#!/bin/bash
#
# Removes the `depends-on-upstream` label from every open pull request whose
# referenced gitea pull requests are all merged, and says so in a comment.
# Removing the label reruns the `depends-upstream` check of that pull request.
#
# Usage: ./scripts/unlabel-upstream-deps.sh
#
# Environment:
#   GITEA_API      api of the repository, e.g. https://gitea.com/api/v1/repos/gitea/docs
#   DEPLOY_TOKEN   token used to remove the label and to comment
#   GITHUB_COM_TOKEN  optional, lifts the rate limit of the github api
#   UPSTREAM_LABEL    label to look for, `depends-on-upstream` by default
#   DRY_RUN        set to 1 to only report what would happen

set -euo pipefail

LABEL="${UPSTREAM_LABEL:-depends-on-upstream}"
API="${GITEA_API:?GITEA_API is required}"
DRY_RUN="${DRY_RUN:-0}"

gitea_api() {
  local method="$1" url="$2" data="${3:-}"
  local args=(--silent --show-error --fail -X "$method")
  if [ -n "${DEPLOY_TOKEN:-}" ]; then args+=(-H "Authorization: token $DEPLOY_TOKEN"); fi
  if [ -n "$data" ]; then args+=(-H 'Content-Type: application/json' --data "$data"); fi
  curl "${args[@]}" "$url"
}

# see the note in check-upstream-deps.sh about the argument name
label_id="$(gitea_api GET "$API/labels?limit=100" | jq -r --arg want "$LABEL" \
  '.[] | select(.name == $want) | .id')"
if [ -z "$label_id" ]; then
  echo "the repository has no \"$LABEL\" label, nothing to do"
  exit 0
fi

pulls="$(gitea_api GET "$API/pulls?state=open&limit=50")"
indexes="$(printf '%s' "$pulls" | jq -r --arg want "$LABEL" \
  '.[] | select([(.labels // [])[].name] | index($want) != null) | .number')"

if [ -z "$indexes" ]; then
  echo "no open pull request carries the \"$LABEL\" label"
  exit 0
fi

here="$(cd "$(dirname "$0")" && pwd)"
work="$(mktemp -d)"
trap 'rm -rf "$work"' EXIT

for index in $indexes; do
  gitea_api GET "$API/pulls/$index" > "$work/pull.json"

  # the check script exits 0 when every reference is merged; it needs the label
  # to be absent from its input to stay quiet about it, so drop it here
  jq 'del(.labels)' "$work/pull.json" > "$work/pull-unlabelled.json"
  # REQUIRE_VERIFIED keeps a dependency whose state could not be determined from
  # counting as merged, which would drop the label too early
  if ! output="$(REQUIRE_VERIFIED=1 "$here/check-upstream-deps.sh" "$work/pull-unlabelled.json" 2>&1)"; then
    echo "#$index still waits for upstream:"
    printf '%s\n' "$output" | sed 's/^/    /'
    continue
  fi

  if printf '%s' "$output" | grep -q 'no upstream dependency declared'; then
    echo "#$index carries the label but declares no dependency, leaving it alone"
    continue
  fi

  if [ "$DRY_RUN" = '1' ]; then
    echo "#$index would lose the label:"
    printf '%s\n' "$output" | sed 's/^/    /'
    continue
  fi

  gitea_api DELETE "$API/issues/$index/labels/$label_id" > /dev/null
  comment="$(printf 'Every referenced gitea pull request is merged, so the `%s` label was removed and the check was rerun.\n\n%s' "$LABEL" "$output")"
  gitea_api POST "$API/issues/$index/comments" "$(jq -n --arg body "$comment" '{body: $body}')" > /dev/null
  echo "#$index unlabelled"
done