package main

import (
	"encoding/json"
	"fmt"
	"log"
	"math"
	"os"
	"os/exec"
	"path/filepath"
	"sort"
	"strings"
	"time"

	"codeberg.org/elisiei/sysbench/internal/hyperfine"
)

const (
	svgW      = 900
	padTop    = 48
	padBottom = 80
	padLeft   = 200
	padRight  = 60
	barHeight = 28
	barGap    = 14
	tickCount = 6
	cornerR   = 0
)

var palette = []string{
	"#5E81AC", "#88C0D0", "#A3BE8C", "#EBCB8B",
	"#D08770", "#BF616A", "#B48EAD", "#8FBCBB",
}

func colour(i int) string { return palette[i%len(palette)] }

func main() {
	dir := resolveDir()
	src := filepath.Join(dir, "results.json")
	dst := filepath.Join(dir, "plot.svg")

	data, err := os.ReadFile(src)
	if err != nil {
		log.Fatalf("read %s: %v", src, err)
	}

	var result hyperfine.Result
	if err := json.Unmarshal(data, &result); err != nil {
		log.Fatalf("parse: %v", err)
	}

	if len(result.Results) == 0 {
		log.Fatal("no benchmark results found")
	}

	svg := render(result.Results, dir)
	if err := os.WriteFile(dst, []byte(svg), 0o644); err != nil {
		log.Fatalf("write %s: %v", dst, err)
	}
	fmt.Printf("plot written to %s\n", dst)

	pngPath := filepath.Join(dir, "plot.png")

	cmd := exec.Command("magick",
		"-density", "192",
		"-background", "none",
		dst,
		pngPath,
	)

	if err := cmd.Run(); err != nil {
		log.Fatalf("convert to png: %v", err)
	}

	fmt.Printf("png written to %s\n", pngPath)
}

func resolveDir() string {
	if len(os.Args) > 1 {
		return os.Args[1]
	}
	return filepath.Join("results", time.Now().Format("2006-01-02"))
}

func render(bs []hyperfine.Benchmark, date string) string {
	sort.Slice(bs, func(i, j int) bool {
		return bs[i].Mean < bs[j].Mean
	})
	n := len(bs)
	chartH := n*(barHeight+barGap) + barGap
	height := padTop + chartH + padBottom

	maxMean := 0.0
	for _, b := range bs {
		if b.Mean > maxMean {
			maxMean = b.Mean
		}
	}
	scale := niceMax(maxMean, tickCount)
	chartW := svgW - padLeft - padRight

	var sb strings.Builder

	fmt.Fprintf(&sb, `<svg xmlns="http://www.w3.org/2000/svg" width="%d" height="%d" font-family="monospace" font-size="13">`, svgW, height)
	fmt.Fprintln(&sb)
	fmt.Fprintf(&sb, `  <rect width="%d" height="%d" fill="#2E3440"/>`, svgW, height)
	fmt.Fprintln(&sb)
	title := fmt.Sprintf("system fetch benchmark — %s", filepath.Base(date))
	fmt.Fprintf(&sb, `  <text x="%d" y="28" fill="#ECEFF4" font-size="15" font-weight="bold" text-anchor="middle">%s</text>`, svgW/2, title)
	fmt.Fprintln(&sb)

	for i := 0; i <= tickCount; i++ {
		val := scale * float64(i) / float64(tickCount)
		x := padLeft + int(float64(chartW)*val/scale)
		yTop := padTop
		yBot := padTop + chartH
		fmt.Fprintf(&sb, `  <line x1="%d" y1="%d" x2="%d" y2="%d" stroke="#434C5E" stroke-width="1"/>`, x, yTop, x, yBot)
		fmt.Fprintln(&sb)
		label := fmtTime(val)
		fmt.Fprintf(&sb, `  <text x="%d" y="%d" fill="#8FBCBB" text-anchor="middle">%s</text>`, x, padTop+chartH+18, label)
		fmt.Fprintln(&sb)
	}

	fmt.Fprintf(&sb, `  <text x="%d" y="%d" fill="#8FBCBB" text-anchor="middle">time (s)</text>`, padLeft+chartW/2, padTop+chartH+38)
	fmt.Fprintln(&sb)

	for i, b := range bs {
		y := padTop + barGap + i*(barHeight+barGap)
		barW := int(float64(chartW) * b.Mean / scale)
		if barW < 1 {
			barW = 1
		}
		col := colour(i)

		label := trimCommand(b.Command, 28)
		fmt.Fprintf(&sb, `  <text x="%d" y="%d" fill="#D8DEE9" text-anchor="end">%s</text>`,
			padLeft-8, y+barHeight-8, label)
		fmt.Fprintln(&sb)

		fmt.Fprintf(&sb, `  <rect x="%d" y="%d" width="%d" height="%d" rx="%d" fill="%s"/>`,
			padLeft, y, barW, barHeight, cornerR, col)
		fmt.Fprintln(&sb)

		fmt.Fprintf(&sb, `  <text x="%d" y="%d" fill="#ECEFF4" font-size="11">%s</text>`,
			padLeft+barW+8+(int(float64(chartW)*b.Stddev/scale)), y+barHeight-8, fmtTime(b.Mean))
		fmt.Fprintln(&sb)
	}

	fmt.Fprintln(&sb, `</svg>`)
	return sb.String()
}

func niceMax(max float64, ticks int) float64 {
	raw := max / float64(ticks)
	exp := math.Floor(math.Log10(raw))
	mag := math.Pow(10, exp)
	nice := math.Ceil(raw/mag) * mag
	return nice * float64(ticks)
}

func fmtTime(s float64) string {
	switch {
	case s == 0:
		return "0"
	case s < 0.001:
		return fmt.Sprintf("%.0fµs", s*1e6)
	case s < 1:
		return fmt.Sprintf("%.0fms", s*1e3)
	default:
		return fmt.Sprintf("%.2fs", s)
	}
}

func trimCommand(cmd string, max int) string {
	parts := strings.Fields(cmd)
	base := parts[0]
	if idx := strings.LastIndexAny(base, "/\\"); idx >= 0 {
		base = base[idx+1:]
	}
	if len(cmd) <= max {
		return cmd
	}
	if len(base) <= max {
		return base
	}
	return base[:max-1] + "..."
}