package main

import (
	"context"
	"encoding/json"
	"io"
	"log"
	"net/http"
	"os"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/gofiber/fiber/v2"
	"github.com/gofiber/fiber/v2/middleware/cors"
	"github.com/gofiber/fiber/v2/middleware/etag"
	"github.com/google/go-github/v50/github"
	"golang.org/x/oauth2"
)

var monitored_instances = []Instance{}

var number_re = regexp.MustCompile(`(?m)(\d+)`)

type Instance struct {
	Name        string `json:"name"`
	ApiUrl      string `json:"api_url"`
	Locations   string `json:"locations"`
	Version     string `json:"version"`
	UpToDate    bool   `json:"up_to_date"`
	Cdn         bool   `json:"cdn"`
	Registered  int    `json:"registered"`
	LastChecked int64  `json:"last_checked"`
	Cache       bool   `json:"cache"`
	S3Enabled   bool   `json:"s3_enabled"`
}

type FrontendConfig struct {
	S3Enabled bool `json:"s3Enabled"`
}

func monitorInstances() {
	ctx := context.Background()
	var tc *http.Client
	if os.Getenv("GITHUB_TOKEN") != "" {
		ts := oauth2.StaticTokenSource(
			&oauth2.Token{AccessToken: os.Getenv("GITHUB_TOKEN")},
		)
		tc = oauth2.NewClient(ctx, ts)
	}
	gh_client := github.NewClient(tc)
	// do forever
	for {
		// send a request to get markdown from GitHub
		resp, err := http.Get("https://raw.githubusercontent.com/wiki/TeamPiped/Piped-Frontend/Instances.md")
		if err != nil {
			log.Print(err)
			continue
		}

		// Find Latest Commit from GitHub
		var latest string
		{
			commits, _, err := gh_client.Repositories.ListCommits(ctx, "TeamPiped", "Piped-Backend", &github.CommitsListOptions{
				ListOptions: github.ListOptions{
					PerPage: 1,
				},
			})
			if err != nil {
				log.Print(err)
				time.Sleep(time.Second * 5)
				continue
			}
			latest = commits[0].GetSHA()
		}

		if resp.StatusCode == 200 {

			// parse the response
			buf := new(strings.Builder)
			_, err := io.Copy(buf, resp.Body)

			if err != nil {
				log.Print(err)
				continue
			}

			lines := strings.Split(buf.String(), "\n")

			instances := []Instance{}

			skipped := 0
			for _, line := range lines {
				split := strings.Split(line, "|")
				if len(split) >= 5 {
					if skipped < 2 {
						skipped++
						continue
					}
					ApiUrl := strings.TrimSpace(split[1])
					resp, err := http.Get(ApiUrl + "/healthcheck")
					if err != nil {
						log.Print(err)
						continue
					}
					LastChecked := time.Now().Unix()
					if resp.StatusCode != 200 {
						continue
					}
					resp, err = http.Get(ApiUrl + "/registered/badge")
					if err != nil {
						log.Print(err)
						continue
					}
					registered, err := strconv.ParseInt(number_re.FindString(resp.Request.URL.Path), 10, 32)
					if err != nil {
						log.Print(err)
						continue
					}
					resp, err = http.Get(ApiUrl + "/version")
					if err != nil {
						log.Print(err)
						continue
					}
					if resp.StatusCode != 200 {
						continue
					}
					buf := new(strings.Builder)
					_, err = io.Copy(buf, resp.Body)
					if err != nil {
						log.Print(err)
						continue
					}
					version := strings.TrimSpace(buf.String())
					version_split := strings.Split(version, "-")
					hash := version_split[len(version_split)-1]

					resp, err = http.Get(ApiUrl + "/config")
					if err != nil {
						log.Print(err)
						continue
					}
					if resp.StatusCode != 200 {
						continue
					}

					bytes, err := io.ReadAll(resp.Body)

					if err != nil {
						log.Print(err)
						continue
					}

					var config FrontendConfig

					err = json.Unmarshal(bytes, &config)

					if err != nil {
						log.Print(err)
						continue
					}

					cache_working := false

					resp, err = http.Get(ApiUrl + "/trending?region=US")
					if err != nil {
						log.Print(err)
						continue
					}
					if resp.StatusCode == 200 {
						old_timing := resp.Header.Get("Server-Timing")
						resp, err = http.Get(ApiUrl + "/trending?region=US")
						if err != nil {
							log.Print(err)
							continue
						}
						if resp.StatusCode == 200 {
							new_timing := resp.Header.Get("Server-Timing")
							if old_timing == new_timing {
								cache_working = true
							}
						}
					}

					instances = append(instances, Instance{
						Name:        strings.TrimSpace(split[0]),
						ApiUrl:      ApiUrl,
						Locations:   strings.TrimSpace(split[2]),
						Cdn:         strings.TrimSpace(split[3]) == "Yes",
						Registered:  int(registered),
						LastChecked: LastChecked,
						Version:     version,
						UpToDate:    strings.Contains(latest, hash),
						Cache:       cache_working,
						S3Enabled:   config.S3Enabled,
					})

				}
			}

			// update the global instances variable
			monitored_instances = instances
		}
		resp.Body.Close()
		time.Sleep(time.Minute)
	}
}

func main() {
	go monitorInstances()

	app := fiber.New()
	app.Use(cors.New())
	app.Use(etag.New())

	app.Get("/", func(c *fiber.Ctx) error {
		return c.JSON(monitored_instances)
	})

	app.Listen(":3000")
}