package hpds_node

import (
	"context"
	"encoding/json"
	"fmt"
	"net/http"

	"git.hpds.cc/Component/network"
	"git.hpds.cc/Component/network/log"
	"git.hpds.cc/pavement/hpds_node/config"
)

const (
	mqLogPrefix = "\033[33m[hpds:mq]\033[0m "
)

// MessageQueue is the orchestrator of hpds. There are two types of mq:
// one is Upstream MessageQueue, which is used to connect to multiple downstream mq,
// another one is Downstream MessageQueue (will call it as MessageQueue directly), which is used
// to connected by `Message Queue`, `Access Point` and `Stream Function`
type MessageQueue interface {
	// ConfigWorkflow will register workflows from config files to messageQueue.
	ConfigWorkflow(conf string) error

	// ConfigMesh will register edge-mesh config URL
	ConfigMesh(url string) error

	// ListenAndServe start mq as server.
	ListenAndServe() error

	// AddDownstreamMq will add downstream mq.
	AddDownstreamMq(downstream MessageQueue) error

	// Addr returns the listen address of mq.
	Addr() string

	// Stats return insight data
	Stats() int

	// Close will close the mq.
	Close() error

	// InitOptions initialize options
	InitOptions(opts ...Option)

	// ReadConfigFile(conf string) error
	// AddWorkflow(wf ...core.Workflow) error
	// ConfigDownstream(opts ...interface{}) error
	// Connect() error
	// RemoveDownstreamMq(downstream MessageQueue) error
	// ListenAddr() string
}

// messageQueue is the implementation of MessageQueue interface.
type messageQueue struct {
	name           string
	addr           string
	hasDownStreams bool
	server         *network.Server
	client         *network.Client
	downstreamMqs  []MessageQueue
	wfc            *config.WorkflowConfig
}

var _ MessageQueue = &messageQueue{}

// NewMqWithOptions create a messageQueue instance.
func NewMqWithOptions(name string, opts ...Option) MessageQueue {
	options := NewOptions(opts...)
	zipper := createMessageQueueServer(name, options, nil)
	_ = zipper.ConfigMesh(options.MeshConfigURL)

	return zipper
}

// NewMq create a messageQueue instance from config files.
func NewMq(conf string) (MessageQueue, error) {
	confWf, err := config.ParseWorkflowConfig(conf)
	if err != nil {
		log.Errorf("%s[ERR] %v", mqLogPrefix, err)
		return nil, err
	}
	// listening address
	listenAddr := fmt.Sprintf("%s:%d", confWf.Host, confWf.Port)

	options := NewOptions()
	options.MqAddr = listenAddr
	zipper := createMessageQueueServer(confWf.Name, options, confWf)
	// messageQueue workflow
	err = zipper.configWorkflow(confWf)

	return zipper, err
}

// NewDownstreamMq create a messageQueue descriptor for downstream messageQueue.
func NewDownstreamMq(name string, opts ...Option) MessageQueue {
	options := NewOptions(opts...)
	client := network.NewClient(name, network.ClientTypeMessageQueue, options.ClientOptions...)

	return &messageQueue{
		name:   name,
		addr:   options.MqAddr,
		client: client,
	}
}

/*************** Server ONLY ***************/
// createMessageQueueServer create a messageQueue instance as server.
func createMessageQueueServer(name string, options *Options, cfg *config.WorkflowConfig) *messageQueue {
	// create underlying QUIC server
	srv := network.NewServer(name, options.ServerOptions...)
	z := &messageQueue{
		server: srv,
		name:   name,
		addr:   options.MqAddr,
		wfc:    cfg,
	}
	// initialize
	z.init()
	return z
}

// ConfigWorkflow will read workflows from config files and register them to messageQueue.
func (z *messageQueue) ConfigWorkflow(conf string) error {
	cfg, err := config.ParseWorkflowConfig(conf)
	if err != nil {
		log.Errorf("%s[ERR] %v", mqLogPrefix, err)
		return err
	}
	log.Debugf("%sConfigWorkflow cfg=%+v", mqLogPrefix, cfg)
	return z.configWorkflow(cfg)
}

func (z *messageQueue) configWorkflow(config *config.WorkflowConfig) error {
	z.wfc = config
	z.server.ConfigMetadataBuilder(newMetadataBuilder())
	z.server.ConfigRouter(newRouter(config.Functions))
	return nil
}

