package com.imyeyu.spring.util;

import com.imyeyu.java.TimiJava;
import com.imyeyu.java.bean.timi.TimiCode;
import com.imyeyu.java.bean.timi.TimiException;
import com.imyeyu.java.ref.Ref;
import com.imyeyu.spring.annotation.table.AutoUUID;
import com.imyeyu.spring.annotation.table.Column;
import com.imyeyu.spring.annotation.table.Id;
import com.imyeyu.spring.annotation.table.Table;
import com.imyeyu.spring.annotation.table.Transient;
import com.imyeyu.spring.entity.Creatable;
import com.imyeyu.spring.entity.Deletable;
import com.imyeyu.spring.entity.Destroyable;
import com.imyeyu.spring.entity.Updatable;
import com.imyeyu.spring.mapper.BaseMapper;
import com.imyeyu.utils.Text;
import com.imyeyu.utils.Time;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.builder.annotation.ProviderContext;

import java.lang.reflect.Field;
import java.lang.reflect.ParameterizedType;
import java.lang.reflect.Type;
import java.util.ArrayList;
import java.util.List;
import java.util.Map;
import java.util.UUID;
import java.util.concurrent.ConcurrentHashMap;
import java.util.stream.Collectors;

/**
 * 通用 Mapper SQL 代理器
 *
 * @author 夜雨
 * @since 2025-02-05 23:34
 */
public class SQLProvider {

	/** 反射缓存 */
	private static final Map<Class<?>, EntityMeta> ENTITY_META_CACHE = new ConcurrentHashMap<>();

	public String count(ProviderContext context) {
		EntityMeta meta = getEntityMeta(context);
		StringBuilder sql = new StringBuilder();
		sql.append("SELECT COUNT(*) FROM `%s` WHERE 1 = 1".formatted(meta.table));
		if (meta.canDelete) {
			sql.append(" AND (`deleted_at` IS NULL OR %s < `deleted_at`)".formatted(Time.now()));
		}
		return sql.toString();
	}

	public String listOrder(ProviderContext context, @Param("offset") Long offset, @Param("limit") Integer limit, @Param("orderMap") Map<String, BaseMapper.OrderType> orderMap)  {
		EntityMeta meta = getEntityMeta(context);
		StringBuilder sql = new StringBuilder();
		sql.append("SELECT %s FROM `%s` WHERE 1 = 1".formatted(meta.selectAllClause, meta.table));
		if (meta.canDelete) {
			sql.append(" AND (`deleted_at` IS NULL OR %s < `deleted_at`)".formatted(Time.now()));
		}
		if (TimiJava.isNotEmpty(orderMap)) {
			sql.append(" ORDER BY ");
			for (Map.Entry<String, BaseMapper.OrderType> item : orderMap.entrySet()) {
				sql.append(Text.camelCase2underscore(item.getKey())).append(' ').append(item.getValue().toString());
				sql.append(", ");
			}
			sql.deleteCharAt(sql.length() - 2);
		}
		return sql.append(" LIMIT %s, %s".formatted(offset, limit)).toString();
	}

	/**
	 * 插入
	 * <p><i>不实现 {@link Creatable} 也允许调用是合理的，某些数据属于关联数据，不参与主创建过程</i></p>
	 *
	 * @param entity 实体
	 * @return SQL
	 */
	public String insert(ProviderContext context, Object entity) {
		EntityMeta meta = getEntityMeta(entity.getClass());
		String columns = meta.fieldColumnList.stream().map(fc -> "`%s`".formatted(fc.columnName)).collect(Collectors.joining(", "));
		String values = meta.fieldColumnList.stream().map(fc -> {
			try {
				if (fc.isAutoUUID && TimiJava.isEmpty(Ref.getFieldValue(entity, fc.field, String.class))) {
					String uuid = UUID.randomUUID().toString();
					if (fc.isAutoUpperUUID) {
						uuid = uuid.toUpperCase();
					}
					Ref.setFieldValue(entity, fc.field, uuid);
				}
			} catch (IllegalAccessException e) {
				throw new TimiException(TimiCode.ERROR).msgKey("auto set field:%s value error".formatted(fc.fieldName));
			}
			if (entity instanceof Creatable creatableEntity && creatableEntity.getCreatedAt() == null) {
				creatableEntity.setCreatedAt(Time.now());
			}
			return "#{%s}".formatted(fc.fieldName);
		}).collect(Collectors.joining(", "));
		return "INSERT INTO `%s` (%s) VALUES (%s)".formatted(meta.table, columns, values);
	}

