#!/usr/bin/env python
# coding: utf-8
"""
Convert Jupyter notebooks (.ipynb) to executable Python scripts (.py).

Converts IPython magics to plain Python:
    !command          -> subprocess.run('command', shell=True)
    %cd path          -> os.chdir('path')
    %env VAR=value    -> os.environ['VAR'] = 'value'
    %%file filename   -> with open('filename', 'w') as f: f.write(...)
    %%capture         -> (skipped)
    /content/...      -> _WORKING_DIR + /...
"""

import nbformat
import re
import sys
import os
import urllib.request
import urllib.parse
from pathlib import Path


def needs_fstring(cmd: str) -> bool:
    """Check if command has Python variable interpolation like {var_name}."""
    pattern = r"(?<!\$)\{([a-zA-Z_][a-zA-Z0-9_]*)\}"
    return bool(re.search(pattern, cmd))


def github_blob_to_raw(url: str) -> str:
    """Convert GitHub blob URL to raw URL."""
    # https://github.com/user/repo/blob/branch/path
    #   -> https://raw.githubusercontent.com/user/repo/branch/path
    # Compare the parsed host exactly (not as a substring) so a URL
    # like https://attacker.example.com/github.com/blob/... does NOT
    # get rewritten to a github raw URL. Closes CodeQL alert
    # py/incomplete-url-substring-sanitization.
    parsed = urllib.parse.urlparse(url)
    if parsed.netloc != "github.com" or "/blob/" not in parsed.path:
        return url
    new_path = parsed.path.replace("/blob/", "/", 1)
    return urllib.parse.urlunparse(
        parsed._replace(netloc = "raw.githubusercontent.com", path = new_path)
    )


def download_notebook(url: str) -> tuple[str, str]:
    """Download notebook from URL. Returns (content, filename)."""
    # Convert blob URL to raw if needed
    raw_url = github_blob_to_raw(url)

    # Extract filename from URL
    parsed = urllib.parse.urlparse(raw_url)
    filename = os.path.basename(urllib.parse.unquote(parsed.path))

    # Download
    print(f"Downloading {url}...")
    with urllib.request.urlopen(raw_url, timeout = 60) as response:
        content = response.read().decode("utf-8")

    return content, filename


def is_url(path: str) -> bool:
    """Check if path is a URL."""
    return path.startswith("http://") or path.startswith("https://")


def replace_colab_paths(source: str) -> str:
    """Replace Colab-specific /content/ paths with current working directory."""
    # Replace /content/ with f-string using _WORKING_DIR
    source = source.replace('"/content/', 'f"{_WORKING_DIR}/')
    source = source.replace("'/content/", "f'{_WORKING_DIR}/")
    return source


def convert_cell_to_python(source: str) -> str:
    """Convert a cell's IPython magics to plain Python."""
    lines = source.split("\n")
    result = []
    i = 0

    while i < len(lines):
        line = lines[i]
        stripped = line.strip()
        indent = line[: len(line) - len(line.lstrip())]

        # Skip %%capture
        if stripped.startswith("%%capture"):
            i += 1
            continue

        # Handle %%file magic
        if stripped.startswith("%%file "):
            filename = stripped[7:].strip()
            file_lines = []
            i += 1
            while i < len(lines):
                file_lines.append(lines[i])
                i += 1
            file_content = "\n".join(file_lines)
            file_content = file_content.replace('"""', r"\"\"\"")
            result.append(f'{indent}with open({filename!r}, "w") as _f:')
            result.append(f'{indent}    _f.write("""{file_content}""")')
            continue

        # Handle ! shell commands
        if stripped.startswith("!"):
            cmd_lines = [stripped[1:]]
            while cmd_lines[-1].rstrip().endswith("\\") and i + 1 < len(lines):
                i += 1
                cmd_lines.append(lines[i].strip())
            full_cmd = "\n".join(cmd_lines)

            f_prefix = "f" if needs_fstring(full_cmd) else ""
            if "\n" in full_cmd:
                escaped_cmd = full_cmd.replace('"""', r"\"\"\"")
                if escaped_cmd.rstrip().endswith('"'):
                    escaped_cmd = escaped_cmd.rstrip() + " "
                result.append(
                    f'{indent}subprocess.run({f_prefix}"""{escaped_cmd}""", shell=True)'
                )
            else:
                result.append(
                    f"{indent}subprocess.run({f_prefix}{full_cmd!r}, shell=True)"
                )

        # %cd path -> os.chdir(path)
        elif stripped.startswith("%cd "):
            path = stripped[4:].strip()
            result.append(f"{indent}os.chdir({path!r})")

