package infra

import (
	"fmt"
	"os"
	"sort"
	"strconv"
	"time"

	"github.com/shirou/gopsutil/v4/cpu"
	"github.com/shirou/gopsutil/v4/disk"
	"github.com/shirou/gopsutil/v4/host"
	"github.com/shirou/gopsutil/v4/load"
	"github.com/shirou/gopsutil/v4/mem"
	"github.com/shirou/gopsutil/v4/net"
	"github.com/shirou/gopsutil/v4/process"
	"github.com/shirou/gopsutil/v4/sensors"
)

// isAndroidHost indica si el host es Android (incluido Termux). Se usa para
// evitar rutas de gopsutil que invocan os.FindProcess -> pidfd_open, syscall
// bloqueado por el seccomp de Android que mata el proceso con SIGSYS.
func isAndroidHost() bool {
	if os.Getenv("ANDROID_ROOT") != "" || os.Getenv("ANDROID_DATA") != "" {
		return true
	}
	if _, err := os.Stat("/system/build.prop"); err == nil {
		return true
	}
	return false
}

// pseudoFstypes son filesystems virtuales que no representan almacenamiento
// real y se ignoran al recolectar metricas de particiones.
var pseudoFstypes = map[string]bool{
	"tmpfs":     true,
	"devtmpfs":  true,
	"overlay":   true,
	"squashfs":  true,
	"proc":      true,
	"sysfs":     true,
	"cgroup":    true,
	"cgroup2":   true,
	"devpts":    true,
	"mqueue":    true,
	"debugfs":   true,
	"tracefs":   true,
	"fusectl":   true,
	"configfs":  true,
	"pstore":    true,
	"bpf":       true,
	"securityfs": true,
}

// CollectHostMetrics recolecta metricas del host actual (CPU, memoria, swap,
// disco, red, temperaturas y procesos) y las devuelve como un slice de
// PromSample con nombres estilo node_exporter simplificados.
//
// Es robusta: cada grupo de colector se ejecuta en su propio bloque con manejo
// de error local. Si un colector secundario falla (red, temperaturas, etc.) se
// omite ese grupo sin abortar. Solo retorna error si falla la informacion
// basica de host (uptime), que se considera el minimo imprescindible.
//
// Funciona en Linux amd64 y Android/Termux (linux arm64): las temperaturas son
// best-effort y se omiten si no hay sensores disponibles (tipico en Android).
func CollectHostMetrics() ([]PromSample, error) {
	var samples []PromSample

	// --- Host basico: uptime (imprescindible, error si falla) ---
	uptime, err := host.Uptime()
	if err != nil {
		return nil, fmt.Errorf("collect host uptime: %w", err)
	}
	samples = append(samples, PromSample{
		Name:  "node_uptime_seconds",
		Value: float64(uptime),
	})

	// --- Load average (linux/darwin; best-effort) ---
	if avg, err := load.Avg(); err == nil && avg != nil {
		samples = append(samples,
			PromSample{Name: "node_load1", Value: avg.Load1},
			PromSample{Name: "node_load5", Value: avg.Load5},
			PromSample{Name: "node_load15", Value: avg.Load15},
		)
	}

	// --- CPU global (intervalo corto de muestreo) ---
	if pcts, err := cpu.Percent(200*time.Millisecond, false); err == nil && len(pcts) > 0 {
		samples = append(samples, PromSample{
			Name:  "node_cpu_percent",
			Value: pcts[0],
		})
	}

	// --- CPU por nucleo ---
	if pcts, err := cpu.Percent(200*time.Millisecond, true); err == nil {
		for i, p := range pcts {
			samples = append(samples, PromSample{
				Name:   "node_cpu_core_percent",
				Labels: map[string]string{"core": strconv.Itoa(i)},
				Value:  p,
			})
		}
	}

	// --- Memoria virtual ---
	if vm, err := mem.VirtualMemory(); err == nil && vm != nil {
		samples = append(samples,
			PromSample{Name: "node_mem_total_bytes", Value: float64(vm.Total)},
			PromSample{Name: "node_mem_used_bytes", Value: float64(vm.Used)},
			PromSample{Name: "node_mem_available_bytes", Value: float64(vm.Available)},
			PromSample{Name: "node_mem_used_percent", Value: vm.UsedPercent},
		)
	}

	// --- Swap ---
	if sw, err := mem.SwapMemory(); err == nil && sw != nil {
		samples = append(samples,
			PromSample{Name: "node_swap_total_bytes", Value: float64(sw.Total)},
			PromSample{Name: "node_swap_used_bytes", Value: float64(sw.Used)},
		)
	}

