package fetcher

import (
	"context"
	"encoding/base64"
	"io"
	"log"
	"net/http"
	"strings"
	"time"

	"gitrepo.ru/neonxp/idecnode/pkg/config"
	"gitrepo.ru/neonxp/idecnode/pkg/idec"
)

type Fetcher struct {
	idec   *idec.IDEC
	config *config.Config
	client *http.Client
}

func New(i *idec.IDEC, cfg *config.Config) *Fetcher {
	return &Fetcher{
		idec:   i,
		config: cfg,
		client: &http.Client{
			Timeout: 60 * time.Second,
		},
	}
}

func (f *Fetcher) Run(ctx context.Context) error {
	for _, node := range f.config.Fetch {
		messagesToDownloads := []string{}
		log.Println("fetching", node)
		for _, echoID := range node.Echos {
			missed, err := f.getMissedEchoMessages(node, echoID)
			if err != nil {
				return err
			}
			messagesToDownloads = append(messagesToDownloads, missed...)
		}
		if err := f.downloadMessages(node, messagesToDownloads); err != nil {
			return err
		}
	}
	log.Println("finished")
	return nil
}

func (f *Fetcher) downloadMessages(node config.Node, messagesToDownloads []string) error {
	var slice []string
	for {
		limit := min(20, len(messagesToDownloads))
		if limit == 0 {
			return nil
		}
		slice, messagesToDownloads = messagesToDownloads[:limit-1], messagesToDownloads[limit:]
		if err := f.downloadMessagesChunk(node, slice); err != nil {
			return err
		}
	}
}

func (f *Fetcher) getMissedEchoMessages(node config.Node, echoID string) ([]string, error) {
	missed := []string{}
	messages, err := f.idec.GetMessagesByEcho(echoID, 0, 0)
	if err != nil {
		return nil, err
	}

	messagesIndex := map[string]struct{}{}
	for _, msgID := range messages {
		messagesIndex[msgID] = struct{}{}
	}

	p := formatCommand(node, "u/e", echoID)
	resp, err := f.client.Get(p)
	if err != nil {
		return nil, err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, err
	}
	lines := strings.Split(string(data), "\n")
	for _, line := range lines {
		if strings.Contains(line, ".") {
			// echo name
			continue
		}
		if line == "" {
			continue
		}
		if _, exist := messagesIndex[line]; !exist {
			missed = append(missed, line)
		}
	}

	return missed, nil
}

func (f *Fetcher) downloadMessagesChunk(node config.Node, messages []string) error {
	p := formatCommand(node, "u/m", messages...)

	resp, err := f.client.Get(p)
	if err != nil {
		return err
	}
	defer resp.Body.Close()
	data, err := io.ReadAll(resp.Body)
	if err != nil {
		return err
	}
	lines := strings.Split(string(data), "\n")

	for _, line := range lines {
		if line == "" {
			continue
		}
		p := strings.Split(line, ":")

		rawMessage, err := base64.StdEncoding.DecodeString(p[1])
		if err != nil {
			return err
		}
		if err := f.idec.SaveBundleMessage(p[0], string(rawMessage)); err != nil {
			return err
		}
	}

	return nil
}

func formatCommand(node config.Node, method string, args ...string) string {
	segments := []string{node.Addr, method}
	segments = append(segments, args...)
	p := strings.Join(segments, "/")

	return p
}

func min(x, y int) int {
	if x < y {
		return x
	}
	return y
}