package health

import (
	"context"
	"os"
	"strings"
	"time"

	agentpb "git.ipao.vip/rogee/go-sip/gen/agent"
	"github.com/shirou/gopsutil/v4/cpu"
	"github.com/shirou/gopsutil/v4/disk"
	"github.com/shirou/gopsutil/v4/mem"
	"github.com/shirou/gopsutil/v4/process"
)

// Sampler uses gopsutil for host/process observations. Unsupported or
// unconfigured dimensions stay explicitly unknown instead of being reported as
// zero capacity.
type Sampler struct {
	Now func() time.Time
}

func (s Sampler) Sample(ctx context.Context, spoolRoot string) *agentpb.ResourceSample {
	now := time.Now
	if s.Now != nil {
		now = s.Now
	}
	sample := &agentpb.ResourceSample{
		ObservedAtUnixMs: now().UnixMilli(),
		SampleFresh:      true,
	}
	var missing []string

	if values, err := cpu.PercentWithContext(ctx, 0, false); err != nil || len(values) == 0 {
		missing = append(missing, "cpu")
	} else {
		sample.CpuUsedRatio = values[0] / 100
	}
	if value, err := mem.VirtualMemoryWithContext(ctx); err != nil {
		missing = append(missing, "memory")
	} else {
		sample.MemoryAvailableBytes = int64(value.Available)
	}
	if spoolRoot == "" {
		missing = append(missing, "spool")
	} else if value, err := disk.UsageWithContext(ctx, spoolRoot); err != nil {
		missing = append(missing, "spool")
	} else {
		sample.SpoolUsedBytes = int64(value.Used)
		sample.SpoolCapacityBytes = int64(value.Total)
	}
	proc, err := process.NewProcess(int32(os.Getpid()))
	if err != nil {
		missing = append(missing, "fd")
	} else if limits, limitErr := proc.RlimitUsageWithContext(ctx, true); limitErr != nil {
		missing = append(missing, "fd")
	} else {
		found := false
		for _, limit := range limits {
			if limit.Resource == process.RLIMIT_NOFILE {
				sample.FdUsed = int64(limit.Used)
				sample.FdLimit = int64(limit.Soft)
				found = true
				break
			}
		}
		if !found {
			missing = append(missing, "fd")
		}
	}

	// Media-port and AI-provider quotas are owned by the Cell/Dispatcher, not
	// this host sampler. Keep them unknown until those sources are connected.
	missing = append(missing, "media_ports", "ai_quota")
	if len(missing) != 0 {
		sample.SampleFresh = false
		sample.MissingReason = strings.Join(missing, ",")
	}
	return sample
}