@PYTHON@
# vim: set ts=4 et:

import json
import os
import shutil
import sys
import boto3
from botocore.exceptions import ClientError
from datetime import datetime, timedelta
from pyhocon import ConfigFactory

if len(sys.argv) != 2:
    sys.exit("Usage: " + os.path.basename(__file__) + " <profile>")

PROFILE = sys.argv[1]

SCRIPT_DIR = os.path.dirname(os.path.realpath(__file__))

# path to the profile config file
PROFILE_CONF = os.path.join(SCRIPT_DIR, '..', 'profiles', PROFILE + '.conf')

# load the profile's build configuration
BUILDS = ConfigFactory.parse_file(PROFILE_CONF)['BUILDS']

# where we store the profile's builds' config/output
PROFILE_DIR = os.path.join(SCRIPT_DIR, 'profile', PROFILE)
if not os.path.exists(PROFILE_DIR):
    os.makedirs(PROFILE_DIR)

# fold these build config keys' dict to scalar
FOLD_DICTS = {
    'ami_access': ',{0}',
    'ami_regions': ',{0}',
    'repos': "\n@{1} {0}",
    'pkgs': ' {0}@{1}',
    'kernel_modules': ',{0}',
    'kernel_options': ' {0}'
}

NOW = datetime.utcnow()
ONE_DAY = timedelta(days=1)


# func to fold dict down to scalar
def fold(fdict, ffmt):
    folded = ''
    for fkey, fval in fdict.items():
        fkey = fkey.strip('"')    # complex keys may be in quotes
        if fval is True:
            folded += ffmt[0] + fkey
        elif fval not in [None, False]:
            folded += ffmt.format(fkey, fval)
    return folded[1:]


# list of AWS regions, and whether they're enabled
all_regions = {}
AWS = boto3.session.Session()
sys.stderr.write("\n>>> Determining region availability...")
sys.stderr.flush()
for region in AWS.get_available_regions('ec2'):
    ec2 = AWS.client('ec2', region_name=region)
    try:
        ec2.describe_regions()
    except ClientError as e:
        if e.response['Error']['Code'] == 'AuthFailure':
            sys.stderr.write('-')
            sys.stderr.flush()
            all_regions[region] = False
            continue
        elif e.response['Error']['Code'] == 'UnauthorizedOperation':
            # have access to the region, but not to ec2:DescribeRegions
            pass
        else:
            raise
    sys.stderr.write('+')
    sys.stderr.flush()
    all_regions[region] = True
sys.stderr.write("\n")

for region, available in all_regions.items():
    if available is False:
        sys.stderr.write(f"*** WARNING: skipping disabled region {region}\n")

print()

# parse/resolve HOCON profile's builds' config
for build, cfg in BUILDS.items():
    print(f">>> Resolving configuration for '{build}'")
    build_dir = os.path.join(PROFILE_DIR, build)

    # make a fresh profile build directory
    if os.path.exists(build_dir):
        shutil.rmtree(build_dir)
    os.makedirs(build_dir)

    # populate profile build vars
    cfg['profile'] = PROFILE
    cfg['profile_build'] = build

    # mostly edge-related temporal substitutions
    if cfg['end_of_life'] == '@TOMORROW@':
        cfg['end_of_life'] = (NOW + ONE_DAY).isoformat(timespec='seconds')
    elif cfg['end_of_life'] is not None:
        # to explicitly UTC-ify end_of_life
        cfg['end_of_life'] = datetime.fromisoformat(
            cfg['end_of_life'] + '+00:00').isoformat(timespec='seconds')
    if cfg['revision'] == '@NOW@':
        cfg['revision'] = NOW.strftime('%Y%m%d%H%M%S')

    # 'ALL' region expansion (or retraction)
    if 'ALL' in cfg['ami_regions']:
        all_val = cfg['ami_regions']['ALL']
        if all_val not in [None, False]:
            cfg['ami_regions'] = all_regions
        else:
            cfg['ami_regions'] = {}
    else:
        # warn/remove disabled regions
        for region, enabled in all_regions.items():
            if enabled is not False or region not in cfg['ami_regions']:
                continue
            if cfg['ami_regions'][region] not in [None, False]:
                cfg['ami_regions'][region] = False

    # fold dict vars to scalars
    for foldkey, foldfmt in FOLD_DICTS.items():
        cfg[foldkey] = fold(cfg[foldkey], foldfmt)

    # fold 'svcs' dict to scalar
    lvls = {}
    for svc, lvl in cfg['svcs'].items():
        if lvl is True:
            # service in default runlevel
            lvls['default'].append(svc)
        elif lvl not in [None, False]:
            # service in specified runlevel (skip svc when false/null)
            if lvl not in lvls.keys():
                lvls[lvl] = []
            lvls[lvl].append(svc)
    cfg['svcs'] = ' '.join(
        str(lvl) + '=' + ','.join(
            str(svc) for svc in svcs
        ) for lvl, svcs in lvls.items()
    )

    # resolve ami_name and ami_desc
    cfg['ami_name'] = cfg['ami_name'].format(var=cfg)
    cfg['ami_desc'] = cfg['ami_desc'].format(var=cfg)

    # write build vars file
    with open(os.path.join(build_dir, 'vars.json'), 'w') as out:
        json.dump(cfg, out, indent=4, separators=(',', ': '))

print()