import re
import os

from ase.db.core import default_key_descriptions


def process_metadata(db, html=True):
    meta = {}

    if db.python:
        if isinstance(db.python, str):
            with open(db.python) as fd:
                code = fd.read()
            path = os.path.dirname(db.python)
            mod = {}
            code = 'import sys; sys.path[:0] = ["{}"]; {}'.format(path, code)

            # We use eval here instead of exec because it works on both
            # Python 2 and 3.
            eval(compile(code, db.python, 'exec'), mod, mod)
        else:
            mod = db.python
    else:
        mod = {}

    for key, default in [('title', 'ASE database'),
                         ('default_columns', None),
                         ('special_keys', []),
                         ('key_descriptions', {}),
                         ('layout', None),
                         ('unique_key', 'id')]:
        meta[key] = mod.get(key, meta.get(key, default))

    if not meta['default_columns']:
        meta['default_columns'] = ['id', 'formula']

    # Also fill in default key-descriptions:
    kd = default_key_descriptions.copy()
    kd.update(meta['key_descriptions'])
    meta['key_descriptions'] = kd

    # Long description may be missing:
    for key, (short, long, unit) in kd.items():
        if not long:
            kd[key] = (short, short, unit)

    sk = []
    for special in meta['special_keys']:
        kind = special[0]
        if kind == 'SELECT':
            key = special[1]
            choises = sorted({row.get(key)
                              for row in
                              db.select(key,
                                        columns=['key_value_pairs'],
                                        include_data=False)})
            if key in kd:
                longkey = kd[key][1]
            else:
                longkey = key
            special = ['SELECT', key, longkey, choises]
        elif kind == 'BOOL':
            key = special[1]
            if key in kd:
                longkey = kd[key][1]
            else:
                longkey = key
            special = ['BOOL', key, longkey]
        else:
            # RANGE
            pass
        sk.append(special)
    meta['special_keys'] = sk

    sub = re.compile(r'`(.)_(.)`')
    sup = re.compile(r'`(.*)\^\{?(.*?)\}?`')

    # Convert LaTeX to HTML or raw text:
    for key, value in meta['key_descriptions'].items():
        short, long, unit = value
        if html:
            unit = sub.sub(r'\1<sub>\2</sub>', unit)
            unit = sup.sub(r'\1<sup>\2</sup>', unit)
            unit = unit.replace(r'\text{', '').replace('}', '')
        else:
            unit = sub.sub(r'\1_\2', unit)
            unit = sup.sub(r'\1^\2', unit)
        meta['key_descriptions'][key] = (short, long, unit)

    all_keys1 = set(meta['key_descriptions'])
    for row in db.select(columns=['key_value_pairs'], include_data=False):
        all_keys1.update(row._keys)
    all_keys2 = []
    for key in all_keys1:
        short, long, unit = meta['key_descriptions'].get(key, ('', '', ''))
        all_keys2.append((key, long, unit))
    meta['all_keys'] = sorted(all_keys2)

    return meta