// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this
// file, You can obtain one at http://mozilla.org/MPL/2.0/.

package qemu

import (
	"encoding/json"
	"fmt"
	"io"
	"io/ioutil"
	"math"
	"net"
	"os"
	"os/exec"
	"runtime"
	"strconv"
	"strings"
	"syscall"

	"github.com/google/uuid"
	multierror "github.com/hashicorp/go-multierror"
	"github.com/talos-systems/go-procfs/procfs"

	"github.com/talos-systems/talos/pkg/machinery/constants"
	"github.com/talos-systems/talos/pkg/provision"
	"github.com/talos-systems/talos/pkg/provision/providers/vm"
)

//nolint: gocyclo
func (p *provisioner) createNode(state *vm.State, clusterReq provision.ClusterRequest, nodeReq provision.NodeRequest, opts *provision.Options) (provision.NodeInfo, error) {
	arch := Arch(opts.TargetArch)
	pidPath := state.GetRelativePath(fmt.Sprintf("%s.pid", nodeReq.Name))

	var pflashImages []string

	if pflashSpec := arch.PFlash(opts.UEFIEnabled); pflashSpec != nil {
		var err error

		if pflashImages, err = p.createPFlashImages(state, nodeReq.Name, pflashSpec); err != nil {
			return provision.NodeInfo{}, fmt.Errorf("error creating flash images: %w", err)
		}
	}

	vcpuCount := int64(math.RoundToEven(float64(nodeReq.NanoCPUs) / 1000 / 1000 / 1000))
	if vcpuCount < 2 {
		vcpuCount = 1
	}

	memSize := nodeReq.Memory / 1024 / 1024

	diskPaths, err := p.CreateDisks(state, nodeReq)
	if err != nil {
		return provision.NodeInfo{}, err
	}

	logFile, err := os.OpenFile(state.GetRelativePath(fmt.Sprintf("%s.log", nodeReq.Name)), os.O_APPEND|os.O_CREATE|os.O_RDWR, 0o666)
	if err != nil {
		return provision.NodeInfo{}, err
	}

	defer logFile.Close() //nolint: errcheck

	cmdline := procfs.NewDefaultCmdline()

	// backwards compatibility to boot initrd from Talos < 0.8
	// we can remove it once we stop testing upgrades from versions < 0.8
	cmdline.Append("slub_debug", "P")
	cmdline.Append("page_poison", "1")

	// required to get kernel console
	cmdline.Append("console", arch.Console())

	// reboot configuration
	cmdline.Append("reboot", "k")
	cmdline.Append("panic", "1")
	cmdline.Append("talos.shutdown", "halt")

	// Talos config
	cmdline.Append("talos.platform", "metal")

	var nodeConfig string

	if nodeReq.Config != nil {
		cmdline.Append("talos.config", "{TALOS_CONFIG_URL}") // to be patched by launcher

		nodeConfig, err = nodeReq.Config.String()
		if err != nil {
			return provision.NodeInfo{}, err
		}
	}

	nodeUUID := uuid.New()

	apiPort, err := p.findBridgeListenPort(clusterReq)
	if err != nil {
		return provision.NodeInfo{}, fmt.Errorf("error finding listen address for the API: %w", err)
	}

	launchConfig := LaunchConfig{
		QemuExecutable:    arch.QemuExecutable(),
		DiskPaths:         diskPaths,
		VCPUCount:         vcpuCount,
		MemSize:           memSize,
		KernelArgs:        cmdline.String(),
		MachineType:       arch.QemuMachine(),
		PFlashImages:      pflashImages,
		EnableKVM:         opts.TargetArch == runtime.GOARCH,
		BootloaderEnabled: opts.BootloaderEnabled,
		NodeUUID:          nodeUUID,
		Config:            nodeConfig,
		NetworkConfig:     state.VMCNIConfig,
		CNI:               clusterReq.Network.CNI,
		CIDR:              clusterReq.Network.CIDR,
		IP:                nodeReq.IP,
		Hostname:          nodeReq.Name,
		GatewayAddr:       clusterReq.Network.GatewayAddr,
		MTU:               clusterReq.Network.MTU,
		Nameservers:       clusterReq.Network.Nameservers,
		TFTPServer:        nodeReq.TFTPServer,
		IPXEBootFileName:  nodeReq.IPXEBootFilename,
		APIPort:           apiPort,
	}

