From fb6447ce2f25c4cfbe99c64f9141df20533ed676 Mon Sep 17 00:00:00 2001
From: David Arnold <dgx.arnold@gmail.com>
Date: Sat, 2 Mar 2024 00:25:23 +0100
Subject: [PATCH] wip: impl nix expr writer

---
 nvchecker/__main__.py |   3 ++
 nvchecker/core.py     | 105 +++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 107 insertions(+), 1 deletion(-)

diff --git a/nvchecker/__main__.py b/nvchecker/__main__.py
index 09a3ce44..d849a13c 100755
--- a/nvchecker/__main__.py
+++ b/nvchecker/__main__.py
@@ -91,6 +91,9 @@ def main() -> None:
     vers.update(newvers)
     core.write_verfile(newverf, vers)
 
+  if options.nix_expr_folder is not None:
+    core.write_nix_expr_files(options, results)
+
   if args.failures and has_failures:
     sys.exit(3)
 
diff --git a/nvchecker/core.py b/nvchecker/core.py
index cb8805f2..fd981b14 100644
--- a/nvchecker/core.py
+++ b/nvchecker/core.py
@@ -8,6 +8,7 @@
 import asyncio
 from asyncio import Queue
 import logging
+import subprocess
 import argparse
 from typing import (
   Tuple, NamedTuple, Optional, List, Union,
@@ -20,6 +21,8 @@
 import re
 import contextvars
 import json
+import string
+import urllib
 
 import structlog
 
@@ -153,6 +156,99 @@ def write_verfile(file: Path, versions: VersData) -> None:
   ) + '\n'
   safe_overwrite(file, data)
 
+def lock_source_nix(type: str, ref: str, target: str) -> str:
+  if type in ["github", "gitlab"]:
+    owner, _, repo = target.rpartition("/")
+    owner = urllib.parse.quote_plus(owner)
+    ref = urllib.parse.quote_plus(ref)
+    fetchtree = f'type = "{type}"; owner = "{owner}"; repo = "{repo}"; ref = "{ref}";'
+    nix = (
+      f'owner = "{owner}";'
+      f' repo = "{repo}";'
+    )
+  if type in ["git"]:
+    url = target
+    fetchtree = f'type = "{type}"; url = "{url}"; ref = "{ref}"; shallow = true;'
+    nix = (
+      f'url = "{url}";'
+    )
+
+  command = [
+    'nix',
+    'eval',
+    '--impure',
+    '--json',
+    '--expr',
+    # removing outPath ensures the stringer renders the entire attrset
+    'builtins.removeAttrs (builtins.fetchTree {' + fetchtree + '}) ["outPath"]'
+  ]
+  tmpl = string.Template("""
+    type = "$type";
+    $nix
+    narHash = "$narHash";
+    rev = "$rev";""")
+  try:
+    result = subprocess.run(command, check=True, capture_output=True, text=True)
+    output = json.loads(result.stdout)
+    return tmpl.substitute(type=type, nix=nix, **output)
+  except subprocess.CalledProcessError as e:
+    error_message = "Locking the source in nix failed; stderr from the nix command: \n"
+    error_message += e.stderr
+    logger.error(error_message, type=type, ref=ref)
+    raise e
+
+def write_nix_expr_files(opt: Options, results: List[Result]) -> None:
+  oldvers = {}
+  if opt.ver_files is not None:
+    oldverf = opt.ver_files[0]
+    newverf = opt.ver_files[1]
+    oldvers = read_verfile(oldverf)
+    newvers = read_verfile(newverf)
+
+  names = []
+  tmpl = string.Template("""
+  pname = "$name";
+  version = "$version";
+  meta = {
+    url = "$url";
+    description = "Sources for $name ($version)";
+  };
+  src = builtins.fetchTree {$fetchTreeArgs
+  };
+  passthru = builtins.fromJSON ''$passthru'';""")
+  for r in results:
+    oldver = oldvers.get(r.name, None)
+    if not oldver or oldver != r.version:
+      file = opt.nix_expr_folder / (r.name + ".nix")
+      logger.info("update nix", name=r.name, file=file)
+      type = r.conf.get("source")
+      target = r.conf.get(type)
+      ref = r.gitref or r.revision or r.version
+      try:
+        fetchTreeArgs=lock_source_nix(type, ref, target)
+      except:
+        continue
+      data = '{'
+      data += tmpl.substitute(
+        name=r.name,
+        version=r.version,
+        url=r.url,
+        fetchTreeArgs=fetchTreeArgs,
+        passthru=json.dumps(r.conf.get("passthru", {})),
+      )
+      data += '\n}'
+      safe_overwrite(file, data)
+      names.append(r.name)
+
+  if opt.ver_files is not None:
+    for name in names:
+      try:
+        oldvers[name] = newvers[name]
+      except KeyError:
+          logger.warning('nonexistent in newver, ignored', name=name)
+          continue
+    write_verfile(oldverf, oldvers)
+
 class Options(NamedTuple):
   ver_files: Optional[Tuple[Path, Path]]
   max_concurrency: int
@@ -161,6 +257,7 @@ class Options(NamedTuple):
   source_configs: Dict[str, Dict[str, Any]]
   httplib: Optional[str]
   http_timeout: int
+  nix_expr_folder: Optional[Path]
 
 def load_file(
   file: str, *,
@@ -175,6 +272,7 @@ def load_file(
   ver_files: Optional[Tuple[Path, Path]] = None
   keymanager = KeyManager(None)
   source_configs = {}
+  nix_expr_folder: Optional[Path] = None
 
   if '__config__' in config:
     c = config.pop('__config__')
@@ -189,6 +287,11 @@ def load_file(
       newver = d / newver_s
       ver_files = oldver, newver
 
+    if 'nix-expr-folder' in c:
+      nix_expr_s = os.path.expandvars(
+        os.path.expanduser(c.get('nix-expr-folder')))
+      nix_expr_folder = d / nix_expr_s
+
     if use_keymanager:
       keyfile = c.get('keyfile')
       if keyfile:
@@ -212,7 +315,7 @@ def load_file(
 
   return cast(Entries, config), Options(
     ver_files, max_concurrency, proxy, keymanager,
-    source_configs, httplib, http_timeout,
+    source_configs, httplib, http_timeout, nix_expr_folder,
   )
 
 def setup_httpclient(