#!/usr/bin/env bash
set -euo pipefail

MIGRATION_DIR="${1:-db/migrations}"
DB_CONNECTION_STRING="${2:-}"

if [ ! -d "$MIGRATION_DIR" ]; then
  echo "Migration directory not found: $MIGRATION_DIR" >&2
  exit 1
fi

mapfile -t files < <(find "$MIGRATION_DIR" -maxdepth 1 -type f -name 'V*.sql' | sort)

if [ "${#files[@]}" -eq 0 ]; then
  echo "No migration files found in $MIGRATION_DIR" >&2
  exit 1
fi

declare -A seen_versions=()
duplicate_found=0

for file in "${files[@]}"; do
  name="$(basename "$file")"
  version="${name#V}"
  version="${version%%__*}"
  if [ -n "${seen_versions[$version]:-}" ]; then
    echo "Duplicate migration version detected: V$version" >&2
    echo "  - ${seen_versions[$version]}" >&2
    echo "  - $file" >&2
    duplicate_found=1
  else
    seen_versions["$version"]="$file"
  fi
done

if [ "$duplicate_found" -ne 0 ]; then
  exit 1
fi

if [ -z "$DB_CONNECTION_STRING" ]; then
  echo "Duplicate version check passed."
  exit 0
fi

if ! command -v psql >/dev/null 2>&1; then
  echo "psql is required for database dry-run validation." >&2
  exit 1
fi

mapfile -t executed_versions < <(
  psql "$DB_CONNECTION_STRING" -Atc "SELECT version FROM schema_migrations ORDER BY version;" 2>/dev/null || true
)

declare -A executed_map=()
for version in "${executed_versions[@]}"; do
  if [ -n "$version" ]; then
    executed_map["$version"]=1
  fi
done

for file in "${files[@]}"; do
  name="$(basename "$file")"
  version="${name#V}"
  version="${version%%__*}"
  if [ -n "${executed_map[$version]:-}" ]; then
    continue
  fi
  echo "Dry-run migration V$version: $name"
  psql "$DB_CONNECTION_STRING" -v ON_ERROR_STOP=1 <<PSQL
BEGIN;
\\i $file
ROLLBACK;
PSQL
done

echo "Migration dry-run validation passed."