package config

import "fmt"

type MangleAction string

const (
	MangleMark     MangleAction = "mark"
	MangleConnMark MangleAction = "connmark"
	MangleClassify MangleAction = "classify"
	MangleDSCP     MangleAction = "dscp"
	MangleTOS      MangleAction = "tos"
	MangleTProxy   MangleAction = "tproxy"
	MangleSave     MangleAction = "save"
	MangleRestore  MangleAction = "restore"
	MangleContinue MangleAction = "continue"
	MangleDrop     MangleAction = "drop"
	MangleLog      MangleAction = "log"
	MangleNFLog    MangleAction = "nflog"
	MangleECN      MangleAction = "ecn"
	MangleTCPMSS   MangleAction = "tcpmss"
	MangleChecksum MangleAction = "checksum"
	MangleInline   MangleAction = "inline"
)

type MangleChain string

const (
	ManglePrerouting  MangleChain = "prerouting"
	MangleForward     MangleChain = "forward"
	ManglePostrouting MangleChain = "postrouting"
	MangleInput       MangleChain = "input"
	MangleOutput      MangleChain = "output"
)

type MangleRule struct {
	Action MangleAction `yaml:"action"`
	Chain  MangleChain  `yaml:"chain"`

	// MarkValue is the value to set (required for mark, connmark, classify, dscp, tos actions).
	MarkValue string `yaml:"mark_value,omitempty"`

	Source string `yaml:"source,omitempty"`
	Dest   string `yaml:"dest,omitempty"`

	Proto string   `yaml:"proto,omitempty"`
	DPort PortSpec `yaml:"dport,omitempty"`
	SPort PortSpec `yaml:"sport,omitempty"`

	// User/group match (only valid for output chain).
	User string `yaml:"user,omitempty"`

	// Packet or connection mark test. Format: [!]value[/mask][:C]
	Mark string `yaml:"mark,omitempty"`

	// Packet length match.
	Length string `yaml:"length,omitempty"`

	// TOS field match.
	TOS string `yaml:"tos,omitempty"`

	// Conntrack helper match.
	Helper string `yaml:"helper,omitempty"`

	// Match probability (0.0 to 1.0).
	Probability float64 `yaml:"probability,omitempty"`

	// DSCP field match.
	DSCP string `yaml:"dscp,omitempty"`

	// Connection state match.
	State string `yaml:"state,omitempty"`

	// Time-based restrictions.
	Time *TimeSpec `yaml:"time,omitempty"`

	Comment string `yaml:"comment,omitempty"`
}

var validMangleActions = map[MangleAction]bool{
	MangleMark: true, MangleConnMark: true, MangleClassify: true,
	MangleDSCP: true, MangleTOS: true, MangleTProxy: true,
	MangleSave: true, MangleRestore: true, MangleContinue: true,
	MangleDrop: true, MangleLog: true, MangleNFLog: true,
	MangleECN: true, MangleTCPMSS: true, MangleChecksum: true,
	MangleInline: true,
}

var validMangleChains = map[MangleChain]bool{
	ManglePrerouting: true, MangleForward: true,
	ManglePostrouting: true, MangleInput: true,
	MangleOutput: true,
}

// markValueRequiredActions lists actions that require a mark_value.
var markValueRequiredActions = map[MangleAction]bool{
	MangleMark: true, MangleConnMark: true, MangleClassify: true,
	MangleDSCP: true, MangleTOS: true,
}

func (c *Config) validateMangle() error {
	for i, m := range c.Mangle {
		if !validMangleActions[m.Action] {
			return fmt.Errorf("mangle[%d]: unknown action %q", i, m.Action)
		}
		if !validMangleChains[m.Chain] {
			return fmt.Errorf("mangle[%d]: unknown chain %q", i, m.Chain)
		}

		if markValueRequiredActions[m.Action] && m.MarkValue == "" {
			return fmt.Errorf("mangle[%d]: mark_value required for %s action", i, m.Action)
		}
	}
	return nil
}