[CLI] Add stdin support for json2c command (#11289)

* Implement stdin for json2c command

* Refactor

* Handle json decode error

* Add stdin support for c2json cli command

* Refactor to prevent code duplication

* Change exit(1) to return False in c2json command

* Remove unused import

4 files changed, 70 insertions, 35 deletions

diff --git a/lib/python/qmk/cli/c2json.py b/lib/python/qmk/cli/c2json.py
index 8c8bd1f57e..2b3bb774f7 100644
--- a/lib/python/qmk/cli/c2json.py
+++ b/lib/python/qmk/cli/c2json.py
@@ -1,7 +1,6 @@
 """Generate a keymap.json from a keymap.c file.
 """
 import json
-import sys
 
 from milc import cli
 
@@ -21,19 +20,14 @@ def c2json(cli):
 
     This command uses the `qmk.keymap` module to generate a keymap.json from a keymap.c file. The generated keymap is written to stdout, or to a file if -o is provided.
     """
-    cli.args.filename = qmk.path.normpath(cli.args.filename)
+    if cli.args.filename != '-':
+        cli.args.filename = qmk.path.normpath(cli.args.filename)
 
-    # Error checking
-    if not cli.args.filename.exists():
-        cli.log.error('C file does not exist!')
-        cli.print_usage()
-        exit(1)
-
-    if str(cli.args.filename) == '-':
-        # TODO(skullydazed/anyone): Read file contents from STDIN
-        cli.log.error('Reading from STDIN is not (yet) supported.')
-        cli.print_usage()
-        exit(1)
+        # Error checking
+        if not cli.args.filename.exists():
+            cli.log.error('C file does not exist!')
+            cli.print_usage()
+            return False
 
     # Environment processing
     if cli.args.output == ('-'):
@@ -47,7 +41,7 @@ def c2json(cli):
         keymap_json = qmk.keymap.generate_json(keymap_json['keymap'], keymap_json['keyboard'], keymap_json['layout'], keymap_json['layers'])
     except KeyError:
         cli.log.error('Something went wrong. Try to use --no-cpp.')
-        sys.exit(1)
+        return False
 
     if cli.args.output:
         cli.args.output.parent.mkdir(parents=True, exist_ok=True)
diff --git a/lib/python/qmk/cli/json2c.py b/lib/python/qmk/cli/json2c.py
index 426078063c..97d8fb0c33 100755
--- a/lib/python/qmk/cli/json2c.py
+++ b/lib/python/qmk/cli/json2c.py
@@ -1,6 +1,7 @@
 """Generate a keymap.c from a configurator export.
 """
 import json
+import sys
 
 from milc import cli
 
@@ -17,26 +18,31 @@ def json2c(cli):
 
     This command uses the `qmk.keymap` module to generate a keymap.c from a configurator export. The generated keymap is written to stdout, or to a file if -o is provided.
     """
-    # Error checking
-    if cli.args.filename and cli.args.filename.name == '-':
-        # TODO(skullydazed/anyone): Read file contents from STDIN
-        cli.log.error('Reading from STDIN is not (yet) supported.')
-        cli.print_usage()
-        return False
 
-    if not cli.args.filename.exists():
-        cli.log.error('JSON file does not exist!')
-        cli.print_usage()
+    try:
+        # Parse the configurator from stdin
+        if cli.args.filename and cli.args.filename.name == '-':
+            user_keymap = json.load(sys.stdin)
+
+        else:
+            # Error checking
+            if not cli.args.filename.exists():
+                cli.log.error('JSON file does not exist!')
+                return False
+
+            # Parse the configurator json file
+            else:
+                user_keymap = json.loads(cli.args.filename.read_text())
+
+    except json.decoder.JSONDecodeError as ex:
+        cli.log.error('The JSON input does not appear to be valid.')
+        cli.log.error(ex)
         return False
 
     # Environment processing
     if cli.args.output and cli.args.output.name == '-':
         cli.args.output = None
 
-    # Parse the configurator json
-    with cli.args.filename.open('r') as fd:
-        user_keymap = json.load(fd)
-
     # Generate the keymap
     keymap_c = qmk.keymap.generate_c(user_keymap['keyboard'], user_keymap['layout'], user_keymap['layers'])
 
diff --git a/lib/python/qmk/keymap.py b/lib/python/qmk/keymap.py
index 31c61ae6a8..266532f503 100644
--- a/lib/python/qmk/keymap.py
+++ b/lib/python/qmk/keymap.py
@@ -3,6 +3,7 @@
 from pathlib import Path
 import json
 import subprocess
+import sys
 
 from pygments.lexers.c_cpp import CLexer
 from pygments.token import Token
@@ -312,16 +313,17 @@ def list_keymaps(keyboard, c=True, json=True, additional_files=None, fullpath=Fa
     return sorted(names)
 
 
-def _c_preprocess(path):
+def _c_preprocess(path, stdin=None):
     """ Run a file through the C pre-processor
 
     Args:
-        path: path of the keymap.c file
+        path: path of the keymap.c file (set None to use stdin)
+        stdin: stdin pipe (e.g. sys.stdin)
 
     Returns:
         the stdout of the pre-processor
     """
-    pre_processed_keymap = qmk.commands.run(['cpp', path], stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
+    pre_processed_keymap = qmk.commands.run(['cpp', path] if path else ['cpp'], stdin=stdin, stdout=subprocess.PIPE, stderr=subprocess.PIPE, universal_newlines=True)
     return pre_processed_keymap.stdout
 
 
@@ -451,17 +453,23 @@ def parse_keymap_c(keymap_file, use_cpp=True):
     Currently only cares about the keymaps array.
 
