use std::str;

use super::Q3BspFile;
use crate::coords::CoordSystem;
use crate::helpers::slice_to_u32;
use crate::traits::textures::*;
use crate::types::{ParseError, Result};

const TEXTURE_LUMP_SIZE: usize = 64 + 4 + 4;

/// Try to parse the given buffer as an entities lump.
/// # Format
/// Each entity is:
/// string[64] name     Texture name.
/// int flags           Surface flags.
/// int contents        Content flags.
/// Length of entities is total lump size / TEXTURE_LUMP_SIZE (64 + 4 + 4)
pub fn from_data(lump: &[u8]) -> Result<Box<[Texture]>> {
    if lump.is_empty() || lump.len() % TEXTURE_LUMP_SIZE != 0 {
        return Err(ParseError::Invalid);
    }
    let length = lump.len() / TEXTURE_LUMP_SIZE;

    let mut textures = Vec::with_capacity(length);
    for n in 0..length {
        let offset = n * TEXTURE_LUMP_SIZE;
        textures.push(Texture {
            name: str::from_utf8(&lump[offset..offset + 64])
                .map_err(|_| ParseError::Invalid)?
                .trim_matches('\0')
                .to_owned(),
            surface: SurfaceFlags::from_bits_truncate(slice_to_u32(
                &lump[offset + 64..offset + 68],
            )),
            contents: ContentsFlags::from_bits_truncate(slice_to_u32(
                &lump[offset + 68..offset + 72],
            )),
        });
    }

    Ok(textures.into_boxed_slice())
}

impl<T: CoordSystem> HasTextures for Q3BspFile<T> {
    type TexturesIter<'a> = std::slice::Iter<'a, Texture>;

    fn textures_iter(&self) -> Self::TexturesIter<'_> {
        self.textures.iter()
    }

    fn get_texture(&self, idx: u32) -> Option<&Texture> {
        if idx >= self.textures.len() as u32 {
            None
        } else {
            Some(&self.textures[idx as usize])
        }
    }
}

#[test]
fn textures_single_texture() {
    let buf: &[u8] = &[
        b'T', b'E', b'S', b'T', b' ', b'T', b'E', b'X', b'T', b'U', b'R', b'E', 0x00, 0x00, 0x00,
        0x00, // name (padded to 64 bytes)
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x43, 0x00, 0x04, 0x00, // surface flags
        0x09, 0x00, 0x00, 0x00, // contents flags
    ];

    let lump = from_data(buf).unwrap();

    assert_eq!(lump.len(), 1);

    assert_eq!(lump[0].name, "TEST TEXTURE");
    assert_eq!(
        lump[0].surface,
        SurfaceFlags::NO_DAMAGE | SurfaceFlags::SLICK | SurfaceFlags::FLESH | SurfaceFlags::DUST
    );
    assert_eq!(lump[0].contents, ContentsFlags::SOLID | ContentsFlags::LAVA);
}

#[test]
fn textures_multiple_textures() {
    let buf: &[u8] = &[
        b'T', b'E', b'S', b'T', b' ', b'T', b'E', b'X', b'T', b'U', b'R', b'E', b'1', 0x00, 0x00,
        0x00, // name (padded to 64 bytes)
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x43, 0x00, 0x04, 0x00, // surface flags
        0x09, 0x00, 0x00, 0x00, // contents flags
        b'T', b'E', b'S', b'T', b' ', b'T', b'E', b'X', b'T', b'U', b'R', b'E', b'2', 0x00, 0x00,
        0x00, // name (padded to 64 bytes)
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x2c, 0x10, 0x00, 0x00, // surface flags
        0x01, 0x00, 0x00, 0x00, // contents flags
        b'T', b'E', b'S', b'T', b' ', b'T', b'E', b'X', b'T', b'U', b'R', b'E', b'3', 0x00, 0x00,
        0x00, // name (padded to 64 bytes)
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x0a, 0x00, 0x00, // surface flags
        0x41, 0x00, 0x00, 0x00, // contents flags
    ];

    let lump = from_data(buf).unwrap();

    assert_eq!(lump.len(), 3);

    assert_eq!(lump[0].name, "TEST TEXTURE1");
    assert_eq!(lump[1].name, "TEST TEXTURE2");
    assert_eq!(lump[2].name, "TEST TEXTURE3");

    assert_eq!(
        lump[0].surface,
        SurfaceFlags::NO_DAMAGE | SurfaceFlags::SLICK | SurfaceFlags::FLESH | SurfaceFlags::DUST
    );
    assert_eq!(
        lump[1].surface,
        SurfaceFlags::METAL_STEPS
            | SurfaceFlags::NO_MARKS
            | SurfaceFlags::LADDER
            | SurfaceFlags::SKY
    );
    assert_eq!(
        lump[2].surface,
        SurfaceFlags::POINT_LIGHT | SurfaceFlags::SKIP
    );

    assert_eq!(lump[0].contents, ContentsFlags::SOLID | ContentsFlags::LAVA);
    assert_eq!(lump[1].contents, ContentsFlags::SOLID);
    assert_eq!(lump[2].contents, ContentsFlags::SOLID | ContentsFlags::FOG);
}