package slashing

import (
	"time"

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

// Default parameter namespace
const (
	DefaultParamspace = "slashing"
)

// Parameter store key
var (
	KeyMaxEvidenceAge           = []byte("MaxEvidenceAge")
	KeySignedBlocksWindow       = []byte("SignedBlocksWindow")
	KeyMinSignedPerWindow       = []byte("MinSignedPerWindow")
	KeyDoubleSignUnbondDuration = []byte("DoubleSignUnbondDuration")
	KeyDowntimeUnbondDuration   = []byte("DowntimeUnbondDuration")
	KeySlashFractionDoubleSign  = []byte("SlashFractionDoubleSign")
	KeySlashFractionDowntime    = []byte("SlashFractionDowntime")
)

// ParamTypeTable for slashing module
func ParamTypeTable() params.TypeTable {
	return params.NewTypeTable().RegisterParamSet(&Params{})
}

// Params - used for initializing default parameter for slashing at genesis
type Params struct {
	MaxEvidenceAge           time.Duration `json:"max-evidence-age"`
	SignedBlocksWindow       int64         `json:"signed-blocks-window"`
	MinSignedPerWindow       sdk.Dec       `json:"min-signed-per-window"`
	DoubleSignUnbondDuration time.Duration `json:"double-sign-unbond-duration"`
	DowntimeUnbondDuration   time.Duration `json:"downtime-unbond-duration"`
	SlashFractionDoubleSign  sdk.Dec       `json:"slash-fraction-double-sign"`
	SlashFractionDowntime    sdk.Dec       `json:"slash-fraction-downtime"`
}

// Implements params.ParamStruct
func (p *Params) KeyValuePairs() params.KeyValuePairs {
	return params.KeyValuePairs{
		{KeyMaxEvidenceAge, &p.MaxEvidenceAge},
		{KeySignedBlocksWindow, &p.SignedBlocksWindow},
		{KeyMinSignedPerWindow, &p.MinSignedPerWindow},
		{KeyDoubleSignUnbondDuration, &p.DoubleSignUnbondDuration},
		{KeyDowntimeUnbondDuration, &p.DowntimeUnbondDuration},
		{KeySlashFractionDoubleSign, &p.SlashFractionDoubleSign},
		{KeySlashFractionDowntime, &p.SlashFractionDowntime},
	}
}

// Default parameters used by Cosmos Hub
func DefaultParams() Params {
	return Params{
		// defaultMaxEvidenceAge = 60 * 60 * 24 * 7 * 3
		// TODO Temporarily set to 2 minutes for testnets.
		MaxEvidenceAge: 60 * 2 * time.Second,

		// TODO Temporarily set to five minutes for testnets
		DoubleSignUnbondDuration: 60 * 5 * time.Second,

		// TODO Temporarily set to 100 blocks for testnets
		SignedBlocksWindow: 100,

		// TODO Temporarily set to 10 minutes for testnets
		DowntimeUnbondDuration: 60 * 10 * time.Second,

		MinSignedPerWindow: sdk.NewDecWithPrec(5, 1),

		SlashFractionDoubleSign: sdk.NewDec(1).Quo(sdk.NewDec(20)),

		SlashFractionDowntime: sdk.NewDec(1).Quo(sdk.NewDec(100)),
	}
}

// MaxEvidenceAge - Max age for evidence - 21 days (3 weeks)
// MaxEvidenceAge = 60 * 60 * 24 * 7 * 3
func (k Keeper) MaxEvidenceAge(ctx sdk.Context) (res time.Duration) {
	k.paramspace.Get(ctx, KeyMaxEvidenceAge, &res)
	return
}

// SignedBlocksWindow - sliding window for downtime slashing
func (k Keeper) SignedBlocksWindow(ctx sdk.Context) (res int64) {
	k.paramspace.Get(ctx, KeySignedBlocksWindow, &res)
	return
}

// Downtime slashing threshold - default 50% of the SignedBlocksWindow
func (k Keeper) MinSignedPerWindow(ctx sdk.Context) int64 {
	var minSignedPerWindow sdk.Dec
	k.paramspace.Get(ctx, KeyMinSignedPerWindow, &minSignedPerWindow)
	signedBlocksWindow := k.SignedBlocksWindow(ctx)
	return sdk.NewDec(signedBlocksWindow).Mul(minSignedPerWindow).RoundInt64()
}

// Double-sign unbond duration
func (k Keeper) DoubleSignUnbondDuration(ctx sdk.Context) (res time.Duration) {
	k.paramspace.Get(ctx, KeyDoubleSignUnbondDuration, &res)
	return
}

// Downtime unbond duration
func (k Keeper) DowntimeUnbondDuration(ctx sdk.Context) (res time.Duration) {
	k.paramspace.Get(ctx, KeyDowntimeUnbondDuration, &res)
	return
}

// SlashFractionDoubleSign - currently default 5%
func (k Keeper) SlashFractionDoubleSign(ctx sdk.Context) (res sdk.Dec) {
	k.paramspace.Get(ctx, KeySlashFractionDoubleSign, &res)
	return
}

// SlashFractionDowntime - currently default 1%
func (k Keeper) SlashFractionDowntime(ctx sdk.Context) (res sdk.Dec) {
	k.paramspace.Get(ctx, KeySlashFractionDowntime, &res)
	return
}

// GetParams returns the total set of slashing parameters.
func (k Keeper) GetParams(ctx sdk.Context) (params Params) {
	k.paramspace.GetParamSet(ctx, &params)
	return params
}