package metrics

import (
	"fmt"
	"strconv"

	"hamlab/internal/sensors"
)

// The collector as a sensors.Provider: every number in a Sample, one sensor each. The
// IDs are built from names the hardware reports (chip, label, interface, device, mount),
// never from enumeration order like hwmon3, which moves between boots.

// flattener turns one Sample into sensors. With want set it builds only those, so walking
// the whole ring for a history costs string compares, not allocations.
type flattener struct {
	want func(id string) bool
	seen map[string]int
	out  []sensors.Sensor
}

type bounds struct{ min, max, warn, crit *float64 }

var pct = bounds{min: sensors.F(0), max: sensors.F(100)}

func upTo(max float64) bounds { return bounds{min: sensors.F(0), max: sensors.F(max)} }

func (f *flattener) add(id, name, kind, unit string, v any, t int64, b bounds, labels ...string) {
	f.seen[id]++
	if n := f.seen[id]; n > 1 { // two identical chips: the second is coretemp_2
		id = fmt.Sprintf("%s_%d", id, n)
	}
	if f.want != nil && !f.want(id) {
		return
	}
	s := sensors.Sensor{ID: id, Name: name, Kind: kind, Unit: unit, Value: v, T: t, Min: b.min, Max: b.max, Warn: b.warn, Crit: b.crit}
	if len(labels) > 0 {
		s.Labels = make(map[string]string, len(labels)/2)
		for i := 0; i+1 < len(labels); i += 2 {
			s.Labels[labels[i]] = labels[i+1]
		}
	}
	f.out = append(f.out, s)
}

func ratio(part, whole uint64) float64 {
	if whole == 0 {
		return 0
	}
	return round1(float64(part) / float64(whole) * 100)
}

func flatten(s Sample, want func(id string) bool) []sensors.Sensor {
	f := &flattener{want: want, seen: map[string]int{}}
	t, none := s.T, bounds{}

	f.add("cpu.usage", "CPU", "usage", "%", s.CPU, t, pct)
	for i, c := range s.Cores {
		n := strconv.Itoa(i)
		f.add("cpu.core."+n+".usage", "Core "+n, "usage", "%", c, t, pct, "core", n)
	}
	if c := cpuTemp(s.Temps); c > 0 {
		f.add("cpu.temp", "CPU temperature", "temperature", "°C", c, t, none)
	}
	if s.CPUPower > 0 {
		f.add("cpu.power", "CPU power", "power", "W", s.CPUPower, t, none)
	}
	for i, w := range s.CPUPowerPkgs {
		n := strconv.Itoa(i)
		f.add("cpu.package."+n+".power", "CPU "+strconv.Itoa(i+1)+" power", "power", "W", w, t, none, "package", n)
	}
	for i, w := range []string{"1", "5", "15"} {
		f.add("load."+w, "Load "+w+" min", "load", "", s.Load[i], t, none)
	}
	f.add("uptime", "Uptime", "duration", "s", s.Uptime, t, none)
	f.add("hamlab.sample_interval", "Sampling interval", "duration", "ms", float64(s.Interval), t, none)

	for _, m := range []struct {
		id, name string
		v        Mem
	}{{"mem", "Memory", s.Mem}, {"swap", "Swap", s.Swap}} {
		f.add(m.id+".total", m.name+" total", "bytes", "B", float64(m.v.Total), t, none)
		f.add(m.id+".used", m.name+" used", "bytes", "B", float64(m.v.Used), t, upTo(float64(m.v.Total)))
		f.add(m.id+".avail", m.name+" available", "bytes", "B", float64(m.v.Avail), t, upTo(float64(m.v.Total)))
		f.add(m.id+".used_pct", m.name+" used", "usage", "%", ratio(m.v.Used, m.v.Total), t, pct)
	}
	f.add("mem.free", "Memory free", "bytes", "B", float64(s.Mem.Free), t, upTo(float64(s.Mem.Total)))
	f.add("mem.cached", "Memory cached", "bytes", "B", float64(s.Mem.Cached), t, upTo(float64(s.Mem.Total)))
	f.add("mem.buffers", "Memory buffers", "bytes", "B", float64(s.Mem.Buffers), t, upTo(float64(s.Mem.Total)))

