package api

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

	"gitea.dooplex.hu/admin/felhom-hub/internal/osupdates"
)

// OSUpdateService is the hub half of the guest fast lane (`11` §8 step 2; hub v0.130.0).
type OSUpdateService interface {
	Ingest(hostID string, r osupdates.Report) error
	DesiredBlock(hostID string) osupdates.Block
}

// SetOSUpdateService wires the OS-update service. nil → the report endpoint answers 503 and no block is merged.
func (h *Handler) SetOSUpdateService(s OSUpdateService) { h.osUpdates = s }

// handleOSReport: POST /api/v1/hosts/{id}/os-report — the agent's report after every OS-leg run. Per-host key,
// SELF-SCOPED (a host reports only for itself).
func (h *Handler) handleOSReport(w http.ResponseWriter, r *http.Request, pathHostID string) {
	authHostID, _, isGlobal, ok := h.checkAuthHost(r)
	if !ok {
		http.Error(w, "Unauthorized", http.StatusUnauthorized)
		return
	}
	if pathHostID == "" || (!isGlobal && authHostID != pathHostID) {
		http.Error(w, "Forbidden: host_id mismatch", http.StatusForbidden)
		return
	}
	if h.osUpdates == nil {
		http.Error(w, "os updates not configured", http.StatusServiceUnavailable)
		return
	}
	body, err := io.ReadAll(io.LimitReader(r.Body, 4<<20))
	if err != nil {
		http.Error(w, "read error", http.StatusBadRequest)
		return
	}
	var rep osupdates.Report
	if err := json.Unmarshal(body, &rep); err != nil || rep.RunID == "" {
		http.Error(w, "body must be an os report with run_id", http.StatusBadRequest)
		return
	}
	if err := h.osUpdates.Ingest(pathHostID, rep); err != nil {
		h.logger.Printf("[WARN] os-report from %s: %v", pathHostID, err)
		http.Error(w, err.Error(), http.StatusBadRequest)
		return
	}
	writeJSON(w, http.StatusOK, map[string]any{"ok": true})
}

// mergeOSUpdate adds the hub-OWNED `os_update` block to a host's desired state at read time (like
// mergeWireguard): the stored operator blob is never modified. No service → pass-through unchanged.
func (h *Handler) mergeOSUpdate(hostID, desired string) string {
	if h.osUpdates == nil {
		return desired
	}
	var doc map[string]interface{}
	if err := json.Unmarshal([]byte(desired), &doc); err != nil {
		h.logger.Printf("[ERROR] os_update merge %s: stored desired_json unparsable: %v (serving unmerged)", hostID, err)
		return desired
	}
	doc["os_update"] = h.osUpdates.DesiredBlock(hostID)
	out, err := json.Marshal(doc)
	if err != nil {
		return desired
	}
	return string(out)
}