package agent

import (
	"encoding/json"
	"os"
	"path/filepath"
	"slices"

	llmgwv1 "gitea.mynodes.xyz/ilker/llmgw/api/gen/llmgw/v1"
)

// controlPlanesFile keeps the control planes the leader last named, beside
// the agent's configuration rather than in it: the configuration is the
// operator's, and a list rewritten in it would be a file nobody wrote.
var controlPlanesFile = "/var/lib/llmgw-agent/control-planes.json"

// servers is every address to dial, in the order to try them: the
// configuration's, then any the leader named that it lacks.
func (a *Agent) servers() []string {
	a.mu.Lock()
	defer a.mu.Unlock()
	if len(a.serverList) == 0 {
		return a.cfg.Servers
	}
	return a.serverList
}

// mergeServers puts the leader's list after the configured one, without
// repeats, and says whether that changed anything.
func mergeServers(configured, told []string, secure bool) []string {
	out := slices.Clone(configured)
	for _, s := range told {
		fixed, err := normalizeOne(s, secure)
		if err != nil {
			continue
		}
		if !slices.Contains(out, fixed) {
			out = append(out, fixed)
		}
	}
	return out
}

// setControlPlanes takes the leader's list: used from the next reconnect,
// and kept for the next start.
func (a *Agent) setControlPlanes(m *llmgwv1.ControlPlanes) {
	told := m.GetServers()
	merged := mergeServers(a.cfg.Servers, told, a.cfg.TLS.Enabled())
	a.mu.Lock()
	changed := !slices.Equal(merged, a.serverList)
	a.serverList = merged
	a.mu.Unlock()
	if !changed {
		return
	}
	a.log.Info("the control planes to dial", "servers", merged)
	b, _ := json.Marshal(told)
	if err := os.MkdirAll(filepath.Dir(controlPlanesFile), 0o755); err == nil {
		tmp := controlPlanesFile + ".new"
		if err := os.WriteFile(tmp, b, 0o644); err == nil {
			_ = os.Rename(tmp, controlPlanesFile)
		}
	}
}

// loadControlPlanes is the list kept from the last time the leader named it.
func loadControlPlanes(configured []string, secure bool) []string {
	b, err := os.ReadFile(controlPlanesFile)
	if err != nil {
		return configured
	}
	var told []string
	if json.Unmarshal(b, &told) != nil {
		return configured
	}
	return mergeServers(configured, told, secure)
}