tree-sitter: partially rewrite update script in python

The update script is getting out of hand, so we should rewrite it in
something that resembles sanity, i.e. Python

This is the first step, rewriting the part that checks and fetches a
release.

Next up is integrating latestGithubRepos into that script.

pkgs/development/tools/parsing/tree-sitter/default.nix

@@ -28,7 +28,7 @@ let
   # to update:
   # 1) change all these hashes
   # 2) nix-build -A tree-sitter.updater.update-all-grammars
-  # 3) OPTIONAL: Set GITHUB_TOKEN env variable to avoid api rate limit
+  # 3) Set GITHUB_TOKEN env variable to avoid api rate limit (Use a Personal Access Token from https://github.com/settings/tokens It does not need any permissions)
   # 4) run the ./result script that is output by that (it updates ./grammars)
   version = "0.20.7";
   sha256 = "sha256-5ILiN5EfJ7WpeYBiXynfcLucdp8zmxVOj4gLkaFQYts=";
@@ -42,8 +42,8 @@ let
     fetchSubmodules = true;
   };
 
-  update-all-grammars = import ./update.nix {
-    inherit writeShellScript nix-prefetch-git curl jq xe src formats lib;
+  update-all-grammars = callPackage ./update.nix {
+    inherit src;
   };
 
   fetchGrammar = (v: fetchgit { inherit (v) url rev sha256 fetchSubmodules; });

pkgs/development/tools/parsing/tree-sitter/update.nix

@@ -1,7 +1,10 @@
 { writeShellScript
+, writeText
+, writers
 , nix-prefetch-git
 , formats
 , lib
+, coreutils
 , curl
 , jq
 , xe
@@ -404,28 +407,80 @@ let
   # TODO
   urlEscape = x: x;
 
-  # generic bash script to find the latest github release for a repo
-  latestGithubRelease = { orga, repo }: writeShellScript "latest-github-release" ''
-    set -euo pipefail
+  # update one tree-sitter grammar repo and print their nix-prefetch-git output
+  updateGrammar = writers.writePython3 "latest-github-release" {
+    flakeIgnore = ["E501"];
+  } ''
+    from urllib.parse import quote
+    import json
+    import subprocess as sub
+    import os
+    import sys
 
-    args=( '--silent' )
-    if [ -n "''${GITHUB_TOKEN:-}" ]; then
-      args+=( "-H" "Authorization: token ''${GITHUB_TOKEN}" )
-    fi
-    args+=( "https://api.github.com/repos/${urlEscape orga}/${urlEscape repo}/releases/latest" )
+    debug = True if os.environ.get("DEBUG", False) else False
 
-    res=$(${curl}/bin/curl "''${args[@]}")
+    jsonArg = sys.argv[1]
 
-    if [[ "$(printf "%s" "$res" | ${jq}/bin/jq '.message?')" =~ "rate limit" ]]; then
-      echo "rate limited" >&2
-    fi
-    release="$(printf "%s" "$res" | ${jq}/bin/jq -r '.tag_name' | tr -d \")"
-    # github sometimes returns an empty list even tough there are releases
-    if [ "$release" = "null" ]; then
-      echo "uh-oh, latest for ${orga + "/" + repo} is not there, using HEAD" >&2
-      release="HEAD"
-    fi
-    echo "$release"
+
+    def curl_args(orga, repo, token):
+        """Query the github API via curl"""
+        yield "curl"
+        if not debug:
+            yield "--silent"
+        if token:
+            yield "-H"
+            yield f"Authorization: token {token}"
+        yield f"https://api.github.com/repos/{quote(orga)}/{quote(repo)}/releases/latest"
+
+
+    def curl_result(orga, repo, output):
+        """Parse the curl result of the github API"""
+        res = json.loads(output)
+        message = res.get("message", "")
+        if "rate limit" in message:
+            sys.exit("Rate limited by the Github API")
+        if "Not Found" in message:
+            # repository not there or no releases; if the repo is missing,
+            # we’ll notice when we try to clone it
+            return {}
+        return res
+
+
+    def nix_prefetch_args(url, version_rev):
+        """Prefetch a git repository"""
+        yield "nix-prefetch-git"
+        if not debug:
+            yield "--quiet"
+        yield "--no-deepClone"
+        yield "--url"
+        yield url
+        yield "--rev"
+        yield version_rev
+
+
+    match json.loads(jsonArg):
+        case {"orga": orga, "repo": repo}:
+            token = os.environ.get("GITHUB_TOKEN", None)
+            curl_cmd = list(curl_args(orga, repo, token))
+            if debug:
+                print(curl_cmd, file=sys.stderr)
+            out = sub.check_output(curl_cmd)
+            release = curl_result(orga, repo, out).get("tag_name", None)
+
+            # github sometimes returns an empty list even tough there are releases
+            if not release:
+                print(f"uh-oh, latest for {orga}/{repo} is not there, using HEAD", file=sys.stderr)
+                release = "HEAD"
+
+            print(f"Fetching latest release ({release}) of {orga}/{repo} …", file=sys.stderr)
+            sub.check_call(
+                list(nix_prefetch_args(
+                    url=f"https://github.com/{quote(orga)}/{quote(repo)}",
+                    version_rev=release
+                ))
+            )
+        case _:
+            sys.exit("input json must have `orga` and `repo` keys")
   '';
 
   # find the latest repos of a github organization
@@ -452,18 +507,6 @@ let
       || echo "failed $res"
   '';
 
-  # update one tree-sitter grammar repo and print their nix-prefetch-git output
-  updateGrammar = { orga, repo }: writeShellScript "update-grammar.sh" ''
-    set -euo pipefail
-    latest="$(${latestGithubRelease { inherit orga repo; }})"
-    echo "Fetching latest release ($latest) of ${repo} …" >&2
-    ${nix-prefetch-git}/bin/nix-prefetch-git \
-      --quiet \
-      --no-deepClone \
-      --url "https://github.com/${urlEscape orga}/${urlEscape repo}" \
-      --rev "$latest"
-  '';
-
   foreachSh = attrs: f:
     lib.concatMapStringsSep "\n" f
       (lib.mapAttrsToList (k: v: { name = k; } // v) attrs);
@@ -478,7 +521,10 @@ let
     echo "writing files to $outputDir" 1>&2
     mkdir -p "$outputDir"
     ${foreachSh allGrammars
-      ({name, orga, repo}: ''${updateGrammar { inherit orga repo; }} > $outputDir/${name}.json'')}
+      ({name, orga, repo}: ''
+        ${updateGrammar} '${lib.generators.toJSON {} {inherit orga repo;}}' \
+          > $outputDir/${name}.json
+      '')}
     ( echo "{ lib }:"
       echo "{"
       ${foreachSh allGrammars