	/**
	 * 根据 ID 查询
	 *
	 * @param context 代理器上下文
	 * @param id      ID
	 * @return SQL
	 */
	public String select(ProviderContext context, @Param("id") Object id) {
		EntityMeta meta = getEntityMeta(context);
		TimiException.required(meta.idFieldColumn, "not found id field in %s".formatted(meta.entityClass));

		StringBuilder sql = new StringBuilder();
		sql.append("SELECT %s FROM `%s` WHERE `%s` = #{%s}".formatted(meta.selectAllClause, meta.table, meta.idFieldColumn.columnName, id));
		if (meta.canDelete) {
			sql.append(" AND (`deleted_at` IS NULL OR %s < `deleted_at`)".formatted(Time.now()));
		}
		return sql.append(" LIMIT 1").toString();
	}

	/**
	 * 根据实体非空字段使用等号查询
	 *
	 * @param entity 实体
	 * @return SQL
	 */
	public String selectByExample(Object entity) {
		return selectAllByExample(entity) + BaseMapper.LIMIT_1;
	}

	/**
	 * 根据实体非空字段使用等号查询
	 *
	 * @param entity 实体
	 * @return SQL
	 */
	public String selectAllByExample(Object entity) {
		EntityMeta meta = getEntityMeta(entity.getClass());
		String conditionClause = meta.fieldColumnList.stream()
		                                             .filter(fc -> {
			                                             try {
				                                             return Ref.getFieldValue(entity, fc.field, Object.class) != null;
			                                             } catch (IllegalAccessException e) {
				                                             throw new RuntimeException(e);
			                                             }
		                                             })
		                                             .map(fc -> {
			                                             return "`%s` = #{%s}".formatted(fc.columnName, fc.fieldName);
		                                             })
		                                             .collect(Collectors.joining(" AND "));

		StringBuilder sql = new StringBuilder();
		sql.append("SELECT %s FROM `%s` WHERE %s".formatted(meta.selectAllClause, meta.table, conditionClause));
		if (meta.canDelete) {
			if (TimiJava.isNotEmpty(conditionClause)) {
				sql.append(" AND ");
			}
			sql.append("(`deleted_at` IS NULL OR %s < `deleted_at`)".formatted(Time.now()));
		}
		return sql.toString();
	}

	/**
	 * 根据 ID 更新，需要实体实现 {@link Updatable}
	 *
	 * @param entity 实体
	 * @return SQL
	 */
	public String update(Object entity) {
		EntityMeta meta = getEntityMeta(entity.getClass());
		TimiException.required(meta.idFieldColumn, "not found id field in %s".formatted(meta.entityClass));
		TimiException.required(meta.canUpdate, "not allow update for %s".formatted(meta.entityClass));

		String setClause = meta.fieldColumnList.stream()
		                                       .filter(fc -> !fc.isId)
		                                       .map(fc -> {
			                                       if (entity instanceof Updatable updatableEntity) {
				                                       updatableEntity.setUpdatedAt(Time.now());
			                                       }
												   return "`%s` = #{%s}".formatted(fc.columnName, fc.fieldName);
		                                       })
		                                       .collect(Collectors.joining(", "));
		return "UPDATE `%s` SET %s WHERE `%s` = #{%s}".formatted(meta.table, setClause, meta.idFieldColumn.columnName, meta.idFieldColumn.fieldName);
	}

	/**
	 * 根据 ID 软删除，需要实体实现 {@link Deletable}
	 *
	 * @param context 代理器上下文
	 * @param id      ID
	 * @return SQL
	 */
	public String delete(ProviderContext context, @Param("id") Object id) {
		EntityMeta meta = getEntityMeta(context);
		TimiException.required(meta.idFieldColumn, "not found id field in %s".formatted(meta.entityClass));
		TimiException.requiredTrue(meta.canDelete, "not allow soft delete for %s".formatted(meta.entityClass));

		return "UPDATE `%s` SET `deleted_at` = %s WHERE `%s` = #{id}".formatted(meta.table, Time.now(), meta.idFieldColumn.columnName);
	}

	/**
	 * 硬删除，需要实体实现 {@link Destroyable}
	 *
	 * @param context 代理器上下文
	 * @param id      ID
	 * @return SQL
	 */
	public String destroy(ProviderContext context, @Param("id") Object id) {
		EntityMeta meta = getEntityMeta(context);
		TimiException.required(meta.idFieldColumn, "not found id field in %s".formatted(meta.entityClass));
		TimiException.requiredTrue(meta.canDestroy, "not allow destroy for %s".formatted(meta.entityClass));

		return "DELETE FROM `%s` WHERE `%s` = #{id}".formatted(meta.table, meta.idFieldColumn.columnName);
	}

