implement gwei feature (ethereum gas fees) (#736)

* implement gwei feature (ethereum gas fees)

* fix linter issues

* fixing another linting issues

* typo and linter issue

* added model and view for gwei feature

* added extra folder for reports

* added new line after gwei info

* lint

* changed tx label and table, lint

* lint fixes

6 files changed, 268 insertions, 11 deletions

diff --git a/exports/cryptocurrency/onchain/.gitkeep b/exports/cryptocurrency/onchain/.gitkeep
new file mode 100644
index 00000000000..e69de29bb2d
--- /dev/null
+++ b/exports/cryptocurrency/onchain/.gitkeep
diff --git a/gamestonk_terminal/cryptocurrency/crypto_controller.py b/gamestonk_terminal/cryptocurrency/crypto_controller.py
index 851dbbac310..ec7c58d492b 100644
--- a/gamestonk_terminal/cryptocurrency/crypto_controller.py
+++ b/gamestonk_terminal/cryptocurrency/crypto_controller.py
@@ -38,6 +38,7 @@ from gamestonk_terminal.cryptocurrency.cryptocurrency_helpers import (
     plot_chart,
 )
 from gamestonk_terminal.cryptocurrency.report import report_controller
+from gamestonk_terminal.cryptocurrency.onchain import onchain_controller
 from gamestonk_terminal.cryptocurrency.due_diligence.binance_model import (
     show_available_pairs_for_given_symbol,
 )
@@ -60,13 +61,7 @@ class CryptoController:
         "find",
     ]
 
-    CHOICES_MENUS = [
-        "ta",
-        "dd",
-        "ov",
-        "disc",
-        "report",
-    ]
+    CHOICES_MENUS = ["ta", "dd", "ov", "disc", "report", "onchain"]
 
     SOURCES = {
         "bin": "Binance",
@@ -122,10 +117,11 @@ Note: Some of CoinGecko commands can fail. Team is working on fix.
     find        alternate way to search for coins
     finbrain    crypto sentiment from 15+ major news headlines
 
->   disc        discover trending cryptocurrencies,  e.g.: top gainers, losers, top sentiment
->   ov          overview of the cryptocurrencies,    e.g.: market cap, DeFi, latest news, top exchanges, stables
->   dd          due-diligence for loaded coin,       e.g.: coin information, social media, market stats
->   ta          technical analysis for loaded coin.  e.g.: ema, macd, rsi, adx, bbands, obv
+>   disc        discover trending cryptocurrencies,     e.g.: top gainers, losers, top sentiment
+>   ov          overview of the cryptocurrencies,       e.g.: market cap, DeFi, latest news, top exchanges, stables
+>   dd          due-diligence for loaded coin,          e.g.: coin information, social media, market stats
+>   ta          technical analysis for loaded coin,     e.g.: ema, macd, rsi, adx, bbands, obv
+>   onchain     information on different blockchains,   e.g.: eth gas fees
 >   report      generate automatic report
 """
         print(help_text)
@@ -586,6 +582,15 @@ Note: Some of CoinGecko commands can fail. Team is working on fix.
         else:
             return True
 
