#!/usr/bin/env bash

set -euo pipefail

ROOT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
ENV_FILE="${ENV_FILE:-$ROOT_DIR/.env}"
DUMP_FILE=""
TARGET_HOST="127.0.0.1"
TARGET_PORT="3306"
TARGET_USER="root"
TARGET_PASSWORD=""
DRY_RUN=0
FORCE=0

if [[ -f "$ENV_FILE" ]]; then
    set -a
    # shellcheck disable=SC1090
    source "$ENV_FILE"
    set +a
fi

# Use password from .env if not overridden
TARGET_PASSWORD="${TARGET_PASSWORD:-${DOCKER_DB_ROOT_PASSWORD:-}}"

usage() {
    cat <<EOF
Usage: $(basename "$0") --from FILE [options]

Restores a full database dump (produced by db-export.sh) into a MySQL instance.
Works with both the local Docker container and a remote MySQL server.

Options:
  --from FILE         Dump file to restore (.sql or .sql.gz) (required)
  --host HOST         Target MySQL host     (default: 127.0.0.1)
  --port PORT         Target MySQL port     (default: 3306)
  --user USER         Target MySQL user     (default: root)
  --password PASS     Target MySQL password (default: from .env DOCKER_DB_ROOT_PASSWORD)
  --dry-run           Show what would happen without executing
  --force             Skip the confirmation prompt
  -h, --help          Show this help

Examples:
  # Restore into local Docker container (new server, container must be running)
  $(basename "$0") --from backups/2025-01-01_12-00-00.sql.gz

  # Restore into a remote MySQL server
  $(basename "$0") --from backups/dump.sql.gz \\
    --host db.example.com --port 3306 \\
    --user root --password secret
EOF
}

log() { printf '[db-import] %s\n' "$*"; }
die() { printf 'ERROR: %s\n' "$*" >&2; exit 1; }

mysql_cmd() {
    mysql \
        --host="$TARGET_HOST" \
        --port="$TARGET_PORT" \
        --user="$TARGET_USER" \
        --password="$TARGET_PASSWORD" \
        --connect-timeout=10 \
        "$@"
}

# ── argument parsing ──────────────────────────────────────────────────────────

while (($#)); do
    case "$1" in
        --from)     DUMP_FILE="$2";     shift ;;
        --host)     TARGET_HOST="$2";   shift ;;
        --port)     TARGET_PORT="$2";   shift ;;
        --user)     TARGET_USER="$2";   shift ;;
        --password) TARGET_PASSWORD="$2"; shift ;;
        --dry-run)  DRY_RUN=1 ;;
        --force)    FORCE=1 ;;
        -h|--help)  usage; exit 0 ;;
        *) printf 'Unknown option: %s\n\n' "$1" >&2; usage >&2; exit 1 ;;
    esac
    shift
done

# ── validation ────────────────────────────────────────────────────────────────

[[ -z "$DUMP_FILE" ]] && { usage >&2; die "--from FILE is required"; }
[[ -f "$DUMP_FILE" ]] || die "file not found: $DUMP_FILE"
[[ -z "$TARGET_PASSWORD" ]] && die "no password set — use --password or set DOCKER_DB_ROOT_PASSWORD in .env"

if ! command -v mysql >/dev/null 2>&1; then
    die "'mysql' client not found. Install it: apt install mysql-client  or  brew install mysql-client"
fi

cd "$ROOT_DIR"

# ── preview ───────────────────────────────────────────────────────────────────

file_size="$(du -sh "$DUMP_FILE" | cut -f1)"

printf '\nMigration plan:\n'
printf '  Source file : %s (%s)\n' "$DUMP_FILE" "$file_size"
printf '  Target host : %s:%s\n'   "$TARGET_HOST" "$TARGET_PORT"
printf '  Target user : %s\n\n'    "$TARGET_USER"

if [[ "$DRY_RUN" -eq 1 ]]; then
    log "dry-run mode — nothing imported"
    exit 0
fi

if [[ "$FORCE" -eq 0 ]]; then
    printf 'WARNING: this will DROP and recreate all databases in the dump.\n'
    read -r -p "Continue? [y/N] " confirm
    [[ "$confirm" =~ ^[Yy]$ ]] || { log "aborted"; exit 0; }
fi

# ── connectivity check ────────────────────────────────────────────────────────

log "checking connection to ${TARGET_HOST}:${TARGET_PORT}..."
if ! mysql_cmd --execute="SELECT 1;" >/dev/null 2>&1; then
    die "cannot connect to MySQL at ${TARGET_HOST}:${TARGET_PORT} as ${TARGET_USER}"
fi
log "connection OK"

# ── import ────────────────────────────────────────────────────────────────────

log "restoring $DUMP_FILE → ${TARGET_HOST}:${TARGET_PORT}..."
log "this may take several minutes..."

if [[ "$DUMP_FILE" == *.gz ]]; then
    zcat "$DUMP_FILE" | mysql_cmd
else
    mysql_cmd < "$DUMP_FILE"
fi

log "import complete"
log ""
log "next steps on the new server:"
log "  1. Update realmlist:  bash scripts/sync-realmlist.sh"
log "  2. Start the server:  bash scripts/prod-deploy.sh --no-build"