Make condax install idempotent

.pre-commit-config.yaml

@@ -1,14 +1,14 @@
 minimum_pre_commit_version: '2.9.0'
 repos:
 - repo: https://github.com/Zac-HD/shed
-  rev: 0.10.5
+  rev: 2024.3.1
   hooks:
     - id: shed
       # args: [--refactor, --py39-plus]
       types_or: [python, markdown, rst]
 
 - repo: https://github.com/pre-commit/mirrors-mypy
-  rev: v0.982
+  rev: v1.11.0
   hooks:
   - id: mypy
     additional_dependencies: [types-requests, types-PyYAML]

condax/activation.py

@@ -2,7 +2,7 @@
 
 
 def write_activating_entrypoint_unix(executable, prefix):
-    template = dedent(
+    dedent(
         f"""
         #!/bin/sh
         export PATH="$PATH:{prefix}/bin"
@@ -14,7 +14,7 @@ def write_activating_entrypoint_unix(executable, prefix):
 
 def write_activating_entrypoint_windows(executable, prefix):
     # TODO: Verify if this is right?
-    template = dedent(
+    dedent(
         f"""
         SET PATH="%PATH%;{prefix}\\Library\\bin;{prefix}\\Scripts"
 

condax/conda.py

@@ -1,3 +1,4 @@
+import enum
 import json
 import logging
 import os
@@ -28,9 +29,17 @@ def write_condarc_to_prefix(
         fo.write("\n")
 
 
+class CreateResult(enum.Enum):
+    CREATED = enum.auto()
+    ALREADY_EXISTS = enum.auto()
+
+
 def create_conda_environment(
     package: str, channels: Optional[List[str]] = None
-) -> None:
+) -> CreateResult:
+    if conda_environment_exists(package):
+        return CreateResult.ALREADY_EXISTS
+
     conda_exe = CONFIG.conda_executable
     assert conda_exe is not None
     prefix = conda_env_prefix(package)
@@ -56,6 +65,12 @@ def create_conda_environment(
     )
 
     write_condarc_to_prefix(prefix, channels)
+    return CreateResult.CREATED
+
+
+def conda_environment_exists(package: str):
+    prefix = conda_env_prefix(package)
+    return prefix.exists()
 
 
 def install_conda_packages(

condax/core.py

@@ -172,7 +172,14 @@ def install_package(
 ) -> None:
     if channels is None:
         channels = CONFIG.channels
-    conda.create_conda_environment(package, channels=channels)
+    res = conda.create_conda_environment(package, channels=channels)
+    if res == conda.CreateResult.ALREADY_EXISTS:
+        typer.secho(
+            f"`{package}` already installed, skipping installation",
+            err=True,
+            fg=typer.colors.YELLOW,
+        )
+        return
     executables_to_link = conda.determine_executables_from_env(package)
     CONFIG.link_destination.mkdir(parents=True, exist_ok=True)
     create_links(
@@ -205,12 +212,12 @@ def inject_packages(
             CONFIG.link_destination.mkdir(parents=True, exist_ok=True)
             create_links(executables_to_link, link_conflict_action, env_prefix=prefix)
     with prefix_metadata(prefix) as metadata:
-        metadata.injected_packages = list(
-            sorted(set(metadata.injected_packages) | set(extra_packages))
+        metadata.injected_packages = sorted(
+            set(metadata.injected_packages) | set(extra_packages)
         )
         if include_apps:
-            metadata.injected_packages_with_apps = list(
-                sorted(set(metadata.injected_packages_with_apps) | set(extra_packages))
+            metadata.injected_packages_with_apps = sorted(
+                set(metadata.injected_packages_with_apps) | set(extra_packages)
             )
 
     typer.secho(