package handler

import (
	"crypto/rand"
	"encoding/base64"
	"errors"
	"io"
	"net/http"
	"path/filepath"
	"strings"
	"time"

	commonmw "gitea.estateliga.work/admin/portal-common/middleware"
	"github.com/go-chi/chi/v5"

	"files-service/internal/config"
	"files-service/internal/model"
	"files-service/internal/repository"
	"files-service/internal/storage"
)

type NodeHandler struct {
	cfg   *config.Config
	repo  *repository.NodeRepository
	store *storage.Storage
}

func NewNodeHandler(cfg *config.Config, repo *repository.NodeRepository, store *storage.Storage) *NodeHandler {
	return &NodeHandler{cfg: cfg, repo: repo, store: store}
}

func (h *NodeHandler) List(w http.ResponseWriter, r *http.Request) {
	userID := commonmw.GetUserID(r.Context())
	scope := r.URL.Query().Get("scope")
	parentID := emptyToNil(r.URL.Query().Get("parent_id"))
	nodes, err := h.repo.List(r.Context(), userID, subordinates(r), scope, parentID)
	if err != nil {
		writeInternalError(w, r, err, "failed to list files")
		return
	}
	writeJSON(w, http.StatusOK, nodes)
}

func (h *NodeHandler) Get(w http.ResponseWriter, r *http.Request) {
	node, ok := h.requireNode(w, r)
	if !ok {
		return
	}
	writeJSON(w, http.StatusOK, node)
}

func (h *NodeHandler) CreateFolder(w http.ResponseWriter, r *http.Request) {
	var req model.CreateFolderRequest
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	req.Title = strings.TrimSpace(req.Title)
	if req.Title == "" {
		writeError(w, http.StatusBadRequest, "title is required")
		return
	}
	userID := commonmw.GetUserID(r.Context())
	if !h.requireWritableParent(w, r, userID, req.ParentID) {
		return
	}
	node, err := h.repo.CreateFolder(r.Context(), req.Title, req.ParentID, userID)
	if err != nil {
		writeInternalError(w, r, err, "failed to create folder")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.folder_create", "files_node", node.ID, "{}")
	writeJSON(w, http.StatusCreated, node)
}

func (h *NodeHandler) ListOfficeLinks(w http.ResponseWriter, r *http.Request) {
	userID := commonmw.GetUserID(r.Context())
	links, err := h.repo.ListOfficeExternalURLs(r.Context(), userID, subordinates(r))
	if err != nil {
		writeInternalError(w, r, err, "failed to list office links")
		return
	}
	writeJSON(w, http.StatusOK, links)
}

func (h *NodeHandler) CreateOfficeDocument(w http.ResponseWriter, r *http.Request) {
	var req model.CreateOfficeDocumentRequest
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	req.Title = strings.TrimSpace(req.Title)
	req.OfficeID = strings.TrimSpace(req.OfficeID)
	req.OfficeFormat = strings.Trim(strings.ToLower(req.OfficeFormat), ". ")
	if req.Title == "" {
		writeError(w, http.StatusBadRequest, "title is required")
		return
	}
	if req.OfficeID == "" {
		writeError(w, http.StatusBadRequest, "office_id is required")
		return
	}
	if !allowedOfficeFormat(req.OfficeFormat) {
		writeError(w, http.StatusBadRequest, "office_format is not allowed")
		return
	}
	userID := commonmw.GetUserID(r.Context())
	if !h.requireWritableParent(w, r, userID, req.ParentID) {
		return
	}
	externalURL := "/office/" + req.OfficeID
	originalFilename := req.Title + "." + req.OfficeFormat
	mimeType := req.OfficeFormat
	node, err := h.repo.CreateOfficeDocument(r.Context(), &model.Node{
		ParentID:         req.ParentID,
		Title:            req.Title,
		OwnerUserID:      userID,
		OriginalFilename: &originalFilename,
		MimeType:         &mimeType,
		Extension:        &req.OfficeFormat,
		SizeBytes:        req.SizeBytes,
		OfficeFormat:     &req.OfficeFormat,
		ExternalURL:      &externalURL,
	})
	if err != nil {
		writeInternalError(w, r, err, "failed to create office document")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.office_document_create", "files_node", node.ID, "{}")
	writeJSON(w, http.StatusCreated, node)
}