     Args:
-        keymap_file: path of the keymap.c file
+        keymap_file: path of the keymap.c file (or '-' to use stdin)
 
         use_cpp: if True, pre-process the file with the C pre-processor
 
     Returns:
         a dictionary containing the parsed keymap
     """
-    if use_cpp:
-        keymap_file = _c_preprocess(keymap_file)
+    if keymap_file == '-':
+        if use_cpp:
+            keymap_file = _c_preprocess(None, sys.stdin)
+        else:
+            keymap_file = sys.stdin.read()
     else:
-        keymap_file = keymap_file.read_text()
+        if use_cpp:
+            keymap_file = _c_preprocess(keymap_file)
+        else:
+            keymap_file = keymap_file.read_text()
 
     keymap = dict()
     keymap['layers'] = _get_layers(keymap_file)
diff --git a/lib/python/qmk/tests/test_cli_commands.py b/lib/python/qmk/tests/test_cli_commands.py
index ee8b1144c1..a8159c9c08 100644
--- a/lib/python/qmk/tests/test_cli_commands.py
+++ b/lib/python/qmk/tests/test_cli_commands.py
@@ -8,11 +8,20 @@ is_windows = 'windows' in platform.platform().lower()
 
 
 def check_subcommand(command, *args):
-    cmd = ['bin/qmk', command] + list(args)
+    cmd = ['bin/qmk', command, *args]
     result = run(cmd, stdout=PIPE, stderr=STDOUT, universal_newlines=True)
     return result
 
 
+def check_subcommand_stdin(file_to_read, command, *args):
+    """Pipe content of a file to a command and return output.
+    """
+    with open(file_to_read) as my_file:
+        cmd = ['bin/qmk', command, *args]
+        result = run(cmd, stdin=my_file, stdout=PIPE, stderr=STDOUT, universal_newlines=True)
+    return result
+
+
 def check_returncode(result, expected=[0]):
     """Print stdout if `result.returncode` does not match `expected`.
     """
@@ -129,6 +138,12 @@ def test_json2c():
     assert result.stdout == '#include QMK_KEYBOARD_H\nconst uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {\t[0] = LAYOUT_ortho_1x1(KC_A)};\n\n'
 
 
+def test_json2c_stdin():
+    result = check_subcommand_stdin('keyboards/handwired/onekey/keymaps/default_json/keymap.json', 'json2c', '-')
+    check_returncode(result)
+    assert result.stdout == '#include QMK_KEYBOARD_H\nconst uint16_t PROGMEM keymaps[][MATRIX_ROWS][MATRIX_COLS] = {\t[0] = LAYOUT_ortho_1x1(KC_A)};\n\n'
+
+
 def test_info():
     result = check_subcommand('info', '-kb', 'handwired/onekey/pytest')
     check_returncode(result)
@@ -186,6 +201,18 @@ def test_c2json_nocpp():
     assert result.stdout.strip() == '{"keyboard": "handwired/onekey/pytest", "documentation": "This file is a keymap.json file for handwired/onekey/pytest", "keymap": "default", "layout": "LAYOUT", "layers": [["KC_ENTER"]]}'
 
 
+def test_c2json_stdin():
+    result = check_subcommand_stdin("keyboards/handwired/onekey/keymaps/default/keymap.c", "c2json", "-kb", "handwired/onekey/pytest", "-km", "default", "-")
+    check_returncode(result)
+    assert result.stdout.strip() == '{"keyboard": "handwired/onekey/pytest", "documentation": "This file is a keymap.json file for handwired/onekey/pytest", "keymap": "default", "layout": "LAYOUT_ortho_1x1", "layers": [["KC_A"]]}'
+
+
+def test_c2json_nocpp_stdin():
+    result = check_subcommand_stdin("keyboards/handwired/onekey/keymaps/pytest_nocpp/keymap.c", "c2json", "--no-cpp", "-kb", "handwired/onekey/pytest", "-km", "default", "-")
+    check_returncode(result)
+    assert result.stdout.strip() == '{"keyboard": "handwired/onekey/pytest", "documentation": "This file is a keymap.json file for handwired/onekey/pytest", "keymap": "default", "layout": "LAYOUT", "layers": [["KC_ENTER"]]}'
+
+
 def test_clean():
     result = check_subcommand('clean', '-a')
     check_returncode(result)