package main

import "encoding/json"
import "fmt"
import "net/http"
import "strings"
import "sync"
import "time"

import "github.com/rs/zerolog/log"

const NodeInfoSchemaVersionTwoName = "http://nodeinfo.diaspora.software/ns/schema/2.0"

const NODE_TIMEOUT = time.Second * 10
const ONE_HOUR = time.Second * 60 * 60
const ONE_DAY = time.Second * 60 * 60 * 24

type ServerImplementation int

const (
	ServerUnknown ServerImplementation = iota
	ServerMastodon
	ServerPleroma
)

type Instance struct {
	sync.Mutex
	errorCount    uint
	highestId     int
	hostName      string
	up            bool
	identified    bool
	impl          ServerImplementation
	lastError     *time.Time
	lastSuccess   *time.Time
	nextCheck     *time.Time
	nodeInfoUrl   string
	serverVersion string
}

func NewInstance(hostname string) *Instance {
	foreverago := time.Now().Add((-1 * 86400 * 365 * 100) * time.Second)
	i := new(Instance)
	i.hostName = hostname
	i.nextCheck = &foreverago
	i.up = false
	go func() {
		i.detectNodeType()
	}()
	return i
}

func (i *Instance) setNextCheck(d *time.Duration) {
	i.Lock()
	defer i.Unlock()
	then := time.Now().Add(*d)
	i.nextCheck = &then
}

func (i *Instance) dueForCheck() bool {
	i.Lock()
	defer i.Unlock()
	return i.nextCheck.Before(time.Now())
}

func (i *Instance) detectNodeType() {
	i.Lock()
	if i.impl > ServerUnknown {
		i.Unlock()
		return
	}
	i.Unlock()
	i.fetchNodeInfo()
}

type NodeInfoWellKnownResponse struct {
	Links []struct {
		Rel  string `json:"rel"`
		Href string `json:"href"`
	} `json:"links"`
}

type NodeInfoVersionTwoSchema struct {
	Version  string `json:"version"`
	Software struct {
		Name    string `json:"name"`
		Version string `json:"version"`
	} `json:"software"`
	Protocols []string `json:"protocols"`
	Usage     struct {
		Users struct {
			Total          int `json:"total"`
			ActiveMonth    int `json:"activeMonth"`
			ActiveHalfyear int `json:"activeHalfyear"`
		} `json:"users"`
		LocalPosts int `json:"localPosts"`
	} `json:"usage"`
	OpenRegistrations bool `json:"openRegistrations"`
}

func (i *Instance) registerError() {
	i.Lock()
	defer i.Unlock()
	i.errorCount = i.errorCount + 1
	t := time.Now()
	i.lastError = &t
}

func (i *Instance) registerSuccess() {
	i.Lock()
	defer i.Unlock()
	t := time.Now()
	i.lastSuccess = &t
}

func (i *Instance) fetchNodeInfoURL() {
	url := fmt.Sprintf("https://%s/.well-known/nodeinfo", i.hostName)
	var c = &http.Client{
		Timeout: NODE_TIMEOUT,
	}

	log.Debug().
		Str("url", url).
		Str("hostname", i.hostName).
		Msg("fetching nodeinfo reference URL")

	resp, err := c.Get(url)
	if err != nil {
		log.Error().
			Str("hostname", i.hostName).
			Msg("unable to fetch nodeinfo, node is down?")
		i.registerError()
	} else {
		i.up = true // node is alive and responding to us
		nir := new(NodeInfoWellKnownResponse)
		err = json.NewDecoder(resp.Body).Decode(&nir)
		if err != nil {
			log.Error().
				Str("hostname", i.hostName).
				Msg("unable to parse nodeinfo")
			i.registerError()
			return
		}
		for _, item := range nir.Links {
			if item.Rel == NodeInfoSchemaVersionTwoName {
				log.Info().
					Str("hostname", i.hostName).
					Str("nodeinfourl", item.Href).
					Msg("success fetching url for nodeinfo")

				i.Lock()
				i.nodeInfoUrl = item.Href
				i.Unlock()
				i.registerSuccess()
				return
			}
		}
		log.Error().
			Str("hostname", i.hostName).
			Msg("incomplete nodeinfo")
		i.registerError()
		return
	}
}

func (i *Instance) fetchNodeInfo() {
	i.fetchNodeInfoURL()

	i.Lock()
	failure := false
	if i.nodeInfoUrl == "" {
		log.Error().
			Str("hostname", i.hostName).
			Msg("unable to fetch nodeinfo as nodeinfo URL cannot be determined")
		failure = true
	}
	i.Unlock()

	if failure == true {
		return
	}

	var c = &http.Client{
		Timeout: NODE_TIMEOUT,
	}

	//FIXME make sure the nodeinfourl is on the same domain as the instance
	//hostname
	i.Lock()
	url := i.nodeInfoUrl
	i.Unlock()

	resp, err := c.Get(url)

	if err != nil {
		log.Error().
			Str("hostname", i.hostName).
			Msgf("unable to fetch nodeinfo data: %s", err)
		i.registerError()
	} else {
		ni := new(NodeInfoVersionTwoSchema)
		err = json.NewDecoder(resp.Body).Decode(&ni)
		if err != nil {
			log.Error().
				Str("hostname", i.hostName).
				Msgf("unable to parse nodeinfo: %s", err)
			i.registerError()
			return
		}

		log.Info().
			Str("serverVersion", ni.Software.Version).
			Str("software", ni.Software.Name).
			Str("hostName", i.hostName).
			Str("nodeInfoUrl", i.nodeInfoUrl).
			Msg("received nodeinfo from instance")

		i.Lock()
		defer i.Unlock()
		i.serverVersion = ni.Software.Version

		ni.Software.Name = strings.ToLower(ni.Software.Name)

		if ni.Software.Name == "pleroma" {
			log.Info().
				Str("hostname", i.hostName).
				Str("software", ni.Software.Name).
				Msg("detected server software")
			i.registerSuccess()
			i.identified = true
			i.impl = ServerPleroma
		} else if ni.Software.Name == "mastodon" {
			log.Info().
				Str("hostname", i.hostName).
				Str("software", ni.Software.Name).
				Msg("detected server software")
			i.registerSuccess()
			i.identified = true
			i.impl = ServerMastodon
		} else {
			log.Error().
				Str("hostname", i.hostName).
				Str("software", ni.Software.Name).
				Msg("unknown implementation on server")
			i.registerError()
		}
		return
	}
}

func (i *Instance) fetchRecentToots() ([]byte, error) {
	i.Lock()
	impl := i.impl
	i.Unlock()

	if impl == ServerMastodon {
		return i.fetchRecentTootsJsonFromMastodon()
	} else if impl == ServerPleroma {
		return i.fetchRecentTootsJsonFromPleroma()
	} else {
		panic("unimplemented")
	}
}

func (i *Instance) fetchRecentTootsJsonFromPleroma() ([]byte, error) {
	//url := fmt.Sprintf("https://%s/api/statuses/public_and_external_timeline.json?count=100", i.hostName)
	return nil, nil
}

func (i *Instance) fetchRecentTootsJsonFromMastodon() ([]byte, error) {
	//url := fmt.Sprintf("https://%s/api/v1/timelines/public?limit=40&local=true", i.hostName)
	return nil, nil
}