func (z *messageQueue) ConfigMesh(url string) error {
	if url == "" {
		return nil
	}

	log.Printf("%sDownloading mesh config...", mqLogPrefix)
	// download mesh conf
	res, err := http.Get(url)
	if err != nil {
		return err
	}
	defer func() {
		_ = res.Body.Close()
	}()

	decoder := json.NewDecoder(res.Body)
	var configs []config.MeshMessageQueue
	err = decoder.Decode(&configs)
	if err != nil {
		log.Errorf("%s downloaded the Mesh config with err=%v", mqLogPrefix, err)
		return err
	}

	log.Printf("%s Successfully downloaded the Mesh config. ", mqLogPrefix)

	if len(configs) == 0 {
		return nil
	}

	for _, downstream := range configs {
		if downstream.Name == z.name {
			continue
		}
		addr := fmt.Sprintf("%s:%d", downstream.Host, downstream.Port)
		opts := []Option{WithMqAddr(addr)}
		if downstream.Credential != "" {
			opts = append(opts, WithCredential(downstream.Credential))
		}
		_ = z.AddDownstreamMq(NewDownstreamMq(downstream.Name, opts...))
	}

	return nil
}

// ListenAndServe will start messageQueue service.
func (z *messageQueue) ListenAndServe() error {
	log.Debugf("%sCreating MessageQueue Server ...", mqLogPrefix)
	// check downstream zippers
	for _, ds := range z.downstreamMqs {
		if dsZipper, ok := ds.(*messageQueue); ok {
			go func(dsZipper *messageQueue) {
				_ = dsZipper.client.Connect(context.Background(), dsZipper.addr)
				z.server.AddDownstreamServer(dsZipper.addr, dsZipper.client)
			}(dsZipper)
		}
	}
	return z.server.ListenAndServe(context.Background(), z.addr)
}

// AddDownstreamMq will add downstream messageQueue.
func (z *messageQueue) AddDownstreamMq(downstream MessageQueue) error {
	log.Debugf("%sAddDownStreamMq: %v", mqLogPrefix, downstream)
	z.downstreamMqs = append(z.downstreamMqs, downstream)
	z.hasDownStreams = true
	log.Debugf("%scurrent downStreams: %d", mqLogPrefix, len(z.downstreamMqs))
	return nil
}

// RemoveDownstreamMq remove downstream messageQueue.
func (z *messageQueue) RemoveDownstreamMq(downstream MessageQueue) error {
	index := -1
	for i, v := range z.downstreamMqs {
		if v.Addr() == downstream.Addr() {
			index = i
			break
		}
	}

	// remove from slice
	z.downstreamMqs = append(z.downstreamMqs[:index], z.downstreamMqs[index+1:]...)
	return nil
}

// Addr returns listen address of messageQueue.
func (z *messageQueue) Addr() string {
	return z.addr
}

// Close will close a connection. If messageQueue is Server, close the server. If messageQueue is Client, close the client.
func (z *messageQueue) Close() error {
	if z.server != nil {
		if err := z.server.Close(); err != nil {
			log.Errorf("%s Close(): %v", mqLogPrefix, err)
			return err
		}
	}
	if z.client != nil {
		if err := z.client.Close(); err != nil {
			log.Errorf("%s Close(): %v", mqLogPrefix, err)
			return err
		}
	}
	return nil
}

// Stats inspects current server.
func (z *messageQueue) Stats() int {
	log.Printf("[%s] all connections: %d", z.name, len(z.server.StatsFunctions()))
	for connID, name := range z.server.StatsFunctions() {
		log.Printf("[%s] -> ConnId=%s, Name=%s", z.name, connID, name)
	}

	log.Printf("[%s] all downstream mq connected: %d", z.name, len(z.server.DownStreams()))
	for k, v := range z.server.DownStreams() {
		log.Printf("[%s] |> [%s] %s", z.name, k, v.ServerAddr())
	}

	log.Printf("[%s] total DataFrames received: %d", z.name, z.server.StatsCounter())

	return len(z.server.StatsFunctions())
}

func (z *messageQueue) InitOptions(opts ...Option) {
	options := &Options{MqAddr: z.addr}
	for _, o := range opts {
		o(options)
	}
	srv := network.NewServer(z.name, options.ServerOptions...)
	z.server = srv
	if z.wfc != nil {
		_ = z.configWorkflow(z.wfc)
	}
}