package universal

import (
	"fmt"
	"io"
	"net/http"
	"net/url"
	"path/filepath"
	"strings"

	"github.com/debridmediamanager/zurg/internal/config"
	intTor "github.com/debridmediamanager/zurg/internal/torrent"
	zurghttp "github.com/debridmediamanager/zurg/pkg/http"
	"github.com/debridmediamanager/zurg/pkg/logutil"
	"github.com/debridmediamanager/zurg/pkg/realdebrid"
)

type GetFile struct {
	client *zurghttp.HTTPClient
}

func NewGetFile(client *zurghttp.HTTPClient) *GetFile {
	return &GetFile{client: client}
}

// HandleGetRequest handles a GET request universally for both WebDAV and HTTP
func (gf *GetFile) HandleGetRequest(directory, torrentName, fileName string, resp http.ResponseWriter, req *http.Request, torMgr *intTor.TorrentManager, cfg config.ConfigInterface, log *logutil.Logger) {
	torrents, ok := torMgr.DirectoryMap.Get(directory)
	if !ok {
		log.Warnf("Cannot find directory %s", directory)
		http.Error(resp, "File not found", http.StatusNotFound)
		return
	}
	torrent, ok := torrents.Get(torrentName)
	if !ok {
		log.Warnf("Cannot find torrent %sfrom path %s", torrentName, req.URL.Path)
		http.Error(resp, "File not found", http.StatusNotFound)
		return
	}

	file, ok := torrent.SelectedFiles.Get(fileName)
	if !ok {
		log.Warnf("Cannot find file %s from path %s", fileName, req.URL.Path)
		http.Error(resp, "File not found", http.StatusNotFound)
		return
	}

	if !strings.HasPrefix(file.Link, "http") {
		// This is a dead file, serve an alternate file
		log.Warnf("File %s is not available", fileName)
		http.Error(resp, "File is not available", http.StatusNotFound)
		return
	}
	link := file.Link

	if download, exists := torMgr.DownloadCache.Get(link); exists {
		if cfg.ShouldServeFromRclone() {
			if cfg.ShouldVerifyDownloadLink() {
				if torMgr.Api.CanFetchFirstByte(download.Download) {
					redirect(resp, req, download.Download, cfg)
					return
				}
			} else {
				redirect(resp, req, download.Download, cfg)
				return
			}
		} else {
			err := gf.streamCachedLinkToResponse(download.Download, resp, req, torMgr, cfg, log)
			if err == nil {
				return
			}
		}
	}

	log.Debugf("Opening file %s from torrent %s (%s)", fileName, torrentName, link)
	unrestrict := torMgr.UnrestrictUntilOk(link)
	if unrestrict == nil {
		log.Warnf("File %s cannot be unrestricted (link=%s)", fileName, link)
		if cfg.EnableRepair() {
			file.Link = "repair"
			torMgr.Repair(torrent)
		} else {
			log.Infof("Repair is disabled, skipping repair for unavailable file %s (link=%s)", fileName, link)
		}
		http.Error(resp, "File is not available", http.StatusNotFound)
		return
	} else {
		if unrestrict.Filename != fileName {
			// this is possible if there's only 1 streamable file in the torrent
			// and then suddenly it's a rar file
			actualExt := filepath.Ext(unrestrict.Filename)
			expectedExt := filepath.Ext(fileName)
			if actualExt != expectedExt && unrestrict.Streamable != 1 {
				log.Warnf("File was changed and is not streamable: %s and %s (link=%s)", fileName, unrestrict.Filename, unrestrict.Link)
				http.Error(resp, "File is not available", http.StatusNotFound)
				return
			} else {
				log.Warnf("Filename mismatch: %s and %s", fileName, unrestrict.Filename)
			}
		}
		torMgr.DownloadCache.Set(link, unrestrict)
		if cfg.ShouldServeFromRclone() {
			if cfg.ShouldVerifyDownloadLink() {
				if !torMgr.Api.CanFetchFirstByte(unrestrict.Download) {
					log.Warnf("File %s is not available", fileName)
					http.Error(resp, "File is not available", http.StatusNotFound)
					return
				}
			}
			redirect(resp, req, unrestrict.Download, cfg)
		} else {
			gf.streamFileToResponse(torrent, file, unrestrict, resp, req, torMgr, cfg, log)
		}
		return
	}
}

