//! # Example: File Import (OBJ)
//!
//! Demonstrates loading a Wavefront OBJ file with `wsg_lib::mesh::load_obj`.
//! Parses the file and prints geometry statistics.
//!
//! ## Build & Run
//! ```sh
//! cargo run -p wsg-lib --example import --features import-obj -- /path/to/model.obj
//! ```
//!
//! Without a file argument, parses a built-in sample triangle.

use wsg_lib::mesh::import::parse_obj;
use wsg_lib::mesh::load_obj;

fn main() {
    let args: Vec<String> = std::env::args().collect();

    let content = if args.len() > 1 {
        let path = &args[1];
        eprintln!("Loading: {path}");
        match load_obj(path) {
            Ok(geom) => {
                print_stats(&geom);
                return;
            }
            Err(e) => {
                eprintln!("Error: {e}");
                std::process::exit(1);
            }
        }
    } else {
        eprintln!("No file argument — parsing a built-in sample.");
        eprintln!("Usage: import <model.obj>");
        // Built-in sample: a simple triangle with UVs and normals
        "v 0.0 0.0 0.0\nv 1.0 0.0 0.0\nv 0.5 1.0 0.0\nvn 0 0 1\nvt 0.0 0.0\nvt 1.0 0.0\nvt 0.5 1.0\nf 1/1/1 2/2/1 3/3/1\n"
    };

    let geom = parse_obj(content).expect("sample should parse");
    print_stats(&geom);
}

fn print_stats(geom: &wsg_lib::Geometry) {
    println!("\n=== Geometry Statistics ===");
    println!("  Vertices: {}", geom.positions.len());
    if let Some(n) = &geom.normals {
        println!("  Normals:  {}", n.len());
    }
    if let Some(uv) = &geom.uvs {
        println!("  UVs:      {}", uv.len());
    }
    if let Some(idx) = &geom.indices {
        println!("  Indices:  {} ({} triangles)", idx.len(), idx.len() / 3);
    }
    if let Err(e) = geom.validate() {
        println!("  Validation FAILED: {e}");
    } else {
        println!("  Validation: OK");
    }
    // Bounding box
    if let Some(bbox) = geom.bbox() {
        println!("  BBox min: {:?}", bbox.min);
        println!("  BBox max: {:?}", bbox.max);
    }
    println!();
}