/*
 * Copyright (c) 2025, Антон Аксенов
 * This file is part of iptvc project
 * MIT License: https://git.axenov.dev/IPTV/iptvc/src/branch/master/LICENSE
 */

package checker

import (
	"axenov/iptv-checker/app"
	"axenov/iptv-checker/app/inifile"
	"axenov/iptv-checker/app/playlist"
	"axenov/iptv-checker/app/tagfile"
	"axenov/iptv-checker/app/utils"
	"context"
	"crypto/tls"
	"encoding/json"
	"io"
	"log"
	"maps"
	"math"
	"math/rand"
	"net/http"
	"os"
	"slices"
	"strings"
	"sync"
	"time"
)

// Checker выполняет проверку плейлистов и каналов.
type Checker struct {
	tagBlocks []tagfile.TagBlock
}

// NewChecker создаёт новый экземпляр Checker.
func NewChecker(tagsPath string) *Checker {
	return &Checker{
		tagBlocks: tagfile.Init(tagsPath),
	}
}

// PrepareListsToCheck готовит список плейлистов для проверки
func (c *Checker) PrepareListsToCheck(files []string, urls []string, codes []string) []playlist.Playlist {
	var lists []playlist.Playlist

	if len(files) > 0 {
		for _, filepath := range files {
			pls, err := playlist.MakeFromFile(filepath)
			if err != nil {
				log.Printf("Warning: %s, skipping\n", err)
				continue
			}

			lists = append(lists, pls)
		}
	}

	if len(urls) > 0 {
		for _, url := range urls {
			pls, err := playlist.MakeFromUrl(url)
			if err != nil {
				log.Printf("Warning: %s, skipping\n", err)
				continue
			}
			lists = append(lists, pls)
		}
	}

	if len(lists) == 0 || len(codes) > 0 {
		ini, err := inifile.Init(app.Args.IniPath)
		if err != nil {
			log.Printf("Warning: %s, all --code flags will be ignored\n", err)
			return lists
		}

		if len(codes) > 0 {
			for _, plsCode := range codes {
				list := ini.Lists[plsCode]
				if list.Url == "" {
					log.Printf("Warning: playlist [%s] not found in ini-file, skipping\n", plsCode)
					continue
				}
				lists = append(lists, list)
			}
		} else {
			if app.Config.Cache.IsActive {
				cachedLists := c.getCachedPlaylists()
				for key := range ini.Lists {
					if _, ok := cachedLists[key]; ok {
						continue
					}
					lists = append(lists, ini.Lists[key])
				}
				log.Printf("Found %d cached playlists\n", len(cachedLists))
			} else {
				lists = slices.Collect(maps.Values(ini.Lists))
			}

			if int(app.Args.RandomCount) > 0 && int(app.Args.RandomCount) <= len(lists) {
				rand.Shuffle(len(lists), func(i int, j int) { lists[i], lists[j] = lists[j], lists[i] })
				lists = lists[:app.Args.RandomCount]
			}
		}
	}

	return lists
}

// getCachedPlaylists возвращает из кеша проверенные ранее плейлисты
func (c *Checker) getCachedPlaylists() map[string]playlist.Playlist {
	result := make(map[string]playlist.Playlist)
	ctx := context.Background()
	iter := app.Cache.Scan(ctx, 0, "*", 100).Iterator()
	for iter.Next(ctx) {
		key := iter.Val()
		value, err := app.Cache.Get(ctx, key).Result()
		if err != nil {
			continue
		}
		var pls playlist.Playlist
		if err := json.Unmarshal([]byte(value), &pls); err != nil {
			continue
		}
		result[pls.Code] = pls
	}
	if err := iter.Err(); err != nil {
		log.Printf("Error scanning cache: %s", err)
	}
	return result
}

// CheckPlaylists проверяет плейлисты и возвращает их же с результатами проверки
func (c *Checker) CheckPlaylists(ctx context.Context, lists []playlist.Playlist) (int, int) {
	count := len(lists)
	if count == 0 {
		log.Println("There are no playlists to check")
		os.Exit(0)
	}

	log.Printf("%d playlists will be checked\n", len(lists))
	step, onlineCount, offlineCount := 0, 0, 0

