package http

import (
	"encoding/json"
	"io"
	"io/fs"
	"mime/multipart"
	"net/http"
	"os"
	"time"

	"forge.cadoles.com/arcad/edge/pkg/bus"
	"forge.cadoles.com/arcad/edge/pkg/module"
	"forge.cadoles.com/arcad/edge/pkg/module/blob"
	"forge.cadoles.com/arcad/edge/pkg/storage"
	"github.com/go-chi/chi/v5"
	"github.com/pkg/errors"
	"gitlab.com/wpetit/goweb/logger"
)

const (
	errorCodeForbidden     = "forbidden"
	errorCodeInternalError = "internal-error"
	errorCodeBadRequest    = "bad-request"
	errorCodeNotFound      = "not-found"
)

type uploadResponse struct {
	Bucket string         `json:"bucket"`
	BlobID storage.BlobID `json:"blobId"`
}

func (h *Handler) handleAppUpload(w http.ResponseWriter, r *http.Request) {
	h.mutex.RLock()
	defer h.mutex.RUnlock()

	ctx := r.Context()

	r.Body = http.MaxBytesReader(w, r.Body, h.uploadMaxFileSize)

	if err := r.ParseMultipartForm(h.uploadMaxFileSize); err != nil {
		logger.Error(ctx, "could not parse multipart form", logger.E(errors.WithStack(err)))
		jsonError(w, http.StatusBadRequest, errorCodeBadRequest)

		return
	}

	_, fileHeader, err := r.FormFile("file")
	if err != nil {
		logger.Error(ctx, "could not read form file", logger.E(errors.WithStack(err)))
		jsonError(w, http.StatusBadRequest, errorCodeBadRequest)

		return
	}

	var metadata map[string]any

	rawMetadata := r.Form.Get("metadata")
	if rawMetadata != "" {
		if err := json.Unmarshal([]byte(rawMetadata), &metadata); err != nil {
			logger.Error(ctx, "could not parse metadata", logger.E(errors.WithStack(err)))
			jsonError(w, http.StatusBadRequest, errorCodeBadRequest)

			return
		}
	}

	ctx = module.WithContext(ctx, map[module.ContextKey]any{
		ContextKeyOriginRequest: r,
	})

	requestMsg := blob.NewMessageUploadRequest(ctx, fileHeader, metadata)

	reply, err := h.bus.Request(ctx, requestMsg)
	if err != nil {
		logger.Error(ctx, "could not retrieve file", logger.E(errors.WithStack(err)))
		jsonError(w, http.StatusInternalServerError, errorCodeInternalError)

		return
	}

	logger.Debug(ctx, "upload reply", logger.F("reply", reply))

	responseMsg, ok := reply.(*blob.MessageUploadResponse)
	if !ok {
		logger.Error(
			ctx, "unexpected upload response message",
			logger.F("message", reply),
		)
		jsonError(w, http.StatusInternalServerError, errorCodeInternalError)

		return
	}

	if !responseMsg.Allow {
		jsonError(w, http.StatusForbidden, errorCodeForbidden)

		return
	}

	encoder := json.NewEncoder(w)
	res := &uploadResponse{
		Bucket: responseMsg.Bucket,
		BlobID: responseMsg.BlobID,
	}

	if err := encoder.Encode(res); err != nil {
		panic(errors.Wrap(err, "could not encode upload response"))
	}
}

func (h *Handler) handleAppDownload(w http.ResponseWriter, r *http.Request) {
	h.mutex.RLock()
	defer h.mutex.RUnlock()

	bucket := chi.URLParam(r, "bucket")
	blobID := chi.URLParam(r, "blobID")

	ctx := logger.With(r.Context(), logger.F("blobID", blobID), logger.F("bucket", bucket))
	ctx = module.WithContext(ctx, map[module.ContextKey]any{
		ContextKeyOriginRequest: r,
	})

	requestMsg := blob.NewMessageDownloadRequest(ctx, bucket, storage.BlobID(blobID))

