Install more conventionally

The current move script does not work for M1 macs, or for anybody with a
custom homebrew prefix. There's also no need for the extra step if the
extension is exposed at a conventional location which homebrew can link
into place.

timescaledb.rb

@@ -5,53 +5,58 @@ class Timescaledb < Formula
   version "2.3.0"
   sha256 "baa8a60230320838c6d5d143846c14edc5238e2979ed2408a980280f05a81b3e"
 
+  depends_on "postgresql"
+
   depends_on "cmake" => :build
-  depends_on "postgresql" => :build
   depends_on "openssl" => :build
   depends_on "xz" => :build
   depends_on "timescaledb-tools" => :recommended
 
   option "with-oss-only", "Build TimescaleDB with only Apache-2 licensed code"
 
   def install
-    ossvar = ""
-    if build.with?("oss-only")
-      ossvar = " -DAPACHE_ONLY=1"
-    end
-    system "./bootstrap -DREGRESS_CHECKS=OFF -DPROJECT_INSTALL_METHOD=\"brew\"#{ossvar}"
-    system "cd ./build && make"
-    system "cd ./build && make install DESTDIR=#{buildpath}/stage"
-    libdir = `pg_config --pkglibdir`
-    sharedir = `pg_config --sharedir`
-    `touch timescaledb_move.sh`
-    `chmod +x timescaledb_move.sh`
-    `echo "#!/bin/bash" >> timescaledb_move.sh`
-    `echo "echo 'Moving files into place...'" >> timescaledb_move.sh`
-    `echo "/usr/bin/install -c -m 755 \\\$(find #{lib} -name timescaledb*.so) #{libdir.strip}/" >> timescaledb_move.sh`
-    `echo "/usr/bin/install -c -m 644 #{share}/timescaledb/* #{sharedir.strip}/extension/" >> timescaledb_move.sh`
-    `echo "echo 'Success.'" >> timescaledb_move.sh`
-    bin.install "timescaledb_move.sh"
-    (lib/"timescaledb").install Dir["stage/**/lib/*"]
-    (share/"timescaledb").install Dir["stage/**/share/postgresql*/extension/*"]
+    system "./bootstrap -DREGRESS_CHECKS=OFF -DPROJECT_INSTALL_METHOD=\"brew\"#{" -DAPACHE_ONLY=1" if build.with?("oss-only")}"
+
+    (buildpath/"build").cd do
+      system "make"
+
+      # CMake installs the files into DESTDIR/$HOMEBREW_PREFIX, so stage it and then unwrap it
+      stage = buildpath/"stage"
+      stage.mkdir
+
+      system "make install DESTDIR=#{stage}"
+
+      # Something like:
+      #   /var/tmp/abc123/stage/usr/local
+      #
+      # which contains files like
+      #   /var/tmp/abc123/stage/usr/local/lib/postgresql/timescaledb.so
+      #
+      stage_prefix = (stage/HOMEBREW_PREFIX.to_s.delete_prefix("/"))
+
+      prefix.install stage_prefix.children
     end
+  end
 
   test do
-    system "test", "-e", "#{lib}/timescaledb/timescaledb.so"
+    system "test", "-e", "#{lib}/postgresql/timescaledb.so"
   end
 
   def caveats
-    pgvar = `find /usr/local/var/postgres* -name "postgresql.conf" | head -n 1`
-    s = "RECOMMENDED: Run 'timescaledb-tune' to update your config settings for TimescaleDB.\n\n"
-    s += "  timescaledb-tune --quiet --yes\n\n"
+    <<~EOS
+      RECOMMENDED: Run 'timescaledb-tune' to update your config settings for TimescaleDB.
+
+        timescaledb-tune --quiet --yes --conf-path #{var/"postgres/postgresql.conf"}
+
+      IF NOT, you'll need to make sure to update #{var/"postgres/postgresql.conf"}
+      to include the extension:
+
+        shared_preload_libraries = 'timescaledb'
 
-    s += "IF NOT, you'll need to make sure to update #{pgvar.strip}\nto include the extension:\n\n"
-    s += "  shared_preload_libraries = 'timescaledb'\n\n"
+      If PostgreSQL is installed via Homebrew, restart it:
 
-    s += "To finish the installation, you will need to run:\n\n"
-    s += "  timescaledb_move.sh\n\n"
+        brew services restart postgresql
 
-    s += "If PostgreSQL is installed via Homebrew, restart it:\n\n"
-    s += "  brew services restart postgresql\n\n"
-    s
+    EOS
   end
 end