use crate::tokenizer::Tokenizer;
use error::SourceFile;
use miette::{Diagnostic, IntoDiagnostic, Result, SourceSpan, bail, miette};
use ray_tracing_core::{
    affine_transform::AffineTransform,
    math::{Dir3, Pos3},
    prelude::Float,
};
use std::{
    collections::HashMap,
    path::{Path, PathBuf},
    sync::Arc,
};
use texture::PbrtTexture;
use thiserror::Error;

#[macro_use]
mod tokenizer;

mod error;

mod texture;
struct Lexer {
    input: Tokenizer,
}

impl Lexer {
    fn new(path: impl AsRef<Path>) -> Result<Self> {
        Ok(Self {
            input: Tokenizer::new(path)?,
        })
    }
}

#[derive(Debug)]
enum CameraType {
    Orthographic {
        frame_aspect_ratio: Option<Float>,
        screen_window: Option<Float>,
        lens_radius: Float,
        focal_distance: Float,
    },
    Perspective {
        frame_aspect_ratio: Option<Float>,
        screen_window: Option<Float>,
        lens_radius: Float,
        focal_distance: Float,
        fov: Float,
    },
}

#[derive(Debug)]
struct PbrtCamera {
    camera_type: CameraType,
    shutter_open: Float,
    shutter_close: Float,
}

#[derive(Debug)]
enum Statement {
    AttributeBegin,
    AttributeEnd,
    WorldBegin,
    Camera(PbrtCamera),
    Include(String),
    ConcatTransform(AffineTransform),
    CoordinateSystem(String),
    CoordSysTransform(String),
    Shape(ShapeType, ShapeAlpha),
    Unknown(String, Vec<String>),
    Transform(AffineTransform),
    Texture(String, Arc<dyn PbrtTexture>),
}

fn parse_look_at(iter: &mut Tokenizer) -> Result<Statement> {
    let eye = Pos3::new(iter.parse_next()?, iter.parse_next()?, iter.parse_next()?);
    let look_at = Pos3::new(iter.parse_next()?, iter.parse_next()?, iter.parse_next()?);
    let up = Dir3::new(iter.parse_next()?, iter.parse_next()?, iter.parse_next()?);

    Ok(Statement::ConcatTransform(
        AffineTransform::look_at(eye, look_at, up)
            .ok_or(miette!("Unable to calculate inverse of matrix"))?,
    ))
}

fn parse_shape(iter: &mut Tokenizer) -> Result<Statement> {
    let shape_type = iter.next().ok_or(miette!("unable to get shape type"))??;

    match shape_type.as_str() {
        "\"sphere\"" => {
            let t = parse_dict!(iter =>
                radius, Float, 1.0;
                zmin, Float, {-radius};
                zmax, Float, {radius};
                phimax, Float, 360.0;
                alpha, ShapeAlpha, ShapeAlpha::None
                =>
                radius, "\"float radius\"", iter.parse_parameter()?;
                zmin, "\"float zmin\"", iter.parse_parameter()?;
                zmax, "\"float zmax\"", iter.parse_parameter()?;
                phimax, "\"float phimax\"", iter.parse_parameter()?;
                alpha, "\"float alpha\"", ShapeAlpha::Value(iter.parse_parameter()?);
                alpha, "\"texture alpha\"", ShapeAlpha::Texture(iter.parse_parameter()?)
            );
            Ok(Statement::Shape(
                ShapeType::Sphere {
                    radius: t.radius,
                    zmin: t.zmin,
                    zmax: t.zmax,
                    phimax: t.phimax,
                },
                t.alpha,
            ))
        }
        "\"trianglemesh\"" => {
            let t = parse_dict!(iter =>
                p, Vec<Pos3>, Vec::new();
                n, Vec<Dir3>, Vec::new();
                s, Vec<Dir3>, Vec::new();
                uv, Vec<[Float; 2]>, Vec::new();
                indices, Vec<usize>, Vec::new();
                alpha, ShapeAlpha, ShapeAlpha::None
                =>
                p, "\"point3 P\"", iter.parse_list_3(Pos3::new)?;
                n, "\"normal N\"", iter.parse_list_3(Dir3::new)?;
                s, "\"normal S\"", iter.parse_list_3(Dir3::new)?;
                uv, "\"point2 uv\"", iter.parse_list_2(|u, v| [u, v])?;
                indices, "\"integer indices\"", iter.parse_list()?;
                alpha, "\"float alpha\"", ShapeAlpha::Value(iter.parse_parameter()?);
                alpha, "\"texture alpha\"", ShapeAlpha::Texture(iter.parse_parameter()?)
            );