+    def call_onchain(self, _):
+        """Process onchain command"""
+        ret = onchain_controller.menu()
+
+        if ret is False:
+            self.print_help()
+        else:
+            return True
+
     def call_find(self, other_args):
         """Process find command"""
         parser = argparse.ArgumentParser(
diff --git a/gamestonk_terminal/cryptocurrency/onchain/__init__.py b/gamestonk_terminal/cryptocurrency/onchain/__init__.py
new file mode 100644
index 00000000000..e69de29bb2d
--- /dev/null
+++ b/gamestonk_terminal/cryptocurrency/onchain/__init__.py
diff --git a/gamestonk_terminal/cryptocurrency/onchain/gasnow_model.py b/gamestonk_terminal/cryptocurrency/onchain/gasnow_model.py
new file mode 100644
index 00000000000..8a538672635
--- /dev/null
+++ b/gamestonk_terminal/cryptocurrency/onchain/gasnow_model.py
@@ -0,0 +1,40 @@
+import pandas as pd
+import requests
+
+
+def get_gwei_fees() -> pd.DataFrame:
+    """Returns the most recent Ethereum gas fees in gwei
+    [Source: https://www.gasnow.org]
+
+    Parameters
+    ----------
+
+    Returns
+    -------
+    pd.DataFrame
+        four gas fees and durations
+            (fees for slow, average, fast and
+            fastest transactions in gwei and
+            its average durations in seconds)
+    """
+
+    r = requests.get("https://www.gasnow.org/api/v3/gas/price")
+
+    if r.status_code == 200:
+        try:
+            data = r.json()["data"]
+            return pd.DataFrame(
+                data=[
+                    ["Fastest", int(data["rapid"] / 1_000_000_000), "~15 sec"],
+                    ["Fast", int(data["fast"] / 1_000_000_000), "~1 min"],
+                    ["Standard", int(data["standard"] / 1_000_000_000), "~3 min"],
+                    ["Slow", int(data["slow"] / 1_000_000_000), ">10 min"],
+                ],
+                columns=["Tx Type", "Fee (gwei)", "Duration"],
+            )
+        except TypeError:
+            print("Error in gasnow JSON response.\n")
+            return pd.DataFrame()
+    else:
+        print("Error in gasnow GET request\n")
+        return pd.DataFrame()
diff --git a/gamestonk_terminal/cryptocurrency/onchain/gasnow_view.py b/gamestonk_terminal/cryptocurrency/onchain/gasnow_view.py
new file mode 100644
index 00000000000..83d3b362ad6
--- /dev/null
+++ b/gamestonk_terminal/cryptocurrency/onchain/gasnow_view.py
@@ -0,0 +1,42 @@
+import os
+
+from tabulate import tabulate
+from gamestonk_terminal.helper_funcs import export_data
+from gamestonk_terminal.cryptocurrency.onchain.gasnow_model import get_gwei_fees
+from gamestonk_terminal import feature_flags as gtff
+
+
+def display_gwei_fees(export: str) -> None:
+    """Current gwei fees
+    [Source: https://www.gasnow.org]
+
+    Parameters
+    ----------
+    export : str
+        Export dataframe data to csv,json,xlsx file
+    """
+
+    df_fees = get_gwei_fees()
+
+    print("Current ETH gas fees (gwei):")
+
+    if gtff.USE_TABULATE_DF:
+        print(
+            tabulate(
+                df_fees.head(4),
+                headers=df_fees.columns,
+                floatfmt=".1f",
+                showindex=False,
+                tablefmt="fancy_grid",
+            ),
+            "\n",
+        )
+    else:
+        print(df_fees.to_string(index=False), "\n")
+
+    export_data(
+        export,
+        os.path.dirname(os.path.abspath(__file__)),
+        "gwei",
+        df_fees,
+    )
diff --git a/gamestonk_terminal/cryptocurrency/onchain/onchain_controller.py b/gamestonk_terminal/cryptocurrency/onchain/onchain_controller.py
new file mode 100644
index 00000000000..32793ee6294
--- /dev/null
+++ b/gamestonk_terminal/cryptocurrency/onchain/onchain_controller.py
@@ -0,0 +1,170 @@
+"""Onchain Controller Module"""
+__docformat__ = "numpy"
+
+import os
+import argparse
+from typing import List
+from prompt_toolkit.completion import NestedCompleter
+
+from gamestonk_terminal import feature_flags as gtff
+from gamestonk_terminal.menu import session
+from gamestonk_terminal.helper_funcs import get_flair, parse_known_args_and_warn
+
+from gamestonk_terminal.cryptocurrency.onchain import gasnow_view
+
