package handler

import (
	"fmt"
	"net/http"
	"os"
	"strconv"
	"strings"
	"sync"
	"time"

	"github.com/gin-gonic/gin"
)

var (
	vkToken      = os.Getenv("VK_TOKEN")
	bodyTemplate = `{"group_id":183208397,"type":"message_new","event_id":"7dff3c1982dfbd9e6011948ab9b5da352d903c94","v":"5.131","object":{"message":{"date":%d,"from_id":%d,"id":%d,"out":0,"attachments":[],"conversation_message_id":%d,"fwd_messages":[],"important":false,"is_hidden":false,"peer_id":199640727,"random_id":0,"text":"Test message #%d"},"client_info":{"button_actions":["text","vkpay","open_app","location","open_link","callback","intent_subscribe","intent_unsubscribe"],"keyboard":true,"inline_keyboard":true,"carousel":true,"lang_id":0}}}`
)

func init() {

}

func FloodHandler(c *gin.Context) {
	countStr := c.Query("count")
	if countStr == "" {
		c.String(http.StatusBadRequest, "Please specify the amount of requests in count query parameter")
		return
	}

	count, err := strconv.Atoi(countStr)
	if err != nil || count <= 0 {
		c.String(http.StatusBadRequest, "Invalid count parameter value")
		return
	}

	var sb strings.Builder
	sb.Grow(100 * count)
	for i := 0; i < count; i++ {
		now, st, err := performRequest()
		if err != nil {
			sb.WriteString(fmt.Sprintf("%d: cannot perform request: %s\n", now, err))
			continue
		}
		sb.WriteString(fmt.Sprintf("%d: received a response with code: %d\n", now, st))
	}

	c.String(http.StatusOK, sb.String())
}

func ConcurrentFloodHandler(c *gin.Context) {
	workersStr := c.Query("workers")
	if workersStr == "" {
		c.String(http.StatusBadRequest, "Please specify the amount of workers in workers query parameter")
		return
	}
	workers, err := strconv.Atoi(workersStr)
	if err != nil || workers <= 0 {
		c.String(http.StatusBadRequest, "Invalid workers parameter value")
		return
	}
	countStr := c.Query("count")
	if countStr == "" {
		c.String(http.StatusBadRequest, "Please specify the amount of requests per worker in the count query parameter")
		return
	}
	count, err := strconv.Atoi(countStr)
	if err != nil || workers <= 0 {
		c.String(http.StatusBadRequest, "Invalid count parameter value")
		return
	}

	var (
		wg     sync.WaitGroup
		sb     strings.Builder
		sbLock sync.Mutex
	)
	sb.Grow(100 * count * workers)
	wg.Add(workers)
	for i := 0; i < workers; i++ {
		go func() {
			var workerSb strings.Builder
			workerSb.Grow(100 * count)
			for l := 0; l < count; l++ {
				now, st, err := performRequest()
				if err != nil {
					workerSb.WriteString(fmt.Sprintf("%d: cannot perform request: %s\n", now, err))
					continue
				}
				workerSb.WriteString(fmt.Sprintf("%d: received a response with code: %d\n", now, st))
			}
			defer sbLock.Unlock()
			sbLock.Lock()
			sb.WriteString(workerSb.String())
			wg.Done()
		}()
	}
	wg.Wait()
	c.String(http.StatusOK, sb.String())
}

func performRequest() (int64, int, error) {
	now := time.Now().UnixNano()
	req, err := http.NewRequest(http.MethodPost, fmt.Sprintf("http://127.0.0.1:8000/vk/%s", vkToken), strings.NewReader(fmt.Sprintf(bodyTemplate, now, now, now, now, now)))
	if err != nil {
		return now, 0, err
	}

	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return now, 0, err
	}

	resp.Body.Close()
	return now, resp.StatusCode, nil
}