            if t.p.len() < 3 {
                bail!("At least 3 points required.")
            }
            if t.indices.is_empty() && t.p.len() != 3 {
                bail!("Indices required for trianglemesh with more than 3 points.")
            }

            if t.indices.len() % 3 != 0 {
                bail!(
                    "number of indices must be divisible by 3. num indices: {}",
                    t.indices.len()
                )
            }

            if !t.n.is_empty() && t.n.len() != t.p.len() {
                bail!("Number of normals not equal to number of positions.")
            }

            if !t.s.is_empty() && t.s.len() != t.p.len() {
                bail!("Number of tangents not equal to number of positions.")
            }
            if !t.uv.is_empty() && t.uv.len() != t.p.len() {
                bail!("Number of uvs not equal to number of positions.")
            }

            Ok(Statement::Shape(
                ShapeType::TriangleMesh {
                    indices: t.indices,
                    p: t.p,
                    n: t.n,
                    s: t.s,
                    uv: t.uv,
                },
                t.alpha,
            ))
        }
        "\"bilinearmesh\"" => {
            let t = parse_dict!(iter =>
                p, Vec<Pos3>, Vec::new();
                n, Vec<Dir3>, Vec::new();
                uv, Vec<[Float; 2]>, Vec::new();
                indices, Vec<usize>, Vec::new();
                alpha, ShapeAlpha, ShapeAlpha::None
                =>
                p, "\"point3 P\"", iter.parse_list_3(Pos3::new)?;
                n, "\"normal N\"", iter.parse_list_3(Dir3::new)?;
                uv, "\"point2 uv\"", iter.parse_list_2(|u, v| [u, v])?;
                indices, "\"integer indices\"", iter.parse_list()?;
                alpha, "\"float alpha\"", ShapeAlpha::Value(iter.parse_parameter()?);
                alpha, "\"texture alpha\"", ShapeAlpha::Texture(iter.parse_parameter()?)
            );

            if t.p.len() < 4 {
                bail!("At least 4 points required.")
            }
            if t.indices.is_empty() && t.p.len() != 4 {
                bail!("Indices required for trianglemesh with more than 4 points.")
            }

            if t.indices.len() % 4 != 0 {
                bail!(
                    "number of indices must be divisible by 4. num indices: {}",
                    t.indices.len()
                )
            }

            if !t.n.is_empty() && t.n.len() != t.p.len() {
                bail!("Number of normals not equal to number of positions.")
            }

            if !t.uv.is_empty() && t.uv.len() != t.p.len() {
                bail!("Number of uvs not equal to number of positions.")
            }

            Ok(Statement::Shape(
                ShapeType::BilinearMesh {
                    indices: t.indices,
                    p: t.p,
                    n: t.n,
                    uv: t.uv,
                },
                t.alpha,
            ))
        }
        "\"loopsubdiv\"" => {
            let t = parse_dict!(iter =>
                levels, u32, 3;
                indices, Vec<usize>, Vec::new();
                p, Vec<Pos3>, Vec::new();
                alpha, ShapeAlpha, ShapeAlpha::None
                =>
                levels, "\"integer levels\"", iter.parse_parameter()?;
                indices, "\"integer indices\"", iter.parse_list()?;
                p, "\"point3 P\"", iter.parse_list_3(Pos3::new)?;
                alpha, "\"float alpha\"", ShapeAlpha::Value(iter.parse_parameter()?);
                alpha, "\"texture alpha\"", ShapeAlpha::Texture(iter.parse_parameter()?)
            );

            if t.indices.is_empty() {
                bail!("indices are a required field")
            }

            if t.p.is_empty() {
                bail!("p is a required field")
            }

            Ok(Statement::Shape(
                ShapeType::LoopSubDiv {
                    levels: t.levels,
                    indices: t.indices,
                    p: t.p,
                },
                t.alpha,
            ))
        }
        "\"disk\"" => {
            let t = parse_dict!(iter =>
                height, Float, 0.0;
                radius, Float, 1.0;
                innerradius, Float, 0.0;
                phimax, Float, 360.0;
                alpha, ShapeAlpha, ShapeAlpha::None
                =>
                height, "\"float height\"", iter.parse_parameter()?;
                radius, "\"float radius\"", iter.parse_parameter()?;
                innerradius, "\"float innerradius\"", iter.parse_parameter()?;
                phimax, "\"float phimax\"", iter.parse_parameter()?;
                alpha, "\"float alpha\"", ShapeAlpha::Value(iter.parse_parameter()?);
                alpha, "\"texture alpha\"", ShapeAlpha::Texture(iter.parse_parameter()?)
            );

