package types

import (
	"encoding"
	"errors"
	"fmt"
	"github.com/docker/libkv/store"
	"github.com/ryanuber/go-glob"
	"strings"
)

// Backend holds backend configuration.
type Backend struct {
	Servers        map[string]Server `json:"servers,omitempty"`
	CircuitBreaker *CircuitBreaker   `json:"circuitBreaker,omitempty"`
	LoadBalancer   *LoadBalancer     `json:"loadBalancer,omitempty"`
	MaxConn        *MaxConn          `json:"maxConn,omitempty"`
}

// MaxConn holds maximum connection configuration
type MaxConn struct {
	Amount        int64  `json:"amount,omitempty"`
	ExtractorFunc string `json:"extractorFunc,omitempty"`
}

// LoadBalancer holds load balancing configuration.
type LoadBalancer struct {
	Method string `json:"method,omitempty"`
	Sticky bool   `json:"sticky,omitempty"`
}

// CircuitBreaker holds circuit breaker configuration.
type CircuitBreaker struct {
	Expression string `json:"expression,omitempty"`
}

// Server holds server configuration.
type Server struct {
	URL    string `json:"url,omitempty"`
	Weight int    `json:"weight"`
}

// Route holds route configuration.
type Route struct {
	Rule string `json:"rule,omitempty"`
}

// Frontend holds frontend configuration.
type Frontend struct {
	EntryPoints    []string         `json:"entryPoints,omitempty"`
	Backend        string           `json:"backend,omitempty"`
	Routes         map[string]Route `json:"routes,omitempty"`
	PassHostHeader bool             `json:"passHostHeader,omitempty"`
	Priority       int              `json:"priority"`
}

// LoadBalancerMethod holds the method of load balancing to use.
type LoadBalancerMethod uint8

const (
	// Wrr (default) = Weighted Round Robin
	Wrr LoadBalancerMethod = iota
	// Drr = Dynamic Round Robin
	Drr
)

var loadBalancerMethodNames = []string{
	"Wrr",
	"Drr",
}

// NewLoadBalancerMethod create a new LoadBalancerMethod from a given LoadBalancer.
func NewLoadBalancerMethod(loadBalancer *LoadBalancer) (LoadBalancerMethod, error) {
	if loadBalancer != nil {
		for i, name := range loadBalancerMethodNames {
			if strings.EqualFold(name, loadBalancer.Method) {
				return LoadBalancerMethod(i), nil
			}
		}
	}
	return Wrr, ErrInvalidLoadBalancerMethod
}

// ErrInvalidLoadBalancerMethod is thrown when the specified load balancing method is invalid.
var ErrInvalidLoadBalancerMethod = errors.New("Invalid method, using default")

// Configuration of a provider.
type Configuration struct {
	Backends  map[string]*Backend  `json:"backends,omitempty"`
	Frontends map[string]*Frontend `json:"frontends,omitempty"`
}

// ConfigMessage hold configuration information exchanged between parts of traefik.
type ConfigMessage struct {
	ProviderName  string
	Configuration *Configuration
}

// Constraint hold a parsed constraint expresssion
type Constraint struct {
	Key string
	// MustMatch is true if operator is "==" or false if operator is "!="
	MustMatch bool
	// TODO: support regex
	Regex string
}

// NewConstraint receive a string and return a *Constraint, after checking syntax and parsing the constraint expression
func NewConstraint(exp string) (*Constraint, error) {
	sep := ""
	constraint := &Constraint{}

	if strings.Contains(exp, "==") {
		sep = "=="
		constraint.MustMatch = true
	} else if strings.Contains(exp, "!=") {
		sep = "!="
		constraint.MustMatch = false
	} else {
		return nil, errors.New("Constraint expression missing valid operator: '==' or '!='")
	}

	kv := strings.SplitN(exp, sep, 2)
	if len(kv) == 2 {
		// At the moment, it only supports tags
		if kv[0] != "tag" {
			return nil, errors.New("Constraint must be tag-based. Syntax: tag==us-*")
		}

		constraint.Key = kv[0]
		constraint.Regex = kv[1]
		return constraint, nil
	}

	return nil, errors.New("Incorrect constraint expression: " + exp)
}

func (c *Constraint) String() string {
	if c.MustMatch {
		return c.Key + "==" + c.Regex
	}
	return c.Key + "!=" + c.Regex
}

var _ encoding.TextUnmarshaler = (*Constraint)(nil)

// UnmarshalText define how unmarshal in TOML parsing
func (c *Constraint) UnmarshalText(text []byte) error {
	constraint, err := NewConstraint(string(text))
	if err != nil {
		return err
	}
	c.Key = constraint.Key
	c.MustMatch = constraint.MustMatch
	c.Regex = constraint.Regex
	return nil
}

var _ encoding.TextMarshaler = (*Constraint)(nil)

// MarshalText encodes the receiver into UTF-8-encoded text and returns the result.
func (c *Constraint) MarshalText() (text []byte, err error) {
	return []byte(c.String()), nil
}

// MatchConstraintWithAtLeastOneTag tests a constraint for one single service
func (c *Constraint) MatchConstraintWithAtLeastOneTag(tags []string) bool {
	for _, tag := range tags {
		if glob.Glob(c.Regex, tag) {
			return true
		}
	}
	return false
}

//Set []*Constraint
func (cs *Constraints) Set(str string) error {
	exps := strings.Split(str, ",")
	if len(exps) == 0 {
		return errors.New("Bad Constraint format: " + str)
	}
	for _, exp := range exps {
		constraint, err := NewConstraint(exp)
		if err != nil {
			return err
		}
		*cs = append(*cs, constraint)
	}
	return nil
}

// Constraints holds a Constraint parser
type Constraints []*Constraint

//Get []*Constraint
func (cs *Constraints) Get() interface{} { return []*Constraint(*cs) }

//String returns []*Constraint in string
func (cs *Constraints) String() string { return fmt.Sprintf("%+v", *cs) }

//SetValue sets []*Constraint into the parser
func (cs *Constraints) SetValue(val interface{}) {
	*cs = Constraints(val.(Constraints))
}

// Type exports the Constraints type as a string
func (cs *Constraints) Type() string {
	return fmt.Sprint("constraint")
}

// Store holds KV store cluster config
type Store struct {
	store.Store
	Prefix string // like this "prefix" (without the /)
}

// Cluster holds cluster config
type Cluster struct {
	Node  string `description:"Node name"`
	Store *Store
}

// Auth holds authentication configuration (BASIC, DIGEST, users)
type Auth struct {
	Basic  *Basic
	Digest *Digest
}

// Users authentication users
type Users []string

// Basic HTTP basic authentication
type Basic struct {
	Users `mapstructure:","`
}

// Digest HTTP authentication
type Digest struct {
	Users `mapstructure:","`
}

// CanonicalDomain returns a lower case domain with trim space
func CanonicalDomain(domain string) string {
	return strings.ToLower(strings.TrimSpace(domain))
}

// Statistics provides options for monitoring request and response stats
type Statistics struct {
	RecentErrors int `description:"Number of recent errors logged"`
}