// mesht creates, inspects and edits 3D models (OBJ and STL) from the
// command line, with ASCII multi-view rendering so agents can "see"
// a model before and after editing it.
package main

import (
	"flag"
	"fmt"
	"math"
	"os"
	"strconv"
	"strings"

	"gitea.brasse-pc.eu/brasse/agent-tools/mesh-tool/mesh"
)

var version = "dev"

const usage = `mesht - 3D model tool for agents (OBJ + STL)

Usage:
  mesht info <file>                     stats: size, volume, watertightness
  mesht view <file> [flags]             ASCII render from several angles
  mesht create <primitive> [flags]      box|sphere|cylinder|cone|plane|torus
  mesht transform <file> [flags]        scale/rotate/translate/mirror/center/fit
  mesht merge <a> <b> ... -o <out>      combine several files into one
  mesht convert <in> -o <out>           obj <-> stl
  mesht version

View flags:
  --views front,side,top,iso,back       which views to draw (default front,side,top)
  --width <n>                           characters per view (default 64)
  --object <name>                       only draw one object from the file

Create flags (always with -o <out.obj|out.stl>):
  box:      --size x,y,z          (default 1,1,1)
  sphere:   --radius r --segments n --rings n     (default 1, 24, 12)
  cylinder: --radius r --height h --segments n    (default 0.5, 1, 24)
  cone:     --radius r --height h --segments n    (default 0.5, 1, 24)
  plane:    --size w,d            (default 1,1)
  torus:    --radius R --tube r --segments n --rings n (default 1, 0.25, 24, 12)
  --name <s>                      object name in the output

Transform flags (applied in this order):
  --center                 move bounding-box center to the origin
  --mirror x|y|z           mirror across that axis' plane
  --scale s | x,y,z        uniform or per-axis scale
  --rotate x,y,z           degrees around X, then Y, then Z
  --translate x,y,z        move
  --fit n                  uniformly scale so the largest dimension = n
  --object <name>          only transform the named object (obj files)
  -o <out>                 output file (default: overwrite input)

Common:
  --ascii                  write text STL instead of binary
  Formats are picked from file extensions (.obj, .stl).

Axes: +Y is up, +X right, +Z toward the front viewer (right-handed).
`

func main() {
	if len(os.Args) < 2 {
		fmt.Print(usage)
		os.Exit(2)
	}
	switch os.Args[1] {
	case "info":
		cmdInfo(os.Args[2:])
	case "view":
		cmdView(os.Args[2:])
	case "create":
		cmdCreate(os.Args[2:])
	case "transform":
		cmdTransform(os.Args[2:])
	case "merge":
		cmdMerge(os.Args[2:])
	case "convert":
		cmdConvert(os.Args[2:])
	case "version", "--version", "-v":
		fmt.Println("mesht", version)
	case "help", "--help", "-h":
		fmt.Print(usage)
	default:
		die("unknown command %q — run 'mesht help'", os.Args[1])
	}
}

// parseInterspersed lets flags appear before or after positional args.
func parseInterspersed(fs *flag.FlagSet, args []string) {
	var flags, pos []string
	for i := 0; i < len(args); i++ {
		a := args[i]
		if len(a) > 1 && a[0] == '-' {
			flags = append(flags, a)
			name := strings.TrimLeft(a, "-")
			if !strings.Contains(name, "=") {
				f := fs.Lookup(name)
				isBool := false
				if f != nil {
					if bv, ok := f.Value.(interface{ IsBoolFlag() bool }); ok && bv.IsBoolFlag() {
						isBool = true
					}
				}
				if !isBool && i+1 < len(args) {
					i++
					flags = append(flags, args[i])
				}
			}
		} else {
			pos = append(pos, a)
		}
	}
	fs.Parse(append(flags, pos...))
}

func parseVec(s string, uniformOK bool) (mesh.Vec3, error) {
	parts := strings.Split(s, ",")
	switch len(parts) {
	case 1:
		if !uniformOK {
			return mesh.Vec3{}, fmt.Errorf("%q: want x,y,z", s)
		}
		v, err := strconv.ParseFloat(strings.TrimSpace(parts[0]), 64)
		return mesh.Vec3{X: v, Y: v, Z: v}, err
	case 3:
		var v [3]float64
		for i, p := range parts {
			f, err := strconv.ParseFloat(strings.TrimSpace(p), 64)
			if err != nil {
				return mesh.Vec3{}, fmt.Errorf("%q: bad number %q", s, p)
			}
			v[i] = f
		}
		return mesh.Vec3{X: v[0], Y: v[1], Z: v[2]}, nil
	}
	return mesh.Vec3{}, fmt.Errorf("%q: want one value or x,y,z", s)
}

