Add CLI

README.rst

@@ -248,4 +248,4 @@ Todos and future features
   - Maybe just give a style method ?
 - Add tests
 - Add the option to force all rows to contain an even number of seats
-- Add a CLI for SVG files generation
+- Add a simpler way to input parameters in CLI

src/parliamentarch/__main__.py

@@ -0,0 +1,64 @@
+import argparse
+import json
+import sys
+
+from . import get_svg_from_attribution, SeatData
+
+def main():
+    # return None (or nothing) is good
+    # return a non-zero integer or an error message for an error
+
+    parser = argparse.ArgumentParser(
+        prog="ParliamentArch",
+        description="Generate arch-like parliament diagrams.",
+    )
+
+    # input filename (json)
+    parser.add_argument("input",
+        type=argparse.FileType("rb"),
+        help="""A readable JSON file containing the named parameters to use when
+        creating the diagram. The parameters are as the get_svg_from_attribution
+        function takes them, except that the "attrib" parameter should be a
+        sequence of dicts (JSON objects) with key/value pairs being parameters
+        to SeatData, and the optional nseats (defaulting to 1) being the number
+        of seats of that party.""",
+    )
+    # each possible parameter separately ?
+    # TODO do this programmatically using inspect
+    # only require input if not all required are passed specifically
+
+    # output filename
+    parser.add_argument("--output",
+        type=argparse.FileType("w+"), # TODO check : write mode, clobber if exists, create if not
+        help="""The file in which to write the SVG diagram. If not passed, the
+        SVG code will be printed in the standard output.""",
+        # TODO: make sure that this argument is optional and defaults to None
+    )
+    # whether to print the resulting file's content (when the output file is not given)
+    parser.add_argument("-p", "--print",
+        action="store_true",
+        help="""Pass this to print the SVG code in the standard output even when
+        an output file is passed.""",
+    )
+    # if both are given, do both
+    # if none are given, only print
+
+
+    args = parser.parse_args()
+
+    with args.input as f:
+        kwparams = json.load(f)
+    kwparams["attrib"] = {SeatData(**d): n for d in kwparams["attrib"] if (n := d.pop("nseats", 1))}
+
+    result = get_svg_from_attribution(**kwparams)
+
+    file_output = args.output is not None
+    if file_output:
+        with args.output as f:
+            f.write(result)
+    if args.print or not file_output:
+        print(result)
+
+
+if __name__ == "__main__":
+    sys.exit(main())