<?php

if (! defined('ABSPATH')) {
    exit;
}

// STL parser and calculation engine for standalone plugin use.
// This code is ported from the 3d-parser-api-main ParserController logic.

if (! defined('PPC3D_LAYER_HEIGHT_MM')) {
    define('PPC3D_LAYER_HEIGHT_MM', 0.2);
}

if (! defined('PPC3D_PRINTER_SPEED_MM_PER_S')) {
    define('PPC3D_PRINTER_SPEED_MM_PER_S', 90);
}

if (! defined('PPC3D_MATERIAL_DENSITY')) {
    define('PPC3D_MATERIAL_DENSITY', 0.139419183);
}

if (! defined('PPC3D_SUPPORT_MATERIAL_PERCENTAGE')) {
    define('PPC3D_SUPPORT_MATERIAL_PERCENTAGE', 0.008);
}

function ppc3d_parse_stl_file($file_path, $unit, $scale)
{
    $vertices = array();
    $faces = array();

    $file = fopen($file_path, 'r');
    if (! $file) {
        throw new RuntimeException('Unable to open STL file: ' . $file_path);
    }

    fseek($file, 80);
    $triangles = unpack('V', fread($file, 4))[1];

    for ($i = 0; $i < $triangles; $i++) {
        fread($file, 12);
        $faceVertices = array();

        for ($j = 0; $j < 3; $j++) {
            $vertex = unpack('f*', fread($file, 12));
            $index = count($vertices);
            $vertices[] = $vertex;
            $faceVertices[] = $index;
        }

        $faces[] = $faceVertices;
        fread($file, 2);
    }

    fclose($file);

    if ($unit === 'inch') {
        $scale *= 25.4;
    }

    foreach ($vertices as &$vertex) {
        $vertex = array_map(function ($v) use ($scale) {
            return $v * $scale;
        }, $vertex);
    }
    unset($vertex);

    return array('vertices' => $vertices, 'faces' => $faces);
}

function ppc3d_tetrahedron_volume($v0, $v1, $v2)
{
    $volume = (1 / 6) * abs(
        $v0[1] * ($v1[2] * $v2[3] - $v2[2] * $v1[3]) +
        $v1[1] * ($v2[2] * $v0[3] - $v0[2] * $v2[3]) +
        $v2[1] * ($v0[2] * $v1[3] - $v1[2] * $v0[3])
    );

    return $volume;
}

function ppc3d_calculate_stl_volume($parsed_data, $unit, $scale, $layer_height_mm, $printer_speed_mm_per_s)
{
    // `ppc3d_parse_stl_file` already applied unit/scale to vertices,
    // use the parsed vertices directly to avoid double-scaling.
    $scaled_vertices = $parsed_data['vertices'];

    $total_volume = 0;
    foreach ($parsed_data['faces'] as $faceVertices) {
        $v0 = $scaled_vertices[$faceVertices[0]];
        $v1 = $scaled_vertices[$faceVertices[1]];
        $v2 = $scaled_vertices[$faceVertices[2]];

        $tetrahedron_volume = ppc3d_tetrahedron_volume($v0, $v1, $v2);
        if ($tetrahedron_volume !== false) {
            $total_volume += $tetrahedron_volume;
        } else {
            // Handle error in volume calculation
            return false;
        }
    }
    
    $total_volume_cm3 = $total_volume / 1000.0;

    return $total_volume_cm3;
}

function ppc3d_calculate_printing_time($parsed_data, $layer_height, $printer_speed)
{
    $max_z = max(array_map(function ($vertex) {
        return $vertex[2];
    }, $parsed_data['vertices']));

    $num_layers = ceil($max_z / $layer_height);
    $printing_time_hours = ($num_layers * $layer_height) / $printer_speed;

    return $printing_time_hours;
}

function ppc3d_calculate_total_grams($parsed_data)
{
    $density = PPC3D_MATERIAL_DENSITY; // grams per cubic centimeter (g/cm³)
    $total_volume_mm3 = 0;

    foreach ($parsed_data['faces'] as $faceVertices) {
        $v0 = $parsed_data['vertices'][$faceVertices[0]];
        $v1 = $parsed_data['vertices'][$faceVertices[1]];
        $v2 = $parsed_data['vertices'][$faceVertices[2]];

        $tetrahedron_volume = ppc3d_tetrahedron_volume($v0, $v1, $v2);
        if ($tetrahedron_volume === false) {
            return false;
        }

        $total_volume_mm3 += $tetrahedron_volume;
    }

    // Convert mm³ to cm³ and multiply by density (g/cm³)
    $total_volume_cm3 = $total_volume_mm3 / 1000.0;

    return $total_volume_cm3 * $density;
}

function ppc3d_calculate_triangle_surface_area($v0, $v1, $v2)
{
    $a = sqrt(pow($v1[1] - $v0[1], 2) + pow($v1[2] - $v0[2], 2) + pow($v1[3] - $v0[3], 2));
    $b = sqrt(pow($v2[1] - $v1[1], 2) + pow($v2[2] - $v1[2], 2) + pow($v2[3] - $v1[3], 2));
    $c = sqrt(pow($v0[1] - $v2[1], 2) + pow($v0[2] - $v2[2], 2) + pow($v0[3] - $v2[3], 2));

    $s = ($a + $b + $c) / 2;
    $area = sqrt($s * ($s - $a) * ($s - $b) * ($s - $c));

    return $area;
}