package handlers

import (
	"context"
	"encoding/json"
	"io"
	"log/slog"
	"net/http"
	"regexp"

	"github.com/andyleap/hnh-map/internal/app"
	"github.com/andyleap/hnh-map/internal/app/services"
)

// maxClientBodySize is the maximum size for position and marker update request bodies.
const maxClientBodySize = 2 * 1024 * 1024 // 2 MB

var clientPath = regexp.MustCompile(`client/([^/]+)/(.*)`)

// ClientRouter handles /client/* requests with token-based auth.
func (h *Handlers) ClientRouter(rw http.ResponseWriter, req *http.Request) {
	matches := clientPath.FindStringSubmatch(req.URL.Path)
	if matches == nil {
		JSONError(rw, http.StatusBadRequest, "Client token not found", "BAD_REQUEST")
		return
	}
	ctx := req.Context()
	username, err := h.Auth.ValidateClientToken(ctx, matches[1])
	if err != nil {
		HandleServiceError(rw, err)
		return
	}
	ctx = context.WithValue(ctx, app.ClientUsernameKey, username)
	req = req.WithContext(ctx)

	switch matches[2] {
	case "locate":
		h.clientLocate(rw, req)
	case "gridUpdate":
		h.clientGridUpdate(rw, req)
	case "gridUpload":
		h.clientGridUpload(rw, req)
	case "positionUpdate":
		h.clientPositionUpdate(rw, req)
	case "markerUpdate":
		h.clientMarkerUpdate(rw, req)
	case "":
		http.Redirect(rw, req, "/", http.StatusFound)
	case "checkVersion":
		if req.FormValue("version") == app.ClientVersion {
			rw.WriteHeader(http.StatusOK)
		} else {
			JSONError(rw, http.StatusBadRequest, "version mismatch", "BAD_REQUEST")
		}
	default:
		JSONError(rw, http.StatusNotFound, "not found", "NOT_FOUND")
	}
}

func (h *Handlers) clientLocate(rw http.ResponseWriter, req *http.Request) {
	gridID := req.FormValue("gridID")
	result, err := h.Client.Locate(req.Context(), gridID)
	if err != nil {
		HandleServiceError(rw, err)
		return
	}
	rw.Header().Set("Content-Type", "text/plain")
	rw.WriteHeader(http.StatusOK)
	_, _ = rw.Write([]byte(result))
}

func (h *Handlers) clientGridUpdate(rw http.ResponseWriter, req *http.Request) {
	defer req.Body.Close()
	var grup services.GridUpdate
	if err := json.NewDecoder(req.Body).Decode(&grup); err != nil {
		slog.Error("error decoding grid request", "error", err)
		JSONError(rw, http.StatusBadRequest, "error decoding request", "BAD_REQUEST")
		return
	}
	result, err := h.Client.ProcessGridUpdate(req.Context(), grup)
	if err != nil {
		slog.Error("grid update failed", "error", err)
		HandleServiceError(rw, err)
		return
	}
	rw.Header().Set("Content-Type", "application/json")
	rw.WriteHeader(http.StatusOK)
	_ = json.NewEncoder(rw).Encode(result.Response)
}

func (h *Handlers) clientGridUpload(rw http.ResponseWriter, req *http.Request) {
	ct := req.Header.Get("Content-Type")
	if fixed := services.FixMultipartContentType(ct); fixed != ct {
		req.Header.Set("Content-Type", fixed)
	}
	if err := req.ParseMultipartForm(app.MultipartMaxMemory); err != nil {
		slog.Error("multipart parse error", "error", err)
		JSONError(rw, http.StatusBadRequest, "invalid multipart", "BAD_REQUEST")
		return
	}
	id := req.FormValue("id")
	extraData := req.FormValue("extraData")
	file, _, err := req.FormFile("file")
	if err != nil {
		slog.Error("form file error", "error", err)
		JSONError(rw, http.StatusBadRequest, "missing file", "BAD_REQUEST")
		return
	}
	defer file.Close()
	if err := h.Client.ProcessGridUpload(req.Context(), id, extraData, file); err != nil {
		slog.Error("grid upload failed", "error", err)
		HandleServiceError(rw, err)
	}
}

func (h *Handlers) clientPositionUpdate(rw http.ResponseWriter, req *http.Request) {
	defer req.Body.Close()
	buf, err := io.ReadAll(io.LimitReader(req.Body, maxClientBodySize+1))
	if err != nil {
		slog.Error("error reading position update", "error", err)
		JSONError(rw, http.StatusBadRequest, "failed to read body", "BAD_REQUEST")
		return
	}
	if len(buf) > maxClientBodySize {
		JSONError(rw, http.StatusRequestEntityTooLarge, "request body too large", "PAYLOAD_TOO_LARGE")
		return
	}
	if err := h.Client.UpdatePositions(req.Context(), buf); err != nil {
		slog.Error("position update failed", "error", err)
		HandleServiceError(rw, err)
	}
}

func (h *Handlers) clientMarkerUpdate(rw http.ResponseWriter, req *http.Request) {
	defer req.Body.Close()
	buf, err := io.ReadAll(io.LimitReader(req.Body, maxClientBodySize+1))
	if err != nil {
		slog.Error("error reading marker update", "error", err)
		JSONError(rw, http.StatusBadRequest, "failed to read body", "BAD_REQUEST")
		return
	}
	if len(buf) > maxClientBodySize {
		JSONError(rw, http.StatusRequestEntityTooLarge, "request body too large", "PAYLOAD_TOO_LARGE")
		return
	}
	if err := h.Client.UploadMarkers(req.Context(), buf); err != nil {
		slog.Error("marker update failed", "error", err)
		HandleServiceError(rw, err)
	}
}