	for _, x := range s.Temps {
		b := bounds{}
		if x.Max > 0 {
			b.warn = sensors.F(x.Max)
		}
		if x.Crit > 0 {
			b.crit = sensors.F(x.Crit)
		}
		labels := []string{"chip", x.Chip, "label", x.Label}
		if x.Chip == "coretemp" { // a two-socket board has a coretemp chip per CPU, both with a "Core 0"
			labels = append(labels, "package", strconv.Itoa(x.Pkg))
		}
		f.add(sensors.ID("temp", sensors.Seg(x.Chip), sensors.Seg(x.Label)), x.Chip+" "+x.Label, "temperature", "°C", x.C, t, b, labels...)
	}
	for _, x := range s.Fans {
		f.add(sensors.ID("fan", sensors.Seg(x.Chip), sensors.Seg(x.Label)), x.Chip+" "+x.Label, "fan", "rpm", float64(x.RPM), t, none, "chip", x.Chip, "label", x.Label)
	}

	for _, x := range s.Net {
		p := "net." + sensors.Seg(x.Iface)
		f.add(p+".rx", x.Iface+" receive", "rate", "B/s", x.RxBps, t, none, "iface", x.Iface)
		f.add(p+".tx", x.Iface+" transmit", "rate", "B/s", x.TxBps, t, none, "iface", x.Iface)
		f.add(p+".rx_total", x.Iface+" received", "bytes", "B", float64(x.RxTotal), t, none, "iface", x.Iface)
		f.add(p+".tx_total", x.Iface+" transmitted", "bytes", "B", float64(x.TxTotal), t, none, "iface", x.Iface)
		f.add(p+".up", x.Iface+" link", "state", "", x.Up, t, none, "iface", x.Iface)
	}

	for _, x := range s.Disks {
		p := "disk." + sensors.Seg(x.Name)
		f.add(p+".read", x.Name+" read", "rate", "B/s", x.ReadBps, t, none, "device", x.Name, "model", x.Model)
		f.add(p+".write", x.Name+" write", "rate", "B/s", x.WriteBps, t, none, "device", x.Name, "model", x.Model)
		f.add(p+".util", x.Name+" busy", "usage", "%", x.UtilPct, t, pct, "device", x.Name, "model", x.Model)
		f.add(p+".size", x.Name+" size", "bytes", "B", float64(x.Size), t, none, "device", x.Name, "model", x.Model)
		if x.Temp > 0 {
			f.add(p+".temp", x.Name+" temperature", "temperature", "°C", x.Temp, t, none, "device", x.Name, "model", x.Model)
		}
	}

	for _, x := range s.FS {
		p := "fs." + sensors.Seg(x.Mount)
		// remote says the bytes are on another machine (a CIFS or NFS share), so a view of
		// this machine's hardware can leave it out without losing the sensor
		lbl := []string{"mount", x.Mount, "fstype", x.Type}
		if x.Remote {
			lbl = append(lbl, "remote", "1")
		}
		if x.Disk != "" {
			lbl = append(lbl, "disk", x.Disk)
		}
		f.add(p+".size", x.Mount+" size", "bytes", "B", float64(x.Size), s.fsT, none, lbl...)
		f.add(p+".used", x.Mount+" used", "bytes", "B", float64(x.Used), s.fsT, upTo(float64(x.Size)), lbl...)
		f.add(p+".used_pct", x.Mount+" used", "usage", "%", ratio(x.Used, x.Size), s.fsT, pct, lbl...)
	}

