"""DataDog Agent entrypoint script.

This application provides a way to fill in DataDog Agent configuration files
using Jinja templates and provided values in environment variables.
After updating the configuration, the application will run DataDog Agent.
"""

import fnmatch
import os
import sys

import jinja2

template_dir = os.getenv('TEMPLATE_DIR', '/opt/entrypoint/templates.d')
config_dir = os.getenv('CONFIG_DIR', '/etc/datadog-agent/conf.d')

environment = os.getenv('Environment')

if not os.path.isdir(template_dir):
    print('Error: template directory "{}" not found'.format(template_dir))
    sys.exit(1)

tpl = jinja2.Environment(
    loader=jinja2.FileSystemLoader(template_dir),
    autoescape=jinja2.select_autoescape())

env = os.environ

for template_file in os.listdir(template_dir):
    if not fnmatch.fnmatch(template_file, '*.yaml'):
        continue

    template_name, _ = os.path.splitext(template_file)
    config_path = os.path.join(config_dir, template_name + '.d', 'conf.yaml')

    print('Processing "{}" template to "{}"'.format(
        template_file, config_path))

    try:
        template = tpl.get_template(template_file)
        template.stream(env).dump(config_path)
    except jinja2.TemplateNotFound as exc:
        print('Error: can\'t read the template file "{}": {}'.format(
            template_file, exc))
        sys.exit(1)
    except FileNotFoundError as exc:
        print('Error: can\'t render the template file "{}": {}'.format(
            template_file, exc))
        sys.exit(1)

print('Launching DataDog Agent')
sys.stdout.flush()

try:
    os.execl('/init', '/init')
except OSError as exc:
    print("Error: can't launch DataDog agent: {}".format(exc))
    sys.exit(1)