package query

import (
	"go.mongodb.org/mongo-driver/bson"
	"go.mongodb.org/mongo-driver/bson/primitive"

	"github.com/mainnika/mongox-go-driver/mongox/base"
	"github.com/mainnika/mongox-go-driver/mongox/errors"
)

// Compose is a function to compose filters into a single query
func Compose(filters ...interface{}) *Query {

	q := &Query{}

	for _, f := range filters {
		if !Push(q, f) {
			panic(errors.InternalErrorf("unknown filter %v", f))
		}
	}

	return q
}

// Push applies single filter to a query
func Push(q *Query, f interface{}) bool {

	ok := false
	ok = ok || applyBson(q, f)
	ok = ok || applyLimit(q, f)
	ok = ok || applySort(q, f)
	ok = ok || applySkip(q, f)
	ok = ok || applyProtection(q, f)
	ok = ok || applyPreloader(q, f)

	return ok
}

// applyBson is a fallback for a custom bson.M
func applyBson(q *Query, f interface{}) bool {

	if f, ok := f.(bson.M); ok {
		q.And(f)
		return true
	}

	return false
}

// applyLimits extends query with a limiter
func applyLimit(q *Query, f interface{}) bool {

	if f, ok := f.(Limiter); ok {
		q.limiter = f
		return true
	}

	return false
}

// applySort extends query with a sort rule
func applySort(q *Query, f interface{}) bool {

	if f, ok := f.(Sorter); ok {
		q.sorter = f
		return true
	}

	return false
}

// applySkip extends query with a skip number
func applySkip(q *Query, f interface{}) bool {

	if f, ok := f.(Skipper); ok {
		q.skipper = f
		return true
	}

	return false
}

func applyProtection(q *Query, f interface{}) bool {

	var x *primitive.ObjectID
	var v *int64

	switch f := f.(type) {
	case base.Protection:
		x = &f.X
		v = &f.V
	case *base.Protection:
		if f == nil {
			return false
		}
		x = &f.X
		v = &f.V

	default:
		return false
	}

	if x.IsZero() {
		q.And(primitive.M{"_x": primitive.M{"$exists": false}})
		q.And(primitive.M{"_v": primitive.M{"$exists": false}})
	} else {
		q.And(primitive.M{"_x": *x})
		q.And(primitive.M{"_v": *v})
	}

	return true
}

func applyPreloader(q *Query, f interface{}) bool {

	if f, ok := f.(Preloader); ok {
		q.preloader = f
		return true
	}

	return false
}