Config API, Part II

This patch completes the implementation of the API, making the entire MMGen
code base usable as a library for external projects.  A usage example can be
found in the script `examples/coin-daemon-info.py`.

Testing:

    $ test/test.py -e coin_daemon_info

examples/coin-daemon-info.py

@@ -0,0 +1,94 @@
+#!/usr/bin/env python3
+#
+# mmgen = Multi-Mode GENerator, a command-line cryptocurrency wallet
+# Copyright (C)2013-2023 The MMGen Project <mmgen@tuta.io>
+# Licensed under the GNU General Public License, Version 3:
+#   https://www.gnu.org/licenses
+# Public project repositories:
+#   https://github.com/mmgen/mmgen
+#   https://gitlab.com/mmgen/mmgen
+
+"""
+examples/coin-daemon-info.py:
+    Get info about multiple running coin daemons.
+    Demonstrates use of the MMGen Config API.
+"""
+
+# Instructions
+#
+#  Testing mode:
+#
+#   1) From the MMGen repository root, start the mainnet test suite daemons as follows
+#      (note that openethereum is the default testing daemon for ETH):
+#
+#       test/start-coin-daemons.py btc ltc eth
+#
+#   2) Then run the script as follows:
+#
+#       PYTHONPATH=. MMGEN_TEST_SUITE=1 examples/coin-daemon-info.py btc ltc eth
+#
+#  Live mode:
+#
+#   1) Start up one or more of bitcoind, litecoind or geth with the standard mainnet ports
+#      and datadirs.  For geth, the options ‘--http --http.api=eth,web3’ are required.
+#
+#   2) Then run the script as follows:
+#
+#       PYTHONPATH=. examples/coin-daemon-info.py btc ltc eth
+
+import sys,os,asyncio
+
+from mmgen.exception import SocketError
+from mmgen.cfg import Config
+from mmgen.rpc import rpc_init
+from mmgen.util import make_timestr
+
+async def get_rpc(cfg):
+	try:
+		return await rpc_init(cfg)
+	except SocketError as e:
+		return False
+
+async def main(coins):
+
+	rpcs = {}
+	cfgs = {}
+	test_suite = os.getenv('MMGEN_TEST_SUITE')
+	base_cfg = Config({'pager':True})
+
+	for coin in coins:
+		cfg_in = {
+			'coin': coin,
+			'test_suite': test_suite,
+		}
+		if coin == 'eth' and not test_suite:
+			cfg_in.update({'daemon_id': 'geth'})
+		cfgs[coin] = Config(cfg_in)
+		rpcs[coin] = await get_rpc(cfgs[coin])
+
+	def gen_output():
+		fs = '{:4} {:7} {:6} {:<5} {:<8} {:30} {:13} {:23} {}'
+		yield fs.format('Coin','Network','Status','Port','Chain','Latest Block','Daemon','Version','Datadir')
+		for coin,rpc in rpcs.items():
+			info = ('Down','-','-','-','-','-','-') if rpc is False else (
+				'Up',
+				rpc.port,
+				rpc.chain,
+				'{:<8} [{}]'.format(rpc.blockcount, make_timestr(rpc.cur_date)),
+				rpc.daemon.coind_name,
+				rpc.daemon_version_str,
+				rpc.daemon.datadir
+			)
+			yield fs.format( coin.upper(), cfgs[coin].network, *info )
+
+	base_cfg._util.stdout_or_pager('\n'.join(gen_output()))
+
+all_coins = ('btc', 'ltc', 'eth')
+
+coins = sys.argv[1:]
+
+if coins and all(coin in all_coins for coin in coins):
+	asyncio.run(main(coins))
+else:
+	print(f'You must supply one or more of the following coins on the command line:\n  {all_coins}')
+	sys.exit(1)