/*
Package container encapuslates both the metadata structure and main
operations to be presented to the user in the `cmd` module.

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"
	"regexp"

	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"
	"github.com/opencontainers/runtime-spec/specs-go"
	log "github.com/sirupsen/logrus"
	"gopkg.in/guregu/null.v4"
)

// Container houses the metadata that may be specified by this utility when
// creating a container. A couple of fields (Name and Image) are mandatory to
// specify, but the rest will use the libpod or otherwise sensible defaults.
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     []specs.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"`
	Devices    []string          `toml:"devices,omitempty"`
	CapAdd     []string          `toml:"cap_add,omitempty"`
	Privileged null.Bool         `toml:"privileged,omitempty"`
	Sysctl     map[string]string `toml:"sysctl,omitempty"`

	conn       context.Context
	getCData   func() *define.InspectContainerData
	invalCData func()
	wasRunning bool
}

// Init will initialize a new container structure by filling in network details
// and by querying other metadata from libpod, if possible.
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

	c.watchCData()
	c.wasRunning = c.IsRunning()
	return nil
}

// LogEntry will return a *logrus.LogEntry, with some basic fields populated
// for this container. The idea is that the calling code would add other fields
// (optionally) and do something with the error.
func (c *Container) LogEntry() *log.Entry {
	f := log.Fields{
		"container":  c.Name,
		"wasRunning": c.wasRunning,
	}
	cdata := c.getCData()
	if cdata != nil && cdata.ID != "" {
		f["id"] = cdata.ID[:12] + "…"
	}
	if cdata != nil && cdata.State != nil {
		f["state"] = 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.Set {
	return cmd.Set{
		ID:       fmt.Sprintf("%s-%s", op, c.Name),
		Commands: cmds,
	}
}

// PullCommands will return a cmd.Set to pull the specified image using the
// libpod API
func (c *Container) PullCommands() cmd.Set {
	return c.newCommandSet("PULL", cmd.Commands{
		cmd.NewFunc("do_pull", func() error {
			c.invalCData()
			return c.pull()
		}),
	})
}

// CreateCommands returns a cmd.Set that will create a container from the
// configured metadata. The container should not exist.
func (c *Container) CreateCommands() cmd.Set {
	if c.Image == "" {
		return c.newCommandSet("CREATE", cmd.Commands{
			cmd.NewFunc("image_error", func() error {
				return fmt.Errorf("image not configured")
			}),
		})
	}
	nets := map[string]types.PerNetworkOptions{}
	dns := []net.IP{}
	for i := range c.Networks {
		if c.Networks[i].IPv6.Valid && !c.Networks[i].IPv6.Bool {
			if c.Sysctl == nil {
				c.Sysctl = make(map[string]string, 1)
			}
			c.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)
		}
		if c.Networks[i].IPv4Addresses != nil {
			ips = append(ips, c.Networks[i].IPv4Addresses...)
		}
		if c.Networks[i].IPv6Addresses != nil {
			ips = append(ips, c.Networks[i].IPv6Addresses...)
		}
		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",
		})
	}

	devs := make([]specs.LinuxDevice, len(c.Devices))
	for i, d := range c.Devices {
		devs[i] = specs.LinuxDevice{Path: d}
	}

	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:        c.Sysctl,
			Env:           c.Env,
			Command:       c.Command,
		},
		ContainerStorageConfig: specgen.ContainerStorageConfig{
			Image:           c.Image,
			Mounts:          c.Mounts,
			Devices:         devs,
			ImageVolumeMode: "tmpfs",
		},
		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),
			CapAdd:     c.CapAdd,
			Privileged: c.Privileged.ValueOrZero(),
		},
	}

	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
				}
				c.invalCData()
				return c.pull()
			}
			return nil
		}),
		cmd.NewFunc("validate_spec", spec.Validate),
		cmd.NewFunc("do_create", func() error {
			if _, err := containers.CreateWithSpec(c.conn, &spec, nil); err != nil {
				return err
			}
			c.invalCData()
			return nil
		}),
	})
}

// RecreateCommands will stop (if running), remove (if exists), (re)create, and restart (if
// it was initially running) a container. The image is not pulled.
func (c *Container) RecreateCommands() cmd.Set {
	return c.newCommandSet("RECREATE", cmd.Commands{
		cmd.NewSet(c.RemoveCommands()),
		cmd.NewSet(c.CreateCommands()),
	})
}

// RemoveCommands removes a container (as if by `podman rm -f`)
func (c *Container) RemoveCommands() cmd.Set {
	return c.newCommandSet("REMOVE", cmd.Commands{
		cmd.NewFunc("remove_if_exists", func() error {
			cdata := c.getCData()
			if cdata == nil || cdata.ID == "" {
				return nil
			}
			yes := true
			_, err := containers.Remove(c.conn, cdata.ID, &containers.RemoveOptions{Force: &yes})
			c.invalCData()
			return err
		}),
	})
}

