Filter input files according to Veda (#231)

This PR filters input files according to Veda in case just an input
folder is specified (and not a list of input files).

xl2times/__main__.py

@@ -454,6 +454,8 @@ def run(args: argparse.Namespace) -> str | None:
             for path in Path(args.input[0]).rglob("*")
             if path.suffix in [".xlsx", ".xlsm"] and not path.name.startswith("~")
         ]
+        if utils.is_veda_based(input_files):
+            input_files = utils.filter_veda_filename_patterns(input_files)
         logger.info(f"Loading {len(input_files)} files from {args.input[0]}")
     else:
         input_files = args.input

xl2times/utils.py

@@ -12,7 +12,7 @@
 from collections.abc import Iterable
 from dataclasses import replace
 from math import floor, log10
-from pathlib import Path
+from pathlib import Path, PurePath
 
 import loguru
 import numpy
@@ -315,6 +315,57 @@ def round_sig(x, sig_figs):
 default_log_name = "log" if default_log_name == "" else default_log_name
 
 
+def _case_insensitive_match(path: str, pattern: str) -> bool:
+    """Do case-insensitive path match. Convert to lowercase first, because
+    case_sensitive parameter in match is not available before Python 3.12.
+    """
+    return PurePath(path.lower()).match(pattern.lower())
+
+
+def is_veda_based(files: list[str]) -> bool:
+    """Determine whether the model follows Veda file structure.
+    This function does not verify file extensions.
+    """
+    marker = "SysSettings.*"
+
+    matches = [file for file in files if _case_insensitive_match(file, marker)]
+
+    if len(matches) == 1:
+        return True
+    elif len(matches) > 1:
+        raise ValueError(f"Only one {marker} expected. Multiple detected: {matches}")
+    else:
+        return False
+
+
+def filter_veda_filename_patterns(files: list[str]) -> list[str]:
+    """Filter files by patterns recognised by Veda.
+    This function does not verify file extensions.
+    """
+    legal_paths = (
+        "BY_Trans.*",
+        "LMA*.*",
+        "Set*.*",
+        "SysSettings.*",
+        "VT_*.*",
+        "SubRES_TMPL/SubRES_*.*",
+        "SuppXLS/Demands/Dem_Alloc+Series.*",
+        "SuppXLS/Demands/ScenDem_*.*",
+        "SuppXLS/ParScenFiles/Scen_Par-*.*",
+        "SuppXLS/Scen_*.*",
+        "SuppXLS/Trades/ScenTrade_*.*",
+    )
+    # Generate a set of fiels that match the patterns
+    filtered = {
+        file
+        for file in files
+        for legal_path in legal_paths
+        if _case_insensitive_match(file, legal_path)
+    }
+    # Return as a list
+    return list(filtered)
+
+
 def get_logger(log_name: str = default_log_name, log_dir: str = ".") -> loguru.Logger:
     """Return a configured loguru logger.