Allow to read options from a file

Pipfile

@@ -18,6 +18,7 @@ click-help-colors = "*"
 colorama = "*"
 click-completion = "*"
 halo = "*"
+pyyaml = "*"
 
 [dev-packages]
 twine = "*"

gradient/cli/common.py

@@ -2,8 +2,14 @@
 import json
 
 import click
+import yaml
+from click.exceptions import Exit
 from click_didyoumean import DYMMixin
 from click_help_colors import HelpColorsGroup
+from gradient.cli import cli_types
+
+OPTIONS_FILE_PARAMETER_NAME = "options_file"
+
 
 api_key_option = click.option(
     "--apiKey",
@@ -47,3 +53,77 @@ def decorator(f):
         f.invoke = functools.partial(new_invoke, f)
 
     return decorator
+
+
+def get_option_name(options_strings):
+    for opt in options_strings:
+        if not opt.startswith("-"):
+            return opt
+
+        if opt.startswith("--"):
+            return opt[2:]
+
+
+class ReadValueFromConfigFile(click.Parameter):
+    def handle_parse_result(self, ctx, opts, args):
+        config_file = ctx.params.get(OPTIONS_FILE_PARAMETER_NAME)
+        if config_file:
+            with open(config_file) as f:
+                config_data = yaml.load(f, Loader=yaml.FullLoader)
+                option_name = get_option_name(self.opts)
+                value = config_data.get(option_name)
+                if value is not None:
+                    if isinstance(value, dict):
+                        value = json.dumps(value)
+
+                    opts[self.name] = value
+
+        return super(ReadValueFromConfigFile, self).handle_parse_result(
+            ctx, opts, args)
+
+
+class ArgumentReadValueFromConfigFile(ReadValueFromConfigFile, click.Argument):
+    pass
+
+
+class OptionReadValueFromConfigFile(ReadValueFromConfigFile, click.Option):
+    pass
+
+
+def generate_options_template(ctx, param, value):
+    if not value:
+        return value
+
+    params = {}
+    for param in ctx.command.params:
+        option_name = get_option_name(param.opts)
+        option_value = ctx.params.get(param.name) or param.default
+
+        if isinstance(param.type, cli_types.ChoiceType):
+            for key, val in param.type.type_map.items():
+                if val == option_value:
+                    option_value = key
+
+        params[option_name] = option_value
+
+    with open(value, "w") as f:
+        yaml.safe_dump(params, f, default_flow_style=False)
+
+    raise Exit  # to stop execution without executing the command
+
+
+def options_file(f):
+    options = [
+        click.option(
+            "--optionsFile",
+            OPTIONS_FILE_PARAMETER_NAME,
+            help="Path to YAML file with predefined options",
+        ),
+        click.option(
+            "--optionsFileTemplate",
+            callback=generate_options_template,
+            expose_value=False,
+            help="Generate template options file"
+        )
+    ]
+    return functools.reduce(lambda x, opt: opt(x), reversed(options), f)