	for idx := range lists {
		pls := lists[idx]
		step++

		var err error
		if pls.Source == "-f" {
			// direct m3u path
			log.Printf("[%.3d/%.3d] Playlist from filesystem\n", step, count)
			log.Printf("Reading file... (%s)\n", pls.Url)
			err = pls.ReadFromFs()
		} else if pls.Source == "-u" {
			// direct m3u url
			log.Printf("[%.3d/%.3d] Playlist [%s]\n", step, count, pls.Url)
			log.Printf("Fetching... (%s)\n", pls.Url)
			err = pls.Download()
		} else {
			// from ini
			log.Printf("[%.3d/%.3d] Playlist [%s]\n", step, count, pls.Code)
			log.Printf("Fetching... (%s)\n", pls.Url)
			err = pls.Download()
		}

		if err != nil {
			log.Printf("Cannot read playlist [%s]: %s\n", pls.Url, err)
			offlineCount++
			c.cachePlaylist(pls)
			continue
		}

		log.Println("Parsing content...")
		pls.IsOnline = true
		onlineCount++
		pls = pls.Parse()

		log.Printf("Parsed, checking channels (%d)...\n", len(pls.Channels))
		pls = c.CheckChannels(ctx, pls)
		lists[idx] = pls
		c.cachePlaylist(pls)
	}

	return onlineCount, offlineCount
}

func (c *Checker) cachePlaylist(pls playlist.Playlist) {
	if !app.Config.Cache.IsActive {
		return
	}

	jsonBytes, err := json.Marshal(pls)
	if err != nil {
		log.Printf("Error while saving playlist to cache: %s", err)
		return
	}

	key := pls.Code
	if key == "" {
		key = "raw:" + utils.Md5str(pls.Url)
	}

	ctx := context.Background()
	ttl := time.Duration(app.Config.Cache.Ttl) * time.Second
	written := app.Cache.Set(ctx, key, string(jsonBytes), ttl)
	if written.Err() != nil {
		log.Printf("Error while saving playlist to cache: %s", written.Err())
		return
	}

	log.Println("Cached sucessfully")
}

// CheckChannels проверяет каналы и возвращает их же с результатами проверки
func (c *Checker) CheckChannels(ctx context.Context, pls playlist.Playlist) playlist.Playlist {
	type errorData struct {
		tvChannel playlist.Channel
		err       error
	}

	count := len(pls.Channels)
	if count == 0 {
		log.Println("There are no channels to check, skipping")
		return pls
	}

	pls.OnlineCount = 0
	pls.OfflineCount = 0

	timeout, routines := calcParameters(count)
	tr := &http.Transport{
		TLSClientConfig: &tls.Config{InsecureSkipVerify: true},
	}
	httpClient := http.Client{
		Timeout:   timeout,
		Transport: tr,
	}
	chSemaphores := make(chan struct{}, routines)
	chOnline := make(chan playlist.Channel, len(pls.Channels))
	chOffline := make(chan playlist.Channel, len(pls.Channels))
	chError := make(chan errorData, len(pls.Channels))
	var wg sync.WaitGroup

	startTime := time.Now()
	for _, tvChannel := range pls.Channels {
		wg.Add(1)
		go func(tvChannel playlist.Channel) {
			defer func() {
				if r := recover(); r != nil {
					log.Printf("Panic while checking channel '%s': %v", tvChannel.Title, r)
				}
				<-chSemaphores
				wg.Done()
			}()
			chSemaphores <- struct{}{}

			tvChannel.Tags = c.getTagsForChannel(tvChannel)

			req, err := http.NewRequestWithContext(ctx, "GET", tvChannel.URL, nil)
			if err != nil {
				data := errorData{tvChannel: tvChannel, err: err}
				chError <- data
				return
			}

			req.Header.Set("User-Agent", "Mozilla/5.0 WINK/1.31.1 (AndroidTV/9) HlsWinkPlayer")
			req.Header.Set("Range", "bytes=0-511") // 512 B, but sometimes servers ignore it
			resp, err := httpClient.Do(req)
			tvChannel.CheckedAt = time.Now().Unix()
			if err != nil {
				data := errorData{tvChannel: tvChannel, err: err}
				chError <- data
				return
			}

			tvChannel.Status = resp.StatusCode
			tvChannel.IsOnline = tvChannel.Status < http.StatusBadRequest
			tvChannel.ContentType = resp.Header.Get("Content-Type")
			chunk := io.LimitReader(resp.Body, 512) // just for sure
			bodyBytes, err := io.ReadAll(chunk)
			if err != nil {
				_ = resp.Body.Close()
				data := errorData{tvChannel: tvChannel, err: err}
				chError <- data
				return
			}
			bodyString := string(bodyBytes)
			_ = resp.Body.Close()
			contentType := http.DetectContentType(bodyBytes)

