Add flag for specifying NSIS template

This allows specifying a external file instead of only using
the built-in file generic.nsi.j2
Usage: `--template=builtin:generic.nsi.j2` (default)
or `--template=any/readable/file.nsi.j2`

Author: oddstr13

syrup/__main__.py

@@ -4,6 +4,7 @@
 import click
 
 from .functions import (
+    DEFAULT_NSIS_TEMPLATE,
     cleanArtifacts,
     cleanBuild,
     copySrc,
@@ -37,8 +38,19 @@ def clean(build_dir, artifact_dir, clean_artifacts, **kwargs):
 def validate_version(ctx, param, value):
     try:
         return Version(*[int(x) if x else 0 for x in value.split(".")])
-    except:
-        raise click.BadParameter("version must be in major.minor.build format. (1.0.0)")
+    except Exception as ex:
+        raise click.BadParameter(
+            "version must be in major.minor.build format. (1.0.0)"
+        ) from ex
+
+
+def validate_template(ctx, param, value):
+    if value.startswith("builtin:"):
+        return value
+
+    return click.Path(
+        exists=True, resolve_path=True, readable=True, file_okay=True, dir_okay=False
+    )(value=value, param=param, ctx=ctx)
 
 
 @cli.command()
@@ -118,6 +130,12 @@ def validate_version(ctx, param, value):
     "--website-url",
     help="Website(about) URL to display in 'Add/Remove Programs'. mailto: is allowed.",
 )
+@click.option(
+    "--template",
+    help="Jinja2 NSIS Template",
+    default=DEFAULT_NSIS_TEMPLATE,
+    callback=validate_template,
+)
 @click.pass_context
 def build(
     ctx,
@@ -135,6 +153,7 @@ def build(
     help_url,
     update_url,
     website_url,
+    template,
     executable,
     postinstall,
 ):
@@ -153,6 +172,7 @@ def build(
         build_dir=build_dir,
         artifact_dir=artifact_dir,
         executables=executable,
+        template_name=template,
         version=version,
         icon=icon,
         license=license,

syrup/functions.py

@@ -271,15 +271,34 @@ def makeIco(icon, name, build_dir):
     return fn
 
 
-def compileNSISTemplate(build_dir, artifact_dir, executables, **kwargs):
+DEFAULT_NSIS_TEMPLATE = "builtin:generic.nsi.j2"
+
+
+def compileNSISTemplate(
+    build_dir,
+    artifact_dir,
+    executables,
+    template_name=DEFAULT_NSIS_TEMPLATE,
+    **kwargs,
+):
     "Generates NSIS script from jinja2 template"
     print("Generating NSIS script...")
-    loader = jinja2.PackageLoader(__package__)
+    loader = jinja2.ChoiceLoader(
+        [
+            jinja2.PrefixLoader(
+                {
+                    "builtin": jinja2.PackageLoader(__package__),
+                },
+                delimiter=":",
+            ),
+            jinja2.FileSystemLoader("/", followlinks=True),
+        ]
+    )
     env = jinja2.Environment(
         loader=loader, autoescape=False, undefined=jinja2.StrictUndefined
     )
 
-    template = env.get_template("generic.nsi.j2")
+    template = env.get_template(template_name)
 
     install_files = []
     install_dirs = []
@@ -320,7 +339,7 @@ def compileNSISTemplate(build_dir, artifact_dir, executables, **kwargs):
     }
     template_variables.update(kwargs)
 
-    nsis_script = os.path.join(build_dir, "generic.nsi")
+    nsis_script = os.path.join(build_dir, "syrup.nsi")
     with open(nsis_script, "w", encoding="UTF-8") as fh:  # TODO: Temp file name.
         template.stream(**template_variables).dump(fh)
     return nsis_script