import os
from glob import glob
from yaml import full_load as _load

"""
Interface to the instance configuration.

The instance configuration is expected to be found under
$HOME/etc/config.yaml and the configuration for the individual
surveys should be under $HOME/etc/surveys/*.yaml. In both cases,
$HOME is the home directory of the user running this script.
"""

prefix = os.environ.get("DOUGAL_ROOT", os.environ.get("HOME", ".")+"/software")

def read (file = None):
	if file is None:
		file = prefix+"/etc/config.yaml"
	with open(file, "r") as fd:
		cfg = _load(fd)

		if "db" in cfg and "connection_string" in cfg["db"] and os.environ.get("PGDATABASE"):
			# This should cause the PostgreSQL library to use the environment variables
			cfg["db"]["connection_string"] = ""
			print("Using environment variables for database connection")

		return cfg

def files (globspec = None, include_archived = False):
	"""
	Read and parse survey configuration files.

	Arguments:

	globspec (string): a glob spec matching the selection of files to read.
	If not provided, a default value will be used.

	include_archived (bool): whether to include surveys marked as archived or
	not. Defaults to ignoring archived surveys.

	Note that file names starting with `.` or `_` (dot or underscore) will
	never be read (and there is no option to override this). Intended for
	quickly and temporarily “disabling” a survey configuration by renaming
	the relevant file.
	"""
	tuples = []

	if globspec is None:
		globspec = prefix+'/etc/surveys/*.yaml'

	for filepath in glob(globspec):
		filepath = os.path.abspath(filepath)
		if os.path.basename(filepath).startswith("_") or os.path.basename(filepath).startswith("."):
			continue

		survey = read(filepath)

		if not include_archived and "archived" in survey and survey["archived"] is not False:
			continue

		tuples.append((filepath, survey))

	return tuples

def surveys (globspec = None, include_archived = False):
	return [i[1] for i in files(globspec, include_archived)]