/*
Copyright © 2022 Joel D. Elkins <joel@elkins.co>

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the Software is
furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
THE SOFTWARE.
*/

package container

import (
	"context"
	"fmt"
	"net"
	"os/exec"

	cmd "gitea.elkins.co/Networking/ccl/internal/pkg/command"
	"gitea.elkins.co/Networking/ccl/internal/pkg/network"
	"github.com/containers/common/libnetwork/types"
	"github.com/containers/podman/v4/libpod/define"
	"github.com/containers/podman/v4/pkg/bindings/containers"
	"github.com/containers/podman/v4/pkg/bindings/images"
	"github.com/containers/podman/v4/pkg/specgen"
	spec "github.com/opencontainers/runtime-spec/specs-go"
	log "github.com/sirupsen/logrus"
	"gopkg.in/guregu/null.v4"
)

type Container struct {
	Category   string            `toml:"category"`
	Name       string            `toml:"name"`
	Image      string            `toml:"image"`
	Hostname   string            `toml:"hostname,omitempty"`
	Command    []string          `toml:"cmd,omitempty"`
	Arguments  string            `toml:"arguments,omitempty"`
	Networks   []network.Network `toml:"networks,omitempty"`
	Env        map[string]string `toml:"env,omitempty"`
	Mounts     []spec.Mount      `toml:"mounts,omitempty"`
	Restart    string            `toml:"restart,omitempty"`
	Umask      null.Int          `toml:"umask,omitempty"`
	User       string            `toml:"user,omitempty"`
	ExposeTcp  []uint16          `toml:"expose_tcp,omitempty"`
	ExposeUdp  []uint16          `toml:"expose_udp,omitempty"`
	PortsTcp   map[uint16]uint16 `toml:"ports,omitempty"`
	NetNS      string            `toml:"netns,omitempty"`
	StartGroup int               `toml:"group,omitempty"`

	conn       context.Context
	cdata      *define.InspectContainerData
	wasRunning null.Bool
}

func (c *Container) Init(conn context.Context, nets []network.Network) error {
	// initialize user-provided definitions
	for i := range c.Networks {
		var n *network.Network
		for j := range nets {
			if nets[j].Name == c.Networks[i].Name {
				n = &nets[j]
			}
		}
		if n == nil {
			continue
		}
		if len(c.Networks[i].DNS) == 0 {
			c.Networks[i].DNS = n.DNS
		}
		if !c.Networks[i].IPv6.Valid {
			if n.IPv6.Valid {
				c.Networks[i].IPv6 = n.IPv6
			} else {
				c.Networks[i].IPv6.SetValid(true)
			}
		}
	}
	for i := range c.Mounts {
		if c.Mounts[i].Type == "" {
			c.Mounts[i].Type = "bind"
		}
	}

	if !c.Umask.Valid {
		c.Umask.SetValid(0o022)
	}

	if c.NetNS == "" {
		c.NetNS = string(specgen.Bridge)
	}

	if conn == nil {
		return fmt.Errorf("conn is nil: %s", c.Name)
	}
	c.conn = conn
	err := c.populateCData()
	c.wasRunning.SetValid(c.IsRunning())
	return err
}

func (c *Container) LogEntry() *log.Entry {
	f := log.Fields{
		"container": c.Name,
	}
	if c.cdata != nil && c.cdata.ID != "" {
		f["id"] = c.cdata.ID[:12] + "…"
	}
	if c.cdata.State != nil {
		f["state"] = c.cdata.State.Status
	}
	return log.WithFields(f)
}

func (c *Container) pull() error {
	_, err := images.Pull(c.conn, c.Image, &images.PullOptions{})
	return err
}

func (c *Container) newCommandSet(op string, cmds cmd.Commands) cmd.CommandSet {
	return cmd.CommandSet{
		ID:       fmt.Sprintf("%s-%s", op, c.Name),
		Commands: cmds,
	}
}

func (c *Container) PullCommands() cmd.CommandSet {
	return c.newCommandSet("PULL", cmd.Commands{
		cmd.NewFunc("do_pull", func() error {
			return c.pull()
		}),
	})
}

