core: add an Arch type (MR 2252)

Move pmb/parse/arch.py over to core and refactor it as an Arch type,
similar to how Chroot was done. Fix all the uses (that I can find) of
arch in the codebase that need adjusting.

The new Arch type is an Enum, making it clear what architectures can be
represented and making it much easier to reason about. Since we support
~5 (kinda) different representations of an Architecture (Alpine, Kernel,
target triple, platform, and QEMU), we now formalise that the Alpine
format is what we represent internally, with methods to convert to any
of the others as-needed.

Signed-off-by: Caleb Connolly <caleb@postmarketos.org>

pmb/helpers/repo.py

@@ -10,10 +10,11 @@ See also:
 import os
 import hashlib
 from pmb.core import get_context
+from pmb.core.arch import Arch
 from pmb.core.pkgrepo import pkgrepo_paths
 from pmb.helpers import logging
 from pathlib import Path
-from typing import List
+from typing import List, Optional
 
 import pmb.config.pmaports
 from pmb.types import PmbArgs
@@ -69,7 +70,6 @@ def urls(user_repository=True, postmarketos_mirror=True, alpine=True):
 
     # Local user repository (for packages compiled with pmbootstrap)
     if user_repository:
-        channel = pmb.config.pmaports.read_config()["channel"]
         # FIXME: We shouldn't hardcod this here
         for channel in pmb.config.pmaports.all_channels():
             ret.append(f"/mnt/pmbootstrap/packages/{channel}")
@@ -98,7 +98,7 @@ def urls(user_repository=True, postmarketos_mirror=True, alpine=True):
     return ret
 
 
-def apkindex_files(arch=None, user_repository=True, pmos=True,
+def apkindex_files(arch: Optional[Arch]=None, user_repository=True, pmos=True,
                    alpine=True) -> List[Path]:
     """Get a list of outside paths to all resolved APKINDEX.tar.gz files for a specific arch.
 
@@ -109,7 +109,7 @@ def apkindex_files(arch=None, user_repository=True, pmos=True,
     :returns: list of absolute APKINDEX.tar.gz file paths
     """
     if not arch:
-        arch = pmb.config.arch_native
+        arch = Arch.native()
 
     ret = []
     # Local user repository (for packages compiled with pmbootstrap)
@@ -144,7 +144,7 @@ def update(arch=None, force=False, existing_only=False):
         return False
 
     # Architectures and retention time
-    architectures = [arch] if arch else pmb.config.build_device_architectures
+    architectures = [arch] if arch else Arch.supported()
     retention_hours = pmb.config.apkindex_retention_time
     retention_seconds = retention_hours * 3600
 
@@ -152,13 +152,13 @@ def update(arch=None, force=False, existing_only=False):
     # outdated: {URL: apkindex_path, ... }
     # outdated_arches: ["armhf", "x86_64", ... ]
     outdated = {}
-    outdated_arches = []
+    outdated_arches: List[Arch] = []
     for url in urls(False):
         for arch in architectures:
             # APKINDEX file name from the URL
-            url_full = url + "/" + arch + "/APKINDEX.tar.gz"
+            url_full = f"{url}/{arch}/APKINDEX.tar.gz"
             cache_apk_outside = get_context().config.work / f"cache_apk_{arch}"
-            apkindex = cache_apk_outside / f"APKINDEX.{apkindex_hash(url)}.tar.gz"
+            apkindex = cache_apk_outside / f"{apkindex_hash(url)}.tar.gz"
 
             # Find update reason, possibly skip non-existing or known 404 files
             reason = None
@@ -186,7 +186,7 @@ def update(arch=None, force=False, existing_only=False):
     # Bail out or show log message
     if not len(outdated):
         return False
-    logging.info("Update package index for " + ", ".join(outdated_arches) +
+    logging.info("Update package index for " + ", ".join([str(a) for a in outdated_arches]) +
                  " (" + str(len(outdated)) + " file(s))")
 
     # Download and move to right location
@@ -206,7 +206,7 @@ def update(arch=None, force=False, existing_only=False):
     return True
 
 
-def alpine_apkindex_path(repo="main", arch=None):
+def alpine_apkindex_path(repo="main", arch: Optional[Arch]=None):
     """Get the path to a specific Alpine APKINDEX file on disk and download it if necessary.
 
     :param repo: Alpine repository name (e.g. "main")
@@ -215,10 +215,10 @@ def alpine_apkindex_path(repo="main", arch=None):
     """
     # Repo sanity check
     if repo not in ["main", "community", "testing", "non-free"]:
-        raise RuntimeError("Invalid Alpine repository: " + repo)
+        raise RuntimeError(f"Invalid Alpine repository: {repo}")
 
     # Download the file
-    arch = arch or pmb.config.arch_native
+    arch = arch or Arch.native()
     update(arch)
 
     # Find it on disk