package handlers

import (
	"crypto/sha256"
	"dwelling-upload/internal/configuration"
	"dwelling-upload/pkg/logging"
	"dwelling-upload/pkg/server"
	"dwelling-upload/pkg/utils"
	"encoding/base64"
	"encoding/hex"
	"fmt"
	"html/template"
	"io"
	"net/http"
	"os"
	"path"
	"time"

	"github.com/eknkc/amber"
)

var defaultAmberOptions = amber.Options{PrettyPrint: false, LineNumbers: false}

var compiledTemplates map[string]*template.Template

type IndexData struct {
	MainSite         string
	FileMaxSz        string
	StorageCapacity  int64
	StorageUsed      int64
	StorageAvailable int64
	StorageCapStr    string
	StorageUsedStr   string
	StorageAvailStr  string
}

type UploadedData struct {
	MainSite     string
	DownloadURL  string
	KeepForHours int
}

type UploadHandlers struct {
	conf        *configuration.Configuration
	logErr      *logging.Logger
	logUpload   *logging.Logger
	logDownload *logging.Logger
}

func NewUploadHandlers(conf *configuration.Configuration, lErr, lUp, lDown *logging.Logger) *UploadHandlers {
	compiledTemplates = amber.MustCompileDir(conf.WebDir+"/templates",
		amber.DefaultDirOptions, defaultAmberOptions)

	return &UploadHandlers{
		conf:        conf,
		logErr:      lErr,
		logUpload:   lUp,
		logDownload: lDown}
}

func (h *UploadHandlers) Index(w http.ResponseWriter, r *http.Request) {
	var storCapacity int64 = h.conf.Uploads.Limits.Storage << 20
	var fMaxSize int64 = h.conf.Uploads.Limits.FileSize << 20
	var storSize int64 = 0

	storSize, err := utils.DirectorySize(h.conf.Uploads.Directory)
	if err != nil {
		h.logErr.Printf("cannot compute storage size: %s", err)
	}

	_, _, capStr := utils.ConvertFileSize(storCapacity)
	_, _, usedStr := utils.ConvertFileSize(storSize)
	_, _, availStr := utils.ConvertFileSize(storCapacity - storSize)
	_, _, fMaxSzStr := utils.ConvertFileSize(fMaxSize)

	if err := compiledTemplates["index"].Execute(w, &IndexData{
		MainSite:         utils.MainSite(r.Host),
		FileMaxSz:        fMaxSzStr,
		StorageCapacity:  storCapacity,
		StorageCapStr:    capStr,
		StorageAvailable: storCapacity - storSize,
		StorageAvailStr:  availStr,
		StorageUsed:      storSize,
		StorageUsedStr:   usedStr,
	}); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		h.logErr.Fatalln("failed to execute Index template:", err)
	}
}

func (h *UploadHandlers) Upload(w http.ResponseWriter, r *http.Request) {
	var fMaxSizeBytes int64 = h.conf.Uploads.Limits.FileSize << 20

	r.Body = http.MaxBytesReader(w, r.Body, fMaxSizeBytes)

	if err := r.ParseMultipartForm(fMaxSizeBytes); err != nil {
		h.logErr.Println("failed to parse form:", err)
		http.Error(w, "request too big", http.StatusExpectationFailed)
		return
	}

	f, fHandler, err := r.FormFile("file")
	if err != nil {
		h.logErr.Println("failed to open incoming file:", err)
		w.WriteHeader(http.StatusInternalServerError)
		return
	}
	defer func() {
		os.Remove(fHandler.Filename)
		f.Close()
	}()

	s256 := sha256.New()
	if _, err := io.Copy(s256, f); err != nil {
		h.logErr.Println("failed to compute SHA-256 hash:", err)
		w.WriteHeader(http.StatusInternalServerError)
		return
	}

	fSha256 := hex.EncodeToString(s256.Sum(nil))
	s256.Write([]byte(h.conf.HashSalt))
	fSaltedHash := base64.RawURLEncoding.EncodeToString(s256.Sum(nil))

	f.Seek(0, io.SeekStart)

	fPath := path.Join(h.conf.Uploads.Directory, fSaltedHash)

	_, err = os.Stat(fPath)
	if os.IsNotExist(err) {
		fDst, err := os.Create(fPath)
		if err != nil {
			h.logErr.Println("failed to open file for writing", err)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}

		n, err := io.Copy(fDst, f)
		if err != nil {
			h.logErr.Println("failed to copy uploaded file to destination:", err)
			w.WriteHeader(http.StatusInternalServerError)
			return
		}
		fmt.Println(n, err)
		fDst.Sync()
		fDst.Close()

		h.logUpload.Printf("| %s | %s | %s | SHA256 %s | %s | %d", r.RemoteAddr, utils.NetworkType(r.Host),
			fHandler.Filename, fSha256, fSaltedHash, fHandler.Size)

		w.WriteHeader(http.StatusCreated)
	} else {
		os.Chtimes(fPath, time.Now(), time.Now())
	}

	downloadURL := path.Join("/f", fSaltedHash, fHandler.Filename)

	if err := compiledTemplates["uploaded"].Execute(w, &UploadedData{
		MainSite:     utils.MainSite(r.Host),
		DownloadURL:  downloadURL,
		KeepForHours: h.conf.Uploads.Limits.KeepForHours,
	}); err != nil {
		w.WriteHeader(http.StatusInternalServerError)
		h.logErr.Fatalln("failed to execute Index template:", err)
	}
}

func (h *UploadHandlers) Download(w http.ResponseWriter, r *http.Request) {
	saltedHash := server.GetURLParam(r, "hash")
	name := server.GetURLParam(r, "name")

	path := path.Join(h.conf.Uploads.Directory, saltedHash)

	stat, err := os.Stat(path)
	if os.IsNotExist(err) {
		w.WriteHeader(http.StatusNotFound)
		return
	}

	w.Header().Add("Content-Disposition", fmt.Sprintf("attachment; filename=\"%s\"", name))
	// w.Header().Add("Content-Type", "application/octet-stream")

	fd, err := os.Open(path)
	if err != nil {
		h.logErr.Println("failed to open file to read:", err)
		w.WriteHeader(http.StatusInternalServerError)
		return
	}
	defer fd.Close()

	h.logDownload.Printf("| %s | %s | %s | %s", r.RemoteAddr, utils.NetworkType(r.Host), name, saltedHash)

	http.ServeContent(w, r, path, stat.ModTime(), fd)
}