package httpserver

import (
	"encoding/json"
	"net/http"
	"os"

	"github.com/go-chi/chi/v5"

	"github.com/tim/cairnquire/apps/server/internal/sync"
)

func (s *Server) handleSyncInit(w http.ResponseWriter, r *http.Request) {
	var req sync.InitRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid request body"})
		return
	}

	if req.DeviceID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "deviceId is required"})
		return
	}

	principal, ok := requirePrincipal(r)
	if !ok {
		writeJSON(w, http.StatusUnauthorized, map[string]string{"error": "authentication required"})
		return
	}

	snapshot, err := s.syncService.InitSync(r.Context(), req.DeviceID, principal.UserID)
	if err != nil {
		s.logger.Error("sync init failed", "error", err)
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "failed to initialize sync"})
		return
	}

	writeJSON(w, http.StatusOK, sync.InitResponse{
		SnapshotID:     snapshot.ID,
		ServerSnapshot: snapshot.Files,
	})
}

func (s *Server) handleSyncDelta(w http.ResponseWriter, r *http.Request) {
	var req sync.DeltaRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid request body"})
		return
	}

	if req.SnapshotID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "snapshotId is required"})
		return
	}

	result, err := s.syncService.ApplyDelta(r.Context(), req.SnapshotID, sync.Delta{Changes: req.ClientDelta})
	if err != nil {
		s.logger.Error("sync delta failed", "error", err)
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "failed to apply delta"})
		return
	}

	writeJSON(w, http.StatusOK, sync.DeltaResponse{
		ServerDelta: result.ServerDelta,
		Conflicts:   result.Conflicts,
	})
}

func (s *Server) handleSyncResolve(w http.ResponseWriter, r *http.Request) {
	var req sync.ResolveRequest
	if err := json.NewDecoder(r.Body).Decode(&req); err != nil {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "invalid request body"})
		return
	}

	if req.SnapshotID == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "snapshotId is required"})
		return
	}

	snapshot, err := s.syncService.ResolveConflicts(r.Context(), req.SnapshotID, req.Resolutions)
	if err != nil {
		s.logger.Error("sync resolve failed", "error", err)
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "failed to resolve conflicts"})
		return
	}

	writeJSON(w, http.StatusOK, sync.ResolveResponse{
		NewSnapshotID: snapshot.ID,
	})
}

func (s *Server) handleContentFetch(w http.ResponseWriter, r *http.Request) {
	hash := chi.URLParam(r, "hash")
	if hash == "" {
		writeJSON(w, http.StatusBadRequest, map[string]string{"error": "hash is required"})
		return
	}

	content, err := s.syncService.GetContent(hash)
	if err != nil {
		if os.IsNotExist(err) {
			writeJSON(w, http.StatusNotFound, map[string]string{"error": "content not found"})
			return
		}
		s.logger.Error("content fetch failed", "error", err, "hash", hash)
		writeJSON(w, http.StatusInternalServerError, map[string]string{"error": "failed to fetch content"})
		return
	}

	w.Header().Set("Content-Type", "application/octet-stream")
	w.Header().Set("Cache-Control", "public, max-age=31536000, immutable")
	w.Header().Set("ETag", "\""+hash+"\"")
	w.WriteHeader(http.StatusOK)
	w.Write(content)
}