#!/usr/bin/env python3
# -*- coding: utf-8 -*-
import argparse
import glob
import logging
import os
import textwrap

import nbconvert
from yapf.yapflib.yapf_api import FormatCode

BASE_PATH = os.path.split(os.path.abspath(__file__))[0]
DO_NOT_EDIT = """
# DO NOT EDIT 
# Autogenerated from the notebook {notebook}. 
# Edit the notebook and then sync the output with this file.
#
# flake8: noqa
# DO NOT EDIT 
"""

logger = logging.getLogger('notebook-exporter')
logger.setLevel(logging.INFO)
ch = logging.StreamHandler()
ch.setLevel(logging.INFO)
logger.addHandler(ch)

parser = argparse.ArgumentParser(description="""
Sync notebooks to python by exporting. The exported files are
always written in ../python relative to the notebooks. 
Requires nbconvert and yapf.
""")
parser.add_argument('--full-path', '-fp', type=str, default=None,
                    help='Full Path to notebook to convert. Converts all '
                         'notebooks in FULL_PATH by default. If not '
                         'specified, searches for examples in '
                         '../examples/notebooks (relative to this file).')
parser.add_argument('--notebook', '-nb', type=str, default=None,
                    help='Name of a single notebook to export.  If not '
                         'provided, all notebooks found are exported. Appends '
                         '.ipynb if NOTEBOOK does not end with this '
                         'extension.')
parser.add_argument('--force', '-f', action='store_true',
                    help='Force conversion if python file in destination '
                         'exists and is newer than notebook.')


def is_newer(file1, file2, strict=True):
    """
    Determine if file1 has been modified after file2

    Parameters
    ----------
    file1 : str
        File path. May not exist, in which case False is returned.
    file1 : str
        File path. Must exist.
    strict : bool
        Use strict inequality test (>). If False, then returns True for files
        with the same modified time.

    Returns
    -------
    newer : bool
        True if file1 is strictly newer than file 2
    """
    try:
        t1 = os.path.getmtime(file1)
        t2 = os.path.getmtime(file2)
    except FileNotFoundError:
        return False
    if strict:
        return t1 > t2
    return t1 >= t2


def main():
    args = parser.parse_args()
    full_path = args.full_path
    force = args.force
    if full_path is None:
        full_path = os.path.join(BASE_PATH, '..', 'examples', 'notebooks')
    notebook = args.notebook
    if notebook is None:
        notebooks = glob.glob(os.path.join(full_path, '*.ipynb'))
    else:
        if not notebook.endswith('.ipynb'):
            notebook = notebook + '.ipynb'
        notebook = os.path.abspath(os.path.join(full_path, notebook))
        if not os.path.exists(notebook):
            raise FileNotFoundError('Notebook {0} not found.'.format(notebook))
        notebooks = [notebook]
    if not notebooks:
        import warnings
        warnings.warn('No notebooks found', UserWarning)
    for nb in notebooks:
        nb_full_name = os.path.split(nb)[1]
        nb_name = os.path.splitext(nb_full_name)[0]
        py_name = nb_name + '.py'
        # Get base directory to notebook
        out_file = os.path.split(nb)[0]
        # Write to ../python
        out_file = os.path.join(out_file, '..', 'python', py_name)
        if is_newer(out_file, nb) and not force:
            logger.info('Skipping {0}, exported version newer than '
                        'notebook'.format(nb_name))
            continue
        logger.info('Converting {0}'.format(nb_name))
        with open(nb, 'r') as nb_file:
            converter = nbconvert.PythonExporter()
            python = converter.from_file(nb_file)
            code = python[0].split('\n')
            code_out = []
            for i, block in enumerate(code):
                if 'get_ipython' in block:
                    continue
                elif block.startswith('# In[ ]:'):
                    continue
                if block.startswith('#'):
                    # Wrap comments from Markdown
                    block = textwrap.fill(block, width=74)
                    block = block.replace('\n', '\n# ')
                code_out.append(block)
            if not code_out[0]:
                code_out = code_out[1:]
            loc = 0
            if 'coding' in code_out[0]:
                loc = 1
            code_out.insert(loc, DO_NOT_EDIT.format(notebook=nb_full_name))
            code_out = '\n'.join(code_out)
            code_out, success = FormatCode(code_out, style_config='pep8')
            with open(out_file, 'w') as of:
                of.write(code_out)


if __name__ == '__main__':
    main()