	if !nodeReq.PXEBooted {
		launchConfig.KernelImagePath = strings.ReplaceAll(clusterReq.KernelPath, constants.ArchVariable, opts.TargetArch)
		launchConfig.InitrdPath = strings.ReplaceAll(clusterReq.InitramfsPath, constants.ArchVariable, opts.TargetArch)
		launchConfig.ISOPath = strings.ReplaceAll(clusterReq.ISOPath, constants.ArchVariable, opts.TargetArch)
	}

	launchConfig.StatePath, err = state.StatePath()
	if err != nil {
		return provision.NodeInfo{}, err
	}

	launchConfigFile, err := os.Create(state.GetRelativePath(fmt.Sprintf("%s.config", nodeReq.Name)))
	if err != nil {
		return provision.NodeInfo{}, err
	}

	if err = json.NewEncoder(launchConfigFile).Encode(&launchConfig); err != nil {
		return provision.NodeInfo{}, err
	}

	if _, err = launchConfigFile.Seek(0, io.SeekStart); err != nil {
		return provision.NodeInfo{}, err
	}

	defer launchConfigFile.Close() //nolint: errcheck

	cmd := exec.Command(clusterReq.SelfExecutable, "qemu-launch")
	cmd.Stdout = logFile
	cmd.Stderr = logFile
	cmd.Stdin = launchConfigFile
	cmd.SysProcAttr = &syscall.SysProcAttr{
		Setsid: true, // daemonize
	}

	if err = cmd.Start(); err != nil {
		return provision.NodeInfo{}, err
	}

	if err = ioutil.WriteFile(pidPath, []byte(strconv.Itoa(cmd.Process.Pid)), os.ModePerm); err != nil {
		return provision.NodeInfo{}, fmt.Errorf("error writing PID file: %w", err)
	}

	// no need to wait here, as cmd has all the Stdin/out/err via *os.File

	nodeInfo := provision.NodeInfo{
		ID:   pidPath,
		UUID: nodeUUID,
		Name: nodeReq.Name,
		Type: nodeReq.Type,

		NanoCPUs: nodeReq.NanoCPUs,
		Memory:   nodeReq.Memory,
		DiskSize: nodeReq.Disks[0].Size,

		PrivateIP: nodeReq.IP,

		APIPort: apiPort,
	}

	return nodeInfo, nil
}

func (p *provisioner) createNodes(state *vm.State, clusterReq provision.ClusterRequest, nodeReqs []provision.NodeRequest, opts *provision.Options) ([]provision.NodeInfo, error) {
	errCh := make(chan error)
	nodeCh := make(chan provision.NodeInfo, len(nodeReqs))

	for _, nodeReq := range nodeReqs {
		go func(nodeReq provision.NodeRequest) {
			nodeInfo, err := p.createNode(state, clusterReq, nodeReq, opts)
			if err == nil {
				nodeCh <- nodeInfo
			}

			errCh <- err
		}(nodeReq)
	}

	var multiErr *multierror.Error

	for range nodeReqs {
		multiErr = multierror.Append(multiErr, <-errCh)
	}

	close(nodeCh)

	nodesInfo := make([]provision.NodeInfo, 0, len(nodeReqs))

	for nodeInfo := range nodeCh {
		nodesInfo = append(nodesInfo, nodeInfo)
	}

	return nodesInfo, multiErr.ErrorOrNil()
}

func (p *provisioner) findBridgeListenPort(clusterReq provision.ClusterRequest) (int, error) {
	l, err := net.Listen("tcp", net.JoinHostPort(clusterReq.Network.GatewayAddr.String(), "0"))
	if err != nil {
		return 0, err
	}

	port := l.Addr().(*net.TCPAddr).Port

	return port, l.Close()
}