package runtime

import (
	"bytes"
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"io"
	"net/http"
	"net/url"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/mhsanaei/3x-ui/v3/database/model"
	"github.com/mhsanaei/3x-ui/v3/logger"
)

const remoteHTTPTimeout = 10 * time.Second

var remoteHTTPClient = &http.Client{
	Transport: &http.Transport{
		MaxIdleConns:        64,
		MaxIdleConnsPerHost: 4,
		IdleConnTimeout:     60 * time.Second,
	},
}

type envelope struct {
	Success bool            `json:"success"`
	Msg     string          `json:"msg"`
	Obj     json.RawMessage `json:"obj"`
}

type Remote struct {
	node *model.Node

	mu            sync.RWMutex
	remoteIDByTag map[string]int
}

func NewRemote(n *model.Node) *Remote {
	return &Remote{
		node:          n,
		remoteIDByTag: make(map[string]int),
	}
}

func (r *Remote) Name() string { return "node:" + r.node.Name }

func (r *Remote) baseURL() string {
	bp := r.node.BasePath
	if bp == "" {
		bp = "/"
	}
	if !strings.HasSuffix(bp, "/") {
		bp += "/"
	}
	return fmt.Sprintf("%s://%s:%d%s", r.node.Scheme, r.node.Address, r.node.Port, bp)
}

func (r *Remote) do(ctx context.Context, method, path string, body any) (*envelope, error) {
	if r.node.ApiToken == "" {
		return nil, errors.New("node has no API token configured")
	}

	target := r.baseURL() + strings.TrimPrefix(path, "/")

	var (
		reqBody     io.Reader
		contentType string
	)
	switch b := body.(type) {
	case nil:
	case url.Values:
		reqBody = strings.NewReader(b.Encode())
		contentType = "application/x-www-form-urlencoded"
	default:
		buf, err := json.Marshal(b)
		if err != nil {
			return nil, fmt.Errorf("marshal body: %w", err)
		}
		reqBody = bytes.NewReader(buf)
		contentType = "application/json"
	}

	cctx, cancel := context.WithTimeout(ctx, remoteHTTPTimeout)
	defer cancel()
	req, err := http.NewRequestWithContext(cctx, method, target, reqBody)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Authorization", "Bearer "+r.node.ApiToken)
	req.Header.Set("Accept", "application/json")
	if contentType != "" {
		req.Header.Set("Content-Type", contentType)
	}

	resp, err := remoteHTTPClient.Do(req)
	if err != nil {
		return nil, fmt.Errorf("%s %s: %w", method, path, err)
	}
	defer resp.Body.Close()

	raw, err := io.ReadAll(resp.Body)
	if err != nil {
		return nil, fmt.Errorf("read body: %w", err)
	}
	if resp.StatusCode != http.StatusOK {
		return nil, fmt.Errorf("%s %s: HTTP %d", method, path, resp.StatusCode)
	}

	var env envelope
	if err := json.Unmarshal(raw, &env); err != nil {
		return nil, fmt.Errorf("decode envelope: %w", err)
	}
	if !env.Success {
		return &env, fmt.Errorf("remote: %s", env.Msg)
	}
	return &env, nil
}

func (r *Remote) resolveRemoteID(ctx context.Context, tag string) (int, error) {
	if id, ok := r.cacheGet(tag); ok {
		return id, nil
	}
	if err := r.refreshRemoteIDs(ctx); err != nil {
		return 0, err
	}
	if id, ok := r.cacheGet(tag); ok {
		return id, nil
	}
	return 0, fmt.Errorf("remote inbound with tag %q not found on node %s", tag, r.node.Name)
}

func (r *Remote) cacheGet(tag string) (int, bool) {
	r.mu.RLock()
	defer r.mu.RUnlock()
	id, ok := r.remoteIDByTag[tag]
	return id, ok
}

func (r *Remote) cacheSet(tag string, id int) {
	r.mu.Lock()
	defer r.mu.Unlock()
	r.remoteIDByTag[tag] = id
}

func (r *Remote) cacheDel(tag string) {
	r.mu.Lock()
	defer r.mu.Unlock()
	delete(r.remoteIDByTag, tag)
}

func (r *Remote) refreshRemoteIDs(ctx context.Context) error {
	env, err := r.do(ctx, http.MethodGet, "panel/api/inbounds/list", nil)
	if err != nil {
		return err
	}
	var list []struct {
		Id  int    `json:"id"`
		Tag string `json:"tag"`
	}
	if err := json.Unmarshal(env.Obj, &list); err != nil {
		return fmt.Errorf("decode inbound list: %w", err)
	}
	next := make(map[string]int, len(list))
	for _, ib := range list {
		if ib.Tag == "" {
			continue
		}
		next[ib.Tag] = ib.Id
	}
	r.mu.Lock()
	r.remoteIDByTag = next
	r.mu.Unlock()
	return nil
}

func (r *Remote) AddInbound(ctx context.Context, ib *model.Inbound) error {
	payload := wireInbound(ib)
	env, err := r.do(ctx, http.MethodPost, "panel/api/inbounds/add", payload)
	if err != nil {
		return err
	}
	var created struct {
		Id  int    `json:"id"`
		Tag string `json:"tag"`
	}
	if len(env.Obj) > 0 {
		if err := json.Unmarshal(env.Obj, &created); err == nil && created.Id > 0 && created.Tag != "" {
			r.cacheSet(created.Tag, created.Id)
		}
	}
	return nil
}

