#!/bin/bash

set -e

# Parse Hack source and filter noisy node objects.

hh_parse --full-fidelity-text-json $@ |
  jq '.parse_tree' |

  # Remove low-value elements and simplify name tokens.
  jq "$(
    cat <<-JQ
    # Return true if an element is low value.
    def trivia:
      (. == [] or . == {}) or
      type == "object" and
      (
        .kind == "markup_section" or
        .kind == "whitespace" or
        .kind == "end_of_file" or
        .kind == "end_of_line" or
        .kind == "missing" or
        (
          .kind == "token" and

          # Note: parenthesis matter here.
          (.token.kind | IN(";", ":", ",", "[", "]", "{", "}", "(", ")", "<<", ">>"))
        )
      );

    # Transform/replace some objects with a simplified version.
    def transform:

      # {
      #   "kind": "token",
      #   "token": {
      #     "kind": "final",
      #     "text": "final"
      #   }
      # }

      if type == "object" and
        .kind == "token" and
        .token.kind == .token.text

      then .token.text

      # {
      #   "kind": "token",
      #   "token": {
      #     "kind": "XHP_class_name",
      #     "text": ":head"
      #   }
      # }

      elif type == "object" and
        .kind == "token" and
        has("token") and
        (.token | keys) == ["kind", "text"]

      then {(.token.kind): .token.text}

      # {
      #   "kind": "list_item",
      #   "list_item": {
      #      "kind": "...",
      #   }
      # }

      elif type == "object" and .kind == "list_item" and has("list_item")
      then .list_item


      # "...": {
      #   "kind": "list",
      #   "elements": [
      #     {}
      #   ]
      # }

      elif type == "object" and .kind == "list" and has("elements")
      then .elements

      else .
      end;

    walk(
      if type == "object" then

        # Remove keys with low-value values.
        with_entries(select(.value | trivia | not)) | map_values(transform)

      elif type == "array" then

        # Remove low-value array elements.
        map(select(trivia | not)) | map(transform)

      else .
      end
    )
JQ
  )"