func cmdInfo(args []string) {
	if len(args) != 1 {
		die("info takes exactly one file")
	}
	scene, err := mesh.ReadFile(args[0])
	if err != nil {
		die("%v", err)
	}
	merged := scene.Merged()
	mn, mx := merged.BBox()
	size := mx.Sub(mn)
	center := mn.Add(size.Mul(0.5))
	fmt.Printf("file:     %s\n", args[0])
	fmt.Printf("objects:  %d\n", len(scene.Meshes))
	fmt.Printf("verts:    %d\n", scene.TotalVerts())
	fmt.Printf("tris:     %d\n", scene.TotalTris())
	fmt.Printf("bbox min: (%.4g, %.4g, %.4g)\n", mn.X, mn.Y, mn.Z)
	fmt.Printf("bbox max: (%.4g, %.4g, %.4g)\n", mx.X, mx.Y, mx.Z)
	fmt.Printf("size:     %.4g x %.4g x %.4g (X Y Z)\n", size.X, size.Y, size.Z)
	fmt.Printf("center:   (%.4g, %.4g, %.4g)\n", center.X, center.Y, center.Z)
	fmt.Printf("area:     %.6g\n", merged.SurfaceArea())
	if b, nm := merged.EdgeStats(); b == 0 && nm == 0 {
		fmt.Printf("volume:   %.6g (closed mesh)\n", merged.Volume())
	} else {
		fmt.Printf("volume:   n/a (open mesh: %d boundary edges, %d non-manifold edges)\n", b, nm)
	}
	if len(scene.Meshes) > 1 {
		fmt.Println("per object:")
		for _, m := range scene.Meshes {
			closed := "open"
			if m.Closed() {
				closed = "closed"
			}
			fmt.Printf("  %-24s %7d verts %7d tris  %s\n", m.Name, len(m.Verts), len(m.Tris), closed)
		}
	}
}

func cmdView(args []string) {
	fs := flag.NewFlagSet("view", flag.ExitOnError)
	views := fs.String("views", "front,side,top", "comma-separated view list")
	width := fs.Int("width", 64, "characters per view")
	object := fs.String("object", "", "only draw this object")
	parseInterspersed(fs, args)
	if fs.NArg() != 1 {
		die("view takes exactly one file")
	}
	scene, err := mesh.ReadFile(fs.Arg(0))
	if err != nil {
		die("%v", err)
	}
	m := scene.Merged()
	if *object != "" {
		if m = scene.Mesh(*object); m == nil {
			die("no object named %q in %s (use 'mesht info' to list)", *object, fs.Arg(0))
		}
	}
	for _, name := range strings.Split(*views, ",") {
		name = strings.TrimSpace(strings.ToLower(name))
		v, ok := mesh.Views[name]
		if !ok {
			die("unknown view %q (available: %s)", name, strings.Join(mesh.ViewOrder, ", "))
		}
		fmt.Println(mesh.RenderASCII(m, v, *width))
	}
}

func cmdCreate(args []string) {
	if len(args) < 1 {
		die("create needs a primitive: box, sphere, cylinder, cone, plane, torus")
	}
	prim := args[0]
	fs := flag.NewFlagSet("create", flag.ExitOnError)
	size := fs.String("size", "1,1,1", "box/plane size")
	radius := fs.Float64("radius", 0, "radius")
	tube := fs.Float64("tube", 0.25, "torus tube radius")
	height := fs.Float64("height", 1, "height")
	segments := fs.Int("segments", 24, "segments around")
	rings := fs.Int("rings", 12, "rings (sphere/torus)")
	name := fs.String("name", "", "object name")
	out := fs.String("o", "", "output file (.obj or .stl)")
	ascii := fs.Bool("ascii", false, "write text STL")
	parseInterspersed(fs, args[1:])
	if *out == "" {
		die("create needs -o <out.obj|out.stl>")
	}
	var m *mesh.Mesh
	switch prim {
	case "box":
		sz, err := parseVec(*size, true)
		if err != nil {
			die("--size: %v", err)
		}
		m = mesh.Box(sz)
	case "sphere":
		m = mesh.Sphere(defRadius(*radius, 1), *segments, *rings)
	case "cylinder":
		m = mesh.Cylinder(defRadius(*radius, 0.5), *height, *segments)
	case "cone":
		m = mesh.Cone(defRadius(*radius, 0.5), *height, *segments)
	case "plane":
		sz, err := parseVec(*size, true)
		if err != nil {
			die("--size: %v", err)
		}
		m = mesh.Plane(sz.X, sz.Z)
	case "torus":
		m = mesh.Torus(defRadius(*radius, 1), *tube, *segments, *rings)
	default:
		die("unknown primitive %q", prim)
	}
	if *name != "" {
		m.Name = *name
	}
	scene := &mesh.Scene{Meshes: []*mesh.Mesh{m}}
	if err := mesh.WriteFile(*out, scene, *ascii); err != nil {
		die("%v", err)
	}
	fmt.Printf("%s  (%s: %d verts, %d tris)\n", *out, m.Name, len(m.Verts), len(m.Tris))
}

func defRadius(r, def float64) float64 {
	if r <= 0 {
		return def
	}
	return r
}

