slicer-service/api/internal/slicer/slicer.go

package slicer

import (
	"bufio"
	"context"
	"encoding/json"
	"fmt"
	"math"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"
	"time"

	"github.com/sotigr/slic3r-api/internal/cli"
)

// ModelSize holds the bounding box dimensions of the model in millimeters.
type ModelSize struct {
	X float64 `json:"x_mm"`
	Y float64 `json:"y_mm"`
	Z float64 `json:"z_mm"`
}

// FFFResult holds the analysis results for a Fused Filament Fabrication print.
type FFFResult struct {
	PrintTimeSeconds int64   `json:"print_time_seconds"`
	FilamentWeightG  float64 `json:"filament_weight_g"`
}

// SLAResult holds the analysis results for a Stereolithography (resin) print.
type SLAResult struct {
	PrintTimeSeconds int64   `json:"print_time_seconds"`
	MaterialVolumeMl float64 `json:"material_volume_ml"`
}

// AnalyzeOptions configures optional parameters for analysis.
type AnalyzeOptions struct {
	// Scale is the target size in millimeters applied before slicing.
	// The model is scaled uniformly so its longest axis fits within Scale mm.
	// A value of 0 means no scaling.
	Scale float64
}

// SlicerService analyzes 3D model files using PrusaSlicer.
type SlicerService interface {
	AnalyzeFFF(modelPath string, opts AnalyzeOptions) (*FFFResult, error)
	AnalyzeSLA(modelPath string, opts AnalyzeOptions) (*SLAResult, error)
}

type prusaSlicerService struct {
	fffConfigPath string
	slaConfigPath string
}

// NewSlicerService creates a SlicerService backed by PrusaSlicer CLI.
func NewSlicerService(fffConfigPath, slaConfigPath string) SlicerService {
	return &prusaSlicerService{
		fffConfigPath: fffConfigPath,
		slaConfigPath: slaConfigPath,
	}
}

// bedDimensions parses bed_shape and max_print_height from a PrusaSlicer INI config.
// Returns the usable bed width (xMM), depth (yMM), and max height (zMM).
func bedDimensions(configPath string) (xMM, yMM, zMM float64) {
	data, err := os.ReadFile(configPath)
	if err != nil {
		return
	}

	bedShapeRe := regexp.MustCompile(`^bed_shape\s*=\s*(.+)$`)
	maxHeightRe := regexp.MustCompile(`^max_print_height\s*=\s*([\d.]+)`)
	pointRe := regexp.MustCompile(`([\d.]+)x([\d.]+)`)

	minX := math.MaxFloat64
	minY := math.MaxFloat64
	maxX := -math.MaxFloat64
	maxY := -math.MaxFloat64

	scanner := bufio.NewScanner(strings.NewReader(string(data)))
	for scanner.Scan() {
		line := scanner.Text()
		if m := bedShapeRe.FindStringSubmatch(line); m != nil {
			for _, pt := range pointRe.FindAllStringSubmatch(m[1], -1) {
				x, _ := strconv.ParseFloat(pt[1], 64)
				y, _ := strconv.ParseFloat(pt[2], 64)
				if x < minX {
					minX = x
				}
				if x > maxX {
					maxX = x
				}
				if y < minY {
					minY = y
				}
				if y > maxY {
					maxY = y
				}
			}
		}
		if m := maxHeightRe.FindStringSubmatch(line); m != nil {
			zMM, _ = strconv.ParseFloat(m[1], 64)
		}
	}

	if maxX > -math.MaxFloat64 {
		xMM = maxX - minX
		yMM = maxY - minY
	}
	return
}

// parsePrintTime converts a PrusaSlicer time string like "3h 27m 26s" into seconds.
func parsePrintTime(s string) int64 {
	var h, m, sec int64
	if match := regexp.MustCompile(`(\d+)h`).FindStringSubmatch(s); match != nil {
		h, _ = strconv.ParseInt(match[1], 10, 64)
	}
	if match := regexp.MustCompile(`(\d+)m`).FindStringSubmatch(s); match != nil {
		m, _ = strconv.ParseInt(match[1], 10, 64)
	}
	if match := regexp.MustCompile(`(\d+)s`).FindStringSubmatch(s); match != nil {
		sec, _ = strconv.ParseInt(match[1], 10, 64)
	}
	return h*3600 + m*60 + sec
}

// scaleArgs returns --scale-to-fit CLI arguments for the given options, or nil if no scaling is needed.
// Scale is treated as the target size in mm; the model is scaled uniformly to fit within a cube of that size.
func scaleArgs(opts AnalyzeOptions) []string {
	if opts.Scale > 0 {
		s := strconv.FormatFloat(opts.Scale, 'f', -1, 64)
		return []string{"--scale-to-fit", s + "," + s + "," + s}
	}
	return nil
}