func (h *NodeHandler) UploadFile(w http.ResponseWriter, r *http.Request) {
	if !h.store.Configured() {
		writeError(w, http.StatusServiceUnavailable, "storage not configured")
		return
	}
	if err := r.ParseMultipartForm(64 << 20); err != nil {
		writeError(w, http.StatusBadRequest, "invalid multipart")
		return
	}
	file, header, err := r.FormFile("file")
	if err != nil {
		writeError(w, http.StatusBadRequest, "file is required")
		return
	}
	defer file.Close()

	filename := filepath.Base(header.Filename)
	ext := strings.ToLower(strings.TrimPrefix(filepath.Ext(filename), "."))
	if !storage.AllowedExtension(ext) {
		writeError(w, http.StatusBadRequest, "file type is not allowed")
		return
	}
	title := strings.TrimSpace(r.FormValue("title"))
	if title == "" {
		title = strings.TrimSuffix(filename, filepath.Ext(filename))
	}
	userID := commonmw.GetUserID(r.Context())
	parentID := emptyToNil(r.FormValue("parent_id"))
	if !h.requireWritableParent(w, r, userID, parentID) {
		return
	}
	key := storage.GenerateKey(userID, filename)
	contentType := storage.GuessContentType(filename, header.Header.Get("Content-Type"))
	if err := h.store.PutObject(r.Context(), key, file, header.Size, contentType); err != nil {
		writeInternalError(w, r, err, "failed to upload file")
		return
	}
	node, err := h.repo.CreateFile(r.Context(), &model.Node{
		ParentID:         parentID,
		Title:            title,
		OwnerUserID:      userID,
		StorageKey:       &key,
		OriginalFilename: &filename,
		MimeType:         &contentType,
		Extension:        &ext,
		SizeBytes:        header.Size,
	})
	if err != nil {
		writeInternalError(w, r, err, "failed to create file")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.file_upload", "files_node", node.ID, "{}")
	writeJSON(w, http.StatusCreated, node)
}

func (h *NodeHandler) Update(w http.ResponseWriter, r *http.Request) {
	var req model.UpdateNodeRequest
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	if req.Title != nil {
		title := strings.TrimSpace(*req.Title)
		if title == "" {
			writeError(w, http.StatusBadRequest, "title is required")
			return
		}
		req.Title = &title
	}
	userID := commonmw.GetUserID(r.Context())
	node, err := h.repo.Update(r.Context(), chi.URLParam(r, "id"), userID, req)
	if errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "file not found")
		return
	}
	if err != nil {
		writeInternalError(w, r, err, "failed to update file")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.node_update", "files_node", node.ID, "{}")
	writeJSON(w, http.StatusOK, node)
}

func (h *NodeHandler) Move(w http.ResponseWriter, r *http.Request) {
	var req model.MoveNodeRequest
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	userID := commonmw.GetUserID(r.Context())
	if !h.requireWritableParent(w, r, userID, req.ParentID) {
		return
	}
	node, err := h.repo.Move(r.Context(), chi.URLParam(r, "id"), userID, subordinates(r), req.ParentID)
	if errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "file not found")
		return
	}
	if errors.Is(err, model.ErrInvalidMove) {
		writeError(w, http.StatusBadRequest, "folder cannot be moved inside itself")
		return
	}
	if err != nil {
		writeInternalError(w, r, err, "failed to move file")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.node_move", "files_node", node.ID, "{}")
	writeJSON(w, http.StatusOK, node)
}

