package httpserver

import (
	"fmt"
	"image"
	"image/color"
	"image/draw"
	"image/png"
	"math"
	"net/http"
	"sort"
	"strings"

	"kubeviz/internal/analyze"
	"kubeviz/internal/graph"
	"kubeviz/internal/model"
)

type point struct {
	X float64
	Y float64
}

func (s *Server) handleExportSVG(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	resp, ok := s.exportGraph(w, r)
	if !ok {
		return
	}
	svg := renderSVG(resp)
	w.Header().Set("Content-Type", "image/svg+xml")
	w.Header().Set("Content-Disposition", "inline; filename=graph.svg")
	_, _ = w.Write([]byte(svg))
}

func (s *Server) handleExportPNG(w http.ResponseWriter, r *http.Request) {
	if r.Method != http.MethodGet {
		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
		return
	}
	resp, ok := s.exportGraph(w, r)
	if !ok {
		return
	}
	img := renderPNG(resp)
	w.Header().Set("Content-Type", "image/png")
	w.Header().Set("Content-Disposition", "inline; filename=graph.png")
	_ = png.Encode(w, img)
}

func (s *Server) exportGraph(w http.ResponseWriter, r *http.Request) (model.GraphResponse, bool) {
	sid, err := s.sessionID(w, r)
	if err != nil {
		http.Error(w, "session error", http.StatusInternalServerError)
		return model.GraphResponse{}, false
	}
	dataset := s.store.GetDataset(sid)
	if dataset == nil {
		http.Error(w, "no manifests uploaded", http.StatusNotFound)
		return model.GraphResponse{}, false
	}
	filters := graph.Filters{
		Namespace:       r.URL.Query().Get("namespace"),
		Kind:            r.URL.Query().Get("kind"),
		Query:           r.URL.Query().Get("q"),
		FocusID:         r.URL.Query().Get("focus"),
		Relations:       parseRelations(r.URL.Query().Get("relations")),
		GroupBy:         r.URL.Query().Get("groupBy"),
		CollapsedGroups: parseCSVSet(r.URL.Query().Get("collapsed")),
	}
	checkCfg := analyze.DefaultConfig()
	if raw := r.URL.Query().Get("checkRules"); raw != "" {
		checkCfg = analyze.ConfigFromEnabled(parseCSVSet(raw))
	}
	_, healthHints := analyze.AnalyzeDataset(dataset, checkCfg)
	return graph.BuildGraph(dataset, filters, healthHints), true
}

func layout(nodes []model.GraphNode) map[string]point {
	out := map[string]point{}
	sorted := make([]model.GraphNode, len(nodes))
	copy(sorted, nodes)
	sort.Slice(sorted, func(i, j int) bool { return sorted[i].ID < sorted[j].ID })

	n := len(sorted)
	if n == 0 {
		return out
	}
	centerX, centerY := 640.0, 360.0
	radius := 220.0
	if n > 40 {
		radius = 280
	}
	for i, node := range sorted {
		angle := 2 * math.Pi * float64(i) / float64(n)
		out[node.ID] = point{
			X: centerX + radius*math.Cos(angle),
			Y: centerY + radius*math.Sin(angle),
		}
	}
	return out
}

func renderSVG(resp model.GraphResponse) string {
	coords := layout(resp.Nodes)
	var b strings.Builder
	b.WriteString(`<svg xmlns="http://www.w3.org/2000/svg" width="1280" height="720" viewBox="0 0 1280 720">`)
	b.WriteString(`<rect width="100%" height="100%" fill="#f5f7fb"/>`)
	for _, edge := range resp.Edges {
		s, sok := coords[edge.Source]
		t, tok := coords[edge.Target]
		if !sok || !tok {
			continue
		}
		b.WriteString(fmt.Sprintf(`<line x1="%.1f" y1="%.1f" x2="%.1f" y2="%.1f" stroke="#9ca3af" stroke-width="1.5"/>`, s.X, s.Y, t.X, t.Y))
	}
	for _, node := range resp.Nodes {
		p := coords[node.ID]
		fill := "#2563eb"
		if node.IsSensitive {
			fill = "#dc2626"
		}
		label := escapeXML(fmt.Sprintf("%s/%s", node.Kind, node.Name))
		b.WriteString(fmt.Sprintf(`<circle cx="%.1f" cy="%.1f" r="20" fill="%s" opacity="0.9"/>`, p.X, p.Y, fill))
		b.WriteString(fmt.Sprintf(`<text x="%.1f" y="%.1f" font-size="11" fill="#111827" text-anchor="middle">%s</text>`, p.X, p.Y+34, label))
	}
	b.WriteString(`</svg>`)
	return b.String()
}

func renderPNG(resp model.GraphResponse) image.Image {
	img := image.NewRGBA(image.Rect(0, 0, 1280, 720))
	draw.Draw(img, img.Bounds(), &image.Uniform{C: color.RGBA{245, 247, 251, 255}}, image.Point{}, draw.Src)

	coords := layout(resp.Nodes)

	edgeColor := color.RGBA{156, 163, 175, 255}
	for _, edge := range resp.Edges {
		s, sok := coords[edge.Source]
		t, tok := coords[edge.Target]
		if !sok || !tok {
			continue
		}
		drawLine(img, int(s.X), int(s.Y), int(t.X), int(t.Y), edgeColor)
	}

	for _, node := range resp.Nodes {
		p := coords[node.ID]
		fill := color.RGBA{37, 99, 235, 255}
		if node.IsSensitive {
			fill = color.RGBA{220, 38, 38, 255}
		}
		drawCircle(img, int(p.X), int(p.Y), 20, fill)
	}

	return img
}

func drawLine(img *image.RGBA, x0, y0, x1, y1 int, c color.Color) {
	dx := abs(x1 - x0)
	sx := -1
	if x0 < x1 {
		sx = 1
	}
	dy := -abs(y1 - y0)
	sy := -1
	if y0 < y1 {
		sy = 1
	}
	err := dx + dy
	for {
		if image.Pt(x0, y0).In(img.Bounds()) {
			img.Set(x0, y0, c)
		}
		if x0 == x1 && y0 == y1 {
			break
		}
		e2 := 2 * err
		if e2 >= dy {
			err += dy
			x0 += sx
		}
		if e2 <= dx {
			err += dx
			y0 += sy
		}
	}
}

func drawCircle(img *image.RGBA, cx, cy, r int, c color.Color) {
	for y := -r; y <= r; y++ {
		for x := -r; x <= r; x++ {
			if x*x+y*y <= r*r {
				px := cx + x
				py := cy + y
				if image.Pt(px, py).In(img.Bounds()) {
					img.Set(px, py, c)
				}
			}
		}
	}
}

func abs(v int) int {
	if v < 0 {
		return -v
	}
	return v
}

func escapeXML(s string) string {
	replacer := strings.NewReplacer("&", "&amp;", "<", "&lt;", ">", "&gt;", `"`, "&quot;")
	return replacer.Replace(s)
}