/*
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 (
	"fmt"
	"os"
	"os/exec"
	"strconv"
	"strings"

	"gitea.elkins.co/Networking/ccl/internal/pkg/command"
	"gitea.elkins.co/Networking/ccl/internal/pkg/network"
)

type Container struct {
	Category       string
	Name           string
	Image          string
	Hostname       string
	Command        string
	Arguments      string
	Networks       []network.Network
	createCommands []command.Command
	upCommands     []command.Command
	pid            int
}

func (c *Container) flushIPv6Commands() []command.Command {
	cmds := []command.Command{}
	flush6Routes := false
	if len(c.Networks) > 0 && !*c.Networks[0].IPv6 {
		cmds = append(cmds, command.NewShell(fmt.Sprintf("ip netns exec %s sysctl -w net.ipv6.conf.default.accept_ra=0", c.Name)))
		cmds = append(cmds, command.NewShell(fmt.Sprintf("ip netns exec %s sysctl -w net.ipv6.conf.all.accept_ra=0", c.Name)))
		flush6Routes = true
	}
	for i, n := range c.Networks {
		// Note, n.IPv6 should never be nil, since we forcibly create the
		// value in Init() if not specified in the config file
		if !*n.IPv6 {
			cmds = append(cmds, command.NewShell(fmt.Sprintf("ip netns exec %s sysctl -w net.ipv6.conf.eth%d.accept_ra=0", c.Name, i)))
			cmds = append(cmds, command.NewShell(fmt.Sprintf("ip netns exec %s ip -6 address flush dev eth%d scope global", c.Name, i)))
			flush6Routes = true
		}
	}
	if flush6Routes {
		cmds = append(cmds, command.NewShell(fmt.Sprintf("ip netns exec %s ip -6 route flush proto ra", c.Name)))
	}
	return cmds
}

func (c *Container) CreateCommands() []command.Command {
	if len(c.createCommands) == 0 {
		c.initCommands()
	}
	return c.createCommands
}

func (c *Container) RecreateCommands() []command.Command {
	wasRunning := false
	return []command.Command{
		command.NewFunc("stash_run_state", func() string {
			wasRunning = c.isRunning()
			runMsg := "not running. Will not start it after recreating."
			if wasRunning {
				runMsg = "running. Will restart after recreating."
			}
			return fmt.Sprintf("Container %s is %s.", c.Name, runMsg)
		}),
		command.NewSet(c.DestroyCommands()),
		command.NewSet(c.CreateCommands()),
		command.NewConditional("start_if_was_running",
			func() bool { return wasRunning },
			command.NewSet(c.StartCommands()),
			command.NewNop(),
		),
	}
}

func (c *Container) DestroyCommands() []command.Command {
	cmds := c.StopCommands()
	cmds = append(cmds, command.NewShell("podman rm "+c.Name))
	return cmds
}

func (c *Container) StartCommands() []command.Command {
	if len(c.upCommands) == 0 {
		c.initCommands()
	}
	return []command.Command{
		command.NewConditional("start_unless_running",
			c.isRunning,
			command.NewNop(),
			command.NewSet(c.upCommands),
		),
	}
}

func (c *Container) RestartCommands() []command.Command {
	return []command.Command{
		command.NewSet(c.StopCommands()),
		command.NewShell("sleep 1"),
		command.NewSet(c.StartCommands()),
	}
}

func (c *Container) isRunning() bool {
	pid, err := c.Pid()
	if err != nil {
		return false
	}
	return pid > 1
}

func (c *Container) UpdateCommands() []command.Command {
	wasRunning := false
	return []command.Command{
		command.NewFunc("stash_run_state", func() string {
			wasRunning = c.isRunning()
			runMsg := "not running"
			if wasRunning {
				runMsg = "running"
			}
			return "Container " + c.Name + " is " + runMsg
		}),
		command.NewShell("podman pull " + c.Image),
		command.NewSet(c.RecreateCommands()),
		command.NewConditional("restart_if_was_running",
			func() bool { return wasRunning },
			command.NewSet(c.StartCommands()),
			command.NewNop(),
		),
	}
}

func (c *Container) StopCommands() []command.Command {
	return []command.Command{
		command.NewConditional("stop_if_running",
			c.isRunning,
			command.NewShell("podman stop "+c.Name),
			command.NewNop(),
		),
	}
}

func (c *Container) Init(nets *[]network.Network) {
	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 == nil {
			if n.IPv6 != nil {
				c.Networks[i].IPv6 = n.IPv6
			} else {
				yes := true
				c.Networks[i].IPv6 = &yes
			}
		}
	}
}

func (c *Container) Pid() (pid int, err error) {
	pid_s, err := exec.Command("podman", "inspect", "-f", "{{.State.Pid}}", c.Name).CombinedOutput()
	if err != nil {
		return
	}
	c.pid, err = strconv.Atoi(strings.TrimSuffix(string(pid_s), "\n"))
	return c.pid, err
}

func (c *Container) initCommands() {
	c.createCommands = []command.Command{
		command.NewShell("podman create --name %s%s%s%s%s %s%s"),
	}
	hostname := ""
	if c.Hostname != "" {
		hostname = fmt.Sprintf(" --hostname %s", c.Hostname)
	}
	net := ""
	dns := ""
	if len(c.Networks) > 0 {
		net = " --net " + c.Networks[0].ToArgs()
		if len(c.Networks[0].DNS) > 0 {
			dns = " --dns " + strings.Join(c.Networks[0].DNS, ",")
		}
	}
	args := ""
	if c.Arguments != "" {
		args = " " + c.Arguments
	}
	entry := ""
	if c.Command != "" {
		entry = " " + c.Command
	}
	t, _ := c.createCommands[0].GetShell()
	c.createCommands[0] = command.NewShell(fmt.Sprintf(t, c.Name, hostname, net, dns, args, c.Image, entry))

	if len(c.Networks) > 1 {
		for i := 1; i < len(c.Networks); i++ {
			n := c.Networks[i]
			s := fmt.Sprintf("podman network connect %s %s", n.ToArgs(), c.Name)
			c.createCommands = append(c.createCommands, command.NewShell(s))
		}
	}

	c.upCommands = []command.Command{
		command.NewShell("podman start " + c.Name),
		command.NewFunc("assure_netns", func() string {
			netns_b, err := exec.Command("podman", "inspect", "-f", "{{.NetworkSettings.SandboxKey}}", c.Name).CombinedOutput()
			if err != nil {
				return fmt.Sprintf("%s is not running\n", c.Name)
			}
			netns := strings.TrimRight(string(netns_b), "\n")
			err = exec.Command("rm", "-f", "/var/run/netns/"+c.Name).Run()
			if err != nil {
				return fmt.Sprintln("Error:", err)
			}
			err = exec.Command("ln", "-sf", netns, "/var/run/netns/"+c.Name).Run()
			if err != nil {
				fmt.Fprintln(os.Stderr, "Warning: could not establish network namespace", err)
				return fmt.Sprintln("Error:", err)
			}
			return ""
		}),
	}
	if len(c.Networks) > 0 && !*c.Networks[0].IPv6 {
		c.upCommands = append(c.upCommands, command.NewShell("sleep 1"))
		for _, k := range c.flushIPv6Commands() {
			c.upCommands = append(c.upCommands, k)
		}
	}
}