package simpleorm

import (
	"database/sql"
	"errors"
	"reflect"

	log "gitlab.com/gdulai/simpleloglvl"
)

type ORMExec[T any] struct {
	orm  *ORM
	conn *DBConnection
}

func CreateExecution[T any](orm *ORM, conn *DBConnection) ORMExec[T] {
	return ORMExec[T]{orm: orm, conn: conn}
}

func InitDB(conn *DBConnection, orm *ORM) {
	// Force a real DB interaction
	if _, err := conn.db.Exec(orm.CreateDDL()); err != nil {
		log.LogFatalError("%", err)
	}
}

func (ormExec ORMExec[T]) Select(desc T, whereStmt string, args ...any) ([]T, error) {
	lookup := reflect.TypeOf(desc).Name()
	table, ok := ormExec.orm.cache.Get(lookup)
	if !ok {
		return []T{}, errors.New("Failed to get descriptor from cache! " + lookup)
	}
	sqlStr := table.ToSelectDML()
	if whereStmt != "" {
		sqlStr += " WHERE " + whereStmt
	}
	log.LogDebug("Preparing sql: %s, with args: %s", sqlStr, args)

	stmt, err := ormExec.conn.db.Prepare(sqlStr)
	if err != nil {
		return nil, err
	}
	defer stmt.Close()

	log.LogDebug("Executing statement: %s", stmt)

	var rows *sql.Rows
	if len(args) == 0 {
		rows, err = stmt.Query()
	} else {
		// Flattent args to make sure it can be parsed correctly
		var flatArgs []any
		for _, a := range args {
			if s, ok := a.([]any); ok {
				flatArgs = append(flatArgs, s...)
			} else {
				flatArgs = append(flatArgs, a)
			}
		}
		rows, err = stmt.Query(flatArgs...)

	}

	if err != nil {
		return nil, err
	}

	rowContainer := table.createSelectResultContainer()

	var results []T

	for rows.Next() {
		err = rows.Scan(rowContainer...)
		if err != nil {
			return nil, err
		}

		targetType := table.Type
		parsedResult := reflect.New(targetType)
		for i, fieldVal := range rowContainer {
			parsedResult.Elem().Field(i).Set(reflect.Indirect(reflect.ValueOf(fieldVal)))
		}
		parsedObj := reflect.Indirect(parsedResult).Interface().(T)
		results = append(results, parsedObj)
	}

	return results, nil
}

func (ormExec ORMExec[T]) Insert(src ...T) error {
	typeName := reflect.TypeOf(src[0]).Name()
	table, ok := ormExec.orm.cache.Get(typeName)
	if !ok {
		return errors.New("Could not find table for type " + typeName)
	}

	sql := table.ToInsertDML(len(src))
	var params []any
	for i := range len(src) {
		actualParams := table.prepareParams(src[i])
		if len(params) == 0 {
			params = make([]any, len(src)*len(actualParams))
		}
		for j := range actualParams {
			params[(i*len(actualParams))+j] = actualParams[j]
		}
	}

	log.LogInfo("%s [%s]", sql, params)

	stmt, err := ormExec.conn.db.Prepare(sql)
	if err != nil {
		return err
	}
	defer stmt.Close()

	result, err := stmt.Exec(params...)
	if err != nil {
		return err
	} else {
		rowsAffected, _ := result.RowsAffected()
		log.LogInfo("Inserted %s row", rowsAffected)
	}
	return nil
}

func (ormExec ORMExec[T]) Update(src T) error {
	typeName := reflect.TypeOf(src).Name()
	table, ok := ormExec.orm.cache.Get(reflect.TypeOf(src).Name())
	if !ok {
		return errors.New("Could not find table for type " + typeName)
	}

	sql := table.ToUpdateDML(src)
	params := table.prepareParams(src)

	pk, err := table.getPk(src)
	if err != nil {
		return err
	}
	// Put the pk back at the end
	params = append(params, pk)

	log.LogInfo("%s [%s]", sql, params)

	stmt, err := ormExec.conn.db.Prepare(sql)
	if err != nil {
		return err
	}
	defer stmt.Close()

	result, err := stmt.Exec(params...)
	if err != nil {
		return err
	} else {
		rowsAffected, _ := result.RowsAffected()
		log.LogInfo("Updated %s row", rowsAffected)
	}
	return nil
}

func (ormExec ORMExec[T]) Delete(src T) error {
	typeName := reflect.TypeOf(src).Name()
	table, ok := ormExec.orm.cache.Get(reflect.TypeOf(src).Name())
	if !ok {
		return errors.New("Could not find table for type " + typeName)
	}

	sql := table.ToDeleteDML(src)
	pk, err := table.getPk(src)
	if err != nil {
		return err
	}

	log.LogInfo("%s [%s]", sql, pk)

	stmt, err := ormExec.conn.db.Prepare(sql)
	if err != nil {
		return err
	}
	defer stmt.Close()

	result, err := stmt.Exec(pk)
	if err != nil {
		return err
	} else {
		rowsAffected, _ := result.RowsAffected()
		log.LogInfo("Deleted %s row", rowsAffected)
	}
	return nil
}