/*
 * Copyright (c) 2003, PostgreSQL Global Development Group
 * See the LICENSE file in the project root for more information.
 */
// Copyright (c) 2004, Open Cloud Limited.

package org.postgresql.core;

/**
 * Represents a query that is ready for execution by backend. The main difference from JDBC is ? are
 * replaced with $1, $2, etc.
 */
public class NativeQuery {
  private static final String[] BIND_NAMES = new String[128 * 10];
  private static final int[] NO_BINDS = new int[0];

  public String nativeSql; /* cannot be final because may be changed with the client encryption feature */
  public final int[] bindPositions;
  public final SqlCommand command;
  public final boolean multiStatement;

  static {
    for (int i = 1; i < BIND_NAMES.length; i++) {
      BIND_NAMES[i] = "$" + i;
    }
  }

  public NativeQuery(String nativeSql, SqlCommand dml) {
    this(nativeSql, NO_BINDS, true, dml);
  }

  public NativeQuery(String nativeSql, int[] bindPositions, boolean multiStatement, SqlCommand dml) {
    this.nativeSql = nativeSql;
    this.bindPositions =
        bindPositions == null || bindPositions.length == 0 ? NO_BINDS : bindPositions;
    this.multiStatement = multiStatement;
    this.command = dml;
  }

  /**
   * Stringize this query to a human-readable form, substituting particular parameter values for
   * parameter placeholders.
   *
   * @param parameters a ParameterList returned by this Query's {@link Query#createParameterList}
   *        method, or {@code null} to leave the parameter placeholders unsubstituted.
   * @return a human-readable representation of this query
   */
  public String toString(ParameterList parameters) {
    if (bindPositions.length == 0) {
      return nativeSql;
    }

    int queryLength = nativeSql.length();
    String[] params = new String[bindPositions.length];
    for (int i = 1; i <= bindPositions.length; ++i) {
      String param = parameters == null ? "?" : parameters.toString(i, true);
      params[i - 1] = param;
      queryLength += param.length() - bindName(i).length();
    }

    StringBuilder sbuf = new StringBuilder(queryLength);
    sbuf.append(nativeSql, 0, bindPositions[0]);
    for (int i = 1; i <= bindPositions.length; ++i) {
      sbuf.append(params[i - 1]);
      int nextBind = i < bindPositions.length ? bindPositions[i] : nativeSql.length();
      sbuf.append(nativeSql, bindPositions[i - 1] + bindName(i).length(), nextBind);
    }
    return sbuf.toString();
  }

  /**
   * Returns $1, $2, etc names of bind variables used by backend.
   *
   * @param index index of a bind variable
   * @return bind variable name
   */
  public static String bindName(int index) {
    return index < BIND_NAMES.length ? BIND_NAMES[index] : "$" + index;
  }

  public static StringBuilder appendBindName(StringBuilder sb, int index) {
    if (index < BIND_NAMES.length) {
      return sb.append(bindName(index));
    }
    sb.append('$');
    sb.append(index);
    return sb;
  }

  /**
   * Calculate the text length required for the given number of bind variables
   * including dollars.
   * Do this to avoid repeated calls to
   * AbstractStringBuilder.expandCapacity(...) and Arrays.copyOf
   *
   * @param bindCount total number of parameters in a query
   * @return int total character length for $xyz kind of binds
   */
  public static int calculateBindLength(int bindCount) {
    int res = 0;
    int bindLen = 2; // $1
    int maxBindsOfLen = 9; // $0 .. $9
    while (bindCount > 0) {
      int numBinds = Math.min(maxBindsOfLen, bindCount);
      bindCount -= numBinds;
      res += bindLen * numBinds;
      bindLen++;
      maxBindsOfLen *= 10; // $0..$9 (9 items) -> $10..$99 (90 items)
    }
    return res;
  }

  public SqlCommand getCommand() {
    return command;
  }
}