func cmdTransform(args []string) {
	fs := flag.NewFlagSet("transform", flag.ExitOnError)
	center := fs.Bool("center", false, "move bbox center to origin")
	mirror := fs.String("mirror", "", "x|y|z")
	scale := fs.String("scale", "", "s or x,y,z")
	rotate := fs.String("rotate", "", "degrees x,y,z")
	translate := fs.String("translate", "", "x,y,z")
	fit := fs.Float64("fit", 0, "scale so the largest dimension equals this")
	object := fs.String("object", "", "only transform this object")
	out := fs.String("o", "", "output file (default: overwrite input)")
	ascii := fs.Bool("ascii", false, "write text STL")
	parseInterspersed(fs, args)
	if fs.NArg() != 1 {
		die("transform takes exactly one file")
	}
	in := fs.Arg(0)
	scene, err := mesh.ReadFile(in)
	if err != nil {
		die("%v", err)
	}
	targets := scene.Meshes
	if *object != "" {
		m := scene.Mesh(*object)
		if m == nil {
			die("no object named %q in %s (use 'mesht info' to list)", *object, in)
		}
		targets = []*mesh.Mesh{m}
	}

	if *center {
		mn, mx := mesh.SceneBBox(targets)
		c := mn.Add(mx.Sub(mn).Mul(0.5))
		mesh.ApplyAll(targets, mesh.Translate(c.Mul(-1)))
	}
	if *mirror != "" {
		s := mesh.Vec3{X: 1, Y: 1, Z: 1}
		switch strings.ToLower(*mirror) {
		case "x":
			s.X = -1
		case "y":
			s.Y = -1
		case "z":
			s.Z = -1
		default:
			die("--mirror must be x, y or z")
		}
		mesh.ApplyAll(targets, mesh.ScaleXYZ(s))
	}
	if *scale != "" {
		v, err := parseVec(*scale, true)
		if err != nil {
			die("--scale: %v", err)
		}
		mesh.ApplyAll(targets, mesh.ScaleXYZ(v))
	}
	if *rotate != "" {
		v, err := parseVec(*rotate, false)
		if err != nil {
			die("--rotate: %v", err)
		}
		rot := mesh.RotateZ(v.Z).Mul(mesh.RotateY(v.Y)).Mul(mesh.RotateX(v.X))
		mesh.ApplyAll(targets, rot)
	}
	if *translate != "" {
		v, err := parseVec(*translate, false)
		if err != nil {
			die("--translate: %v", err)
		}
		mesh.ApplyAll(targets, mesh.Translate(v))
	}
	if *fit > 0 {
		mn, mx := mesh.SceneBBox(targets)
		size := mx.Sub(mn)
		longest := math.Max(size.X, math.Max(size.Y, size.Z))
		if longest > 0 {
			f := *fit / longest
			mesh.ApplyAll(targets, mesh.ScaleXYZ(mesh.Vec3{X: f, Y: f, Z: f}))
		}
	}

	if *out == "" {
		*out = in
	}
	if err := mesh.WriteFile(*out, scene, *ascii); err != nil {
		die("%v", err)
	}
	fmt.Printf("%s  (%d objects, %d verts, %d tris)\n", *out, len(scene.Meshes), scene.TotalVerts(), scene.TotalTris())
}

func cmdMerge(args []string) {
	fs := flag.NewFlagSet("merge", flag.ExitOnError)
	out := fs.String("o", "", "output file")
	flatten := fs.Bool("flatten", false, "merge everything into a single object")
	ascii := fs.Bool("ascii", false, "write text STL")
	parseInterspersed(fs, args)
	if fs.NArg() < 2 {
		die("merge needs at least two input files")
	}
	if *out == "" {
		die("merge needs -o <out>")
	}
	scene := &mesh.Scene{}
	for _, path := range fs.Args() {
		s, err := mesh.ReadFile(path)
		if err != nil {
			die("%v", err)
		}
		scene.Append(s)
	}
	if *flatten {
		scene = &mesh.Scene{Meshes: []*mesh.Mesh{scene.Merged()}}
	}
	if err := mesh.WriteFile(*out, scene, *ascii); err != nil {
		die("%v", err)
	}
	fmt.Printf("%s  (%d objects, %d verts, %d tris)\n", *out, len(scene.Meshes), scene.TotalVerts(), scene.TotalTris())
}

func cmdConvert(args []string) {
	fs := flag.NewFlagSet("convert", flag.ExitOnError)
	out := fs.String("o", "", "output file")
	ascii := fs.Bool("ascii", false, "write text STL")
	parseInterspersed(fs, args)
	if fs.NArg() != 1 || *out == "" {
		die("convert takes one input file and -o <out>")
	}
	scene, err := mesh.ReadFile(fs.Arg(0))
	if err != nil {
		die("%v", err)
	}
	if err := mesh.WriteFile(*out, scene, *ascii); err != nil {
		die("%v", err)
	}
	fmt.Printf("%s  (%d objects, %d verts, %d tris)\n", *out, len(scene.Meshes), scene.TotalVerts(), scene.TotalTris())
}

func die(format string, a ...any) {
	fmt.Fprintf(os.Stderr, "mesht: "+format+"\n", a...)
	os.Exit(1)
}