func (gf *GetFile) streamCachedLinkToResponse(url string, resp http.ResponseWriter, req *http.Request, torMgr *intTor.TorrentManager, cfg config.ConfigInterface, log *logutil.Logger) error {
	// Create a new dlReq for the file download.
	dlReq, err := http.NewRequest(http.MethodGet, url, nil)
	if err != nil {
		return fmt.Errorf("file is not available")
	}

	// copy range header if it exists
	if req.Header.Get("Range") != "" {
		dlReq.Header.Add("Range", req.Header.Get("Range"))
	}

	download, err := gf.client.Do(dlReq)
	if err != nil {
		return fmt.Errorf("file is not available")
	}
	defer download.Body.Close()

	if download.StatusCode != http.StatusOK && download.StatusCode != http.StatusPartialContent {
		return fmt.Errorf("file is not available")
	}

	for k, vv := range download.Header {
		for _, v := range vv {
			resp.Header().Add(k, v)
		}
	}

	buf := make([]byte, cfg.GetNetworkBufferSize())
	io.CopyBuffer(resp, download.Body, buf)
	return nil
}

func (gf *GetFile) streamFileToResponse(torrent *intTor.Torrent, file *intTor.File, unrestrict *realdebrid.Download, resp http.ResponseWriter, req *http.Request, torMgr *intTor.TorrentManager, cfg config.ConfigInterface, log *logutil.Logger) {
	// Create a new request for the file download.
	dlReq, err := http.NewRequest(http.MethodGet, unrestrict.Download, nil)
	if err != nil {
		if file != nil {
			log.Errorf("Error creating new request for file %s: %v", file.Path, err)
		}
		http.Error(resp, "File is not available", http.StatusNotFound)
		return
	}

	// copy range header if it exists
	if req.Header.Get("Range") != "" {
		dlReq.Header.Add("Range", req.Header.Get("Range"))
	}

	download, err := gf.client.Do(dlReq)
	if err != nil {
		if file != nil && unrestrict.Streamable == 1 {
			log.Warnf("Cannot download file %s: %v", file.Path, err)
			if cfg.EnableRepair() {
				file.Link = "repair"
				torMgr.Repair(torrent)
			} else {
				log.Infof("Repair is disabled, skipping repair for unavailable file %s (link=%s)", file.Path, file.Link)
			}
		}
		http.Error(resp, "File is not available", http.StatusNotFound)
		return
	}
	defer download.Body.Close()

	if download.StatusCode != http.StatusOK && download.StatusCode != http.StatusPartialContent {
		if file != nil && unrestrict.Streamable == 1 {
			log.Warnf("Received a %s status code for file %s", download.Status, file.Path)
			if cfg.EnableRepair() {
				file.Link = "repair"
				torMgr.Repair(torrent)
			} else {
				log.Infof("Repair is disabled, skipping repair for unavailable file %s (link=%s)", file.Path, file.Link)
			}
		}
		http.Error(resp, "File is not available", http.StatusNotFound)
		return
	}

	for k, vv := range download.Header {
		for _, v := range vv {
			resp.Header().Add(k, v)
		}
	}

	buf := make([]byte, cfg.GetNetworkBufferSize())
	io.CopyBuffer(resp, download.Body, buf)
}

func redirect(resp http.ResponseWriter, req *http.Request, url string, cfg config.ConfigInterface) {
	prefHost := cfg.GetRandomPreferredHost()
	if prefHost != "" {
		url = replaceHostInURL(url, prefHost)
	}
	http.Redirect(resp, req, url, http.StatusFound)
}

func replaceHostInURL(inputURL string, newHost string) string {
	u, err := url.Parse(inputURL)
	if err != nil {
		return ""
	}
	u.Host = newHost
	return u.String()
}