#!/bin/bash
set -Eeuo pipefail

SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
PLUGIN_DIR="$(cd "$SCRIPT_DIR/../.." && pwd)"
COMMON_FILE="$PLUGIN_DIR/scripts/setup/mysql_common.sh"
SETTINGS_FILE="${DA_ALT_MYSQL_SETTINGS_FILE:-$PLUGIN_DIR/plugin-settings.conf}"
LOG_FILE="${DA_ALT_MYSQL_RESTORE_LOG:-$PLUGIN_DIR/data/logs/da-restore.log}"

mkdir -p "$(dirname "$LOG_FILE")"

log() {
  printf '[%s] %s\n' "$(date '+%Y-%m-%d %H:%M:%S')" "$*" >> "$LOG_FILE"
}

die() {
  log "ERROR: $*"
  printf 'alt-mysql native backup restore: %s\n' "$*" >&2
  exit 1
}

url_decode() {
  local encoded="${1//+/ }"
  printf '%b' "${encoded//%/\\x}"
}

native_conf_field() {
  local qs="$1" field="$2" pair
  local -a pairs
  IFS='&' read -ra pairs <<< "$qs"
  for pair in "${pairs[@]}"; do
    if [ "${pair%%=*}" = "$field" ]; then
      printf '%s' "${pair#*=}"
      return 0
    fi
  done
  return 0
}

NATIVE_PRIV_FLAG_MAP=(
  "select_priv:SELECT" "insert_priv:INSERT" "update_priv:UPDATE" "delete_priv:DELETE"
  "create_priv:CREATE" "drop_priv:DROP" "index_priv:INDEX" "alter_priv:ALTER"
  "create_tmp_table_priv:CREATE TEMPORARY TABLES" "lock_tables_priv:LOCK TABLES"
  "create_view_priv:CREATE VIEW" "show_view_priv:SHOW VIEW"
  "create_routine_priv:CREATE ROUTINE" "alter_routine_priv:ALTER ROUTINE"
  "execute_priv:EXECUTE" "event_priv:EVENT" "trigger_priv:TRIGGER"
  "references_priv:REFERENCES"
)

native_conf_privilege_list() {
  local qs="$1"
  local entry flag name value
  local -a privs=()
  for entry in "${NATIVE_PRIV_FLAG_MAP[@]}"; do
    flag="${entry%%:*}"
    name="${entry#*:}"
    value="$(native_conf_field "$qs" "$flag")"
    [ "$value" = "Y" ] && privs+=("$name")
  done
  if [ "${#privs[@]}" -eq 0 ]; then
    printf 'ALL'
  else
    local IFS=,
    printf '%s' "${privs[*]}"
  fi
}

parse_native_db_conf() {
  local conf_file="$1"
  local line key value

  NATIVE_DB_CHARSET=""
  NATIVE_DB_COLLATION=""
  NATIVE_DB_USER_NAMES=()
  NATIVE_DB_USER_HOST=()
  NATIVE_DB_USER_HASH=()
  NATIVE_DB_USER_PLUGIN=()
  NATIVE_DB_USER_PRIVS=()

  [ -r "$conf_file" ] || { log "cannot read conf file: $conf_file"; return 1; }

  while IFS= read -r line || [ -n "$line" ]; do
    [ -n "$line" ] || continue
    [[ "$line" == *=* ]] || continue
    key="${line%%=*}"
    value="${line#*=}"

    case "$key" in
      db_collation)
        NATIVE_DB_CHARSET="$(native_conf_field "$value" DEFAULT_CHARACTER_SET_NAME)"
        NATIVE_DB_COLLATION="$(native_conf_field "$value" DEFAULT_COLLATION_NAME)"
        ;;
      accesshosts) ;;
      *)
        NATIVE_DB_USER_NAMES+=("$key")
        NATIVE_DB_USER_HOST+=("$(native_conf_field "$value" accesshosts)")
        NATIVE_DB_USER_HASH+=("$(url_decode "$(native_conf_field "$value" passwd)")")
        NATIVE_DB_USER_PLUGIN+=("$(native_conf_field "$value" plugin)")
        NATIVE_DB_USER_PRIVS+=("$(native_conf_privilege_list "$value")")
        ;;
    esac
  done < "$conf_file"

  if [ -z "$NATIVE_DB_CHARSET" ]; then
    log "missing db_collation charset in $conf_file"
    return 1
  fi
  if [ "${#NATIVE_DB_USER_NAMES[@]}" -eq 0 ]; then
    log "no MySQL users found in $conf_file"
    return 1
  fi

  return 0
}

if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
  [ -r "$COMMON_FILE" ] || die "missing helper: $COMMON_FILE"
  # shellcheck source=../setup/mysql_common.sh
  source "$COMMON_FILE"
  mysql_load_plugin_settings_file "$SETTINGS_FILE"
  # main() is added in Task 3.
fi