package platform

import (
	"encoding/json"
	"math"
	"mime"
	"net/http"
	"strconv"
	"strings"
)

func canvasSchema(raw json.RawMessage) int {
	var d struct {
		Version int `json:"schema_version"`
	}
	_ = json.Unmarshal(raw, &d)
	return d.Version
}

func acceptsCanvasV2(r *http.Request) bool {
	for _, value := range strings.Split(r.Header.Get("Accept"), ",") {
		typ, params, err := mime.ParseMediaType(strings.TrimSpace(value))
		if err == nil && typ == "application/vnd.foundry.canvas+json" && params["version"] == "2" {
			if value, exists := params["q"]; exists {
				q, e := strconv.ParseFloat(value, 64)
				if e != nil || !(q > 0 && q <= 1) {
					continue
				}
			}
			return true
		}
	}
	return false
}

func canvasPoint(v any) bool {
	p, ok := v.(map[string]any)
	return ok && canvasFields(p, "x", "y") && canvasNumber(p["x"], -1e6, 1e6) && canvasNumber(p["y"], -1e6, 1e6)
}

func validCanvasEdgeData(v any) bool {
	d, ok := v.(map[string]any)
	if !ok || !canvasFields(d, "appearance", "animation", "path", "execution") {
		return false
	}
	for key, value := range d {
		m, ok := value.(map[string]any)
		if !ok {
			return false
		}
		switch key {
		case "appearance":
			if !canvasFields(m, "color", "width", "opacity", "line", "head", "tail") {
				return false
			}
			for k, v := range m {
				switch k {
				case "color":
					s, ok := v.(string)
					if !ok || !canvasColor.MatchString(s) {
						return false
					}
				case "width":
					if !canvasNumber(v, .5, 20) {
						return false
					}
				case "opacity":
					if !canvasNumber(v, .05, 1) {
						return false
					}
				case "line":
					if !canvasChoice(v, "solid", "dashed", "dotted") {
						return false
					}
				case "head", "tail":
					marker, ok := v.(map[string]any)
					if !ok || !canvasFields(marker, "type", "size", "filled") || !canvasChoice(marker["type"], "none", "open-arrow", "triangle", "circle", "diamond", "square") {
						return false
					}
					if v, exists := marker["size"]; exists && !canvasNumber(v, 4, 32) {
						return false
					}
					if v, exists := marker["filled"]; exists {
						if _, ok := v.(bool); !ok {
							return false
						}
					}
				}
			}
		case "animation":
			if !canvasFields(m, "mode", "effect", "direction", "durationMs", "color") {
				return false
			}
			for k, v := range m {
				switch k {
				case "mode":
					if !canvasChoice(v, "off", "always", "executing") {
						return false
					}
				case "effect":
					if !canvasChoice(v, "flow", "dash", "pulse") {
						return false
					}
				case "direction":
					if !canvasChoice(v, "forward", "reverse") {
						return false
					}
				case "durationMs":
					if !canvasNumber(v, 250, 30000) {
						return false
					}
				case "color":
					s, ok := v.(string)
					if !ok || !canvasColor.MatchString(s) {
						return false
					}
				}
			}
		case "execution":
			if !canvasFields(m, "enabled") {
				return false
			}
			if v, exists := m["enabled"]; exists {
				if _, ok := v.(bool); !ok {
					return false
				}
			}
		case "path":
			if !canvasFields(m, "type", "startControl", "endControl", "knots") || m["type"] != "bezier-chain" {
				return false
			}
			for _, k := range []string{"startControl", "endControl"} {
				if v, exists := m[k]; exists && !canvasPoint(v) {
					return false
				}
			}
			knots, ok := m["knots"].([]any)
			if !ok || len(knots) > 64 {
				return false
			}
			seen := map[string]bool{}
			for _, v := range knots {
				knot, ok := v.(map[string]any)
				if !ok || !canvasFields(knot, "id", "position", "in", "out", "mode") {
					return false
				}
				id, ok := knot["id"].(string)
				if !ok || !canvasID.MatchString(id) || seen[id] {
					return false
				}
				seen[id] = true
				for _, k := range []string{"position", "in", "out"} {
					if !canvasPoint(knot[k]) {
						return false
					}
				}
				if !canvasChoice(knot["mode"], "corner", "smooth", "symmetric") {
					return false
				}
				if knot["mode"] != "corner" {
					a, b := knot["in"].(map[string]any), knot["out"].(map[string]any)
					ax, ay, bx, by := a["x"].(float64), a["y"].(float64), b["x"].(float64), b["y"].(float64)
					la, lb := math.Hypot(ax, ay), math.Hypot(bx, by)
					if la > 0 && lb > 0 && (math.Abs((ax/la)*(by/lb)-(ay/la)*(bx/lb)) > 1e-6 || (ax/la)*(bx/lb)+(ay/la)*(by/lb) > 0) {
						return false
					}
					if knot["mode"] == "symmetric" && math.Abs(la-lb) > 1e-6*math.Max(la, lb) {
						return false
					}
				}
			}
		}
	}
	return true
}