            Ok(Statement::Shape(
                ShapeType::Disk {
                    height: t.height,
                    radius: t.radius,
                    innerradius: t.innerradius,
                    phimax: t.phimax,
                },
                t.alpha,
            ))
        }
        "\"plymesh\"" => {
            let t = parse_dict!(iter =>
                filename, String, String::new();
                displacement, Option<String>, None;
                edgelength, Float, 1.0;
                alpha, ShapeAlpha, ShapeAlpha::None
                =>
                filename, "\"string filename\"", iter.parse_parameter()?;
                displacement, "\"string displacement\"", Some(iter.parse_parameter()?);
                edgelength, "\"float edgelength\"", iter.parse_parameter()?;
                alpha, "\"float alpha\"", ShapeAlpha::Value(iter.parse_parameter()?);
                alpha, "\"texture alpha\"", ShapeAlpha::Texture(iter.parse_parameter()?)
            );

            Ok(Statement::Shape(
                ShapeType::PlyMesh {
                    filename: t.filename,
                    displacement: t.displacement,
                    edgelength: t.edgelength,
                },
                t.alpha,
            ))
        }
        _ => Err(miette!("Unknown shape {}", shape_type)),
    }
}

fn parse_camera(tokenizer: &mut Tokenizer) -> Result<Statement> {
    let camera_type = tokenizer
        .next()
        .ok_or(miette!("unable to get shape type"))??;

    match camera_type.as_str() {
        "\"orthographic\"" => {
            let t = parse_dict!(tokenizer =>
                shutteropen, Float, 0.0;
                shutterclose, Float, 1.0;
                frame_aspect_ratio, Option<Float>, None;
                screen_window, Option<Float>, None;
                lens_radius, Float, 0.0;
                focal_distance, Float, Float::powi(10.0, 30)
                =>
                shutteropen, "\"float shutteropen\"", tokenizer.parse_parameter()?;
                shutterclose, "\"float shutterclose\"", tokenizer.parse_parameter()?;
                frame_aspect_ratio, "\"float frameaspectratio\"", Some(tokenizer.parse_parameter()?);
                screen_window, "\"float screenwindow\"", Some(tokenizer.parse_parameter()?);
                lens_radius, "\"float lensradius\"", tokenizer.parse_parameter()?;
                focal_distance, "\"float focaldistance\"", tokenizer.parse_parameter()?
            );

            Ok(Statement::Camera(PbrtCamera {
                camera_type: CameraType::Orthographic {
                    frame_aspect_ratio: t.frame_aspect_ratio,
                    screen_window: t.screen_window,
                    lens_radius: t.lens_radius,
                    focal_distance: t.focal_distance,
                },
                shutter_open: t.shutteropen,
                shutter_close: t.shutterclose,
            }))
        }
        "\"perspective\"" => {
            let t = parse_dict!(tokenizer =>
                shutteropen, Float, 0.0;
                shutterclose, Float, 1.0;
                frame_aspect_ratio, Option<Float>, None;
                screen_window, Option<Float>, None;
                lens_radius, Float, 0.0;
                focal_distance, Float, Float::powi(10.0, 30);
                fov, Float, 90.0
                =>
                shutteropen, "\"float shutteropen\"", tokenizer.parse_parameter()?;
                shutterclose, "\"float shutterclose\"", tokenizer.parse_parameter()?;
                frame_aspect_ratio, "\"float frameaspectratio\"", Some(tokenizer.parse_parameter()?);
                screen_window, "\"float screenwindow\"", Some(tokenizer.parse_parameter()?);
                lens_radius, "\"float lensradius\"", tokenizer.parse_parameter()?;
                focal_distance, "\"float focaldistance\"", tokenizer.parse_parameter()?;
                fov, "\"float fov\"", tokenizer.parse_parameter()?
            );

            Ok(Statement::Camera(PbrtCamera {
                camera_type: CameraType::Perspective {
                    frame_aspect_ratio: t.frame_aspect_ratio,
                    screen_window: t.screen_window,
                    lens_radius: t.lens_radius,
                    focal_distance: t.focal_distance,
                    fov: t.fov,
                },
                shutter_open: t.shutteropen,
                shutter_close: t.shutterclose,
            }))
        }
        _ => Err(miette!("Unknown camera_type {}", camera_type)),
    }
}

impl Lexer {
    fn next(
        &mut self,
        textures: &HashMap<String, Arc<dyn PbrtTexture>>,
    ) -> Option<Result<Statement>> {
        match self.input.next() {
            Some(Ok(s)) => match s.as_str() {
                "AttributeBegin" => Some(Ok(Statement::AttributeBegin)),
                "AttributeEnd" => Some(Ok(Statement::AttributeEnd)),
                "Include" => {
                    let s = self
                        .input
                        .next()
                        .unwrap()
                        .unwrap()
                        .trim_matches('"')
                        .to_string();