			isContentBinary := strings.Contains(contentType, "octet-stream") ||
				strings.Contains(contentType, "video/")

			isContentCorrect := isContentBinary ||
				strings.Contains(bodyString, "#EXTM3U") ||
				strings.Contains(bodyString, "#EXT-X-") ||
				strings.Contains(bodyString, "<MPD ") ||
				strings.Contains(bodyString, "<SegmentTemplate ") ||
				strings.Contains(bodyString, "<AdaptationSet ")

			if tvChannel.Status >= http.StatusBadRequest && !isContentCorrect {
				tvChannel.Error = bodyString
				chOffline <- tvChannel
				return
			}

			chOnline <- tvChannel
			return
		}(tvChannel)
	}

	for idx := 1; idx <= count; idx++ {
		select {
		case tvChannel := <-chOnline:
			tvChannel.IsOnline = true
			pls.Channels[tvChannel.Id] = tvChannel
			if app.Args.Verbose {
				log.Printf("[%.3d/%.3d] ONLINE '%s'\n", idx, count, tvChannel.Title)
				log.Printf("> Id: %s\n", tvChannel.Id)
				log.Printf("> Tags: %s\n", strings.Join(tvChannel.Tags, ","))
				log.Printf("> MimeType: %s\n", tvChannel.ContentType)
			}
		case tvChannel := <-chOffline:
			pls.Channels[tvChannel.Id] = tvChannel
			if app.Args.Verbose {
				log.Printf("[%.3d/%.3d] OFFLINE '%s'\n", idx, count, tvChannel.Title)
				log.Printf("> Id: %s\n", tvChannel.Id)
				log.Printf("> Tags: %s\n", strings.Join(tvChannel.Tags, ","))
				log.Printf("> Status: %d\n", tvChannel.Status)
			}
		case data := <-chError:
			pls.Channels[data.tvChannel.Id] = data.tvChannel
			if app.Args.Verbose {
				log.Printf("[%.3d/%.3d] ERROR '%s'\n", idx, count, data.tvChannel.Title)
				log.Printf("> Id: %s\n", data.tvChannel.Id)
				log.Printf("> Tags: %s\n", strings.Join(data.tvChannel.Tags, ","))
				log.Printf("> Error: %s\n", data.err)
			}
		}
	}

	wg.Wait()
	close(chOnline)
	close(chOffline)
	close(chError)
	pls.CheckedAt = time.Now().Unix()

	for _, tvChannel := range pls.Channels {
		if tvChannel.IsOnline {
			pls.OnlineCount++
		} else {
			pls.OfflineCount++
		}
	}

	log.Printf(
		"Checked successfully! online=%d onlinePercent=%.2f%% offline=%d offlinePercent=%.2f%% elapsedTime=%.2fs",
		pls.OnlineCount,
		float32(pls.OnlineCount)/float32(len(pls.Channels))*100,
		pls.OfflineCount,
		float32(pls.OfflineCount)/float32(len(pls.Channels))*100,
		time.Since(startTime).Seconds(),
	)

	return pls
}

// calcParameters вычисляет оптимальное количество горутин и таймаут запроса
func calcParameters(count int) (time.Duration, int) {
	if count <= 0 {
		return 10 * time.Second, 1
	}

	routines := count
	if routines > 3000 {
		routines = 3000
	}
	if routines < 1 {
		routines = 1
	}

	var digits = 1
	x := count
	for x >= 10 {
		digits++
		x /= 10
	}

	timeout := 10 - int(math.Ceil(float64(digits)*1.5))
	if timeout > 10 {
		timeout = 10
	}
	if timeout < 1 {
		timeout = 1
	}

	duration := time.Duration(timeout) * time.Second
	log.Printf(
		"Check parameters calculated count=%d timeout=%.2fs routines=%d\n",
		count,
		duration.Seconds(),
		routines,
	)

	return duration, routines
}

// getTagsForChannel ищет и возвращает теги для канала
func (c *Checker) getTagsForChannel(tvChannel playlist.Channel) []string {
	var foundTags []string

	for _, block := range c.tagBlocks {
		tags := block.GetTags(tvChannel)
		if tags != nil {
			foundTags = append(foundTags, tags...)
		}
	}

	if len(foundTags) == 0 {
		foundTags = append(foundTags, "untagged")
	} else if len(foundTags) > 0 {
		foundTags = utils.ArrayUnique(foundTags)
	}

	return foundTags
}