From eebd2efcbf76b71838e3387d69d14e0884d33e60 Mon Sep 17 00:00:00 2001
From: Travis Person <travisperson@users.noreply.github.com>
Date: Sat, 5 Sep 2020 00:40:57 +0000
Subject: [PATCH] lotus-shed: add math command

---
 cmd/lotus-shed/main.go |   1 +
 cmd/lotus-shed/math.go | 103 +++++++++++++++++++++++++++++++++++++++++
 2 files changed, 104 insertions(+)
 create mode 100644 cmd/lotus-shed/math.go

diff --git a/cmd/lotus-shed/main.go b/cmd/lotus-shed/main.go
index 5438a31ef6d..fb931decfc1 100644
--- a/cmd/lotus-shed/main.go
+++ b/cmd/lotus-shed/main.go
@@ -31,6 +31,7 @@ func main() {
 		miscCmd,
 		mpoolCmd,
 		genesisVerifyCmd,
+		mathCmd,
 	}
 
 	app := &cli.App{
diff --git a/cmd/lotus-shed/math.go b/cmd/lotus-shed/math.go
new file mode 100644
index 00000000000..434559f09a0
--- /dev/null
+++ b/cmd/lotus-shed/math.go
@@ -0,0 +1,103 @@
+package main
+
+import (
+	"bufio"
+	"fmt"
+	"io"
+	"os"
+	"strings"
+
+	"github.com/urfave/cli/v2"
+
+	"github.com/filecoin-project/lotus/chain/types"
+)
+
+var mathCmd = &cli.Command{
+	Name:  "math",
+	Usage: "utility commands around doing math on a list of numbers",
+	Subcommands: []*cli.Command{
+		mathSumCmd,
+	},
+}
+
+func readLargeNumbers(i io.Reader) ([]types.BigInt, error) {
+	list := []types.BigInt{}
+	reader := bufio.NewReader(i)
+
+	exit := false
+	for {
+		if exit {
+			break
+		}
+
+		line, err := reader.ReadString('\n')
+		if err != nil && err != io.EOF {
+			break
+		}
+		if err == io.EOF {
+			exit = true
+		}
+
+		line = strings.Trim(line, "\n")
+
+		if len(line) == 0 {
+			continue
+		}
+
+		value, err := types.BigFromString(line)
+		if err != nil {
+			return []types.BigInt{}, fmt.Errorf("failed to parse line: %s", line)
+		}
+
+		list = append(list, value)
+	}
+
+	return list, nil
+}
+
+var mathSumCmd = &cli.Command{
+	Name:  "sum",
+	Usage: "Sum numbers",
+	Flags: []cli.Flag{
+		&cli.BoolFlag{
+			Name:  "avg",
+			Value: false,
+			Usage: "Print the average instead of the sum",
+		},
+		&cli.StringFlag{
+			Name:  "format",
+			Value: "raw",
+			Usage: "format the number in a more readable way [fil,bytes2,bytes10]",
+		},
+	},
+	Action: func(cctx *cli.Context) error {
+		list, err := readLargeNumbers(os.Stdin)
+		if err != nil {
+			return err
+		}
+
+		val := types.NewInt(0)
+		for _, value := range list {
+			val = types.BigAdd(val, value)
+		}
+
+		if cctx.Bool("avg") {
+			val = types.BigDiv(val, types.NewInt(uint64(len(list))))
+		}
+
+		switch cctx.String("format") {
+		case "byte2":
+			fmt.Printf("%s\n", types.SizeStr(val))
+		case "byte10":
+			fmt.Printf("%s\n", types.DeciStr(val))
+		case "fil":
+			fmt.Printf("%s\n", types.FIL(val))
+		case "raw":
+			fmt.Printf("%s\n", val)
+		default:
+			return fmt.Errorf("Unknown format")
+		}
+
+		return nil
+	},
+}