package docker

/*
#include <sys/ioctl.h>
#include <linux/fs.h>
#include <errno.h>

// See linux.git/fs/btrfs/ioctl.h
#define BTRFS_IOCTL_MAGIC 0x94
#define BTRFS_IOC_CLONE _IOW(BTRFS_IOCTL_MAGIC, 9, int)

int
btrfs_reflink(int fd_out, int fd_in)
{
  int res;
  res = ioctl(fd_out, BTRFS_IOC_CLONE, fd_in);
  if (res < 0)
    return errno;
  return 0;
}

*/
import "C"
import (
	"fmt"
	"io"
	"io/ioutil"
	"os"
	"strings"
	"syscall"
)

// Compare two Config struct. Do not compare the "Image" nor "Hostname" fields
// If OpenStdin is set, then it differs
func CompareConfig(a, b *Config) bool {
	if a == nil || b == nil ||
		a.OpenStdin || b.OpenStdin {
		return false
	}
	if a.AttachStdout != b.AttachStdout ||
		a.AttachStderr != b.AttachStderr ||
		a.User != b.User ||
		a.Memory != b.Memory ||
		a.MemorySwap != b.MemorySwap ||
		a.CpuShares != b.CpuShares ||
		a.OpenStdin != b.OpenStdin ||
		a.Tty != b.Tty ||
		a.VolumesFrom != b.VolumesFrom {
		return false
	}
	if len(a.Cmd) != len(b.Cmd) ||
		len(a.Dns) != len(b.Dns) ||
		len(a.Env) != len(b.Env) ||
		len(a.PortSpecs) != len(b.PortSpecs) ||
		len(a.Entrypoint) != len(b.Entrypoint) ||
		len(a.Volumes) != len(b.Volumes) {
		return false
	}

	for i := 0; i < len(a.Cmd); i++ {
		if a.Cmd[i] != b.Cmd[i] {
			return false
		}
	}
	for i := 0; i < len(a.Dns); i++ {
		if a.Dns[i] != b.Dns[i] {
			return false
		}
	}
	for i := 0; i < len(a.Env); i++ {
		if a.Env[i] != b.Env[i] {
			return false
		}
	}
	for i := 0; i < len(a.PortSpecs); i++ {
		if a.PortSpecs[i] != b.PortSpecs[i] {
			return false
		}
	}
	for i := 0; i < len(a.Entrypoint); i++ {
		if a.Entrypoint[i] != b.Entrypoint[i] {
			return false
		}
	}
	for key := range a.Volumes {
		if _, exists := b.Volumes[key]; !exists {
			return false
		}
	}
	return true
}

func MergeConfig(userConf, imageConf *Config) {
	if userConf.User == "" {
		userConf.User = imageConf.User
	}
	if userConf.Memory == 0 {
		userConf.Memory = imageConf.Memory
	}
	if userConf.MemorySwap == 0 {
		userConf.MemorySwap = imageConf.MemorySwap
	}
	if userConf.CpuShares == 0 {
		userConf.CpuShares = imageConf.CpuShares
	}
	if userConf.PortSpecs == nil || len(userConf.PortSpecs) == 0 {
		userConf.PortSpecs = imageConf.PortSpecs
	} else {
		for _, imagePortSpec := range imageConf.PortSpecs {
			found := false
			imageNat, _ := parseNat(imagePortSpec)
			for _, userPortSpec := range userConf.PortSpecs {
				userNat, _ := parseNat(userPortSpec)
				if imageNat.Proto == userNat.Proto && imageNat.Backend == userNat.Backend {
					found = true
				}
			}
			if !found {
				userConf.PortSpecs = append(userConf.PortSpecs, imagePortSpec)
			}
		}
	}
	if !userConf.Tty {
		userConf.Tty = imageConf.Tty
	}
	if !userConf.OpenStdin {
		userConf.OpenStdin = imageConf.OpenStdin
	}
	if !userConf.StdinOnce {
		userConf.StdinOnce = imageConf.StdinOnce
	}
	if userConf.Env == nil || len(userConf.Env) == 0 {
		userConf.Env = imageConf.Env
	} else {
		for _, imageEnv := range imageConf.Env {
			found := false
			imageEnvKey := strings.Split(imageEnv, "=")[0]
			for _, userEnv := range userConf.Env {
				userEnvKey := strings.Split(userEnv, "=")[0]
				if imageEnvKey == userEnvKey {
					found = true
				}
			}
			if !found {
				userConf.Env = append(userConf.Env, imageEnv)
			}
		}
	}
	if userConf.Cmd == nil || len(userConf.Cmd) == 0 {
		userConf.Cmd = imageConf.Cmd
	}
	if userConf.Dns == nil || len(userConf.Dns) == 0 {
		userConf.Dns = imageConf.Dns
	} else {
		//duplicates aren't an issue here
		userConf.Dns = append(userConf.Dns, imageConf.Dns...)
	}
	if userConf.Entrypoint == nil || len(userConf.Entrypoint) == 0 {
		userConf.Entrypoint = imageConf.Entrypoint
	}
	if userConf.WorkingDir == "" {
		userConf.WorkingDir = imageConf.WorkingDir
	}
	if userConf.VolumesFrom == "" {
		userConf.VolumesFrom = imageConf.VolumesFrom
	}
	if userConf.Volumes == nil || len(userConf.Volumes) == 0 {
		userConf.Volumes = imageConf.Volumes
	} else {
		for k, v := range imageConf.Volumes {
			userConf.Volumes[k] = v
		}
	}
}

func parseLxcConfOpts(opts ListOpts) ([]KeyValuePair, error) {
	out := make([]KeyValuePair, len(opts))
	for i, o := range opts {
		k, v, err := parseLxcOpt(o)
		if err != nil {
			return nil, err
		}
		out[i] = KeyValuePair{Key: k, Value: v}
	}
	return out, nil
}

func parseLxcOpt(opt string) (string, string, error) {
	parts := strings.SplitN(opt, "=", 2)
	if len(parts) != 2 {
		return "", "", fmt.Errorf("Unable to parse lxc conf option: %s", opt)
	}
	return strings.TrimSpace(parts[0]), strings.TrimSpace(parts[1]), nil
}

func RootIsShared() bool {
	if data, err := ioutil.ReadFile("/proc/self/mountinfo"); err == nil {
		for _, line := range strings.Split(string(data), "\n") {
			cols := strings.Split(line, " ")
			if len(cols) >= 6 && cols[3] == "/" && cols[4] == "/" {
				return strings.HasPrefix(cols[6], "shared")
			}
		}
	}

	// No idea, probably safe to assume so
	return true
}

func BtrfsReflink(fd_out, fd_in uintptr) error {
	res := C.btrfs_reflink(C.int(fd_out), C.int(fd_in))
	if res != 0 {
		return syscall.Errno(res)
	}
	return nil
}

func CopyFile(dstFile, srcFile *os.File) error {
	err := BtrfsReflink(dstFile.Fd(), srcFile.Fd())
	if err == nil {
		return nil
	}

	// Fall back to normal copy
	_, err = io.Copy(dstFile, srcFile)
	return err
}