package resources

import (
	"bytes"
	"context"
	"fmt"
	"os/exec"
	"regexp"
	"runtime"
	"strings"
	"sync/atomic"
	"time"

	cl "github.com/Nv7-Github/go-cl"
	ffi "github.com/filecoin-project/filecoin-ffi"
	"github.com/filecoin-project/lotus/lib/harmony/harmonydb"
	logging "github.com/ipfs/go-log/v2"
	"github.com/pbnjay/memory"

	"golang.org/x/sys/unix"

	"github.com/samber/lo"
)

var LOOKS_DEAD_TIMEOUT = 10 * time.Minute // Time w/o minute heartbeats

type Resources struct {
	Cpu       int
	Gpu       float64
	GpuRam    uint64
	Ram       uint64
	MachineID int
}
type Reg struct {
	Resources
	shutdown atomic.Bool
}

var logger = logging.Logger("harmonytask")

var lotusRE = regexp.MustCompile("lotus-worker|lotus-harmony|yugabyted|yb-master|yb-tserver")

func Register(db *harmonydb.DB, hostnameAndPort string) (*Reg, error) {
	var reg Reg
	var err error
	reg.Resources, err = getResources()
	if err != nil {
		return nil, err
	}
	ctx := context.Background()
	{ // Learn our owner_id while updating harmony_machines
		var ownerID []int
		err := db.Select(ctx, &ownerID, `SELECT id FROM harmony_machines WHERE host_and_port=$1`, hostnameAndPort)
		if err != nil {
			return nil, fmt.Errorf("could not read from harmony_machines: %w", err)
		}
		if len(ownerID) == 0 {
			err = db.QueryRow(ctx, `INSERT INTO harmony_machines 
		(host_and_port, cpu, ram, gpu, gpuram) VALUES
		($1,$2,$3,$4,$5) RETURNING id`,
				hostnameAndPort, reg.Cpu, reg.Ram, reg.Gpu, reg.GpuRam).Scan(&reg.Resources.MachineID)
			if err != nil {
				return nil, err
			}

		} else {
			reg.MachineID = ownerID[0]
			_, err := db.Exec(ctx, `UPDATE harmony_machines SET
		   cpu=$1, ram=$2, gpu=$3, gpuram=$4 WHERE id=$6`,
				reg.Cpu, reg.Ram, reg.Gpu, reg.GpuRam, reg.Resources.MachineID)
			if err != nil {
				return nil, err
			}
		}
		CleanupMachines(context.Background(), db)
	}
	go func() {
		for {
			time.Sleep(time.Minute)
			if reg.shutdown.Load() {
				return
			}
			_, err := db.Exec(ctx, `UPDATE harmony_machines SET last_contact=CURRENT_TIMESTAMP`)
			if err != nil {
				logger.Error("Cannot keepalive ", err)
			}
		}
	}()

	return &reg, nil
}
func CleanupMachines(ctx context.Context, db *harmonydb.DB) int {
	ct, err := db.Exec(ctx, `DELETE FROM harmony_machines WHERE last_contact < $1`,
		time.Now().Add(-1*LOOKS_DEAD_TIMEOUT))
	if err != nil {
		logger.Warn("unable to delete old machines: ", err)
	}
	return ct
}

func (res *Reg) Shutdown() {
	res.shutdown.Store(true)
}

func getResources() (res Resources, err error) {
	b, err := exec.Command(`ps`, `-ef`).CombinedOutput()
	if err != nil {
		logger.Warn("Could not safety check for 2+ processes: ", err)
	} else {
		found := 0
		for _, b := range bytes.Split(b, []byte("\n")) {
			if lotusRE.Match(b) {
				found++
			}
		}
		if found > 1 {
			logger.Warn("lotus-provider's defaults are for running alone. Use task maximums or CGroups.")
		}
	}

	res = Resources{
		Cpu:    runtime.NumCPU(),
		Ram:    memory.FreeMemory(),
		GpuRam: getGpuRam(),
	}

	{ // GPU boolean
		gpus, err := ffi.GetGPUDevices()
		if err != nil {
			logger.Errorf("getting gpu devices failed: %+v", err)
		}
		all := strings.ToLower(strings.Join(gpus, ","))
		if len(gpus) > 1 || strings.Contains(all, "ati") || strings.Contains(all, "nvidia") {
			res.Gpu = 1
		}
	}

	return res, nil
}

func getGpuRam() uint64 {
	platforms, err := cl.GetPlatforms()
	if err != nil {
		logger.Error(err)
		return 0
	}

	return uint64(lo.SumBy(platforms, func(p *cl.Platform) int64 {
		d, err := p.GetDevices(cl.DeviceTypeAll)
		if err != nil {
			logger.Error(err)
			return 0
		}
		return lo.SumBy(d, func(d *cl.Device) int64 { return d.GlobalMemSize() })
	}))
}

func DiskFree(path string) (uint64, error) {
	s := unix.Statfs_t{}
	err := unix.Statfs(path, &s)
	if err != nil {
		return 0, err
	}

	return s.Bfree * uint64(s.Bsize), nil
}

/* NOT for Darwin.
func GetMemFree() uint64 {
	in := unix.Sysinfo_t{}
	err := unix.Sysinfo(&in)
	if err != nil {
		return 0
	}
	// If this is a 32-bit system, then these fields are
	// uint32 instead of uint64.
	// So we always convert to uint64 to match signature.
	return uint64(in.Freeram) * uint64(in.Unit)
}
*/