        # %env VAR=value
        elif stripped.startswith("%env ") and "=" in stripped:
            match = re.match(r"%env\s+(\w+)=(.+)", stripped)
            if match:
                var, val = match.groups()
                result.append(f"{indent}os.environ[{var!r}] = {val!r}")

        # %env VAR
        elif stripped.startswith("%env "):
            var = stripped[5:].strip()
            result.append(f"{indent}os.environ.get({var!r})")

        # %pwd
        elif stripped == "%pwd":
            result.append(f"{indent}os.getcwd()")

        else:
            result.append(line)

        i += 1

    return "\n".join(result)


def convert_notebook(notebook_content: str, source_name: str = "notebook") -> str:
    """Convert notebook JSON content to Python script."""
    # Parse notebook
    if isinstance(notebook_content, str):
        notebook = nbformat.reads(notebook_content, as_version = 4)
    else:
        notebook = notebook_content

    lines = [
        "#!/usr/bin/env python",
        "# coding: utf-8",
        f"# Converted from: {source_name}",
        "",
        "import subprocess",
        "import os",
        "import sys",
        "import re",
        "",
        "# Capture original packages before any installs",
        "_original_packages = subprocess.run(",
        "    [sys.executable, '-m', 'pip', 'freeze'],",
        "    capture_output=True, text=True",
        ").stdout",
        "",
        "# Working directory (replaces Colab's /content/)",
        "_WORKING_DIR = os.getcwd()",
        "",
    ]

    for cell in notebook.cells:
        source = cell.source.strip()
        if not source:
            continue

        if cell.cell_type == "code":
            converted = convert_cell_to_python(source)
            converted = replace_colab_paths(converted)
            lines.append(converted)
            lines.append("")

        elif cell.cell_type == "markdown":
            for line in source.split("\n"):
                lines.append(f"# {line}")
            lines.append("")

    # Add package restoration at the end
    lines.extend(
        [
            "",
            "# Restore original packages (install one by one, skip failures)",
            "for _pkg in _original_packages.strip().split('\\n'):",
            "    if _pkg:",
            "        subprocess.run([sys.executable, '-m', 'pip', 'install', _pkg, '-q'],",
            "                       stderr=subprocess.DEVNULL)",
            "",
        ]
    )

    return "\n".join(lines)


def convert_notebook_to_script(source: str, output_dir: str | None = None):
    """
    Convert a notebook to Python script.

    Args:
        source: Local file path or URL to notebook
        output_dir: Output directory (optional, defaults to current directory)
    """
    if is_url(source):
        content, filename = download_notebook(source)
        source_name = source
    else:
        filename = os.path.basename(source)
        with open(source, "r", encoding = "utf-8") as f:
            content = f.read()
        source_name = source

    # Generate output filename
    output_filename = filename.replace(".ipynb", ".py")
    # Clean up filename
    output_filename = (
        output_filename.replace("(", "").replace(")", "").replace("-", "_")
    )

    # Add output directory if specified
    if output_dir:
        output_path = os.path.join(output_dir, output_filename)
    else:
        output_path = output_filename

    # Convert
    script = convert_notebook(content, source_name)

    # Write output
    with open(output_path, "w", encoding = "utf-8") as f:
        f.write(script)

    print(f"Converted {source} -> {output_path}")
    return output_path


def main():
    import argparse

    class Formatter(
        argparse.ArgumentDefaultsHelpFormatter, argparse.RawDescriptionHelpFormatter
    ):
        pass

    parser = argparse.ArgumentParser(
        description = __doc__,
        formatter_class = Formatter,
        epilog = """
Examples:
  python notebook_to_python.py notebook.ipynb
  python notebook_to_python.py -o scripts/ notebook1.ipynb notebook2.ipynb
  python notebook_to_python.py --output ./converted https://github.com/user/repo/blob/main/notebook.ipynb
  python notebook_to_python.py https://github.com/unslothai/notebooks/blob/main/nb/Oute_TTS_(1B).ipynb
""",
    )
    parser.add_argument(
        "notebooks", nargs = "+", help = "Notebook files or URLs to convert."
    )
    parser.add_argument(
        "-o", "--output", dest = "output_dir", default = ".", help = "Output directory."
    )

    args = parser.parse_args()

    # Create output directory if needed
    os.makedirs(args.output_dir, exist_ok = True)

    for source in args.notebooks:
        try:
            convert_notebook_to_script(
                source, output_dir = args.output_dir if args.output_dir != "." else None
            )
        except Exception as e:
            print(f"ERROR converting {source}: {e}")


if __name__ == "__main__":
    main()