feat: add vesting util functions (backport #11652) (#11667)

* feat: add vesting util functions (#11652)

* feat: add vesting util functions

* changelog

* revert string deletion

* fix build

* Update x/auth/vesting/types/period.go

Co-authored-by: Aleksandr Bezobchuk <alexanderbez@users.noreply.github.com>

Co-authored-by: Aleksandr Bezobchuk <alexanderbez@users.noreply.github.com>
Co-authored-by: Marko <marbar3778@yahoo.com>
(cherry picked from commit c676952278)

# Conflicts:
#	CHANGELOG.md
#	x/auth/vesting/types/period.go

* changelog

* Update x/auth/vesting/types/period.go

Co-authored-by: Federico Kunze Küllmer <31522760+fedekunze@users.noreply.github.com>
Co-authored-by: Federico Kunze Küllmer <federico.kunze94@gmail.com>

CHANGELOG.md

@@ -37,6 +37,10 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
 
+### Improvements
+
+* (x/auth/vesting) [\#11652](https://github.com/cosmos/cosmos-sdk/pull/11652) Add util functions for `Period(s)`
+
 ## [v0.45.3](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.45.3) - 2022-04-12
 
 ### Improvements

x/auth/vesting/types/period.go

@@ -3,23 +3,55 @@ package types
 import (
 	"fmt"
 	"strings"
+	"time"
 
 	yaml "gopkg.in/yaml.v2"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
 // Periods stores all vesting periods passed as part of a PeriodicVestingAccount
 type Periods []Period
 
-// String Period implements stringer interface
+// Duration is converts the period Length from seconds to a time.Duration
+func (p Period) Duration() time.Duration {
+	return time.Duration(p.Length) * time.Second
+}
+
+// String implements the fmt.Stringer interface
 func (p Period) String() string {
 	out, _ := yaml.Marshal(p)
 	return string(out)
 }
 
-// String Periods implements stringer interface
-func (vp Periods) String() string {
-	periodsListString := make([]string, len(vp))
-	for _, period := range vp {
+// TotalLength return the total length in seconds for a period
+func (p Periods) TotalLength() int64 {
+	var total int64
+	for _, period := range p {
+		total += period.Length
+	}
+	return total
+}
+
+// TotalDuration returns the total duration of the period
+func (p Periods) TotalDuration() time.Duration {
+	len := p.TotalLength()
+	return time.Duration(len) * time.Second
+}
+
+// TotalDuration returns the sum of coins for the period
+func (p Periods) TotalAmount() sdk.Coins {
+	total := sdk.Coins{}
+	for _, period := range p {
+		total = total.Add(period.Amount...)
+	}
+	return total
+}
+
+// String implements the fmt.Stringer interface
+func (p Periods) String() string {
+	periodsListString := make([]string, len(p))
+	for _, period := range p {
 		periodsListString = append(periodsListString, period.String())
 	}