import os
import shutil
import hashlib
import tempfile
import secrets
from fastapi import UploadFile
from typing import List
from .. import models

CHUNK_SIZE = 1024 * 1024 * 5 # 5MB

async def save_temp_file(file: UploadFile):
    temp_dir = tempfile.mkdtemp()
    file_path = os.path.join(temp_dir, file.filename)
    sha256_hash = hashlib.sha256()

    with open(file_path, "wb") as f:
        while chunk := await file.read(CHUNK_SIZE):
            f.write(chunk)
            sha256_hash.update(chunk)
    
    return file_path, sha256_hash.hexdigest()

def split_file(file_path: str, accounts: List[models.Account]):
    # Simplified splitting logic for now
    # In a real scenario, we'd split based on available space
    parts = []
    file_size = os.path.getsize(file_path)
    num_accounts = len(accounts)
    part_size = file_size // num_accounts

    with open(file_path, "rb") as f:
        for i, account in enumerate(accounts):
            part_path = f"{file_path}.part{i}"
            with open(part_path, "wb") as part_f:
                remaining = part_size if i < num_accounts - 1 else -1
                while remaining > 0 or remaining == -1:
                    read_size = min(CHUNK_SIZE, remaining) if remaining != -1 else CHUNK_SIZE
                    chunk = f.read(read_size)
                    if not chunk:
                        break
                    part_f.write(chunk)
                    if remaining != -1:
                        remaining -= len(chunk)
            
            part_sha256 = hashlib.sha256(open(part_path, 'rb').read()).hexdigest()

            parts.append({
                "index": i,
                "path": part_path,
                "size": os.path.getsize(part_path),
                "account": account,
                "sha256": part_sha256
            })

    return parts

def generate_token():
    return secrets.token_urlsafe(32)

def merge_files(part_paths: List[str], output_path: str):
    with open(output_path, 'wb') as f_out:
        for part_path in sorted(part_paths):
            with open(part_path, 'rb') as f_in:
                shutil.copyfileobj(f_in, f_out)