                    Some(Ok(Statement::Include(s)))
                }
                "Camera" => Some(parse_camera(&mut self.input)),
                "LookAt" => Some(parse_look_at(&mut self.input)),
                "Identity" => Some(Ok(Statement::ConcatTransform(AffineTransform::identity()))),
                "Translate" => Some(parse_translate(&mut self.input)),
                "Scale" => Some(parse_scale(&mut self.input)),
                "Shape" => Some(parse_shape(&mut self.input)),
                "Rotate" => Some(parse_rotate(&mut self.input)),
                "Transform" => Some(parse_transform(&mut self.input).map(Statement::Transform)),
                "Texture" => Some(
                    texture::parse_texture(&mut self.input)
                        .map(|(name, texture)| Statement::Texture(name, texture)),
                ),
                "ConcatTransform" => {
                    Some(parse_transform(&mut self.input).map(Statement::ConcatTransform))
                }
                "CoordinateSystem" => Some(match self.input.parse_parameter() {
                    Ok(s) => Ok(Statement::CoordinateSystem(s)),
                    Err(e) => Err(e),
                }),
                "CoordSysTransform" => Some(match self.input.parse_parameter() {
                    Ok(s) => Ok(Statement::CoordSysTransform(s)),
                    Err(e) => Err(e),
                }),

                "WorldBegin" => Some(Ok(Statement::WorldBegin)),
                _ => {
                    if s.chars().any(|c| !c.is_ascii_alphabetic()) {
                        Some(Err(miette!("malformed identifier")))
                    } else {
                        let mut v = Vec::new();

                        while let Some(p) = self
                            .input
                            .next_if(|s| !s.starts_with(|c: char| c.is_ascii_alphabetic()))
                        {
                            match p {
                                Ok(c) => v.push(c),
                                Err(e) => return Some(Err(e)),
                            }
                        }

                        Some(Ok(Statement::Unknown(s, v)))
                    }
                }
            },
            Some(Err(e)) => Some(Err(e)),
            None => None,
        }
    }
}

fn parse_transform(input: &mut Tokenizer) -> Result<AffineTransform> {
    if !input
        .next()
        .is_none_or(|p| p.is_ok_and(|p| p.as_str() == "["))
    {
        bail!("expected list.")
    }

    let mut v = [0.0; 16];

    for i in 0..16 {
        v[i] = input
            .next()
            .ok_or(miette!("value expected"))??
            .parse::<Float>()
            .into_diagnostic()?;
    }

    if !input
        .next()
        .is_none_or(|p| p.is_ok_and(|p| p.as_str() == "]"))
    {
        bail!("expected list end.")
    }

    if v[3] != 0.0 || v[7] != 0.0 || v[11] != 0.0 || v[15] != 1.0 {
        bail!("invalid transform entry")
    }

    AffineTransform::new([
        [v[0], v[4], v[8], v[12]],
        [v[1], v[5], v[9], v[13]],
        [v[2], v[6], v[10], v[14]],
    ])
    .ok_or(miette!("Unable to invert transformation"))
}

fn parse_translate(iter: &mut Tokenizer) -> Result<Statement> {
    let pos = Pos3::new(iter.parse_next()?, iter.parse_next()?, iter.parse_next()?);

    Ok(Statement::ConcatTransform(AffineTransform::translation(
        pos,
    )))
}

fn parse_scale(iter: &mut Tokenizer) -> Result<Statement> {
    Ok(Statement::ConcatTransform(AffineTransform::scale(
        iter.parse_next()?,
        iter.parse_next()?,
        iter.parse_next()?,
    )))
}

fn parse_rotate(iter: &mut Tokenizer) -> Result<Statement> {
    let angle = iter
        .next()
        .ok_or(miette!("missing argument"))??
        .parse()
        .into_diagnostic()?;
    let dir = Dir3::new(
        iter.next()
            .ok_or(miette!("missing argument"))??
            .parse()
            .into_diagnostic()?,
        iter.next()
            .ok_or(miette!("missing argument"))??
            .parse()
            .into_diagnostic()?,
        iter.next()
            .ok_or(miette!("missing argument"))??
            .parse()
            .into_diagnostic()?,
    );

