nix: Move docs tools into core infrastructure

nix/README.md

@@ -248,6 +248,27 @@ $ nix-shell --run postgrest-style
 There is also `postgrest-style-check` that exits with a non-zero exit code if
 the check resulted in any uncommitted changes. It's mostly useful for CI.
 
+## Documentation
+
+The following commands can help you when working on the PostgREST docs:
+
+```bash
+# Build the docs
+[nix-shell]$ postgrest-docs-build
+
+# Build the docs and start a livereload server on `http://localhost:5500`
+[nix-shell]$ postgrest-docs-serve
+
+# Run aspell, to verify spelling mistakes
+[nix-shell]$ postgrest-docs-spellcheck
+
+# Detect obsolete entries in postgrest.dict
+[nix-shell]$ postgrest-docs-dictcheck
+
+# Build and run all the validation scripts
+[nix-shell]$ postgrest-docs-check
+```
+
 ## General development tools
 
 Tools like `postgrest-build`, `postgrest-run`, `postgrest-repl` etc. are simple wrappers around

nix/tools/docs.nix

@@ -0,0 +1,125 @@
+{ aspell
+, aspellDicts
+, buildToolbox
+, checkedShellScript
+, python3
+}:
+let
+  python = python3.withPackages (ps: [
+    ps.sphinx
+    ps.sphinx_rtd_theme
+    ps.livereload
+    ps.sphinx-tabs
+    ps.sphinx-copybutton
+    ps.sphinxext-opengraph
+    # TODO: Remove override once new sphinx-intl version (> 2.1.0) is released and available in nixpkgs
+    (ps.sphinx-intl.overrideAttrs (drv: { nativeBuildInputs = drv.nativeBuildInputs ++ [ ps.six ]; }))
+  ]);
+
+  build =
+    checkedShellScript
+      {
+        name = "postgrest-docs-build";
+        docs = "Build the documentation.";
+        args = [ "ARG_POSITIONAL_SINGLE([language], [Language to build docs for.], [\"\"])" ];
+        workingDir = "/docs";
+      }
+      ''
+        # build.sh needs to find "sphinx-build"
+        PATH=${python}/bin:$PATH
+
+        ./build.sh "$_arg_language"
+      '';
+
+  serve =
+    checkedShellScript
+      {
+        name = "postgrest-docs-serve";
+        docs = "Serve the documentation locally with live reload.";
+        args = [ "ARG_POSITIONAL_SINGLE([language], [Language to serve docs for.], [\"\"])" ];
+        workingDir = "/docs";
+      }
+      ''
+        # livereload_docs.py needs to find "sphinx-build"
+        PATH=${python}/bin:$PATH
+
+        ./livereload_docs.py "$_arg_language"
+      '';
+
+  spellcheck =
+    checkedShellScript
+      {
+        name = "postgrest-docs-spellcheck";
+        docs = "Verify spelling mistakes. Bypass if the word is present in postgrest.dict.";
+        workingDir = "/docs";
+      }
+      ''
+        FILES=$(find . -type f -iname '*.rst' | tr '\n' ' ')
+
+        # shellcheck disable=SC2086 disable=SC2016
+        cat $FILES \
+         | grep -v '^\(\.\.\|  \)' \
+         | sed 's/`.*`//g' \
+         | ${aspell}/bin/aspell -d ${aspellDicts.en}/lib/aspell/en_US -p ./postgrest.dict list \
+         | sort -f \
+         | tee misspellings
+        test ! -s misspellings
+      '';
+
+  dictcheck =
+    checkedShellScript
+      {
+        name = "postgrest-docs-dictcheck";
+        docs = "Detect obsolete entries in postgrest.dict that are not used anymore.";
+        workingDir = "/docs";
+      }
+      ''
+        FILES=$(find . -type f -iname '*.rst' | tr '\n' ' ')
+
+        tail -n+2 postgrest.dict \
+         | tr '\n' '\0' \
+         | xargs -0 -i \
+           sh -c "grep \"{}\" $FILES > /dev/null || echo \"{}\"" \
+         | tee unuseddict
+        test ! -s unuseddict
+      '';
+
+  linkcheck =
+    checkedShellScript
+      {
+        name = "postgrest-docs-linkcheck";
+        docs = "Verify that external links are working correctly.";
+        workingDir = "/docs";
+      }
+      ''
+        ${python}/bin/sphinx-build --color -b linkcheck . _build
+      '';
+
+  check =
+    checkedShellScript
+      {
+        name = "postgrest-docs-check";
+        docs = "Build and run all the validation scripts.";
+        workingDir = "/docs";
+      }
+      ''
+        ${build}/bin/postgrest-docs-build
+        ${dictcheck}/bin/postgrest-docs-dictcheck
+        ${linkcheck}/bin/postgrest-docs-linkcheck
+        ${spellcheck}/bin/postgrest-docs-spellcheck
+      '';
+
+in
+buildToolbox
+{
+  name = "postgrest-docs";
+  tools =
+    [
+      build
+      check
+      dictcheck
+      linkcheck
+      serve
+      spellcheck
+    ];
+}