/*
Package config is used manage initialize and house the main program data
structures, as well as marshalling the configuration to and from toml.

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 config

import (
	"context"
	"fmt"
	"net"
	"os"
	"sort"

	"gitea.elkins.co/Networking/ccl/internal/pkg/container"
	"gitea.elkins.co/Networking/ccl/internal/pkg/network"
	"github.com/emirpasic/gods/sets/hashset"
	toml "github.com/pelletier/go-toml"
	log "github.com/sirupsen/logrus"
	"golang.org/x/exp/slices"
	"gopkg.in/guregu/null.v4"
)

const (
	ConfigFileDefault = "/etc/ccl.toml" // ConfigFileDefault is default configuration file path
)

type GlobalOptions struct {
	DNSServer  string `toml:"dns_server,omitempty"`
	TSIGName   string `toml:"tsig_name,omitempty"`
	TSIGKey    string `toml:"tsig_key,omitempty"`
	DomainName string `toml:"domain_name,omitempty"`
}

var (
	ConfigFile = ConfigFileDefault        // ConfigFile is the path to the configuration file to use in a particular invocation.
	Networks   = []*network.Network{}     // Networks is the program-global set of congiured network.Networks structures
	Containers = []*container.Container{} // Containers is the program-global set of configured container.Container structures.
	Options    = new(GlobalOptions)       // Options contains global options, mostly pertaining to dns updates now
)

// Categories returns a slice of all of the distinct categories found in the
// configured containers.
func Categories() []string {
	categories := []string{"all"}
	gs := hashset.New()
	for _, c := range Containers {
		gs.Add(c.Category)
	}
	for _, c := range gs.Values() {
		categories = append(categories, c.(string))
	}
	slices.Sort(categories)
	return categories
}

// Union - given a list of identifiers ("all", a category, or a container
// name), as well as a category mask, will yieLd a list of configured
// containers that match the identifiers but not the mask. As envisioned, the
// default mask would be ".", i.e., the tool would normally exclude containers
// "disabled" by setting their category to a string with a leading period (e.g.
// ".hidden")
func Union(ids []string, catMask []string) (conts []*container.Container) {
	if len(ids) == 0 {
		ids = []string{"all"}
	}
	h := hashset.New()
	for _, id := range ids {
		if j := slices.Index(catMask, id); j >= 0 {
			catMask = slices.Delete(catMask, j, j+1)
		}
		for _, c := range Containers {
			if (id == "all" || (id == "running" && c.IsRunning()) || c.Category == id) && !slices.Contains(catMask, c.Category) {
				h.Add(c.Name)
			}
			if c.Name == id {
				h.Add(c.Name)
			}
		}
	}
	for _, c := range h.Values() {
		name := c.(string)
		match := slices.IndexFunc(Containers, func(c *container.Container) bool { return c.Name == name })
		conts = append(conts, Containers[match])
	}
	if len(conts) == 0 {
		log.WithFields(log.Fields{
			"ids":     ids,
			"catMask": catMask,
		}).Warnln("No matching containers. If disabled, try adding -a")
	}
	slices.SortFunc(conts, func(a, b *container.Container) int {
		if a.Category < b.Category {
			return -1
		}
		if a.Category > b.Category {
			return 1
		}
		if a.Name == b.Name {
			return 0
		}
		if a.Name < b.Name {
			return -1
		}
		return 1
	})
	return
}

// UnionNetworks is like Union but for Networks, and also no mask.
func UnionNetworks(ids []string) []*network.Network {
	nets := make([]*network.Network, len(Networks))
	rejects := []int{}
	copy(nets, Networks)
	for i := range nets {
		if !slices.Contains(ids, nets[i].Name) {
			rejects = append(rejects, i)
		}
	}
	// reverse the rejects list, so we can delete from the end backward
	// and thereby not fuck up sequential indicies
	sort.SliceStable(rejects, func(i, j int) bool {
		return true
	})
	for _, j := range rejects {
		nets = slices.Delete(nets, j, j+1)
	}
	return nets
}

// Init will parse the configuration file, create and populate the in-memory
// data structures. Will call container.Init() on each container created in
// this way.
func Init(conn context.Context) error {
	// A parsing convenience
	type parse struct {
		Networks   []*network.Network     `toml:"networks"`
		Containers []*container.Container `toml:"containers"`
		Options    *GlobalOptions         `toml:"options"`
	}

	f, err := os.ReadFile(ConfigFile)
	if err != nil {
		return err
	}
	p := parse{}
	err = toml.Unmarshal(f, &p)
	if err != nil {
		return err
	}
	Containers, Networks, Options = p.Containers, p.Networks, p.Options
	var dom, dns, tsn, tsk string
	if Options != nil {
		dom = Options.DomainName
		dns = Options.DNSServer
		tsn = Options.TSIGName
		tsk = Options.TSIGKey
	}
	for i := range Containers {
		Containers[i].Init(conn, Networks, dom, dns, tsn, tsk)
	}
	slices.SortFunc(Containers, func(a, b *container.Container) int {
		if a.Name < b.Name {
			return -1
		}
		if a.Name > b.Name {
			return 1
		}
		return 0
	})
	return nil
}

// Show will output a toml configuration of the provided identifiers ("all",
// category, or container name). The resulting string would presumably be sent
// to the terminal or a file.
//
// Other than ordering of fields and possible inclusion of some fields with
// their default values, the generated toml should be completely compatible
// with the actual configuration. Dogfood safe.
func Show(ids []string, contMask []string) string {
	type parse struct {
		Containers []*container.Container `toml:"containers,omitempty"`
		Networks   []*network.Network     `toml:"networks,omitempty"`
	}

	getNet := func(name string) *network.Network {
		for i := range Networks {
			if Networks[i].Name == name {
				return Networks[i]
			}
		}
		return nil
	}

	ipSliceEq := func(a, b []net.IP) bool {
		if len(a) != len(b) {
			return false
		}
		for i := range a {
			if a[i].Equal(b[i]) {
				return false
			}
		}
		return true
	}

	conts := Union(ids, contMask)
	// clear out values equal to the defined networks
	for c := range conts {
		for n := range conts[c].Networks {
			d := getNet(conts[c].Networks[n].Name)
			if d == nil {
				conts[c].LogEntry().WithField("network", conts[c].Networks[n].Name).Warnln("Network defaults not defined")
				continue
			}
			if conts[c].Networks[n].IPv6 == d.IPv6 {
				conts[c].Networks[n].IPv6 = null.Bool{}
			}
			if ipSliceEq(conts[c].Networks[n].DNS, d.DNS) {
				conts[c].Networks[n].DNS = nil
			}
		}
	}
	usednets := hashset.New()
	for _, c := range conts {
		for _, n := range c.Networks {
			usednets.Add(n.Name)
		}
	}
	for _, un := range usednets.Values() {
		ids = append(ids, un.(string))
	}
	nets := UnionNetworks(ids)

	output, err := toml.Marshal(parse{conts, nets})
	if err != nil {
		fmt.Println("could not marshal containers:", err)
		os.Exit(1)
	}
	return string(output)
}