	// --- Particiones fisicas (ignora fstypes pseudo) ---
	if parts, err := disk.Partitions(false); err == nil {
		for _, p := range parts {
			if pseudoFstypes[p.Fstype] {
				continue
			}
			u, err := disk.Usage(p.Mountpoint)
			if err != nil || u == nil {
				continue
			}
			lbl := map[string]string{"mount": p.Mountpoint}
			samples = append(samples,
				PromSample{Name: "node_disk_total_bytes", Labels: lbl, Value: float64(u.Total)},
				PromSample{Name: "node_disk_used_bytes", Labels: lbl, Value: float64(u.Used)},
				PromSample{Name: "node_disk_used_percent", Labels: lbl, Value: u.UsedPercent},
			)
		}
	}

	// --- Contadores I/O por dispositivo ---
	if io, err := disk.IOCounters(); err == nil {
		for dev, c := range io {
			lbl := map[string]string{"device": dev}
			samples = append(samples,
				PromSample{Name: "node_disk_read_bytes", Labels: lbl, Value: float64(c.ReadBytes)},
				PromSample{Name: "node_disk_write_bytes", Labels: lbl, Value: float64(c.WriteBytes)},
			)
		}
	}

	// --- Red por interfaz (excluye loopback "lo") ---
	if nics, err := net.IOCounters(true); err == nil {
		for _, n := range nics {
			if n.Name == "lo" {
				continue
			}
			lbl := map[string]string{"iface": n.Name}
			samples = append(samples,
				PromSample{Name: "node_net_recv_bytes", Labels: lbl, Value: float64(n.BytesRecv)},
				PromSample{Name: "node_net_sent_bytes", Labels: lbl, Value: float64(n.BytesSent)},
				PromSample{Name: "node_net_recv_errs", Labels: lbl, Value: float64(n.Errin)},
				PromSample{Name: "node_net_sent_errs", Labels: lbl, Value: float64(n.Errout)},
			)
		}
	}

	// --- Temperaturas (best-effort; omite el grupo si falla o no hay sensores) ---
	if temps, err := sensors.SensorsTemperatures(); err == nil {
		for _, t := range temps {
			if t.SensorKey == "" {
				continue
			}
			samples = append(samples, PromSample{
				Name:   "node_temp_celsius",
				Labels: map[string]string{"sensor": t.SensorKey},
				Value:  t.Temperature,
			})
		}
	}

	// --- Procesos: total + top 5 por CPU ---
	// En Android (Termux) gopsutil process.Processes() llama internamente a
	// os.FindProcess, que usa el syscall pidfd_open bloqueado por el seccomp de
	// Android (mata el proceso con SIGSYS, no recuperable). Alli contamos los
	// PIDs con process.Pids() (que solo lee /proc, sin FindProcess) y omitimos
	// el top por CPU.
	if isAndroidHost() {
		if pids, err := process.Pids(); err == nil {
			samples = append(samples, PromSample{
				Name:  "node_procs_total",
				Value: float64(len(pids)),
			})
		}
	} else if procs, err := process.Processes(); err == nil {
		samples = append(samples, PromSample{
			Name:  "node_procs_total",
			Value: float64(len(procs)),
		})

		type procStat struct {
			pid  int32
			name string
			cpu  float64
			mem  float32
		}
		stats := make([]procStat, 0, len(procs))
		for _, p := range procs {
			cpuPct, err := p.CPUPercent()
			if err != nil {
				continue
			}
			name, err := p.Name()
			if err != nil {
				name = ""
			}
			memPct, err := p.MemoryPercent()
			if err != nil {
				memPct = 0
			}
			stats = append(stats, procStat{pid: p.Pid, name: name, cpu: cpuPct, mem: memPct})
		}
		sort.Slice(stats, func(i, j int) bool {
			return stats[i].cpu > stats[j].cpu
		})
		top := stats
		if len(top) > 5 {
			top = top[:5]
		}
		for _, s := range top {
			lbl := map[string]string{
				"pid":  strconv.Itoa(int(s.pid)),
				"name": s.name,
			}
			samples = append(samples,
				PromSample{Name: "node_proc_cpu_percent", Labels: lbl, Value: s.cpu},
				PromSample{Name: "node_proc_mem_percent", Labels: lbl, Value: float64(s.mem)},
			)
		}
	}

	return samples, nil
}