func (r *Remote) DelInbound(ctx context.Context, ib *model.Inbound) error {
	id, err := r.resolveRemoteID(ctx, ib.Tag)
	if err != nil {
		logger.Warning("remote DelInbound: tag", ib.Tag, "not found on", r.node.Name)
		return nil
	}
	if _, err := r.do(ctx, http.MethodPost, "panel/api/inbounds/del/"+strconv.Itoa(id), nil); err != nil {
		return err
	}
	r.cacheDel(ib.Tag)
	return nil
}

func (r *Remote) UpdateInbound(ctx context.Context, oldIb, newIb *model.Inbound) error {
	id, err := r.resolveRemoteID(ctx, oldIb.Tag)
	if err != nil {
		return r.AddInbound(ctx, newIb)
	}
	payload := wireInbound(newIb)
	if _, err := r.do(ctx, http.MethodPost, "panel/api/inbounds/update/"+strconv.Itoa(id), payload); err != nil {
		return err
	}
	if oldIb.Tag != newIb.Tag {
		r.cacheDel(oldIb.Tag)
	}
	r.cacheSet(newIb.Tag, id)
	return nil
}

func (r *Remote) AddUser(ctx context.Context, ib *model.Inbound, _ map[string]any) error {
	return r.UpdateInbound(ctx, ib, ib)
}

func (r *Remote) RemoveUser(ctx context.Context, ib *model.Inbound, _ string) error {
	return r.UpdateInbound(ctx, ib, ib)
}

func (r *Remote) RestartXray(ctx context.Context) error {
	_, err := r.do(ctx, http.MethodPost, "panel/api/server/restartXrayService", nil)
	return err
}

func (r *Remote) ResetClientTraffic(ctx context.Context, ib *model.Inbound, email string) error {
	id, err := r.resolveRemoteID(ctx, ib.Tag)
	if err != nil {
		logger.Warning("remote ResetClientTraffic: tag", ib.Tag, "not found on", r.node.Name)
		return nil
	}
	_, err = r.do(ctx, http.MethodPost,
		fmt.Sprintf("panel/api/inbounds/%d/resetClientTraffic/%s", id, url.PathEscape(email)),
		nil)
	return err
}

func (r *Remote) ResetInboundClientTraffics(ctx context.Context, ib *model.Inbound) error {
	id, err := r.resolveRemoteID(ctx, ib.Tag)
	if err != nil {
		logger.Warning("remote ResetInboundClientTraffics: tag", ib.Tag, "not found on", r.node.Name)
		return nil
	}
	_, err = r.do(ctx, http.MethodPost,
		fmt.Sprintf("panel/api/inbounds/resetAllClientTraffics/%d", id), nil)
	return err
}

func (r *Remote) ResetAllTraffics(ctx context.Context) error {
	_, err := r.do(ctx, http.MethodPost, "panel/api/inbounds/resetAllTraffics", nil)
	return err
}

type TrafficSnapshot struct {
	Inbounds      []*model.Inbound
	OnlineEmails  []string
	LastOnlineMap map[string]int64
}

func (r *Remote) FetchTrafficSnapshot(ctx context.Context) (*TrafficSnapshot, error) {
	snap := &TrafficSnapshot{LastOnlineMap: map[string]int64{}}

	envList, err := r.do(ctx, http.MethodGet, "panel/api/inbounds/list", nil)
	if err != nil {
		return nil, err
	}
	if err := json.Unmarshal(envList.Obj, &snap.Inbounds); err != nil {
		return nil, fmt.Errorf("decode inbound list: %w", err)
	}

	envOnlines, err := r.do(ctx, http.MethodPost, "panel/api/inbounds/onlines", nil)
	if err != nil {
		logger.Warning("remote", r.node.Name, "onlines fetch failed:", err)
	} else if len(envOnlines.Obj) > 0 {
		_ = json.Unmarshal(envOnlines.Obj, &snap.OnlineEmails)
	}

	envLastOnline, err := r.do(ctx, http.MethodPost, "panel/api/inbounds/lastOnline", nil)
	if err != nil {
		logger.Warning("remote", r.node.Name, "lastOnline fetch failed:", err)
	} else if len(envLastOnline.Obj) > 0 {
		_ = json.Unmarshal(envLastOnline.Obj, &snap.LastOnlineMap)
	}

	return snap, nil
}

func wireInbound(ib *model.Inbound) url.Values {
	v := url.Values{}
	v.Set("total", strconv.FormatInt(ib.Total, 10))
	v.Set("remark", ib.Remark)
	v.Set("enable", strconv.FormatBool(ib.Enable))
	v.Set("expiryTime", strconv.FormatInt(ib.ExpiryTime, 10))
	v.Set("listen", ib.Listen)
	v.Set("port", strconv.Itoa(ib.Port))
	v.Set("protocol", string(ib.Protocol))
	v.Set("settings", ib.Settings)
	v.Set("streamSettings", ib.StreamSettings)
	v.Set("tag", ib.Tag)
	v.Set("sniffing", ib.Sniffing)
	if ib.TrafficReset != "" {
		v.Set("trafficReset", ib.TrafficReset)
	}
	return v
}