#-----------------------------------------------------------------------------
# Copyright (c) 2012 - 2018, Anaconda, Inc. and Intake contributors
# All rights reserved.
#
# The full license is in the LICENSE file, distributed with this software.
#-----------------------------------------------------------------------------

import appdirs
import json
import os
import subprocess
import sys

from intake.config import conf
from intake.utils import make_path_posix
from .local import YAMLFilesCatalog, Catalog


def load_user_catalog():
    """Return a catalog for the platform-specific user Intake directory"""
    cat_dir = user_data_dir()
    if not os.path.isdir(cat_dir):
        return Catalog()
    else:
        return YAMLFilesCatalog(cat_dir)


def user_data_dir():
    """Return the user Intake catalog directory"""
    return appdirs.user_data_dir(appname='intake', appauthor='intake')


def load_global_catalog():
    """Return a catalog for the environment-specific Intake directory"""
    cat_dir = global_data_dir()
    if not os.path.isdir(cat_dir):
        return Catalog()
    else:
        return YAMLFilesCatalog(cat_dir)


CONDA_VAR = 'CONDA_PREFIX'
VIRTUALENV_VAR = 'VIRTUAL_ENV'


def conda_prefix():
    """Fallback: ask conda in PATH for its prefix"""
    try:
        out = subprocess.check_output(['conda', 'info', '--json'])
        return json.loads(out.decode())["default_prefix"]
    except (subprocess.CalledProcessError, json.JSONDecodeError, OSError):
        return False


def which(program):
    """Emulate posix ``which``"""
    import distutils.spawn
    return distutils.spawn.find_executable(program)


def global_data_dir():
    """Return the global Intake catalog dir for the current environment"""
    prefix = False
    if VIRTUALENV_VAR in os.environ:
        prefix = os.environ[VIRTUALENV_VAR]
    elif CONDA_VAR in os.environ:
        prefix = sys.prefix
    elif which('conda'):
        # conda exists but is not activated
        prefix = conda_prefix()

    if prefix:
        # conda and virtualenv use Linux-style directory pattern
        return make_path_posix(os.path.join(prefix, 'share', 'intake'))
    else:
        return appdirs.site_data_dir(appname='intake', appauthor='intake')


def load_combo_catalog():
    """Load a union of the user and global catalogs for convenience"""
    user_dir = user_data_dir()
    global_dir = global_data_dir()
    desc = 'Generated from data packages found on your intake search path'
    cat_dirs = []
    if os.path.isdir(user_dir):
        cat_dirs.append(user_dir + '/*.yaml')
        cat_dirs.append(user_dir + '/*.yml')
    if os.path.isdir(global_dir):
        cat_dirs.append(global_dir + '/*.yaml')
        cat_dirs.append(global_dir + '/*.yml')
    for path_dir in conf.get('catalog_path', []):
        if path_dir != '':
            if not path_dir.endswith(('yaml', 'yml')):
                cat_dirs.append(path_dir + '/*.yaml')
                cat_dirs.append(path_dir + '/*.yml')
            else:
                cat_dirs.append(path_dir)

    return YAMLFilesCatalog(cat_dirs, name='builtin', description=desc)