package system

import (
	"context"

	"gorm.io/gorm"
)

// AutoCodeMysql MySQL适配器
type AutoCodeMysql struct {
	db     *gorm.DB
	dbList map[string]*gorm.DB
}

// NewAutoCodeMysql 创建MySQL适配器
func NewAutoCodeMysql(db *gorm.DB, dbList map[string]*gorm.DB) *AutoCodeMysql {
	return &AutoCodeMysql{
		db:     db,
		dbList: dbList,
	}
}

// GetDB 获取数据库的所有数据库名
func (s *AutoCodeMysql) GetDB(ctx context.Context) ([]Db, error) {
	var entities []Db
	sql := "SELECT SCHEMA_NAME AS `database` FROM INFORMATION_SCHEMA.SCHEMATA;"
	err := s.db.WithContext(ctx).Raw(sql).Scan(&entities).Error
	return entities, err
}

// GetTables 获取数据库的所有表名
func (s *AutoCodeMysql) GetTables(ctx context.Context, dbName string) ([]Table, error) {
	var entities []Table
	sql := `select table_name as table_name from information_schema.tables where table_schema = ?`
	err := s.db.WithContext(ctx).Raw(sql, dbName).Scan(&entities).Error
	return entities, err
}

// GetColumn 获取指定数据库和指定数据表的所有字段名,类型值等
func (s *AutoCodeMysql) GetColumn(ctx context.Context, tableName, dbName string) ([]Column, error) {
	var entities []Column
	sql := `
	SELECT 
    c.COLUMN_NAME column_name,
    c.DATA_TYPE data_type,
    CASE c.DATA_TYPE
        WHEN 'longtext' THEN c.CHARACTER_MAXIMUM_LENGTH
        WHEN 'varchar' THEN c.CHARACTER_MAXIMUM_LENGTH
        WHEN 'double' THEN CONCAT_WS(',', c.NUMERIC_PRECISION, c.NUMERIC_SCALE)
        WHEN 'decimal' THEN CONCAT_WS(',', c.NUMERIC_PRECISION, c.NUMERIC_SCALE)
        WHEN 'int' THEN c.NUMERIC_PRECISION
        WHEN 'bigint' THEN c.NUMERIC_PRECISION
        ELSE '' 
    END AS data_type_long,
    c.COLUMN_COMMENT column_comment,
    CASE WHEN kcu.COLUMN_NAME IS NOT NULL THEN 1 ELSE 0 END AS primary_key,
    c.ORDINAL_POSITION
FROM 
    INFORMATION_SCHEMA.COLUMNS c
LEFT JOIN 
    INFORMATION_SCHEMA.KEY_COLUMN_USAGE kcu 
ON 
    c.TABLE_SCHEMA = kcu.TABLE_SCHEMA 
    AND c.TABLE_NAME = kcu.TABLE_NAME 
    AND c.COLUMN_NAME = kcu.COLUMN_NAME 
    AND kcu.CONSTRAINT_NAME = 'PRIMARY'
WHERE 
    c.TABLE_NAME = ? 
    AND c.TABLE_SCHEMA = ?
ORDER BY 
    c.ORDINAL_POSITION;`
	err := s.db.WithContext(ctx).Raw(sql, tableName, dbName).Scan(&entities).Error
	return entities, err
}