	gpuSeen := map[string]int{}
	for _, g := range s.GPUs {
		// two identical cards are gpu.<name> and gpu.<name>_2, every sensor of the second under
		// its own stem (not add's suffix on the end of each id, which the page can't find)
		p := "gpu." + sensors.Seg(g.Name)
		if gpuSeen[p]++; gpuSeen[p] > 1 {
			p = fmt.Sprintf("%s_%d", p, gpuSeen[p])
		}
		lbl := []string{"name", g.Name, "driver", g.Driver}
		if g.Bus != "" {
			lbl = append(lbl, "bus", g.Bus)
		}
		if g.Integrated {
			lbl = append(lbl, "integrated", "1")
		}
		if g.UsageSrc != "" {
			f.add(p+".usage", g.Name, "usage", "%", g.Usage, t, pct, lbl...)
		}
		for _, e := range []string{"render", "video", "copy", "video-enhance", "compute"} {
			if v, ok := g.Engines[e]; ok {
				f.add(p+"."+sensors.Seg(e), g.Name+" "+e, "usage", "%", v, t, pct, lbl...)
			}
		}
		if g.Temp > 0 {
			f.add(p+".temp", g.Name+" temperature", "temperature", "°C", g.Temp, t, none, append(lbl, "source", g.TempSrc)...)
		}
		if g.PowerW > 0 || g.PowerCapW > 0 {
			b := none
			if g.PowerCapW > 0 {
				b = upTo(g.PowerCapW)
			}
			f.add(p+".power", g.Name+" power", "power", "W", g.PowerW, t, b, lbl...)
		}
		if g.FanRPM > 0 {
			f.add(p+".fan", g.Name+" fan", "fan", "rpm", float64(g.FanRPM), t, none, lbl...)
		}
		if g.MaxMHz > 0 {
			f.add(p+".freq", g.Name+" clock", "frequency", "MHz", g.MHz, t, upTo(g.MaxMHz), lbl...)
		}
		if g.MemTotal > 0 {
			f.add(p+".mem_used", g.Name+" memory used", "bytes", "B", float64(g.MemUsed), t, upTo(float64(g.MemTotal)), lbl...)
			f.add(p+".mem_total", g.Name+" memory", "bytes", "B", float64(g.MemTotal), t, none, lbl...)
		} else if g.MemUsed > 0 {
			f.add(p+".mem_used", g.Name+" memory used", "bytes", "B", float64(g.MemUsed), t, none, lbl...)
		}
		f.add(p+".clients", g.Name+" clients", "count", "", float64(len(g.Clients)), t, none, lbl...)
	}

	if a := s.ARC; a != nil {
		p := "zfs.arc."
		cap := upTo(float64(a.Max))
		f.add(p+"size", "ARC size", "bytes", "B", float64(a.Size), t, cap)
		f.add(p+"target", "ARC target", "bytes", "B", float64(a.Target), t, cap)
		f.add(p+"min", "ARC floor", "bytes", "B", float64(a.Min), t, none)
		f.add(p+"max", "ARC ceiling", "bytes", "B", float64(a.Max), t, none)
		f.add(p+"mru", "ARC recently used", "bytes", "B", float64(a.MRU), t, cap)
		f.add(p+"mfu", "ARC frequently used", "bytes", "B", float64(a.MFU), t, cap)
		f.add(p+"metadata", "ARC metadata", "bytes", "B", float64(a.Metadata), t, cap)
		f.add(p+"data", "ARC data", "bytes", "B", float64(a.Data), t, cap)
		if a.HitPctKnown {
			f.add(p+"hit_pct", "ARC hit rate", "usage", "%", a.HitPct, t, pct)
		}
		f.add(p+"reads", "ARC reads", "rate", "/s", a.ReadsPerSec, t, none)
		f.add(p+"misses", "ARC misses", "rate", "/s", a.MissesPerSec, t, none)
		f.add(p+"lifetime_hit_pct", "ARC hit rate since boot", "usage", "%", a.LifetimeHitPct, t, pct)
		f.add(p+"no_grow", "ARC held by memory pressure", "state", "", a.NoGrow, t, none)
		if a.Compressed > 0 {
			f.add(p+"compress_ratio", "ARC compression", "ratio", "x", round1(float64(a.Uncompressed)/float64(a.Compressed)*10)/10, t, none)
		}
		if a.L2Size > 0 {
			f.add(p+"l2_size", "L2ARC size", "bytes", "B", float64(a.L2Size), t, none)
			f.add(p+"l2_hit_pct", "L2ARC hit rate", "usage", "%", a.L2HitPct, t, pct)
		}
	}

