package logic

import (
	"bytes"
	"math"
	"math/rand"
	"regexp"
	"strconv"
	"strings"
	"time"
	"toolbox/pkg/learnnumber/data"

	"github.com/signintech/gopdf"
)

type CountingRequest struct {
	TotalCount int    `json:"total_count"`
	IconTypes  int    `json:"icon_types"`
	PaperSize  string `json:"paper_size"`
}

var reSVG = regexp.MustCompile(`([MLQCZmlqcz])|(-?\d+\.?\d*)`)

func GenerateCountingPDF(req CountingRequest) ([]byte, error) {
	rand.Seed(time.Now().UnixNano())
	pdf := &gopdf.GoPdf{}
	rect := gopdf.Rect{W: 595.28, H: 841.89}
	if req.PaperSize == "Letter" { rect = gopdf.Rect{W: 612, H: 792} }
	pdf.Start(gopdf.Config{PageSize: rect})
	pdf.AddPage()

	drawProblem(pdf, req, 0, rect.W, rect.H/2)
	drawProblem(pdf, req, rect.H/2, rect.W, rect.H/2)

	var buf bytes.Buffer
	_, err := pdf.WriteTo(&buf)
	return buf.Bytes(), err
}

func drawProblem(pdf *gopdf.GoPdf, req CountingRequest, startY, pW, pH float64) {
	margin := 40.0
	boxW := (pW - 2*margin) * 0.7
	boxH := pH - 60.0
	x, y := margin, startY + 30.0

	// 1. 绘制方框
	pdf.SetStrokeColor(0, 0, 0); pdf.SetLineWidth(2.0)
	pdf.RectFromUpperLeft(x, y, boxW, boxH)

	// 2. 分配图标数量
	numTypes := req.IconTypes; if numTypes < 1 { numTypes = 1 }
	if numTypes > len(data.CountingIcons) { numTypes = len(data.CountingIcons) }
	
	total := req.TotalCount; if total < numTypes { total = numTypes }
	if total > 30 { total = 30 }

	// 随机选出图标种类
	allIcons := rand.Perm(len(data.CountingIcons))
	selectedIcons := []data.Icon{}
	counts := []int{}
	
	// 先每种分配1个
	rem := total - numTypes
	for i := 0; i < numTypes; i++ {
		selectedIcons = append(selectedIcons, data.CountingIcons[allIcons[i]])
		counts = append(counts, 1)
	}
	// 随机分配剩下的
	for i := 0; i < rem; i++ {
		counts[rand.Intn(numTypes)]++
	}

	// 3. 布局计划 (使用网格，增加 Padding 避开边框)
	rows, cols := 5, 6
	cellW, cellH := boxW/float64(cols), boxH/float64(rows)
	indices := rand.Perm(rows * cols)
	
	// 严格图标大小：单元格的 70%，确保不溢出单元格边界
	iconSize := math.Min(cellW, cellH) * 0.7
	paddingX, paddingY := (cellW - iconSize)/2, (cellH - iconSize)/2

	iconTypeIdx := 0
	countInCurrentType := 0
	
	for i := 0; i < total; i++ {
		cellIdx := indices[i]
		rIdx, cIdx := cellIdx/cols, cellIdx%cols
		
		// 基础位置
		baseX := x + float64(cIdx)*cellW + paddingX
		baseY := y + float64(rIdx)*cellH + paddingY
		
		// 渲染图标
		drawIcon(pdf, selectedIcons[iconTypeIdx], baseX + iconSize/2, baseY + iconSize/2, iconSize)
		
		countInCurrentType++
		if countInCurrentType >= counts[iconTypeIdx] {
			iconTypeIdx++
			countInCurrentType = 0
		}
	}

	// 4. 绘制右侧对照表
	legendX := x + boxW + 20.0
	legendStepY := boxH / float64(numTypes + 1)
	for i := 0; i < numTypes; i++ {
		lY := y + float64(i+1)*legendStepY
		drawIcon(pdf, selectedIcons[i], legendX + 20, lY, 30)
		pdf.SetStrokeColor(150, 150, 150); pdf.SetLineWidth(0.8)
		pdf.RectFromUpperLeft(legendX + 50, lY - 15, 30, 30)
	}
}

func drawIcon(pdf *gopdf.GoPdf, icon data.Icon, cX, cY, size float64) {
	scale := size / 1024.0
	pdf.SetStrokeColor(0, 0, 0); pdf.SetLineWidth(1.5) // 加粗线条
	
	ox, oy := cX - size/2, cY - size/2
	for _, pStr := range icon.Paths {
		pts := parseSmoothPath(pStr, scale, ox, oy)
		if len(pts) > 1 {
			// 如果是闭合路径
			if strings.Contains(strings.ToUpper(pStr), "Z") {
				pdf.Polygon(pts, "D")
			} else {
				for i := 0; i < len(pts)-1; i++ {
					pdf.Line(pts[i].X, pts[i].Y, pts[i+1].X, pts[i+1].Y)
				}
			}
		}
	}
}

// 支持贝塞尔曲线采样，确保图标圆润
func parseSmoothPath(path string, scale, ox, oy float64) []gopdf.Point {
	var pts []gopdf.Point
	matches := reSVG.FindAllStringSubmatch(path, -1)
	var lx, ly float64
	for i := 0; i < len(matches); {
		cmd := matches[i][0]
		if cmd == "M" || cmd == "L" {
			x, _ := strconv.ParseFloat(matches[i+1][0], 64); y, _ := strconv.ParseFloat(matches[i+2][0], 64)
			lx, ly = x, y
			pts = append(pts, gopdf.Point{X: ox + x*scale, Y: oy + y*scale})
			i += 3
		} else if cmd == "C" {
			x1, _ := strconv.ParseFloat(matches[i+1][0], 64); y1, _ := strconv.ParseFloat(matches[i+2][0], 64)
			x2, _ := strconv.ParseFloat(matches[i+3][0], 64); y2, _ := strconv.ParseFloat(matches[i+4][0], 64)
			x, _ := strconv.ParseFloat(matches[i+5][0], 64); y, _ := strconv.ParseFloat(matches[i+6][0], 64)
			for t := 0.25; t <= 1.0; t += 0.25 {
				tx := math.Pow(1-t, 3)*lx + 3*math.Pow(1-t, 2)*t*x1 + 3*(1-t)*math.Pow(t, 2)*x2 + math.Pow(t, 3)*x
				ty := math.Pow(1-t, 3)*ly + 3*math.Pow(1-t, 2)*t*y1 + 3*(1-t)*math.Pow(t, 2)*y2 + math.Pow(t, 3)*y
				pts = append(pts, gopdf.Point{X: ox + tx*scale, Y: oy + ty*scale})
			}
			lx, ly = x, y; i += 7
		} else if cmd == "Q" {
			x1, _ := strconv.ParseFloat(matches[i+1][0], 64); y1, _ := strconv.ParseFloat(matches[i+2][0], 64)
			x, _ := strconv.ParseFloat(matches[i+3][0], 64); y, _ := strconv.ParseFloat(matches[i+4][0], 64)
			for t := 0.25; t <= 1.0; t += 0.25 {
				tx := math.Pow(1-t, 2)*lx + 2*(1-t)*t*x1 + math.Pow(t, 2)*x
				ty := math.Pow(1-t, 2)*ly + 2*(1-t)*t*y1 + math.Pow(t, 2)*y
				pts = append(pts, gopdf.Point{X: ox + tx*scale, Y: oy + ty*scale})
			}
			lx, ly = x, y; i += 5
		} else { i++ }
	}
	return pts
}