package sdkserver

import (
	"crypto/rand"
	"encoding/hex"
	"encoding/json"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"sync"
	"time"
)

const clientUnstuckRequestFile = "scripts/client_unstuck_request.lua"

type clientUnstuckStatus struct {
	RequestID   string `json:"request_id"`
	State       string `json:"state"`
	Error       string `json:"error,omitempty"`
	QueuedAt    int64  `json:"queued_at"`
	CompletedAt int64  `json:"completed_at,omitempty"`
}

var clientUnstuckState struct {
	sync.Mutex
	status clientUnstuckStatus
}

func queueClientUnstuck() (clientUnstuckStatus, error) {
	clientUnstuckState.Lock()
	defer clientUnstuckState.Unlock()
	var nonce [16]byte
	if _, err := rand.Read(nonce[:]); err != nil {
		return clientUnstuckStatus{}, err
	}
	id := hex.EncodeToString(nonce[:])
	// Only a generated hexadecimal nonce is interpolated. No user-supplied
	// command, path, endpoint or Lua source can enter this heartbeat script.
	script := fmt.Sprintf(clientUnstuckLua, id)
	if err := os.MkdirAll(filepath.Dir(clientUnstuckRequestFile), 0700); err != nil {
		return clientUnstuckStatus{}, err
	}
	file, err := os.CreateTemp(filepath.Dir(clientUnstuckRequestFile), ".client-unstuck-*.tmp")
	if err != nil {
		return clientUnstuckStatus{}, err
	}
	defer os.Remove(file.Name())
	if _, err = file.WriteString(script); err != nil {
		file.Close()
		return clientUnstuckStatus{}, err
	}
	if err = file.Close(); err != nil {
		return clientUnstuckStatus{}, err
	}
	if err = os.Rename(file.Name(), clientUnstuckRequestFile); err != nil {
		return clientUnstuckStatus{}, err
	}
	status := clientUnstuckStatus{RequestID: id, State: "queued", QueuedAt: time.Now().UnixMilli()}
	clientUnstuckState.status = status
	Log("[UNSTUCK] UI recovery queued request=" + id)
	return status, nil
}

func apiClientUnstuck(w http.ResponseWriter, r *http.Request) {
	switch r.Method {
	case http.MethodGet:
		clientUnstuckState.Lock()
		status := clientUnstuckState.status
		clientUnstuckState.Unlock()
		writeJSON(w, status)
	case http.MethodPost:
		status, err := queueClientUnstuck()
		if err != nil {
			http.Error(w, "cannot queue UI recovery", http.StatusInternalServerError)
			return
		}
		w.Header().Set("Content-Type", "application/json")
		w.WriteHeader(http.StatusAccepted)
		writeJSON(w, status)
	default:
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
	}
}

func apiClientUnstuckResult(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodPost {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	var result struct {
		RequestID string `json:"request_id"`
		Success   bool   `json:"success"`
		Error     string `json:"error"`
	}
	decoder := json.NewDecoder(http.MaxBytesReader(w, r.Body, 8192))
	decoder.DisallowUnknownFields()
	if err := decoder.Decode(&result); err != nil {
		http.Error(w, "invalid recovery result", http.StatusBadRequest)
		return
	}
	clientUnstuckState.Lock()
	defer clientUnstuckState.Unlock()
	if result.RequestID == "" || result.RequestID != clientUnstuckState.status.RequestID {
		http.Error(w, "recovery request is no longer current", http.StatusConflict)
		return
	}
	clientUnstuckState.status.State = "failed"
	if result.Success {
		clientUnstuckState.status.State = "completed"
	}
	clientUnstuckState.status.Error = result.Error
	clientUnstuckState.status.CompletedAt = time.Now().UnixMilli()
	Log("[UNSTUCK] UI recovery " + clientUnstuckState.status.State + " request=" + result.RequestID)
	writeJSON(w, clientUnstuckState.status)
}

// Named UIManager API observed on the current Client. Clear only network UI
// waits: never close a Battle, change a scene, fabricate a successful gameplay
// response, erase a run, or reset the Client's loading/phase flags.
const clientUnstuckLua = `do
 local id = %q
 if _G.__GAC_UNSTUCK_HTTP and _G.__GAC_UNSTUCK_HTTP.isDone then
  pcall(function() _G.__GAC_UNSTUCK_HTTP:Dispose() end); _G.__GAC_UNSTUCK_HTTP=nil
 end
 if _G.__GAC_UNSTUCK_LAST ~= id then
  _G.__GAC_UNSTUCK_LAST=id
  local ok,err=pcall(function()
   local ui=CS.RPG.Client.GlobalVars.s_UIManager
   if not ui then error('Client UIManager is unavailable') end
   ui:ClearWaitNetPacketFullScreenBlock()
  end)
  CS.UnityEngine.Debug.Log('[GAC_UNSTUCK] request='..id..' success='..tostring(ok)..' '..tostring(err or ''))
  pcall(function()
   local url=_G.__GAC_SRTOOL_LIVE_URL
   if type(url)~='string' or url=='' then return end
   local body='{"request_id":"'..id..'","success":'..tostring(ok)..',"error":'..CS.Newtonsoft.Json.JsonConvert.SerializeObject(tostring(err or ''))..'}'
   local req=CS.UnityEngine.Networking.UnityWebRequest(url..'/api/client/unstuck/result','POST')
   req.uploadHandler=CS.UnityEngine.Networking.UploadHandlerRaw(CS.System.Text.Encoding.UTF8:GetBytes(body))
   req.downloadHandler=CS.UnityEngine.Networking.DownloadHandlerBuffer()
   req:SetRequestHeader('Content-Type','application/json');req.timeout=10
   req:SendWebRequest();_G.__GAC_UNSTUCK_HTTP=req
  end)
 end
end
`