From 78cd653ceec31878a428853a67841728c5b1bb8c Mon Sep 17 00:00:00 2001
From: Emery Hemingway <ehmry@posteo.net>
Date: Mon, 9 Oct 2023 17:20:01 +0100
Subject: [PATCH] Opportunistic ZIP fetching

---
 src/nim_lk.nim | 135 +++++++++++++++++++++----------------------------
 1 file changed, 58 insertions(+), 77 deletions(-)

diff --git a/src/nim_lk.nim b/src/nim_lk.nim
index 18fc92f..2b7f65f 100644
--- a/src/nim_lk.nim
+++ b/src/nim_lk.nim
@@ -22,15 +22,11 @@ proc registryCachePath: string =
       result = home / ".cache"
   result.add "/packages.json"
 
-func isGitUrl(uri: Uri): bool =
-  uri.path.endsWith(".git") or
-    uri.scheme == "git" or
-    uri.scheme.startsWith("git+")
-
-proc isWebGitForgeUrl(uri: Uri): bool =
-  case uri.hostname
-  of "github.com", "git.sr.ht", "codeberg.org": true
-  else: false
+proc isGitUrl(uri: Uri): bool =
+  uri.scheme == "git" or
+    uri.scheme.startsWith("git+") or
+    uri.path.endsWith(".git") or
+    uri.hostname.contains("git")
 
 proc startProcess(cmd: string; cmdArgs: varargs[string]): Process =
   # stderr.writeLine(cmd, " ", join(cmdArgs, " "))
@@ -107,64 +103,54 @@ proc prefetchGit(uri: Uri; version: VersionRange): JsonNode =
     if uri.query.startsWith("subdir="):
       subdir = uri.query[7 .. ^1]
     uri.query = ""
-  let url = $uri
-  let (tag, rev) = matchRev(url, version)
-  var args = @["--quiet", "--fetch-submodules", "--url", url, "--rev", rev]
-  stderr.writeLine "prefetch ", url
-  let dump = execProcess(
-    "nix-prefetch-git",
-    args = args,
-    options = {poUsePath})
-  try: result = parseJson dump
-  except JsonParsingError:
-    stderr.writeLine "failed to parse output of nix-prefetch-git ", join(args, " ")
-    quit(dump)
-  if subdir != "":
-    result["subdir"] = %* subdir
-  result["method"] = %"git"
-  if tag != "":
-    result["ref"] = %tag
-  collectMetadata(result)
-
-proc prefetchGitForge(uri: Uri; version: VersionRange): JsonNode =
-  result = newJObject()
-  var
-    uri = uri
-    subdir = ""
-  uri.scheme.removePrefix("git+")
-  if uri.query != "":
-    if uri.query.startsWith("subdir="):
-      subdir = uri.query[7 .. ^1]
-    uri.query = ""
-  var url = $uri
-  let (tag, rev) = matchRev(url, version)
-
-  uri.scheme = "https"
-  uri.path.removeSuffix(".git")
-  uri.path.add("/archive/")
-  uri.path.add(rev)
-  uri.path.add(".tar.gz")
-  url = $uri
-
-  stderr.writeLine "prefetch ", url
-  var lines = execProcess(
-    "nix-prefetch-url",
-    args = @[url, "--type", "sha256", "--print-path", "--unpack", "--name", "source"],
-    options = {poUsePath})
-  var
-    hash, storePath: string
-    off: int
-  off.inc parseUntil(lines, hash, {'\n'}, off).succ
-  off.inc parseUntil(lines, storePath, {'\n'}, off).succ
-  doAssert off == lines.len, "unrecognized nix-prefetch-url output:\n" & lines
-
-  result["method"] = %"fetchzip"
-  result["path"] = %storePath
-  result["rev"] = %rev
-  result["sha256"] = %hash
-  result["url"] = %url
-  if subdir != "":
-    result["subdir"] = %* subdir
+  let cloneUrl = $uri
+  let (tag, rev) = matchRev(cloneUrl, version)
+  var archiveUri = uri
+  archiveUri.scheme = "https"
+  archiveUri.path.removeSuffix ".git"
+  archiveUri.path.add "/archive/"
+  archiveUri.path.add rev
+  archiveUri.path.add ".tar.gz"
+  let client = newHttpClient()
+  defer: close(client)
+  let
+    archiveUrl = $archiveUri
+    resp = head(client, archiveUrl)
+  if resp.code in {Http200, Http302}:
+    stderr.writeLine "prefetch ", archiveUrl
+    var lines = execProcess(
+      "nix-prefetch-url",
+      args = @[archiveUrl, "--type", "sha256", "--print-path", "--unpack", "--name", "source"],
+      options = {poUsePath})
+    var
+      hash, storePath: string
+      off: int
+    off.inc parseUntil(lines, hash, {'\n'}, off).succ
+    off.inc parseUntil(lines, storePath, {'\n'}, off).succ
+    doAssert off == lines.len, "unrecognized nix-prefetch-url output:\n" & lines
+    result = newJObject()
+    result["method"] = %"fetchzip"
+    result["path"] = %storePath
+    result["rev"] = %rev
+    result["sha256"] = %hash
+    result["url"] = %archiveUrl
+    if subdir != "":
+      result["subdir"] = %* subdir
+  else:
+    stderr.writeLine "fetch of ", archiveUrl, " returned ", resp.code
+    var args = @["--quiet", "--fetch-submodules", "--url", cloneUrl, "--rev", rev]
+    stderr.writeLine "prefetch ", cloneUrl
+    let dump = execProcess(
+      "nix-prefetch-git",
+      args = args,
+      options = {poUsePath})
+    try: result = parseJson dump
+    except JsonParsingError:
+      stderr.writeLine "failed to parse output of nix-prefetch-git ", join(args, " ")
+      quit(dump)
+    if subdir != "":
+      result["subdir"] = %* subdir
+    result["method"] = %"git"
   if tag != "":
     result["ref"] = %tag
   collectMetadata(result)
@@ -237,9 +223,7 @@ proc generateLockfile(): JsonNode =
         if not deps.containsPackage(pkg.name):
           pending.addLast(pkg)
       elif not deps.containsPackageUri(pkg.name):
-        if uri.isWebGitForgeUrl:
-          pkgData = prefetchGitForge(uri, pkg.ver)
-        elif uri.isGitUrl:
+        if uri.isGitUrl:
           pkgData = prefetchGit(uri, pkg.ver)
         else:
           quit("unhandled URI " & $uri)
@@ -252,14 +236,11 @@ proc generateLockfile(): JsonNode =
         pkg = pending.popFirst()
         info = getPackgeUri(pkg.name)
         uri = parseUri info.uri
-      if uri.isWebGitForgeUrl:
-        pkgData = prefetchGitForge(uri, pkg.ver)
+      case info.meth
+      of "git":
+        pkgData = prefetchGit(uri, pkg.ver)
       else:
-        case info.meth
-        of "git":
-          pkgData = prefetchGit(uri, pkg.ver)
-        else:
-          quit("unhandled fetch method " & $info.meth & " for " & info.uri)
+        quit("unhandled fetch method " & $info.meth & " for " & info.uri)
       collectRequires(pending, pkgData["path"].getStr)
       deps.add pkgData
   sort(deps.elems)