#!/bin/bash

# Default installation directory for redis-dump-go
INSTALL_DIR="/usr/local/bin"

# Default redis port
DEFAULT_PORT="6379"

# Function to check for required tools
check_requirements() {
  local missing_counter=0
  local dependencies=('wget' 'redis-cli')

  for dep in "${dependencies[@]}"; do
    if ! type "$dep" > /dev/null 2>&1; then
      echo >&2 "Error: $dep is required but it's not installed."
      ((missing_counter++))
    fi
  done

  if (( missing_counter > 0 )); then
    echo "Please install the missing tools before running this script."
    exit 1
  fi
}

check_requirements

# Function to detect the architecture and set the corresponding binary name
get_arch_name() {
    ARCH=$(uname -m)
    case $ARCH in
        x86_64)
            BIN_ARCH="amd64"
            ;;
        i386 | i686)
            BIN_ARCH="386"
            ;;
        aarch64 | arm64)
            BIN_ARCH="arm64"
            ;;
        arm*)
            BIN_ARCH="armv6"
            ;;
        *)
            echo "Architecture not supported"
            exit 1
            ;;
    esac

    # Always Linux as we run this in a Docker container
    BIN_OS="linux"
    BIN_NAME="redis-dump-go-${BIN_OS}-${BIN_ARCH}.tar.gz"
}

# Function to parse named parameters
parse_params() {
    # Default values of variables set from params
    SRC_HOST=''
    SRC_PORT=$DEFAULT_PORT
    SRC_PASSWORD=''
    DEST_HOST=''
    DEST_PORT=$DEFAULT_PORT
    DEST_PASSWORD=''
    DB_NAMES=() # Array to hold database names

    while :; do
        case "${1-}" in
        -h | --help)
            usage ;;
        --src-host) # Source host (required)
            SRC_HOST="${2-}"
            shift
            ;;
        --src-port) # Source port (optional, default is 6379)
            SRC_PORT="${2-}"
            shift
            ;;
        --src-password) # Source password (optional)
            SRC_PASSWORD="${2-}"
            shift
            ;;
        --dest-host) # Destination host (required)
            DEST_HOST="${2-}"
            shift
            ;;
        --dest-port) # Destination port (optional, default is 6379)
            DEST_PORT="${2-}"
            shift
            ;;
        --dest-password) # Destination password (optional)
            DEST_PASSWORD="${2-}"
            shift
            ;;
        --dbs) # Comma-separated list of database names (optional)
            IFS=',' read -r -a DB_NAMES <<< "${2-}"
            shift
            ;;
        -?*)
            echo "Unknown option: $1" >&2
            exit 1
            ;;
        *) # No more options
            break
            ;;
        esac
        shift
    done

    # Check required parameters
    [[ -z "$SRC_HOST" ]] && { echo "Missing required parameter: --src-host"; exit 1; }
    [[ -z "$DEST_HOST" ]] && { echo "Missing required parameter: --dest-host"; exit 1; }
}

# Usage info
usage() {
    cat <<EOF
    Usage: ${0##*/} [OPTION]...

    Options:
      --src-host HOST             Source Redis host
      --src-port PORT             Source Redis port (default: $DEFAULT_PORT)
      --src-password PASSWORD     Source Redis password (if any)
      --dest-host HOST            Destination Redis host
      --dest-port PORT            Destination Redis port (default: $DEFAULT_PORT)
      --dest-password PASSWORD    Destination Redis password (if any)
      --dbs DBS                   Redis databases (a list of db indexes, comma-separated, default: all databases)
EOF
    exit 1
}

# Parse named parameters
parse_params "$@"

# Detect the architecture and set the binary name
get_arch_name


# Download and install redis-dump-go
echo "Downloading redis-dump-go for ${BIN_OS}-${BIN_ARCH}..."
wget -q -O "/tmp/${BIN_NAME}" "https://github.com/yannh/redis-dump-go/releases/latest/download/${BIN_NAME}"
tar -xzf "/tmp/${BIN_NAME}" -C "${INSTALL_DIR}"
rm "/tmp/${BIN_NAME}"
chmod +x "${INSTALL_DIR}/redis-dump-go"

# Build the base redis-dump-go command with optional password
DUMP_COMMAND_BASE="${INSTALL_DIR}/redis-dump-go -host ${SRC_HOST} -port ${SRC_PORT}"
if [[ -n $SRC_PASSWORD ]]; then
    export REDISDUMPGO_AUTH="$SRC_PASSWORD"
fi

# Build the base redis-cli command with optional password
LOAD_COMMAND_BASE="redis-cli -h ${DEST_HOST} -p ${DEST_PORT}"
if [[ -n $DEST_PASSWORD ]]; then
    LOAD_COMMAND_BASE+=" -a ${DEST_PASSWORD}"
fi

# Check if specific databases were provided
if [ ${#DB_NAMES[@]} -eq 0 ]; then
    # No databases specified, dump all databases
    DUMP_COMMAND="${DUMP_COMMAND_BASE}"
    LOAD_COMMAND="${LOAD_COMMAND_BASE}"

    echo "Dumping all databases from ${SRC_HOST} and restoring to ${DEST_HOST}..."
    $DUMP_COMMAND | $LOAD_COMMAND --pipe
else
    # Loop over each database name and perform the dump
    for DB_NAME in "${DB_NAMES[@]}"; do
        DUMP_COMMAND="${DUMP_COMMAND_BASE} -db $DB_NAME"
        LOAD_COMMAND="${LOAD_COMMAND_BASE}"

        echo "Dumping data from ${SRC_HOST} (DB: $DB_NAME) and restoring to ${DEST_HOST}..."
        $DUMP_COMMAND | $LOAD_COMMAND --pipe
    done
fi

if [[ -n $SRC_PASSWORD ]]; then
    unset REDISDUMPGO_AUTH
fi

echo "Data transfer complete."