//! Module containing the parser for material files from Wavefront OBJ (mtl files).

use std::path::PathBuf;

use parser::{Element, ParserError, LineParser};
use parser::obj::parse_values;

use math::vector::Vector3;

/// Wavefront material file format parser.
pub struct MtlParser {

}

impl MtlParser {

    /// Creates a MtlParser.
    pub fn new() -> MtlParser {
        MtlParser {

        }
    }

}

impl LineParser for MtlParser {
    fn parse_line(&mut self, line_number: usize, line: &str, path: &str) -> Result<Element, ParserError> {

        let mut root = PathBuf::from(path);
        root.pop();

        let mut split = line.split_whitespace();

        if let Some(first) = split.nth(0) {

            let first = first.trim();

            match first {

                // Ignore comments
                "#" => Ok(Element::None),

                // Starts a new material
                "newmtl"  => Ok(Element::NewMaterial(split.nth(0).unwrap().to_owned())),

                "Kd" => {
                    let values = parse_values(line_number, line, path, 3)?;
                    Ok(Element::Diffuse(Vector3::new(
                        values[0] as f32,
                        values[1] as f32,
                        values[2] as f32,
                    )))
                },

                map if map.starts_with("map_") => {

                    let mut full_path = root.clone();
                    full_path.push(split.nth(0).unwrap().to_owned());
                    Ok(Element::Texture(first.to_owned(), full_path.to_str().unwrap().to_owned()))

                },

                // The keyword is not empty and unexpected
                // We don't do this : we simply return an unknown material instruction
                // key if key.len() != 0 => {
                //     Err(ParserError::UnexpectedKeyword(path.to_owned(), line_number, key.to_owned()))
                // },

                // Empty string
                "" => Ok(Element::None),

                // Unknown instruction
                _  => Ok(Element::UnknownMaterialInstruction(line.to_owned())),

            }
        } else {
           Ok(Element::None)
        }
    }
}