// Copyright (c) 2012-present The upper.io/db authors. All rights reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining
// a copy of this software and associated documentation files (the
// "Software"), to deal in the Software without restriction, including
// without limitation the rights to use, copy, modify, merge, publish,
// distribute, sublicense, and/or sell copies of the Software, and to
// permit persons to whom the Software is furnished to do so, subject to
// the following conditions:
//
// The above copyright notice and this permission notice shall be
// included in all copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
// EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
// MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
// NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
// LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
// WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

package db

import (
	"reflect"
)

// Function interface defines methods for representing database functions.
// This is an exported interface but it's rarely used directly, you may want to
// use the `db.Func()` function instead.
type Function interface {
	// Name returns the function name.
	Name() string

	// Argument returns the function arguments.
	Arguments() []interface{}
}

// Func represents a database function and satisfies the db.Function interface.
//
// Examples:
//
//	// MOD(29, 9)
//	db.Func("MOD", 29, 9)
//
//	// CONCAT("foo", "bar")
//	db.Func("CONCAT", "foo", "bar")
//
//	// NOW()
//	db.Func("NOW")
//
//	// RTRIM("Hello  ")
//	db.Func("RTRIM", "Hello  ")
func Func(name string, args ...interface{}) Function {
	if len(args) == 1 {
		if reflect.TypeOf(args[0]).Kind() == reflect.Slice {
			iargs := make([]interface{}, len(args))
			for i := range args {
				iargs[i] = args[i]
			}
			args = iargs
		}
	}
	return &dbFunc{name: name, args: args}
}

type dbFunc struct {
	name string
	args []interface{}
}

func (f *dbFunc) Arguments() []interface{} {
	return f.args
}

func (f *dbFunc) Name() string {
	return f.name
}

var _ Function = &dbFunc{}