package lite

import (
	log "github.com/tendermint/tendermint/libs/log"
	lerr "github.com/tendermint/tendermint/lite/errors"
	"github.com/tendermint/tendermint/types"
)

var _ PersistentProvider = (*multiProvider)(nil)

// multiProvider allows you to place one or more caches in front of a source
// Provider.  It runs through them in order until a match is found.
type multiProvider struct {
	logger    log.Logger
	providers []PersistentProvider
}

// NewMultiProvider returns a new provider which wraps multiple other providers.
func NewMultiProvider(providers ...PersistentProvider) *multiProvider {
	return &multiProvider{
		logger:    log.NewNopLogger(),
		providers: providers,
	}
}

// SetLogger sets logger on self and all subproviders.
func (mc *multiProvider) SetLogger(logger log.Logger) {
	mc.logger = logger
	for _, p := range mc.providers {
		p.SetLogger(logger)
	}
}

// SaveFullCommit saves on all providers, and aborts on the first error.
func (mc *multiProvider) SaveFullCommit(fc FullCommit) (err error) {
	for _, p := range mc.providers {
		err = p.SaveFullCommit(fc)
		if err != nil {
			return
		}
	}
	return
}

// LatestFullCommit loads the latest from all providers and provides
// the latest FullCommit that satisfies the conditions.
// Returns the first error encountered.
func (mc *multiProvider) LatestFullCommit(chainID string, minHeight, maxHeight int64) (fc FullCommit, err error) {
	for _, p := range mc.providers {
		var commit FullCommit
		commit, err = p.LatestFullCommit(chainID, minHeight, maxHeight)
		if lerr.IsErrCommitNotFound(err) {
			err = nil
			continue
		} else if err != nil {
			return
		}
		if fc == (FullCommit{}) {
			fc = commit
		} else if commit.Height() > fc.Height() {
			fc = commit
		}
		if fc.Height() == maxHeight {
			return
		}
	}
	if fc == (FullCommit{}) {
		err = lerr.ErrCommitNotFound()
		return
	}
	return
}

// ValidatorSet returns validator set at height as provided by the first
// provider which has it, or an error otherwise.
func (mc *multiProvider) ValidatorSet(chainID string, height int64) (valset *types.ValidatorSet, err error) {
	for _, p := range mc.providers {
		valset, err = p.ValidatorSet(chainID, height)
		if err == nil {
			// TODO Log unexpected types of errors.
			return valset, nil
		}
	}
	return nil, lerr.ErrUnknownValidators(chainID, height)
}