// parseModelSize extracts the bounding box from PrusaSlicer --info output.
func parseModelSize(output string) ModelSize {
	re := regexp.MustCompile(`Size:\s*([\d.]+)\s*x\s*([\d.]+)\s*x\s*([\d.]+)`)
	if m := re.FindStringSubmatch(output); m != nil {
		x, _ := strconv.ParseFloat(m[1], 64)
		y, _ := strconv.ParseFloat(m[2], 64)
		z, _ := strconv.ParseFloat(m[3], 64)
		return ModelSize{X: x, Y: y, Z: z}
	}
	return ModelSize{}
}
func parseDurationToSeconds(input string) (int, error) {
	// 1. Remove spaces to format the string for time.ParseDuration
	// Example: "2h 41m 24s" -> "2h41m24s"
	cleaned := strings.ReplaceAll(input, " ", "")

	// 2. Parse the string into a time.Duration object
	d, err := time.ParseDuration(cleaned)
	if err != nil {
		return 0, err
	}

	// 3. Convert duration to seconds (as an integer)
	return int(d.Seconds()), nil
}
func (s *prusaSlicerService) AnalyzeFFF(modelPath string, opts AnalyzeOptions) (*FFFResult, error) {
	tmpDir, err := os.MkdirTemp("", "slicer-fff-*")
	if err != nil {
		return nil, fmt.Errorf("create temp dir: %w", err)
	}
	defer os.RemoveAll(tmpDir)

	outputPath := filepath.Join("./", "output.gcode")

	args := []string{"--load", s.fffConfigPath, "--export-gcode", "--info", "--output", outputPath}
	args = append(args, scaleArgs(opts)...)
	args = append(args, modelPath)

	pipe := cli.Pipe{
		Command: "prusa-slicer",
		Args:    args,
	}

	_, _, err = pipe.ExecuteCombined(context.Background())
	if err != nil {
		return nil, fmt.Errorf("prusa-slicer: %w", err)
	}

	gcodeRe := regexp.MustCompile(`\W?\;\W?(.*)=(.*)`)

	b, err := os.ReadFile(outputPath)
	if err != nil {
		return nil, err
	}
	gcodeLines := strings.Split(string(b), "\n")

	filamentGrams := 0.0
	time := 0
	for _, line := range gcodeLines {
		l := strings.TrimSpace(line)

		if strings.HasPrefix(l, ";") {
			matches := gcodeRe.FindStringSubmatch(l)

			if len(matches) > 0 {
				key := strings.TrimSpace(matches[1])
				value := strings.TrimSpace(matches[2])
				switch key {
				case "filament used [g]":
					filamentGrams, _ = strconv.ParseFloat(value, 32)
				}
				if strings.HasPrefix(key, "estimated printing time") {
					time, _ = parseDurationToSeconds(value)
				}
			}
		}
	}

	return &FFFResult{
		PrintTimeSeconds: int64(time),
		FilamentWeightG:  filamentGrams,
	}, nil
}

type slaPwmxOutputConfig struct {
	UsedMaterial     float32 `json:"usedMaterial"`
	PrintTimeSeconds float32 `json:"printTime"`
}

func (s *prusaSlicerService) AnalyzeSLA(modelPath string, opts AnalyzeOptions) (*SLAResult, error) {
	tmpDir, err := os.MkdirTemp("", "slicer-sla-*")
	if err != nil {
		return nil, fmt.Errorf("create temp dir: %w", err)
	}
	defer os.RemoveAll(tmpDir)

	outputPath := filepath.Join("./", "output.pwmx")

	args := []string{"--load", s.slaConfigPath, "--export-sla", "--info", "--output", outputPath}
	args = append(args, scaleArgs(opts)...)
	args = append(args, modelPath)

	pipe := cli.Pipe{
		Command: "prusa-slicer",
		Args:    args,
	}

	_, _, err = pipe.Execute(context.Background())
	if err != nil {
		return nil, fmt.Errorf("prusa-slicer: %w", err)
	}

	pipe = cli.Pipe{
		SuffixSymbol: ">",
		Command:      "unzip",
		Args:         []string{"-p", outputPath, "config.json"},
	}
	outputPipe := cli.Pipe{
		Command: "config.json",
	}
	_, _, err = cli.ExecuteCLIPipeLine(context.Background(), []cli.Pipe{
		pipe, outputPipe,
	})
	if err != nil {
		return nil, fmt.Errorf("sla-analysi: %w", err)
	}

	file, err := os.ReadFile("config.json")
	if err != nil {
		return nil, err
	}

	var outputCfg slaPwmxOutputConfig
	err = json.Unmarshal(file, &outputCfg)
	if err != nil {
		return nil, err
	}

	return &SLAResult{
		PrintTimeSeconds: int64(outputCfg.PrintTimeSeconds),
		MaterialVolumeMl: float64(outputCfg.UsedMaterial),
	}, nil
}