package main

import (
	"embed"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"
	"path/filepath"
	"time"

	"github.com/go-redis/redis/v8"
	"github.com/gorilla/mux"
	"github.com/hibiken/asynq"
	"github.com/rs/cors"
)

// staticFileServer implements the http.Handler interface, so we can use it
// to respond to HTTP requests. The path to the static directory and
// path to the index file within that static directory are used to
// serve the SPA in the given static directory.
type staticFileServer struct {
	staticContents embed.FS
	staticDirPath  string
	indexFileName  string
}

// ServeHTTP inspects the URL path to locate a file within the static dir
// on the SPA handler.
// If path '/' is requested, it will serve the index file, otherwise it will
// serve the file specified by the URL path.
func (srv *staticFileServer) ServeHTTP(w http.ResponseWriter, r *http.Request) {
	// Get the absolute path to prevent directory traversal.
	path, err := filepath.Abs(r.URL.Path)
	if err != nil {
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}

	if path == "/" {
		path = filepath.Join(srv.staticDirPath, srv.indexFileName)
	} else {
		path = filepath.Join(srv.staticDirPath, path)
	}

	f, err := srv.staticContents.Open(path)
	if err != nil {
		status := http.StatusInternalServerError
		if os.IsNotExist(err) {
			status = http.StatusNotFound
		}
		http.Error(w, err.Error(), status)
		return
	}
	defer f.Close()

	if _, err := io.Copy(w, f); err != nil {
		http.Error(w, err.Error(), http.StatusInternalServerError)
		return
	}
}

const (
	addr      = "127.0.0.1:8080"
	redisAddr = "localhost:6379" // TODO: make this configurable
)

//go:embed ui/build/*
var staticContents embed.FS

func main() {
	inspector := asynq.NewInspector(asynq.RedisClientOpt{
		Addr: redisAddr,
	})
	defer inspector.Close()

	rdb := redis.NewClient(&redis.Options{
		Addr: redisAddr,
	})
	defer rdb.Close()

	router := mux.NewRouter()
	router.Use(loggingMiddleware)

	api := router.PathPrefix("/api").Subrouter()
	// Queue endpoints.
	api.HandleFunc("/queues", newListQueuesHandlerFunc(inspector)).Methods("GET")
	api.HandleFunc("/queues/{qname}", newGetQueueHandlerFunc(inspector)).Methods("GET")
	api.HandleFunc("/queues/{qname}", newDeleteQueueHandlerFunc(inspector)).Methods("DELETE")
	api.HandleFunc("/queues/{qname}:pause", newPauseQueueHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}:resume", newResumeQueueHandlerFunc(inspector)).Methods("POST")

	// Queue Historical Stats endpoint.
	api.HandleFunc("/queue_stats", newListQueueStatsHandlerFunc(inspector)).Methods("GET")

	// Task endpoints.
	api.HandleFunc("/queues/{qname}/active_tasks", newListActiveTasksHandlerFunc(inspector)).Methods("GET")
	api.HandleFunc("/queues/{qname}/active_tasks/{task_id}:cancel", newCancelActiveTaskHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/active_tasks:cancel_all", newCancelAllActiveTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/active_tasks:batch_cancel", newBatchCancelActiveTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/pending_tasks", newListPendingTasksHandlerFunc(inspector)).Methods("GET")
	api.HandleFunc("/queues/{qname}/scheduled_tasks", newListScheduledTasksHandlerFunc(inspector)).Methods("GET")
	api.HandleFunc("/queues/{qname}/scheduled_tasks/{task_key}", newDeleteTaskHandlerFunc(inspector)).Methods("DELETE")
	api.HandleFunc("/queues/{qname}/scheduled_tasks:delete_all", newDeleteAllScheduledTasksHandlerFunc(inspector)).Methods("DELETE")
	api.HandleFunc("/queues/{qname}/scheduled_tasks:batch_delete", newBatchDeleteTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/scheduled_tasks/{task_key}:run", newRunTaskHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/scheduled_tasks:run_all", newRunAllScheduledTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/scheduled_tasks:batch_run", newBatchRunTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/scheduled_tasks/{task_key}:kill", newKillTaskHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/scheduled_tasks:kill_all", newKillAllScheduledTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/scheduled_tasks:batch_kill", newBatchKillTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/retry_tasks", newListRetryTasksHandlerFunc(inspector)).Methods("GET")
	api.HandleFunc("/queues/{qname}/retry_tasks/{task_key}", newDeleteTaskHandlerFunc(inspector)).Methods("DELETE")
	api.HandleFunc("/queues/{qname}/retry_tasks:delete_all", newDeleteAllRetryTasksHandlerFunc(inspector)).Methods("DELETE")
	api.HandleFunc("/queues/{qname}/retry_tasks:batch_delete", newBatchDeleteTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/retry_tasks/{task_key}:run", newRunTaskHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/retry_tasks:run_all", newRunAllRetryTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/retry_tasks:batch_run", newBatchRunTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/retry_tasks/{task_key}:kill", newKillTaskHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/retry_tasks:kill_all", newKillAllRetryTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/retry_tasks:batch_kill", newBatchKillTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/dead_tasks", newListDeadTasksHandlerFunc(inspector)).Methods("GET")
	api.HandleFunc("/queues/{qname}/dead_tasks/{task_key}", newDeleteTaskHandlerFunc(inspector)).Methods("DELETE")
	api.HandleFunc("/queues/{qname}/dead_tasks:delete_all", newDeleteAllDeadTasksHandlerFunc(inspector)).Methods("DELETE")
	api.HandleFunc("/queues/{qname}/dead_tasks:batch_delete", newBatchDeleteTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/dead_tasks/{task_key}:run", newRunTaskHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/dead_tasks:run_all", newRunAllDeadTasksHandlerFunc(inspector)).Methods("POST")
	api.HandleFunc("/queues/{qname}/dead_tasks:batch_run", newBatchRunTasksHandlerFunc(inspector)).Methods("POST")

	// Servers endpoints.
	api.HandleFunc("/servers", newListServersHandlerFunc(inspector)).Methods("GET")

	// Scheduler Entry endpoints.
	api.HandleFunc("/scheduler_entries", newListSchedulerEntriesHandlerFunc(inspector)).Methods("GET")
	api.HandleFunc("/scheduler_entries/{entry_id}/enqueue_events", newListSchedulerEnqueueEventsHandlerFunc(inspector)).Methods("GET")

	// Redis info endpoint.
	api.HandleFunc("/redis_info", newRedisInfoHandlerFunc(rdb)).Methods("GET")

	fs := &staticFileServer{
		staticContents: staticContents,
		staticDirPath:  "ui/build",
		indexFileName:  "index.html",
	}
	router.PathPrefix("/").Handler(fs)

	c := cors.New(cors.Options{
		AllowedMethods: []string{"GET", "POST", "DELETE"},
	})
	handler := c.Handler(router)

	srv := &http.Server{
		Handler:      handler,
		Addr:         addr,
		WriteTimeout: 10 * time.Second,
		ReadTimeout:  10 * time.Second,
	}

	fmt.Printf("Asynq Monitoring WebUI server is running on %s\n", addr)
	log.Fatal(srv.ListenAndServe())
}