#!/usr/bin/env bash
# ci-cd.yml › backend — flag destructive EF migrations introduced by this pull request.
#
# A failed deploy rolls the backend binaries back but never the database, so every release must
# leave the PREVIOUS backend working on the NEW schema: add tables/columns now, drop or rename
# them in a later release (expand → contract, docs/40-DEPLOYMENT.md §8).
#   into Dev        → warning
#   into production → failure, unless the PR title contains [allow-destructive-migration]
# shellcheck source=common.sh
source "$(dirname "${BASH_SOURCE[0]}")/common.sh"

: "${BASE_REF:?BASE_REF (the PR target branch) is required}"
base="refs/remotes/origin/$BASE_REF"
git_remote fetch -q --depth 1 "$REPO_GIT_URL" "+refs/heads/$BASE_REF:$base"

# Two-dot tree diff: needs only the two commits, not their history (depth-1 friendly).
mapfile -t files < <(
  git diff --name-only --diff-filter=AM "$base" HEAD -- "$MIGRATIONS_PATH" |
    grep -E '\.cs$' | grep -vE '\.Designer\.cs$|ModelSnapshot\.cs$' || true
)

if ((${#files[@]} == 0)); then
  log "no new or changed migrations"
  exit 0
fi

hits=""
for f in "${files[@]}"; do
  # Only Up() matters — every Down() legitimately drops what its Up() created.
  found="$(awk '
    /override void Up\(/   { up = 1 }
    /override void Down\(/ { up = 0 }
    up && /migrationBuilder\.(DropTable|DropColumn|RenameColumn|RenameTable|DropSchema|DropSequence)\(/ {
      printf "  %s:%d: %s\n", FILENAME, FNR, $0
    }' "$f")"
  hits+="$found"
done

if [[ -z "$hits" ]]; then
  log "checked ${#files[@]} migration file(s): additive only"
  exit 0
fi

printf '%s\n' "$hits"
msg="destructive operation in a migration's Up() — keep the previous release working on the new schema: expand now, contract in a later release (docs/40-DEPLOYMENT.md §8)"
if [[ "$BASE_REF" == production ]]; then
  if [[ "${PR_TITLE:-}" == *"[allow-destructive-migration]"* ]]; then
    warn "$msg — allowed by the [allow-destructive-migration] PR title override"
    exit 0
  fi
  fail "$msg"
fi
warn "$msg"