func (h *NodeHandler) Restore(w http.ResponseWriter, r *http.Request) {
	userID := commonmw.GetUserID(r.Context())
	node, err := h.repo.Restore(r.Context(), chi.URLParam(r, "id"), userID, subordinates(r))
	if errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "file not found")
		return
	}
	if err != nil {
		writeInternalError(w, r, err, "failed to restore file")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.node_restore", "files_node", node.ID, "{}")
	writeJSON(w, http.StatusOK, node)
}

func (h *NodeHandler) Delete(w http.ResponseWriter, r *http.Request) {
	userID := commonmw.GetUserID(r.Context())
	id := chi.URLParam(r, "id")
	purgeAfter := time.Now().Add(30 * 24 * time.Hour)
	if err := h.repo.SoftDelete(r.Context(), id, userID, purgeAfter); errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "file not found")
		return
	} else if err != nil {
		writeInternalError(w, r, err, "failed to delete file")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.node_delete", "files_node", id, "{}")
	w.WriteHeader(http.StatusNoContent)
}

func (h *NodeHandler) Download(w http.ResponseWriter, r *http.Request) {
	node, ok := h.requireNode(w, r)
	if !ok {
		return
	}
	h.streamNode(w, r, node)
}

func (h *NodeHandler) ListAccess(w http.ResponseWriter, r *http.Request) {
	node, ok := h.requireNode(w, r)
	if !ok {
		return
	}
	if node.EffectiveAccess != model.AccessEdit {
		writeError(w, http.StatusForbidden, "edit access required")
		return
	}
	access, err := h.repo.ListAccess(r.Context(), node.ID)
	if err != nil {
		writeInternalError(w, r, err, "failed to list access")
		return
	}
	writeJSON(w, http.StatusOK, access)
}

func (h *NodeHandler) ReplaceAccess(w http.ResponseWriter, r *http.Request) {
	var req model.ReplaceAccessRequest
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	userID := commonmw.GetUserID(r.Context())
	id := chi.URLParam(r, "id")
	if err := h.repo.ReplaceAccess(r.Context(), id, userID, req.Access); errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "file not found")
		return
	} else if err != nil {
		writeInternalError(w, r, err, "failed to update access")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.access_update", "files_node", id, "{}")
	w.WriteHeader(http.StatusNoContent)
}

func (h *NodeHandler) CreatePublicLink(w http.ResponseWriter, r *http.Request) {
	var req model.PublicLinkRequest
	if err := decodeJSON(r, &req); err != nil {
		writeError(w, http.StatusBadRequest, "invalid json")
		return
	}
	if req.ExpiresAt.Before(time.Now().Add(time.Minute)) {
		writeError(w, http.StatusBadRequest, "expires_at must be in future")
		return
	}
	token, err := newToken()
	if err != nil {
		writeInternalError(w, r, err, "failed to create public link")
		return
	}
	userID := commonmw.GetUserID(r.Context())
	id := chi.URLParam(r, "id")
	linkID, err := h.repo.CreatePublicLink(r.Context(), id, userID, token, req.ExpiresAt)
	if errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "file not found")
		return
	}
	if err != nil {
		writeInternalError(w, r, err, "failed to create public link")
		return
	}
	h.repo.Audit(r.Context(), userID, "files.public_link_create", "files_node", id, "{}")
	writeJSON(w, http.StatusCreated, model.PublicLinkResponse{
		ID:        linkID,
		URL:       strings.TrimRight(h.cfg.PublicBaseURL, "/") + "/api/files/public/" + token,
		ExpiresAt: req.ExpiresAt,
	})
}

func (h *NodeHandler) PublicMeta(w http.ResponseWriter, r *http.Request) {
	node, ok := h.publicNode(w, r)
	if !ok {
		return
	}
	response := model.PublicNodeResponse{Node: node}
	if node.NodeType == model.NodeTypeFolder {
		children, err := h.repo.ListChildrenForPublic(r.Context(), node.ID)
		if err != nil {
			writeInternalError(w, r, err, "failed to list folder")
			return
		}
		response.Children = children
	}
	writeJSON(w, http.StatusOK, response)
}