func (c *Container) CreateCommands() cmd.CommandSet {
	if c.Image == "" {
		return c.newCommandSet("CREATE", cmd.Commands{
			cmd.NewFunc("image_error", func() error {
				return fmt.Errorf("Image not configured")
			}),
		})
	}
	sysctl := map[string]string{}
	nets := map[string]types.PerNetworkOptions{}
	dns := []net.IP{}
	for i := range c.Networks {
		if !c.Networks[i].IPv6.Bool {
			sysctl["net.ipv6.conf."+c.Networks[i].Name+".accept_ra"] = "0"
		}
		ips := []net.IP{}
		if c.Networks[i].IPv4Address != nil {
			ips = append(ips, c.Networks[i].IPv4Address)
		}
		if c.Networks[i].IPv6Address != nil {
			ips = append(ips, c.Networks[i].IPv6Address)
		}
		nets[c.Networks[i].Name] = types.PerNetworkOptions{
			StaticIPs:     ips,
			InterfaceName: c.Networks[i].Name,
		}
		dns = append(dns, c.Networks[i].DNS...)
	}

	expose := map[uint16]string{}
	for _, p := range c.ExposeTcp {
		expose[p] = "tcp"
	}
	for _, p := range c.ExposeUdp {
		expose[p] = "udp"
	}

	portMappings := []types.PortMapping{}
	for ph, pc := range c.PortsTcp {
		portMappings = append(portMappings, types.PortMapping{
			HostPort:      ph,
			ContainerPort: pc,
			Protocol:      "tcp",
		})
	}

	spec := specgen.SpecGenerator{
		ContainerBasicConfig: specgen.ContainerBasicConfig{
			Name:          c.Name,
			UtsNS:         specgen.Namespace{NSMode: specgen.Private},
			Hostname:      c.Hostname,
			RawImageName:  c.Image,
			RestartPolicy: c.Restart,
			Sysctl:        sysctl,
			Env:           c.Env,
			Command:       c.Command,
		},
		ContainerStorageConfig: specgen.ContainerStorageConfig{
			Image:  c.Image,
			Mounts: c.Mounts,
		},
		ContainerNetworkConfig: specgen.ContainerNetworkConfig{
			Networks:            nets,
			DNSServers:          dns,
			Expose:              expose,
			PortMappings:        portMappings,
			PublishExposedPorts: len(expose) > 0,
			NetNS:               specgen.Namespace{NSMode: specgen.NamespaceMode(c.NetNS)},
		},
		ContainerSecurityConfig: specgen.ContainerSecurityConfig{
			User:  c.User,
			Umask: fmt.Sprintf("%#o", c.Umask.Int64),
		},
	}

	return c.newCommandSet("CREATE", cmd.Commands{
		cmd.NewFunc("bail_if_exists", func() error {
			if ex, err := containers.Exists(c.conn, c.Name, &containers.ExistsOptions{}); err != nil || ex {
				if err != nil {
					return err
				}
				return fmt.Errorf("Container %s exists already", c.Name)
			}
			return nil
		}),
		cmd.NewFunc("pull_if_necessary", func() error {
			if ex, err := images.Exists(c.conn, c.Image, &images.ExistsOptions{}); err != nil || !ex {
				if err != nil {
					return err
				}
				return c.pull()
			}
			return nil
		}),
		cmd.NewFunc("validate_spec", spec.Validate),
		cmd.NewFunc("do_create", func() error {
			_, err := containers.CreateWithSpec(c.conn, &spec, nil)
			if err != nil {
				return err
			}
			return c.populateCData()
		}),
	})
}

func (c *Container) RecreateCommands() cmd.CommandSet {
	return c.newCommandSet("RECREATE", cmd.Commands{
		cmd.NewSet(c.RemoveCommands()),
		cmd.NewSet(c.CreateCommands()),
	})
}

