package types

import (
	"fmt"
	"time"

	sdk "github.com/cosmos/cosmos-sdk/types"
	paramtypes "github.com/cosmos/cosmos-sdk/x/params/types"
)

// Default parameter namespace
const (
	DefaultSignedBlocksWindow   = int64(100)
	DefaultDowntimeJailDuration = 60 * 10 * time.Second
)

var (
	DefaultMinSignedPerWindow      = sdk.NewDecWithPrec(5, 1)
	DefaultSlashFractionDoubleSign = sdk.NewDec(1).Quo(sdk.NewDec(20))
	DefaultSlashFractionDowntime   = sdk.NewDec(1).Quo(sdk.NewDec(100))
)

// Parameter store keys
var (
	KeySignedBlocksWindow      = []byte("SignedBlocksWindow")
	KeyMinSignedPerWindow      = []byte("MinSignedPerWindow")
	KeyDowntimeJailDuration    = []byte("DowntimeJailDuration")
	KeySlashFractionDoubleSign = []byte("SlashFractionDoubleSign")
	KeySlashFractionDowntime   = []byte("SlashFractionDowntime")
)

// ParamKeyTable for slashing module
func ParamKeyTable() paramtypes.KeyTable {
	return paramtypes.NewKeyTable().RegisterParamSet(&Params{})
}

// NewParams creates a new Params object
func NewParams(
	signedBlocksWindow int64, minSignedPerWindow sdk.Dec, downtimeJailDuration time.Duration,
	slashFractionDoubleSign, slashFractionDowntime sdk.Dec,
) Params {

	return Params{
		SignedBlocksWindow:      signedBlocksWindow,
		MinSignedPerWindow:      minSignedPerWindow,
		DowntimeJailDuration:    downtimeJailDuration,
		SlashFractionDoubleSign: slashFractionDoubleSign,
		SlashFractionDowntime:   slashFractionDowntime,
	}
}

// ParamSetPairs - Implements params.ParamSet
func (p *Params) ParamSetPairs() paramtypes.ParamSetPairs {
	return paramtypes.ParamSetPairs{
		paramtypes.NewParamSetPair(KeySignedBlocksWindow, &p.SignedBlocksWindow, validateSignedBlocksWindow),
		paramtypes.NewParamSetPair(KeyMinSignedPerWindow, &p.MinSignedPerWindow, validateMinSignedPerWindow),
		paramtypes.NewParamSetPair(KeyDowntimeJailDuration, &p.DowntimeJailDuration, validateDowntimeJailDuration),
		paramtypes.NewParamSetPair(KeySlashFractionDoubleSign, &p.SlashFractionDoubleSign, validateSlashFractionDoubleSign),
		paramtypes.NewParamSetPair(KeySlashFractionDowntime, &p.SlashFractionDowntime, validateSlashFractionDowntime),
	}
}

// DefaultParams defines the parameters for this module
func DefaultParams() Params {
	return NewParams(
		DefaultSignedBlocksWindow, DefaultMinSignedPerWindow, DefaultDowntimeJailDuration,
		DefaultSlashFractionDoubleSign, DefaultSlashFractionDowntime,
	)
}

func validateSignedBlocksWindow(i interface{}) error {
	v, ok := i.(int64)
	if !ok {
		return fmt.Errorf("invalid parameter type: %T", i)
	}

	if v <= 0 {
		return fmt.Errorf("signed blocks window must be positive: %d", v)
	}

	return nil
}

func validateMinSignedPerWindow(i interface{}) error {
	v, ok := i.(sdk.Dec)
	if !ok {
		return fmt.Errorf("invalid parameter type: %T", i)
	}

	if v.IsNegative() {
		return fmt.Errorf("min signed per window cannot be negative: %s", v)
	}
	if v.GT(sdk.OneDec()) {
		return fmt.Errorf("min signed per window too large: %s", v)
	}

	return nil
}

func validateDowntimeJailDuration(i interface{}) error {
	v, ok := i.(time.Duration)
	if !ok {
		return fmt.Errorf("invalid parameter type: %T", i)
	}

	if v <= 0 {
		return fmt.Errorf("downtime jail duration must be positive: %s", v)
	}

	return nil
}

func validateSlashFractionDoubleSign(i interface{}) error {
	v, ok := i.(sdk.Dec)
	if !ok {
		return fmt.Errorf("invalid parameter type: %T", i)
	}

	if v.IsNegative() {
		return fmt.Errorf("double sign slash fraction cannot be negative: %s", v)
	}
	if v.GT(sdk.OneDec()) {
		return fmt.Errorf("double sign slash fraction too large: %s", v)
	}

	return nil
}

func validateSlashFractionDowntime(i interface{}) error {
	v, ok := i.(sdk.Dec)
	if !ok {
		return fmt.Errorf("invalid parameter type: %T", i)
	}

	if v.IsNegative() {
		return fmt.Errorf("downtime slash fraction cannot be negative: %s", v)
	}
	if v.GT(sdk.OneDec()) {
		return fmt.Errorf("downtime slash fraction too large: %s", v)
	}

	return nil
}