func (h *NodeHandler) PublicDownload(w http.ResponseWriter, r *http.Request) {
	node, ok := h.publicNode(w, r)
	if !ok {
		return
	}
	h.streamNode(w, r, node)
}

func (h *NodeHandler) requireNode(w http.ResponseWriter, r *http.Request) (*model.Node, bool) {
	node, err := h.repo.GetForUser(r.Context(), chi.URLParam(r, "id"), commonmw.GetUserID(r.Context()), subordinates(r))
	if errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "file not found")
		return nil, false
	}
	if err != nil {
		writeInternalError(w, r, err, "failed to get file")
		return nil, false
	}
	return node, true
}

func (h *NodeHandler) requireWritableParent(w http.ResponseWriter, r *http.Request, userID string, parentID *string) bool {
	if parentID == nil || strings.TrimSpace(*parentID) == "" {
		return true
	}
	parent, err := h.repo.GetForUser(r.Context(), *parentID, userID, subordinates(r))
	if errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "parent folder not found")
		return false
	}
	if err != nil {
		writeInternalError(w, r, err, "failed to check parent folder")
		return false
	}
	if parent.NodeType != model.NodeTypeFolder {
		writeError(w, http.StatusBadRequest, "parent_id must point to folder")
		return false
	}
	if parent.EffectiveAccess != model.AccessEdit {
		writeError(w, http.StatusForbidden, "edit access to parent folder required")
		return false
	}
	return true
}

func (h *NodeHandler) publicNode(w http.ResponseWriter, r *http.Request) (*model.Node, bool) {
	node, err := h.repo.GetByPublicToken(r.Context(), chi.URLParam(r, "token"))
	if errors.Is(err, repository.ErrNotFound) {
		writeError(w, http.StatusNotFound, "public link not found")
		return nil, false
	}
	if err != nil {
		writeInternalError(w, r, err, "failed to open public link")
		return nil, false
	}
	return node, true
}

func (h *NodeHandler) streamNode(w http.ResponseWriter, r *http.Request, node *model.Node) {
	if node.NodeType == model.NodeTypeFolder || node.StorageKey == nil {
		writeError(w, http.StatusBadRequest, "node is not downloadable")
		return
	}
	info, err := h.store.Stat(r.Context(), *node.StorageKey)
	if err != nil {
		writeInternalError(w, r, err, "failed to open file")
		return
	}
	start, end, hasRange := storage.ParseRange(r.Header.Get("Range"), info.Size)
	body, info, err := h.store.GetObject(r.Context(), *node.StorageKey, start, end)
	if err != nil {
		writeInternalError(w, r, err, "failed to stream file")
		return
	}
	defer body.Close()
	filename := node.Title
	if node.OriginalFilename != nil && *node.OriginalFilename != "" {
		filename = *node.OriginalFilename
	}
	w.Header().Set("Content-Disposition", `inline; filename="`+strings.ReplaceAll(filename, `"`, "")+`"`)
	storage.WriteRangeResponse(w, info.ContentType, info.Size, start, end, hasRange)
	_, _ = io.Copy(w, body)
}

func emptyToNil(v string) *string {
	v = strings.TrimSpace(v)
	if v == "" {
		return nil
	}
	return &v
}

func allowedOfficeFormat(format string) bool {
	switch format {
	case "doc", "docx", "odt", "xls", "xlsx", "xlsm", "ods", "ppt", "pptx", "odp":
		return true
	default:
		return false
	}
}

func subordinates(r *http.Request) []string {
	ids := csvHeader(r, "X-User-Subordinates")
	if len(ids) == 0 {
		ids = csvHeader(r, "X-User-Subordinate-Ids")
	}
	return ids
}

func newToken() (string, error) {
	buf := make([]byte, 32)
	if _, err := rand.Read(buf); err != nil {
		return "", err
	}
	return base64.RawURLEncoding.EncodeToString(buf), nil
}