	/**
	 * 根据代理器上下文获取 Mapper 实体类元数据
	 *
	 * @param context 代理器上下文
	 * @return 实体类元数据
	 */
	private EntityMeta getEntityMeta(ProviderContext context) {
		Type[] types = context.getMapperType().getGenericInterfaces();
		ParameterizedType type = (ParameterizedType) types[0];
		Class<?> entityClass = (Class<?>) type.getActualTypeArguments()[0];
		return getEntityMeta(entityClass);
	}

	/**
	 * 获取实体类元数据
	 *
	 * @param entityClass 实体类
	 * @return 元数据
	 */
	private EntityMeta getEntityMeta(Class<?> entityClass) {
		return ENTITY_META_CACHE.computeIfAbsent(entityClass, EntityMeta::new);
	}

	/**
	 * 实体元数据
	 *
	 * @author 夜雨
	 * @since 2025-02-05 23:47
	 */
	private static class EntityMeta {

		/** 实体类 */
		final Class<?> entityClass;

		/** 表名 */
		final String table;

		/** 查询字段映射 */
		final String selectAllClause;

		/** ID 字段 */
		final FieldColumn idFieldColumn;

		/** 只读的列名字段名映射，Map&lt;列名，字段名&gt; */
		final List<FieldColumn> fieldColumnList;

		/** true 为可更新 */
		final boolean canUpdate;

		/** true 为可删除（软删除） */
		final boolean canDelete;

		/** true 为可销毁（硬删除） */
		final boolean canDestroy;

		public EntityMeta(Class<?> entityClass) {
			this.entityClass = entityClass;

			// 表名
			while (entityClass.isAnnotationPresent(Transient.class)) {
				entityClass = entityClass.getSuperclass();
			}
			Table table = entityClass.getAnnotation(Table.class);
			if (table == null) {
				this.table = Text.camelCase2underscore(entityClass.getSimpleName());
			} else {
				this.table = table.value();
				TimiException.required(this.table, String.format("empty table annotation value for %s entity", entityClass.getName()));
			}
			List<Field> allFieldList = Ref.listAllFields(entityClass);

			StringBuilder selectAllClause = new StringBuilder();
			FieldColumn idFieldColumn = null;
			List<FieldColumn> fieldColumnList = new ArrayList<>();
			for (int i = 0; i < allFieldList.size(); i++) {
				Field field = allFieldList.get(i);
				if (field.isAnnotationPresent(Transient.class)) {
					continue;
				}
				FieldColumn fieldColumn = new FieldColumn(field);
				if (fieldColumn.isId) {
					TimiException.requiredNull(idFieldColumn, String.format("multi id field for %s entity", entityClass.getName()));
					idFieldColumn = fieldColumn;
				}
				{
					Column column = field.getAnnotation(Column.class);
					if (column == null) {
						selectAllClause.append('`').append(fieldColumn.columnName).append('`');
						selectAllClause.append(',');
					} else {
						// 处理自定义映射列名
						selectAllClause.append('`').append(column.value()).append('`');
						selectAllClause.append(" AS `").append(fieldColumn.fieldName).append('`');
						selectAllClause.append(',');
					}
				}
				fieldColumnList.add(fieldColumn);
			}
			this.selectAllClause = selectAllClause.substring(0, selectAllClause.length() - 1);
			this.idFieldColumn = idFieldColumn;
			this.fieldColumnList = List.of(fieldColumnList.toArray(new FieldColumn[0])); // 转为只读
			canUpdate = Updatable.class.isAssignableFrom(entityClass);
			canDelete = Deletable.class.isAssignableFrom(entityClass);
			canDestroy = Destroyable.class.isAssignableFrom(entityClass);
		}
	}

	/**
	 * 实体字段属性
	 *
	 * @author 夜雨
	 * @since 2025-02-07 09:54
	 */
	private static class FieldColumn {

		/** 字段 */
		final Field field;

		/** 字段名 */
		final String fieldName;

		/** 列名 */
		final String columnName;

		/** true 为 ID */
		final boolean isId;

		/** true 为自动生成 UUID */
		final boolean isAutoUUID;

		final boolean isAutoUpperUUID;

		public FieldColumn(Field field) {
			this.field = field;

			fieldName = field.getName();
			Column column = field.getAnnotation(Column.class);
			if (column == null) {
				columnName = Text.camelCase2underscore(field.getName());
			} else {
				columnName = column.value();
				TimiException.required(columnName, "empty field:%s column annotation value for %s entity".formatted(field.getName(), field.getDeclaringClass()));
			}
			isId = field.isAnnotationPresent(Id.class);
			isAutoUUID = field.isAnnotationPresent(AutoUUID.class);
			if (isAutoUUID) {
				isAutoUpperUUID = field.getAnnotation(AutoUUID.class).upper();
			} else {
				isAutoUpperUUID = false;
			}
		}
	}
}