package kv

import (
	"fmt"
	"sort"
	"strconv"
	"strings"
	"text/template"

	"github.com/BurntSushi/ty/fun"
	"github.com/containous/traefik/log"
	"github.com/containous/traefik/provider/label"
	"github.com/containous/traefik/types"
	"github.com/docker/libkv/store"
)

func (p *Provider) buildConfiguration() *types.Configuration {
	templateObjects := struct {
		Prefix string
	}{
		// Allow `/traefik/alias` to supersede `p.Prefix`
		Prefix: strings.TrimSuffix(p.get(p.Prefix, p.Prefix+pathAlias), pathSeparator),
	}

	var KvFuncMap = template.FuncMap{
		"List":        p.list,
		"ListServers": p.listServers,
		"Get":         p.get,
		"SplitGet":    p.splitGet,
		"Last":        p.last,

		// Backend functions
		"getSticky":               p.getSticky,
		"hasStickinessLabel":      p.hasStickinessLabel,
		"getStickinessCookieName": p.getStickinessCookieName,
	}

	configuration, err := p.GetConfiguration("templates/kv.tmpl", KvFuncMap, templateObjects)
	if err != nil {
		log.Error(err)
	}

	for key, frontend := range configuration.Frontends {
		if _, ok := configuration.Backends[frontend.Backend]; !ok {
			delete(configuration.Frontends, key)
		}
	}

	return configuration
}

func (p *Provider) getSticky(rootPath string) bool {
	stickyValue := p.get("", rootPath, pathBackendLoadBalancerSticky)
	if len(stickyValue) > 0 {
		log.Warnf("Deprecated configuration found: %s. Please use %s.", pathBackendLoadBalancerSticky, pathBackendLoadBalancerStickiness)
	} else {
		return false
	}

	sticky, err := strconv.ParseBool(stickyValue)
	if err != nil {
		log.Warnf("Invalid %s value: %s.", pathBackendLoadBalancerSticky, stickyValue)
	}

	return sticky
}

func (p *Provider) hasStickinessLabel(rootPath string) bool {
	return p.getBool(false, rootPath, pathBackendLoadBalancerStickiness)
}

func (p *Provider) getStickinessCookieName(rootPath string) string {
	return p.get("", rootPath, pathBackendLoadBalancerStickinessCookieName)
}

func (p *Provider) listServers(backend string) []string {
	serverNames := p.list(backend, pathBackendServers)
	return fun.Filter(p.serverFilter, serverNames).([]string)
}

func (p *Provider) serverFilter(serverName string) bool {
	key := fmt.Sprint(serverName, pathBackendServerURL)
	if _, err := p.kvClient.Get(key, nil); err != nil {
		if err != store.ErrKeyNotFound {
			log.Errorf("Failed to retrieve value for key %s: %s", key, err)
		}
		return false
	}
	return p.checkConstraints(serverName, pathTags)
}

func (p *Provider) checkConstraints(keys ...string) bool {
	joinedKeys := strings.Join(keys, "")
	keyPair, err := p.kvClient.Get(joinedKeys, nil)

	value := ""
	if err == nil && keyPair != nil && keyPair.Value != nil {
		value = string(keyPair.Value)
	}

	constraintTags := label.SplitAndTrimString(value, ",")
	ok, failingConstraint := p.MatchConstraints(constraintTags)
	if !ok {
		if failingConstraint != nil {
			log.Debugf("Constraint %v not matching with following tags: %v", failingConstraint.String(), value)
		}
		return false
	}
	return true
}

func (p *Provider) get(defaultValue string, keyParts ...string) string {
	key := strings.Join(keyParts, "")

	if p.storeType == store.ETCD {
		key = strings.TrimPrefix(key, pathSeparator)
	}

	keyPair, err := p.kvClient.Get(key, nil)
	if err != nil {
		log.Debugf("Cannot get key %s %s, setting default %s", key, err, defaultValue)
		return defaultValue
	} else if keyPair == nil {
		log.Debugf("Cannot get key %s, setting default %s", key, defaultValue)
		return defaultValue
	}

	return string(keyPair.Value)
}

func (p *Provider) getBool(defaultValue bool, keyParts ...string) bool {
	rawValue := p.get(strconv.FormatBool(defaultValue), keyParts...)

	if len(rawValue) == 0 {
		return defaultValue
	}

	value, err := strconv.ParseBool(rawValue)
	if err != nil {
		log.Errorf("Invalid value for %v: %s", keyParts, rawValue)
		return defaultValue
	}
	return value
}

func (p *Provider) list(keyParts ...string) []string {
	rootKey := strings.Join(keyParts, "")

	keysPairs, err := p.kvClient.List(rootKey, nil)
	if err != nil {
		log.Debugf("Cannot list keys under %q: %v", rootKey, err)
		return nil
	}

	directoryKeys := make(map[string]string)
	for _, key := range keysPairs {
		directory := strings.Split(strings.TrimPrefix(key.Key, rootKey), pathSeparator)[0]
		directoryKeys[directory] = rootKey + directory
	}

	keys := fun.Values(directoryKeys).([]string)
	sort.Strings(keys)
	return keys
}

func (p *Provider) splitGet(keyParts ...string) []string {
	value := p.get("", keyParts...)

	if len(value) == 0 {
		return nil
	}
	return label.SplitAndTrimString(value, ",")
}

func (p *Provider) last(key string) string {
	index := strings.LastIndex(key, pathSeparator)
	return key[index+1:]
}