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package me.zzp.ar.sql;

import java.util.Arrays;
import java.util.Deque;
import java.util.LinkedList;
import me.zzp.util.Seq;

/**
 * 实现生成insert、update、delete和select的语句的方法。
 * 由子类自行实现如何填充数据。
 * 
 * @since 1.0
 * @author redraiment
 */
public abstract class AbstractSqlBuilder implements SqlBuilder {
  protected static enum Mode {
    Select,
    Insert,
    Update,
    Delete
  }

  protected Mode mode;
  protected Deque fields;
  protected Deque tables;
  protected Deque conditions;
  protected Deque groups;
  protected Deque having;
  protected Deque orders;
  protected int limit;
  protected int offset;

  protected SqlBuilder start(Mode mode) {
    this.mode = mode;
    fields = new LinkedList<>();
    tables = new LinkedList<>();
    conditions = new LinkedList<>();
    groups = new LinkedList<>();
    having = new LinkedList<>();
    orders = new LinkedList<>();
    limit = offset = -1;
    return this;
  }

  public SqlBuilder addField(String field) {
    fields.addLast(field);
    return this;
  }

  public SqlBuilder addTable(String table) {
    tables.addLast(table);
    return this;
  }

  public SqlBuilder addCondition(String condition) {
    conditions.addLast(condition);
    return this;
  }

  public SqlBuilder addGroup(String group) {
    groups.addLast(group);
    return this;
  }

  public SqlBuilder addHaving(String having) {
    this.having.addLast(having);
    return this;
  }

  public SqlBuilder addOrder(String order) {
    orders.addLast(order);
    return this;
  }

  public SqlBuilder setFields(String... fields) {
    this.fields.clear();
    this.fields.addAll(Arrays.asList(fields));
    return this;
  }

  public SqlBuilder setTables(String... tables) {
    this.tables.clear();
    this.tables.addAll(Arrays.asList(tables));
    return this;
  }

  public SqlBuilder setConditions(String... conditions) {
    this.conditions.clear();
    this.conditions.addAll(Arrays.asList(conditions));
    return this;
  }

  public SqlBuilder setGroups(String... groups) {
    this.groups.clear();
    this.groups.addAll(Arrays.asList(groups));
    return this;
  }

  public SqlBuilder setHaving(String... having) {
    this.having.clear();
    this.having.addAll(Arrays.asList(having));
    return this;
  }

  public SqlBuilder setOrders(String... orders) {
    this.orders.clear();
    this.orders.addAll(Arrays.asList(orders));
    return this;
  }

  public SqlBuilder setLimit(int limit) {
    this.limit = limit;
    return this;
  }

  public SqlBuilder setOffset(int offset) {
    this.offset = offset;
    return this;
  }

  // toString

  private String selectToString() {
    StringBuilder sql = new StringBuilder("select ");
    sql.append(Seq.join(fields, ", "))
       .append(" from ")
       .append(Seq.join(tables, " join "));
    if (!conditions.isEmpty()) {
      sql.append(" where ").append(Seq.join(conditions, " and "));
    }
    if (!groups.isEmpty()) {
      sql.append(" group by ").append(Seq.join(groups, ", "));
      if (!having.isEmpty()) {
        sql.append(" having ").append(Seq.join(having, " and "));
      }
    }
    if (!orders.isEmpty()) {
      sql.append(" order by ").append(Seq.join(orders, ", "));
    }
    if (limit > 0) {
      sql.append(" limit ").append(Integer.toString(limit));
    }
    if (offset > -1) {
      sql.append(" offset ").append(Integer.toString(offset));
    }

    return sql.toString();
  }

  private String insertToString() {
    StringBuilder sql = new StringBuilder("insert into ");
    sql.append(tables.getFirst())
       .append(" (")
       .append(Seq.join(fields, ", "))
       .append(") values (")
       .append(Seq.join(Seq.map(fields, "?"), ", "))
       .append(")");
    return sql.toString();
  }

  private String updateToString() {
    StringBuilder sql = new StringBuilder("update ");
    sql.append(tables.getFirst())
       .append(" set ")
       .append(Seq.join(Seq.map(fields, "%s = ?"), ", "));

    if (!conditions.isEmpty()) {
      sql.append(" where ").append(Seq.join(conditions, " and "));
    }
    return sql.toString();
  }

  private String deleteToString() {
    StringBuilder sql = new StringBuilder("delete from ");
    sql.append(tables.getFirst());
    if (!conditions.isEmpty()) {
      sql.append(" where ").append(Seq.join(conditions, " and "));
    }
    return sql.toString();
  }

  @Override
  public String toString() {
    switch (mode) {
      case Select: return selectToString();
      case Insert: return insertToString();
      case Update: return updateToString();
      case Delete: return deleteToString();
      default: return "";
    }
  }
}