#!/usr/bin/env bash
# Validates Flyway schema migrations under db/migration/.
# - No duplicate version numbers in the repo
# - Migrations already on the base branch are immutable
# - New migrations must use a version number greater than the highest on the base branch
#
# Usage: scripts/check-flyway-migrations.sh [base-ref]
# Default base ref: origin/master (override with FLYWAY_BASE_REF)

set -euo pipefail

ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
MIGRATION_DIR="backend/src/main/resources/db/migration"
BASE_REF="${1:-${FLYWAY_BASE_REF:-origin/master}}"

cd "$ROOT"

if [[ ! -d "$MIGRATION_DIR" ]]; then
  echo "Missing migration directory: $MIGRATION_DIR" >&2
  exit 1
fi

declare -A seen_versions=()
max_local=0

for file in "$MIGRATION_DIR"/V*.sql; do
  [[ -e "$file" ]] || continue
  name="$(basename "$file")"
  if [[ ! "$name" =~ ^V([0-9]+)__.+\.sql$ ]]; then
    echo "ERROR: Invalid migration filename (expected V<number>__description.sql): $name" >&2
    exit 1
  fi
  version="${BASH_REMATCH[1]}"
  version=$((10#$version))
  if [[ -n "${seen_versions[$version]:-}" ]]; then
    echo "ERROR: Duplicate Flyway version V${version}:" >&2
    echo "  ${seen_versions[$version]}" >&2
    echo "  $name" >&2
    exit 1
  fi
  seen_versions[$version]="$name"
  if (( version > max_local )); then
    max_local=$version
  fi
done

if ! git rev-parse --verify "$BASE_REF" >/dev/null 2>&1; then
  echo "Flyway check: unique versions OK (max V${max_local}). Skipping base-branch rules (${BASE_REF} not found)."
  exit 0
fi

max_base=0
while IFS= read -r path; do
  [[ -z "$path" ]] && continue
  name="$(basename "$path")"
  if [[ "$name" =~ ^V([0-9]+)__.+\.sql$ ]]; then
    version="${BASH_REMATCH[1]}"
    version=$((10#$version))
    if (( version > max_base )); then
      max_base=$version
    fi
  fi
done < <(git ls-tree -r --name-only "$BASE_REF" -- "$MIGRATION_DIR" 2>/dev/null | grep -E '/V[0-9]+__.*\.sql$' || true)

while IFS= read -r file; do
  [[ -z "$file" ]] && continue
  if git cat-file -e "$BASE_REF:$file" 2>/dev/null; then
    if ! git diff --quiet "$BASE_REF" -- "$file"; then
      echo "ERROR: Modified existing migration (immutable after merge): $file" >&2
      echo "Create a new V$((max_base + 1))__... migration instead of editing $file." >&2
      exit 1
    fi
  else
    name="$(basename "$file")"
    version="${name#V}"
    version="${version%%__*}"
    version=$((10#$version))
    if (( version <= max_base )); then
      echo "ERROR: New migration $name uses V${version}, but ${BASE_REF} already has migrations up to V${max_base}." >&2
      echo "Use V$((max_base + 1))__your_description.sql or rebase and renumber." >&2
      exit 1
    fi
  fi
done < <(git ls-files "$MIGRATION_DIR"/V*.sql)

echo "Flyway check OK (local max V${max_local}, ${BASE_REF} max V${max_base})."