package engine

import (
	"git.frostfs.info/TrueCloudLab/policy-engine/util"

	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/chain"
	"git.frostfs.info/TrueCloudLab/policy-engine/pkg/resource"
)

type inmemory struct {
	namespace map[chain.Name][]chainWrapper
	resource  map[chain.Name][]chainWrapper
	local     map[chain.Name][]*chain.Chain
}

type chainWrapper struct {
	object string
	chain  *chain.Chain
}

// NewInMemory returns new inmemory instance of chain storage.
func NewInMemory() CachedChainStorage {
	return &inmemory{
		namespace: make(map[chain.Name][]chainWrapper),
		resource:  make(map[chain.Name][]chainWrapper),
		local:     make(map[chain.Name][]*chain.Chain),
	}
}

// IsAllowed implements the Engine interface.
func (s *inmemory) IsAllowed(name chain.Name, namespace string, r resource.Request) (chain.Status, bool) {
	var ruleFound bool
	if local, ok := s.local[name]; ok {
		for _, c := range local {
			if status, matched := c.Match(r); matched && status != chain.Allow {
				return status, true
			}
		}
	}
	if cs, ok := s.namespace[name]; ok {
		status, ok := matchArray(cs, namespace, r)
		if ok && status != chain.Allow {
			return status, true
		}
		ruleFound = ruleFound || ok
	}
	if cs, ok := s.resource[name]; ok {
		status, ok := matchArray(cs, r.Resource().Name(), r)
		if ok {
			return status, true
		}
		ruleFound = ruleFound || ok
	}
	if ruleFound {
		return chain.Allow, true
	}
	return chain.NoRuleFound, false
}

func matchArray(cs []chainWrapper, object string, r resource.Request) (chain.Status, bool) {
	for _, c := range cs {
		if !util.GlobMatch(object, c.object) {
			continue
		}
		if status, matched := c.chain.Match(r); matched {
			return status, true
		}
	}
	return chain.NoRuleFound, false
}

func (s *inmemory) AddResourceChain(name chain.Name, resource string, c *chain.Chain) {
	s.resource[name] = append(s.resource[name], chainWrapper{resource, c})
}

func (s *inmemory) AddNameSpaceChain(name chain.Name, namespace string, c *chain.Chain) {
	s.namespace[name] = append(s.namespace[name], chainWrapper{namespace, c})
}

func (s *inmemory) AddOverride(name chain.Name, c *chain.Chain) {
	s.local[name] = append(s.local[name], c)
}

func (s *inmemory) GetOverride(name chain.Name, chainID chain.ID) (chain *chain.Chain, found bool) {
	chains := s.local[name]

	for _, chain = range chains {
		if chain.ID == chainID {
			found = true
			return
		}
	}

	return
}

func (s *inmemory) RemoveOverride(name chain.Name, chainID chain.ID) (found bool) {
	chains := s.local[name]

	for i, chain := range chains {
		if chain.ID == chainID {
			s.local[name] = append(chains[:i], chains[i+1:]...)
			found = true
			return
		}
	}

	return
}

func (s *inmemory) ListOverrides(name chain.Name) []*chain.Chain {
	return s.local[name]
}