Analyze claude cost

analyze_claude_cost.go

package main

import (
	"encoding/csv"
	"fmt"
	"io"
	"os"
	"sort"
	"strconv"
	"strings"
)

func extractUsername(apiKey string) string {
	// Strip prefix "claude_code_key_"
	s := strings.TrimPrefix(apiKey, "claude_code_key_")
	// Strip the last "_XXXX" suffix (4-char random segment)
	idx := strings.LastIndex(s, "_")
	if idx != -1 {
		s = s[:idx]
	}
	// "sebastian.winkler" -> "Sebastian Winkler"
	parts := strings.Split(s, ".")
	for i, p := range parts {
		if len(p) > 0 {
			parts[i] = strings.ToUpper(p[:1]) + p[1:]
		}
	}
	return strings.Join(parts, " ")
}

func main() {
	if len(os.Args) < 2 {
		fmt.Fprintln(os.Stderr, "Usage: analyze_costs <file.csv>")
		os.Exit(1)
	}

	f, err := os.Open(os.Args[1])
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error opening file: %v\n", err)
		os.Exit(1)
	}
	defer f.Close()

	r := csv.NewReader(f)

	header, err := r.Read()
	if err != nil {
		fmt.Fprintf(os.Stderr, "Error reading header: %v\n", err)
		os.Exit(1)
	}

	colIndex := func(name string) int {
		for i, h := range header {
			if h == name {
				return i
			}
		}
		return -1
	}

	apiKeyCol := colIndex("api_key")
	costCol := colIndex("cost_usd")
	if apiKeyCol == -1 || costCol == -1 {
		fmt.Fprintln(os.Stderr, "Required columns 'api_key' or 'cost_usd' not found")
		os.Exit(1)
	}

	totals := make(map[string]float64)

	for {
		record, err := r.Read()
		if err == io.EOF {
			break
		}
		if err != nil {
			fmt.Fprintf(os.Stderr, "Error reading row: %v\n", err)
			continue
		}

		user := extractUsername(record[apiKeyCol])
		cost, err := strconv.ParseFloat(record[costCol], 64)
		if err != nil {
			continue
		}
		totals[user] += cost
	}

	type entry struct {
		user string
		cost float64
	}

	rows := make([]entry, 0, len(totals))
	var grand float64
	for user, cost := range totals {
		rows = append(rows, entry{user, cost})
		grand += cost
	}
	sort.Slice(rows, func(i, j int) bool {
		return rows[i].cost > rows[j].cost
	})

	fmt.Printf("%-25s %12s %8s\n", "User", "Cost (USD)", "Share")
	fmt.Println(strings.Repeat("-", 48))
	for _, e := range rows {
		share := e.cost / grand * 100
		fmt.Printf("%-25s %12.2f %7.1f%%\n", e.user, e.cost, share)
	}
	fmt.Println(strings.Repeat("-", 48))
	fmt.Printf("%-25s %12.2f %8s\n", "TOTAL", grand, "")
}