package main

import (
	"encoding/json"
	"fmt"
	"math"
	"os"
	"strconv"
	"strings"
	"time"

	"git.davoryn.de/calic/claude-statusline/internal/fetcher"
)

const (
	filledBlock = "\u2593"
	lightBlock  = "\u2591"
)

// stdinData is the JSON structure from Claude Code's stdin.
type stdinData struct {
	ContextWindow struct {
		UsedPercentage float64 `json:"used_percentage"`
	} `json:"context_window"`
}

func bar(pct float64, width int) string {
	pct = math.Max(0, math.Min(100, pct))
	filled := int(math.Floor(pct / (100.0 / float64(width))))
	return strings.Repeat(filledBlock, filled) + strings.Repeat(lightBlock, width-filled)
}

func getContextPart(data *stdinData) string {
	if data == nil {
		return ""
	}
	pct := data.ContextWindow.UsedPercentage
	return fmt.Sprintf("Context %s %d%%", bar(pct, 10), int(pct))
}

func formatMinutes(isoStr string) string {
	if isoStr == "" {
		return ""
	}
	t, err := time.Parse(time.RFC3339, isoStr)
	if err != nil {
		return ""
	}
	mins := int(math.Max(0, time.Until(t).Minutes()))
	return fmt.Sprintf("%dM", mins)
}

func getUsagePart(data *fetcher.CacheData) string {
	if data == nil {
		return ""
	}
	if data.Error != "" {
		switch data.Error {
		case "auth_expired":
			return "Token: session expired"
		case "no_session_key":
			return ""
		default:
			return "Token: error"
		}
	}

	var parts []string

	if data.FiveHour != nil && data.FiveHour.Utilization > 0 {
		pct := data.FiveHour.Utilization
		s := fmt.Sprintf("Token %s %d%%", bar(pct, 10), int(math.Round(pct)))
		if mins := formatMinutes(data.FiveHour.ResetsAt); mins != "" {
			s += " " + mins
		}
		parts = append(parts, s)
	}

	if data.SevenDay != nil && data.SevenDay.Utilization > 20 {
		parts = append(parts, fmt.Sprintf("7d %d%%", int(math.Round(data.SevenDay.Utilization))))
	}

	return strings.Join(parts, " | ")
}

func main() {
	// Read stdin (context window data from Claude Code)
	var input stdinData
	var hasInput bool
	dec := json.NewDecoder(os.Stdin)
	if err := dec.Decode(&input); err == nil {
		hasInput = true
	}

	// Read cache
	maxAge := 900 * time.Second
	if v := os.Getenv("CLAUDE_USAGE_MAX_AGE"); v != "" {
		if secs, err := strconv.Atoi(v); err == nil {
			maxAge = time.Duration(secs) * time.Second
		}
	}
	cache := fetcher.ReadCacheIfFresh(maxAge)

	// Build output
	var parts []string

	if hasInput {
		if ctx := getContextPart(&input); ctx != "" {
			parts = append(parts, ctx)
		}
	}

	if usage := getUsagePart(cache); usage != "" {
		parts = append(parts, usage)
	}

	if len(parts) > 0 {
		fmt.Println(strings.Join(parts, " | "))
	}
}