// StartCommands will start a container if it's not already running.
func (c *Container) StartCommands() cmd.Set {
	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
			}
			cdata := c.getCData()
			if cdata == nil {
				return fmt.Errorf("container %s is not created; cannot start it", c.Name)
			}
			err := containers.Start(c.conn, cdata.ID, nil)
			if err != nil {
				return err
			}
			_, err = containers.Wait(
				c.conn,
				cdata.ID,
				&containers.WaitOptions{Condition: []define.ContainerStatus{define.ContainerStateRunning}},
			)
			if err != nil {
				return err
			}
			c.invalCData()
			cdata = c.getCData()
			if cdata != nil && cdata.HostConfig != nil && cdata.HostConfig.NetworkMode == "bridge" {
				err = c.assureNetNS()
				if err != nil {
					c.LogEntry().WithField("error", err).Warnln("Failed to create network namespace")
				}
			}
			return nil
		}),
	})
}

// IsRunning returns true if libpod reports the container status is running, or
// false otherwise. If an error happens (e.g. the container is not created),
// the default value is false.
func (c *Container) IsRunning() bool {
	cdata := c.getCData()
	if cdata != nil && cdata.State != nil {
		return cdata.State.Running
	}
	return false
}

// IsCreated tests whether libpod sees the container as being created (running or not)
func (c *Container) IsCreated() bool {
	cdata := c.getCData()
	if cdata == nil || cdata.ID == "" {
		return false
	}
	return true
}

// UpdateCommands will pull the image (to force updates) and then recreate the
// container. It will be stopped first.
func (c *Container) UpdateCommands() cmd.Set {
	var startImg string
	return c.newCommandSet("UPDATE", cmd.Commands{
		cmd.NewFunc("get_starting_image", func() error {
			cdata := c.getCData()
			if cdata != nil {
				startImg = cdata.Image
			}
			return nil
		}),
		cmd.NewSet(c.PullCommands()),
		cmd.NewConditional("rebuild_if_updated",
			func() bool {
				tagged, _ := regexp.MatchString(":[-_a-zA-Z0-9]+$", c.Image)
				cImage := c.Image
				if !tagged {
					cImage += ":latest"
				}
				opts := images.ListOptions{
					Filters: map[string][]string{
						"reference": {cImage},
					},
				}
				imgs, err := images.List(c.conn, &opts)
				if len(imgs) < 1 || err != nil {
					return false
				}
				if startImg != imgs[0].Id() {
					return true
				}
				return false
			},
			cmd.NewSet(c.newCommandSet("REBUILD", cmd.Commands{
				cmd.NewSet(c.StopCommands()),
				cmd.NewSet(c.RemoveCommands()),
				cmd.NewSet(c.CreateCommands()),
			})),
			cmd.NewNop(),
		),
	})
}

// ConditionalStartCommands - several of the other command sets would leave the
// container in the stopped state. This set will restart a container if it was
// running when this container was first initialized.
func (c *Container) ConditionalStartCommands() cmd.Set {
	if c.wasRunning {
		return c.StartCommands()
	}
	return cmd.Set{}
}

// StopCommands will stop a container if it is running, defining a 10 second
// timeout before the processes are killed by lippod
func (c *Container) StopCommands() cmd.Set {
	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
			}
			cdata := c.getCData()
			var timeout uint = 10
			err := containers.Stop(c.conn, cdata.ID, &containers.StopOptions{Timeout: &timeout})
			if err != nil {
				return err
			}
			_, err = containers.Wait(
				c.conn,
				cdata.ID,
				&containers.WaitOptions{Condition: []define.ContainerStatus{define.ContainerStateExited}},
			)
			if err != nil {
				return err
			}
			c.invalCData()
			return nil
		}),
	})
}

func (c *Container) watchCData() {
	cdataChan := make(chan chan *define.InspectContainerData)
	cdataInval := make(chan bool)

	go func() {
		var cache *define.InspectContainerData
		for {
			select {
			case dchan := <-cdataChan:
				if cache == nil {
					no := false
					cache, _ = containers.Inspect(c.conn, c.Name, &containers.InspectOptions{Size: &no})
				}
				dchan <- cache
			case <-cdataInval:
				cache = nil
			}
		}
	}()

	c.getCData = func() *define.InspectContainerData {
		cc := make(chan *define.InspectContainerData)
		cdataChan <- cc
		return <-cc
	}
	c.invalCData = func() {
		cdataInval <- true
	}
}

// Pid will return the host process id of the main container process (pid
// 1 inside the container)
func (c *Container) Pid() int {
	cdata := c.getCData()
	if cdata != nil && cdata.State != nil {
		return cdata.State.Pid
	}
	return 0
}

func (c *Container) assureNetNS() error {
	cdata := c.getCData()
	if nil == cdata || nil == cdata.NetworkSettings {
		return fmt.Errorf("network namespace not available")
	}
	netns := 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
}