+# pylint: disable=R1732
+
+
+class OnchainController:
+    """Onchain Controller class"""
+
+    CHOICES = [
+        "cls",
+        "?",
+        "help",
+        "q",
+        "quit",
+    ]
+
+    CHOICES_COMMANDS = [
+        "gwei",
+    ]
+
+    CHOICES += CHOICES_COMMANDS
+
+    def __init__(self):
+        """Constructor"""
+        self.onchain_parser = argparse.ArgumentParser(add_help=False, prog="onchain")
+        self.onchain_parser.add_argument(
+            "cmd",
+            choices=self.CHOICES,
+        )
+
+    def switch(self, an_input: str):
+        """Process and dispatch input
+
+        Parameters
+        -------
+        an_input : str
+            string with input arguments
+
+        Returns
+        -------
+        True, False or None
+            False - quit the menu
+            True - quit the program
+            None - continue in the menu
+        """
+
+        # Empty command
+        if not an_input:
+            print("")
+            return None
+
+        (known_args, other_args) = self.onchain_parser.parse_known_args(
+            an_input.split()
+        )
+
+        # Help menu again
+        if known_args.cmd == "?":
+            print_help()
+            return None
+
+        # Clear screen
+        if known_args.cmd == "cls":
+            os.system("cls||clear")
+            return None
+
+        return getattr(
+            self, "call_" + known_args.cmd, lambda: "Command not recognized!"
+        )(other_args)
+
+    def call_help(self, *_):
+        """Process Help command"""
+        print_help()
+
+    def call_q(self, _):
+        """Process Q command - quit the menu"""
+        return False
+
+    def call_quit(self, _):
+        """Process Quit command - quit the program"""
+        return True
+
+    def call_gwei(self, other_args: List[str]):
+        """Process gwei command"""
+        parser = argparse.ArgumentParser(
+            add_help=False,
+            formatter_class=argparse.ArgumentDefaultsHelpFormatter,
+            prog="onchain",
+            description="""
+                Display ETH gas fees
+                [Source: https://www.gasnow.org]
+            """,
+        )
+
+        parser.add_argument(
+            "--export",
+            choices=["csv", "json", "xlsx"],
+            default="",
+            type=str,
+            dest="export",
+            help="Export dataframe data to csv,json,xlsx file",
+        )
+
+        try:
+            ns_parser = parse_known_args_and_warn(parser, other_args)
+
+            if not ns_parser:
+                return
+
+            gasnow_view.display_gwei_fees(export=ns_parser.export)
+
+        except Exception as e:
+            print(e, "\n")
+
+
+def print_help():
+    """Print help"""
+    print(
+        "https://github.com/GamestonkTerminal/GamestonkTerminal/tree/main/gamestonk_terminal/cryptocurrency/onchain"
+    )
+    print("\nOnchain:")
+    print("   cls           clear screen")
+    print("   ?/help        show this menu again")
+    print("   q             quit this menu, and shows back to main menu")
+    print("   quit          quit to abandon program")
+    print("")
+    print("   gwei          check current eth gas fees")
+    print("")
+
+
+def menu():
+    """Onchain Menu"""
+    onchain_controller = OnchainController()
+    onchain_controller.call_help(None)
+
+    while True:
+        # Get input command from user
+        if session and gtff.USE_PROMPT_TOOLKIT:
+            completer = NestedCompleter.from_nested_dict(
+                {c: None for c in onchain_controller.CHOICES}
+            )
+            an_input = session.prompt(
+                f"{get_flair()} (crypto)>(onchain)> ",
+                completer=completer,
+            )
+        else:
+            an_input = input(f"{get_flair()} (crypto)>(onchain)> ")
+
+        try:
+            process_input = onchain_controller.switch(an_input)
+        except SystemExit:
+            print("The command selected doesn't exist\n")
+            continue
+
+        if process_input is False:
+            return False
+
+        if process_input is True:
+            return True