f)

    # Validate required fields
    for item in data:
        if not all(key in item for key in ["input", "output"]):
            raise ValueError(
                f"Missing required fields in {file_path}. Each item must have 'input' and 'output' fields."
            )

    return data


def write_output(data: Sequence[AlpacaEntry], output_path: str) -> None:
    """Write output in JSON or JSONL format based on file extension."""
    path = Path(output_path)
    is_jsonl = path.suffix.lower() in (".jsonl", ".ljson")
    print(path, is_jsonl)

    with open(output_path, "w", encoding="utf-8") as f:
        if is_jsonl:
            for item in data:
                _ = f.write(json.dumps(item, ensure_ascii=False) + "\n")
        else:
            json.dump(data, f, ensure_ascii=False, indent=2)


def merge_datasets(
    file1: str, file2: str, shuffle: bool = False, omit_instruction: bool = False
) -> Sequence[AlpacaEntry]:
    """Merge two files in JSON/JSONL format."""
    # Load both files
    data1 = load_file(file1)
    data2 = load_file(file2)
    merged_data = list(data1) + list(data2)

    if omit_instruction:
        for item in merged_data:
            _ = item.pop("instruction", None)

    if shuffle:
        random.shuffle(merged_data)

    return merged_data


def parse_args() -> Args:
    """Parse and validate command line arguments."""
    parser = argparse.ArgumentParser(description="Merge two Alpaca-format JSON files")
    _ = parser.add_argument("file1", type=str, help="Path to first JSON file")
    _ = parser.add_argument("file2", type=str, help="Path to second JSON file")
    _ = parser.add_argument("output", type=str, help="Path to output merged JSON file")
    _ = parser.add_argument(
        "--shuffle", action="store_true", help="Shuffle the merged dataset"
    )
    _ = parser.add_argument("--seed", type=int, help="Random seed for shuffling")
    _ = parser.add_argument(
        "--omit-instruction",
        action="store_true",
        help="Omit instruction field from output",
    )

    return parser.parse_args(namespace=Args())


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

    try:
        if args.seed is not None:
            random.seed(args.seed)

        merged_data = merge_datasets(
            args.file1, args.file2, args.shuffle, args.omit_instruction
        )

        write_output(merged_data, args.output)
        print(f"Successfully merged files. Total entries: {len(merged_data)}")

    except Exception as e:
        print(f"Error: {str(e)}")
        exit(1)


if __name__ == "__main__":
    main()