package agent

import (
	"context"
	"os/exec"
	"runtime"
	"strings"
	"time"

	mcpv1 "git.wntrmute.dev/mc/mcp/gen/mcp/v1"
	"git.wntrmute.dev/mc/mcp/internal/registry"
	"golang.org/x/sys/unix"
	"google.golang.org/protobuf/types/known/timestamppb"
)

// NodeStatus returns information about this agent's node.
func (a *Agent) NodeStatus(ctx context.Context, _ *mcpv1.NodeStatusRequest) (*mcpv1.NodeStatusResponse, error) {
	services, err := registry.ListServices(a.DB)
	if err != nil {
		return nil, err
	}

	var componentCount uint32
	for _, svc := range services {
		comps, _ := registry.ListComponents(a.DB, svc.Name)
		componentCount += uint32(len(comps)) //nolint:gosec // bounded by service count
	}

	resp := &mcpv1.NodeStatusResponse{
		NodeName:       a.Config.Agent.NodeName,
		Runtime:        a.Config.Agent.ContainerRuntime,
		ServiceCount:   uint32(len(services)), //nolint:gosec // bounded
		ComponentCount: componentCount,
	}

	// Runtime version.
	cmd := exec.CommandContext(ctx, a.Config.Agent.ContainerRuntime, "--version") //nolint:gosec // trusted config
	if out, err := cmd.Output(); err == nil {
		resp.RuntimeVersion = strings.TrimSpace(string(out))
	}

	// Disk usage for /srv.
	var stat unix.Statfs_t
	if err := unix.Statfs("/srv", &stat); err == nil {
		resp.DiskTotalBytes = stat.Blocks * uint64(stat.Bsize) //nolint:gosec // kernel values
		resp.DiskFreeBytes = stat.Bavail * uint64(stat.Bsize)  //nolint:gosec // kernel values
	}

	// Memory.
	var sysinfo unix.Sysinfo_t
	if err := unix.Sysinfo(&sysinfo); err == nil {
		resp.MemoryTotalBytes = sysinfo.Totalram
		resp.MemoryFreeBytes = sysinfo.Freeram
	}

	// CPU usage approximation: number of goroutines / GOMAXPROCS is a rough
	// indicator. Real CPU monitoring would use /proc/stat, which is a v2 concern.
	resp.CpuUsagePercent = float64(runtime.NumGoroutine()) / float64(runtime.GOMAXPROCS(0)) * 100

	// Uptime: use sysinfo.
	if err := unix.Sysinfo(&sysinfo); err == nil {
		bootTime := time.Now().Add(-time.Duration(sysinfo.Uptime) * time.Second)
		resp.UptimeSince = timestamppb.New(bootTime)
	}

	return resp, nil
}