package qemutils

import (
	"fmt"
	"io/ioutil"
	"os"
	"path"
	"regexp"
	"sort"
	"strings"

	"yunion.io/x/onecloud/pkg/cloudcommon/version"
)

const (
	USER_LOCAL_BIN = "/usr/local/bin"
	USER_BIN       = "/usr/bin"
)

func GetQemu(version string) string {
	return getQemuCmd("qemu-system-x86_64", version)
}

func GetQemuNbd() string {
	return getQemuCmd("qemu-nbd", "")
}

func GetQemuImg() string {
	return getQemuCmd("qemu-img", "")
}

func getQemuCmd(cmd, version string) string {
	if len(version) > 0 {
		return getQemuCmdByVersion(cmd, version)
	} else {
		return getQemuDefaultCmd(cmd)
	}
}

func getQemuCmdByVersion(cmd, version string) string {
	p := path.Join(fmt.Sprintf("/usr/local/qemu-%s/bin", version), cmd)
	if _, err := os.Stat(p); !os.IsNotExist(err) {
		return p
	}
	cmd = cmd + "_" + version
	p = path.Join(USER_LOCAL_BIN, cmd)
	if _, err := os.Stat(p); !os.IsNotExist(err) {
		return p
	}
	p = path.Join(USER_BIN, cmd)
	if _, err := os.Stat(p); !os.IsNotExist(err) {
		return p
	}
	return ""
}

func getQemuVersion(verString string) string {
	s := regexp.MustCompile(`qemu-(?P<ver>\d+(\.\d+)+)$`).FindString(verString)
	if len(s) == 0 {
		return ""
	}
	return s[len("qemu-"):]
}

func getCmdVersion(cmd string) string {
	s := regexp.MustCompile(`_(?P<ver>\d+(\.\d+)+)$`).FindString(cmd)
	if len(s) == 0 {
		return ""
	}
	return s[1:]
}

func getQemuDefaultCmd(cmd string) string {
	var qemus = make([]string, 0)
	if files, err := ioutil.ReadDir("/usr/local"); err == nil {
		for i := 0; i < len(files); i++ {
			if strings.HasPrefix(files[i].Name(), "qemu-") {
				qemus = append(qemus, files[i].Name())
			}
		}
		if len(qemus) > 0 {
			sort.Slice(qemus, func(i, j int) bool {
				return version.LT(getQemuVersion(qemus[i]),
					getQemuVersion(qemus[j]))
			})
			p := fmt.Sprintf("/usr/local/%s/bin/%s", qemus[len(qemus)-1], cmd)
			if _, err := os.Stat(p); !os.IsNotExist(err) {
				return p
			}
		}
	}
	cmds := make([]string, 0)
	if files, err := ioutil.ReadDir(USER_LOCAL_BIN); err == nil {
		for i := 0; i < len(files); i++ {
			if strings.HasPrefix(files[i].Name(), cmd) {
				cmds = append(cmds, files[i].Name())
			}
		}
		if len(cmds) > 0 {
			sort.Slice(cmds, func(i, j int) bool {
				return version.LT(getCmdVersion(cmds[i]),
					getCmdVersion(cmds[j]))
			})
			p := path.Join(USER_LOCAL_BIN, cmds[len(cmds)-1])
			if _, err := os.Stat(p); !os.IsNotExist(err) {
				return p
			}
		}
	}
	return ""
}