	reply, err := h.bus.Request(ctx, requestMsg)
	if err != nil {
		logger.Error(ctx, "could not retrieve file", logger.E(errors.WithStack(err)))
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

		return
	}

	replyMsg, ok := reply.(*blob.MessageDownloadResponse)
	if !ok {
		logger.Error(
			ctx, "unexpected download response message",
			logger.E(errors.WithStack(bus.ErrUnexpectedMessage)),
			logger.F("message", reply),
		)
		jsonError(w, http.StatusInternalServerError, errorCodeInternalError)

		return
	}

	if !replyMsg.Allow {
		jsonError(w, http.StatusForbidden, errorCodeForbidden)

		return
	}

	if replyMsg.Blob == nil {
		jsonError(w, http.StatusNotFound, errorCodeNotFound)

		return
	}

	defer func() {
		if err := replyMsg.Blob.Close(); err != nil {
			logger.Error(ctx, "could not close blob", logger.E(errors.WithStack(err)))
		}
	}()

	http.ServeContent(w, r, string(replyMsg.BlobInfo.ID()), replyMsg.BlobInfo.ModTime(), replyMsg.Blob)
}

func serveFile(w http.ResponseWriter, r *http.Request, fs fs.FS, path string) {
	ctx := logger.With(r.Context(), logger.F("path", path))

	file, err := fs.Open(path)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			http.Error(w, http.StatusText(http.StatusNotFound), http.StatusNotFound)

			return
		}

		logger.Error(ctx, "error while opening fs file", logger.E(errors.WithStack(err)))
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

		return
	}

	defer func() {
		if err := file.Close(); err != nil {
			logger.Error(ctx, "error while closing fs file", logger.E(errors.WithStack(err)))
		}
	}()

	info, err := file.Stat()
	if err != nil {
		logger.Error(ctx, "error while retrieving fs file stat", logger.E(errors.WithStack(err)))
		http.Error(w, http.StatusText(http.StatusInternalServerError), http.StatusInternalServerError)

		return
	}

	reader, ok := file.(io.ReadSeeker)
	if !ok {
		return
	}

	http.ServeContent(w, r, path, info.ModTime(), reader)
}

type jsonErrorResponse struct {
	Error jsonErr `json:"error"`
}

type jsonErr struct {
	Code string `json:"code"`
}

func jsonError(w http.ResponseWriter, status int, code string) {
	w.Header().Add("Content-Type", "application/json")
	w.WriteHeader(status)

	encoder := json.NewEncoder(w)
	response := jsonErrorResponse{
		Error: jsonErr{
			Code: code,
		},
	}

	if err := encoder.Encode(response); err != nil {
		panic(errors.WithStack(err))
	}
}

type uploadedFile struct {
	multipart.File
	header  *multipart.FileHeader
	modTime time.Time
}

// Stat implements fs.File
func (f *uploadedFile) Stat() (fs.FileInfo, error) {
	return &uploadedFileInfo{
		header:  f.header,
		modTime: f.modTime,
	}, nil
}

type uploadedFileInfo struct {
	header  *multipart.FileHeader
	modTime time.Time
}

// IsDir implements fs.FileInfo
func (i *uploadedFileInfo) IsDir() bool {
	return false
}

// ModTime implements fs.FileInfo
func (i *uploadedFileInfo) ModTime() time.Time {
	return i.modTime
}

// Mode implements fs.FileInfo
func (i *uploadedFileInfo) Mode() fs.FileMode {
	return os.ModePerm
}

// Name implements fs.FileInfo
func (i *uploadedFileInfo) Name() string {
	return i.header.Filename
}

// Size implements fs.FileInfo
func (i *uploadedFileInfo) Size() int64 {
	return i.header.Size
}

// Sys implements fs.FileInfo
func (i *uploadedFileInfo) Sys() any {
	return nil
}

var (
	_ fs.File     = &uploadedFile{}
	_ fs.FileInfo = &uploadedFileInfo{}
)