// unexported version just removes the container without attempting a stop.
func (c *Container) RemoveCommands() cmd.CommandSet {
	return c.newCommandSet("remove", cmd.Commands{
		cmd.NewFunc("remove_if_exists", func() error {
			if c.cdata.ID == "" {
				return nil
			}
			yes := true
			_, err := containers.Remove(c.conn, c.cdata.ID, &containers.RemoveOptions{Force: &yes})
			return err
		}),
	})
}

func (c *Container) StartCommands() cmd.CommandSet {
	return c.newCommandSet("START", cmd.Commands{
		cmd.NewFunc("start_container", func() error {
			if c.IsRunning() {
				c.LogEntry().Debugln("Container start was commanded but it is already running. Not a problem.")
				return nil
			}
			err := containers.Start(c.conn, c.cdata.ID, nil)
			if err != nil {
				return err
			}
			_, err = containers.Wait(
				c.conn,
				c.cdata.ID,
				&containers.WaitOptions{Condition: []define.ContainerStatus{define.ContainerStateRunning}},
			)
			if err != nil {
				return err
			}
			err = c.populateCData()
			if err != nil {
				return err
			}
			if c.cdata.HostConfig != nil && c.cdata.HostConfig.NetworkMode == "bridge" {
				err = c.assureNetNS()
				if err != nil {
					c.LogEntry().WithField("error", err).Warnln("Failed to create network namespace")
				}
			}
			return nil
		}),
	})
}

func (c *Container) IsRunning() bool {
	if c.cdata != nil && c.cdata.State != nil {
		return c.cdata.State.Running
	}
	return false
}

func (c *Container) IsCreated() bool {
	if c.cdata == nil || c.cdata.ID == "" {
		return false
	}
	return true
}

func (c *Container) UpdateCommands() cmd.CommandSet {
	return c.newCommandSet("UPDATE", cmd.Commands{
		cmd.NewSet(c.PullCommands()),
		cmd.NewSet(c.StopCommands()),
		cmd.NewSet(c.RemoveCommands()),
		cmd.NewSet(c.CreateCommands()),
	})
}

func (c *Container) ConditionalStartCommands() cmd.CommandSet {
	return c.newCommandSet("CONDSTART", cmd.Commands{
		cmd.NewConditional("restart_if_was_running",
			c.wasRunning.ValueOrZero,
			cmd.NewSet(c.StartCommands()),
			cmd.NewNop(),
		),
	})
}

func (c *Container) StopCommands() cmd.CommandSet {
	return c.newCommandSet("STOP", cmd.Commands{
		cmd.NewFunc("stop_if_running", func() error {
			if !c.IsRunning() {
				c.LogEntry().Debugln("Container stop was commanded but it wasn't running. Not a problem.")
				return nil
			}
			var timeout uint = 10
			err := containers.Stop(c.conn, c.cdata.ID, &containers.StopOptions{Timeout: &timeout})
			if err != nil {
				return err
			}
			_, err = containers.Wait(
				c.conn,
				c.cdata.ID,
				&containers.WaitOptions{Condition: []define.ContainerStatus{define.ContainerStateExited}},
			)
			if err != nil {
				return err
			}
			return c.populateCData()
		}),
	})
}

func (c *Container) populateCData() error {
	// TODO: locking?
	var err error
	no := false
	c.cdata, err = containers.Inspect(c.conn, c.Name, &containers.InspectOptions{Size: &no})
	if err != nil {
		return err
	}
	return nil
}

func (c *Container) Pid() int {
	if c.cdata != nil && c.cdata.State != nil {
		return c.cdata.State.Pid
	}
	return 0
}

func (c *Container) assureNetNS() error {
	if nil == c.cdata || nil == c.cdata.NetworkSettings {
		return fmt.Errorf("Network namespace not available!")
	}
	netns := c.cdata.NetworkSettings.SandboxKey
	if err := exec.Command("rm", "-f", "/var/run/netns/"+c.Name).Run(); err != nil {
		return err
	}
	if err := exec.Command("ln", "-sf", netns, "/var/run/netns/"+c.Name).Run(); err != nil {
		return err
	}
	return nil
}