	if w := s.ZFSWrite; w != nil {
		f.add("zfs.write.dirty", "ZFS write buffer", "bytes", "B", float64(w.Dirty), t, upTo(float64(w.Limit)))
		f.add("zfs.write.limit", "ZFS write buffer limit", "bytes", "B", float64(w.Limit), t, none)
		f.add("zfs.write.delayed", "ZFS writes throttled", "rate", "/s", w.DelayedPerSec, t, none)
		for _, p := range w.Pools {
			pp := "zfs." + sensors.Seg(p.Pool) + "."
			f.add(pp+"write_bps", p.Pool+" writes to disk", "rate", "B/s", p.WriteBps, t, none, "pool", p.Pool)
			f.add(pp+"logical_bps", p.Pool+" writes by programs", "rate", "B/s", p.LogicalBps, t, none, "pool", p.Pool)
			if l := p.Landing; l != nil {
				lp := pp + "landing."
				lbl := []string{"pool", p.Pool, "branch", l.Branch}
				f.add(lp+"pending_bytes", p.Pool+" landing: waiting", "bytes", "B", float64(l.PendingBytes), t, upTo(float64(l.Size)), lbl...)
				f.add(lp+"pending_files", p.Pool+" landing: files waiting", "count", "", float64(l.PendingFiles), t, none, lbl...)
				if l.Size > 0 {
					f.add(lp+"used_pct", p.Pool+" landing: used", "usage", "%", round1(float64(l.Used)/float64(l.Size)*100), t, pct, lbl...)
				}
				f.add(lp+"in_bps", p.Pool+" landing: arriving", "rate", "B/s", l.InBps, t, none, lbl...)
				f.add(lp+"drain_bps", p.Pool+" landing: moving to the pool", "rate", "B/s", l.DrainBps, t, none, lbl...)
				if m := l.Mover; m != nil {
					f.add(lp+"mover", p.Pool+" landing: mover", "state", "", m.State, t, none, lbl...)
					f.add(lp+"queue", p.Pool+" landing: mover queue", "count", "", float64(m.Queue), t, none, lbl...)
				}
			}
		}
	}

	if u := s.UPS; u != nil {
		ut := s.upsT
		f.add("ups.battery", "UPS battery", "usage", "%", u.BatteryPct, ut, pct, "model", u.Model)
		f.add("ups.runtime", "UPS runtime", "duration", "min", u.RuntimeMin, ut, none, "model", u.Model)
		f.add("ups.load", "UPS load", "power", "W", u.LoadW, ut, none, "model", u.Model)
		f.add("ups.load_pct", "UPS load", "usage", "%", u.LoadPct, ut, pct, "model", u.Model)
		f.add("ups.in_v", "UPS input", "voltage", "V", u.InV, ut, none, "model", u.Model)
		f.add("ups.out_v", "UPS output", "voltage", "V", u.OutV, ut, none, "model", u.Model)
		f.add("ups.on_battery", "UPS on battery", "state", "", u.OnBattery, ut, none, "model", u.Model)
		f.add("ups.state", "UPS state", "state", "", u.State, ut, none, "model", u.Model)
		f.add("ups.source", "UPS power source", "state", "", u.Source, ut, none, "model", u.Model)
		f.add("ups.last_event", "UPS last event", "state", "", u.LastEvent, ut, none, "model", u.Model, "driver", u.Driver)
	}
	return f.out
}

// Sensors implements sensors.Provider.
func (c *Collector) Sensors() []sensors.Sensor {
	s, ok := c.Latest()
	if !ok {
		return nil
	}
	return flatten(s, nil)
}

// SensorHistories implements sensors.Historian: the ring, seen through the sensors that
// match. A sensor that didn't exist in a sample (a disk plugged in since) simply has a
// shorter series; nothing is zero-filled. States have no curve and are left out.
func (c *Collector) SensorHistories(match func(id string) bool) []sensors.Series {
	c.mu.RLock()
	defer c.mu.RUnlock()
	by := map[string]*sensors.Series{}
	var order []string
	for _, smp := range c.ring {
		for _, x := range flatten(smp, match) {
			v, ok := x.Value.(float64)
			if !ok {
				continue
			}
			s := by[x.ID]
			if s == nil {
				s = &sensors.Series{ID: x.ID, Unit: x.Unit, T: []int64{}, V: []float64{}}
				by[x.ID] = s
				order = append(order, x.ID)
			}
			s.T, s.V = append(s.T, smp.T), append(s.V, v)
		}
	}
	out := make([]sensors.Series, 0, len(order))
	for _, id := range order {
		out = append(out, *by[id])
	}
	return out
}