package acl

import (
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/core/container"
	v2 "git.frostfs.info/TrueCloudLab/frostfs-node/pkg/services/object/acl/v2"
	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/util/logger"
	apistatus "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/client/status"
	apechain "git.frostfs.info/TrueCloudLab/policy-engine/pkg/chain"
	policyengine "git.frostfs.info/TrueCloudLab/policy-engine/pkg/engine"
)

var errAPEChainNoSource = errors.New("could not get ape chain source for the container")

type apeCheckerImpl struct {
	log    *logger.Logger
	apeSrc container.AccessPolicyEngineChainSource
}

func NewAPEChecker(log *logger.Logger, apeSrc container.AccessPolicyEngineChainSource) v2.APEChainChecker {
	return &apeCheckerImpl{
		log:    log,
		apeSrc: apeSrc,
	}
}

func (c *apeCheckerImpl) CheckIfRequestPermitted(reqInfo v2.RequestInfo) error {
	cnr := reqInfo.ContainerID()

	chainCache, err := c.apeSrc.GetChainSource(cnr)
	if err != nil {
		return errAPEChainNoSource
	}

	request := new(Request)
	request.FromRequestInfo(reqInfo)

	cnrTarget := getResource(reqInfo).Name()

	status, ruleFound, err := chainCache.IsAllowed(apechain.Ingress, policyengine.NewRequestTargetWithContainer(cnrTarget), request)
	if err != nil {
		return err
	}

	if !ruleFound || status == apechain.Allow {
		return nil
	}

	return apeErr(reqInfo, status)
}

const accessDeniedAPEReasonFmt = "access to operation %s is denied by access policy engine: %s"

func apeErr(req v2.RequestInfo, status apechain.Status) error {
	errAccessDenied := &apistatus.ObjectAccessDenied{}
	errAccessDenied.WriteReason(fmt.Sprintf(accessDeniedAPEReasonFmt, req.Operation(), status.String()))
	return errAccessDenied
}