Merge pull request #16 from mundialis/tmp_location

Add functions to create a new temporary location

src/grass_gis_helpers/cleanup.py

@@ -21,7 +21,7 @@
 import gc
 
 import grass.script as grass
-from .location import get_location_size
+from .location import get_location_size, switch_back_original_location
 
 
 def general_cleanup(
@@ -118,3 +118,22 @@ def reset_region(region):
         if grass.find_file(name=region, element="windows")["file"]:
             grass.run_command("g.region", region=region)
             grass.run_command("g.remove", type="region", name=region, **kwargs)
+
+
+def cleaning_tmp_location(original_gisrc, tmp_loc, gisdbase, tmp_gisrc):
+    """Cleaning up things from temporary location
+
+    Args:
+        original_gisrc (str): The path to the original GISRC file
+        tmp_loc (str): The name of the temporary location
+        gisdbase (str): The GISDBASE info
+        tmp_gisrc (str): The path to the temporary GISRC file
+    """
+    # switch back to original gisrc
+    if original_gisrc:
+        switch_back_original_location(original_gisrc)
+    # remove temporary location
+    if tmp_loc:
+        grass.try_rmdir(os.path.join(gisdbase, tmp_loc))
+    if tmp_gisrc:
+        grass.try_remove(tmp_gisrc)

src/grass_gis_helpers/location.py

@@ -4,7 +4,7 @@
 #
 # MODULE:       lib with location related helper functions for GRASS GIS
 #
-# AUTHOR(S):    Lina Krisztian
+# AUTHOR(S):    Lina Krisztian, Anika Weinmann
 #
 # PURPOSE:      lib with location related helper functions for GRASS GIS
 #
@@ -16,6 +16,7 @@
 #
 #############################################################################
 
+import os
 import subprocess
 
 import grass.script as grass
@@ -35,3 +36,76 @@ def get_location_size():
             ),
         )
     )
+
+
+def create_tmp_location(epsg=4326):
+    """Creation of a new temporary location
+
+    Args:
+        epsg (int): The number of the EPSG code
+
+    Returns:
+        tmp_loc (str): The name of the temporary location
+        tmp_gisrc (str): The path to the original GISRC file
+    """
+    current_gisdbase = grass.gisenv()["GISDBASE"]
+    srcgisrc = grass.tempfile()
+    tmp_loc = f"temp_epsg{epsg}_location_{os.getpid()}"
+    gisrc_file = open(srcgisrc, "w")
+    gisrc_file.write("MAPSET: PERMANENT\n")
+    gisrc_file.write(f"GISDBASE: {current_gisdbase}\n")
+    gisrc_file.write(f"LOCATION_NAME: {tmp_loc}\n")
+    gisrc_file.write("GUI: text\n")
+    gisrc_file.close()
+
+    proj_test = grass.parse_command("g.proj", flags="g")
+    if "epsg" in proj_test:
+        epsg_arg = {"epsg": epsg}
+    else:
+        epsg_arg = {"srid": f"EPSG:{epsg}"}
+    # create temp location from input without import
+    grass.verbose(_(f"Creating temporary location with EPSG:{epsg}..."))
+    grass.run_command(
+        "g.proj", flags="c", location=tmp_loc, quiet=True, **epsg_arg
+    )
+
+    # switch to temp location
+    os.environ["GISRC"] = str(srcgisrc)
+    proj = grass.parse_command("g.proj", flags="g")
+    if "epsg" in proj:
+        new_epsg = proj["epsg"]
+    else:
+        new_epsg = proj["srid"].split("EPSG:")[1]
+    if new_epsg != str(epsg):
+        grass.fatal(_("Creation of temporary location failed!"))
+
+    return tmp_loc, srcgisrc
+
+
+def get_current_location():
+    """Get infos to current location
+
+    Returns:
+        loc (str): The name of the current location
+        mapset (str): The name of the current mapset
+        gisdbase (str): The current GISDBASE info
+        gisrc (str): The path to the current GISRC file
+    """
+    # get current location, mapset, ...
+    grassenv = grass.gisenv()
+    loc = grassenv["LOCATION_NAME"]
+    mapset = grassenv["MAPSET"]
+    gisdbase = grassenv["GISDBASE"]
+    gisrc = os.environ["GISRC"]
+    return loc, mapset, gisdbase, gisrc
+
+
+def switch_back_original_location(original_gisrc):
+    """Switching back to original location after the computation in tmp
+    location
+
+    Args:
+        original_gisrc (str): The path to the original GISRC file
+    """
+    # switch to target location
+    os.environ["GISRC"] = str(original_gisrc)