package mount

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"time"

	"github.com/containerd/containerd/mount"
	"github.com/deniswernert/go-fstab"
	"github.com/kairos-io/immucore/pkg/profile"
	"github.com/kairos-io/kairos/pkg/utils"
	"github.com/spectrocloud-labs/herd"
)

type State struct {
	Rootdir     string
	TargetImage string   // e.g. /cOS/active.img
	OverlayDir  []string // e.g. /var
	BindMounts  []string // e.g. /etc/kubernetes
	StateDir    string   // e.g. "/usr/local/.state"

	CustomMounts map[string]string // e.g. diskid : mountpoint

	fstabs []*fstab.Mount
}

func genOpreferenceName(op, s string) string {
	return fmt.Sprintf("%s-%s", op, s)
}

func genOpreferenceFromMap(op string, m map[string]string) (res []string) {
	values := []string{}
	for _, n := range m {
		values = append(values, n)
	}

	res = genOpreference(op, values)
	return
}
func genOpreference(op string, s []string) (res []string) {
	for _, n := range s {
		res = append(res, genOpreferenceName(op, n))
	}
	return
}

const (
	opCustomMounts = "custom-mount"
)

func (s *State) Register(g *herd.Graph) error {

	// TODO: add, hooks, fstab, systemd compat

	g.Add("discover-mount",
		herd.WithDeps("mount-cos-state"),
		herd.WithCallback(
			func(ctx context.Context) error {
				_, err := utils.SH(fmt.Sprintf("losetup --show -f /run/initramfs/cos-state%s", s.TargetImage))
				return err
			},
		))

	g.Add("mount-cos-state",
		herd.WithCallback(
			s.MountOP(
				"/dev/disk/by-label/COS_STATE",
				s.path("/run/initramfs/cos-state"),
				"auto",
				[]string{
					"ro", // or rw
				}, 60*time.Second),
		),
	)

	// overlay mount start
	if rootFSType(s.Rootdir) != "overlay" {
		g.Add("mount-overlay-base",
			herd.WithCallback(
				func(ctx context.Context) error {
					op, err := baseOverlay(profile.Overlay{
						Base:        "/run/overlay",
						BackingBase: "tmpfs:20%",
					})
					if err != nil {
						return err
					}
					s.fstabs = append(s.fstabs, &op.FstabEntry)
					return op.run()
				},
			),
		)
	}

	overlayCondition := herd.ConditionalOption(func() bool { return rootFSType(s.Rootdir) != "overlay" }, herd.WithDeps("mount-overlay-base"))

	// TODO: Add fsck
	// mount overlay
	for _, p := range s.OverlayDir {
		g.Add("mount-overlays-base",
			overlayCondition,
			herd.WithCallback(
				func(ctx context.Context) error {
					op, err := mountWithBaseOverlay(p, s.Rootdir, "/run/overlay")
					if err != nil {
						return err
					}
					s.fstabs = append(s.fstabs, &op.FstabEntry)
					return op.run()
				},
			),
		)
	}

	// custom mounts TODO: disk/path
	for id, mountpoint := range s.CustomMounts {
		g.Add(
			genOpreferenceName(opCustomMounts, mountpoint),
			overlayCondition,
			herd.WithCallback(
				s.MountOP(
					id,
					s.path(mountpoint),
					"auto",
					[]string{
						"ro", // or rw
					}, 60*time.Second),
			),
		)
	}

	// mount state
	// mount state is defined over a custom mount (/usr/local/.state for instance, needs to be mounted over a device)
	for _, p := range s.BindMounts {
		g.Add(
			genOpreferenceName("mount-state", p),
			overlayCondition,
			herd.WithDeps(genOpreferenceFromMap(opCustomMounts, s.CustomMounts)...),
			herd.WithCallback(
				func(ctx context.Context) error {
					op, err := mountBind(p, s.Rootdir, s.StateDir)
					if err != nil {
						return err
					}
					s.fstabs = append(s.fstabs, &op.FstabEntry)
					return op.run()
				},
			),
		)
	}

	// overlay mount end

	g.Add("mount-sysroot",
		herd.WithCallback(
			s.MountOP(
				"/dev/disk/by-label/COS_ACTIVE",
				s.Rootdir,
				"auto",
				[]string{
					"ro", // or rw
					"suid",
					"dev",
					"exec",
					"auto",
					"nouser",
					"async",
				}, 60*time.Second),
		),
	)

	g.Add("mount-oem",
		herd.WithCallback(
			s.MountOP(
				"/dev/disk/by-label/COS_OEM",
				s.path("/oem"),
				"auto",
				[]string{
					"rw",
					"suid",
					"dev",
					"exec",
					"noauto",
					"nouser",
					"async",
				}, 60*time.Second),
		),
	)

	g.Add("write-fstab", herd.WithCallback(s.WriteFstab("foo")))

	return nil
}

func (s *State) path(p ...string) string {
	return filepath.Join(append([]string{s.Rootdir}, p...)...)
}

func (s *State) WriteFstab(fstabFile string) func(context.Context) error {
	return func(ctx context.Context) error {
		for _, fst := range s.fstabs {
			select {
			case <-ctx.Done():
			default:
				f, err := os.OpenFile(fstabFile,
					os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
				if err != nil {
					return err
				}
				defer f.Close()
				if _, err := f.WriteString(fmt.Sprintf("%s\n", fst.String())); err != nil {
					return err
				}
			}
		}
		return nil
	}
}

func (s *State) MountOP(what, where, t string, options []string, timeout time.Duration) func(context.Context) error {
	return func(c context.Context) error {
		for {
			select {
			default:
				time.Sleep(1 * time.Second)
				mountPoint := mount.Mount{
					Type:    t,
					Source:  what,
					Options: options,
				}
				fstab := mountToStab(mountPoint)
				fstab.File = where
				op := mountOperation{
					MountOption: mountPoint,
					FstabEntry:  *fstab,
					Target:      where,
				}

				err := op.run()
				if err != nil {
					continue
				}

				s.fstabs = append(s.fstabs, fstab)

				return nil
			case <-c.Done():
				return fmt.Errorf("context canceled")
			case <-time.After(timeout):
				return fmt.Errorf("timeout exhausted")
			}
		}
	}
}