    Ok(Statement::ConcatTransform(AffineTransform::rotation(
        angle, dir,
    )))
}
struct BytesToChar<I> {
    count: usize,
    iter: I,
}

impl<I> BytesToChar<I> {
    fn new(iter: I) -> Self {
        Self { count: 0, iter }
    }
}

impl<I: Iterator<Item = Result<u8, std::io::Error>>> Iterator for BytesToChar<I> {
    type Item = Result<(usize, char)>;

    fn next(&mut self) -> Option<Self::Item> {
        match self.iter.next()? {
            Ok(a) => {
                self.count += 1;
                if a & 0x80 == 0 {
                    Some(Ok((self.count - 1, char::from(a))))
                } else {
                    todo!()
                }
            }
            Err(e) => Some(Err(e).into_diagnostic()),
        }
    }
}

struct Parser<P> {
    path: P,
    inner: Option<Box<Parser<PathBuf>>>,
    iter: Lexer,
}

impl<P: AsRef<Path> + std::fmt::Debug> Parser<P> {
    fn new(path: P) -> Result<Self> {
        Ok(Self {
            iter: Lexer::new(path.as_ref())?,
            path,
            inner: None,
        })
    }
}

impl<P: AsRef<Path>> Parser<P> {
    fn next(
        &mut self,
        textures: &HashMap<String, Arc<dyn PbrtTexture>>,
    ) -> Option<Result<Statement>> {
        if let Some(iter) = &mut self.inner {
            if let Some(statement) = iter.next(textures) {
                return Some(statement);
            }
            self.inner = None;
        }

        match self.iter.next(textures) {
            Some(Ok(Statement::Include(s))) => {
                let path = self.path.as_ref().parent().unwrap().join(s);
                self.inner = Some(Box::new(Parser::new(path).unwrap()));

                self.next(textures)
            }
            Some(s) => Some(s),
            None => None,
        }
    }
}

#[derive(Debug)]
enum ShapeType {
    Sphere {
        radius: Float,
        zmin: Float,
        zmax: Float,
        phimax: Float,
    },
    TriangleMesh {
        indices: Vec<usize>,
        p: Vec<Pos3>,
        n: Vec<Dir3>,
        s: Vec<Dir3>,
        uv: Vec<[Float; 2]>,
    },
    BilinearMesh {
        indices: Vec<usize>,
        p: Vec<Pos3>,
        n: Vec<Dir3>,
        uv: Vec<[Float; 2]>,
    },
    LoopSubDiv {
        levels: u32,
        indices: Vec<usize>,
        p: Vec<Pos3>,
    },
    Disk {
        height: Float,
        radius: Float,
        innerradius: Float,
        phimax: Float,
    },
    PlyMesh {
        filename: String,
        displacement: Option<String>,
        edgelength: Float,
    },
}

#[derive(Debug)]
enum ShapeAlpha {
    None,
    Value(Float),
    Texture(String),
}

#[derive(Debug)]
struct Shape {
    ctm: AffineTransform,
    material: usize,
    obj: ShapeType,
    alpha: ShapeAlpha,
}

#[derive(Debug)]
pub struct Pbrt {
    settings: PbrtWorldSettings,
    scene: PbrtScene,
}

impl Pbrt {
    fn new(settings: PbrtWorldSettings) -> Self {
        Self {
            settings,
            scene: PbrtScene { shapes: Vec::new() },
        }
    }
}

#[derive(Debug)]
struct PbrtWorldSettings {
    camera: PbrtCamera,
    camera_ctm: AffineTransform,
}

#[derive(Debug)]
struct PbrtScene {
    shapes: Vec<Shape>,
}

fn inner_parse_pbrt(path: impl AsRef<Path> + std::fmt::Debug) -> Result<Pbrt> {
    // unwrap on context.last() ok because context is never empty
    let mut context_ctm = vec![AffineTransform::identity()];

    let mut parser = Parser::new(path)?;

    // parse global settings

    let mut camera = None;

    let mut named_transforms = HashMap::new();

    let mut textures = HashMap::new();

    loop {
        let p = parser.next(&textures).ok_or_else(|| miette!(""))??;
        // dbg!(&p);
        match p {
            Statement::AttributeBegin => context_ctm.push(*context_ctm.last().unwrap()),
            Statement::AttributeEnd => {
                context_ctm.pop();
                if context_ctm.is_empty() {
                    return Err(miette!("Attribute end does not match."));
                }
            }
            Statement::Include(_) => unreachable!(),
            Statement::ConcatTransform(affine_transform) => {
                *context_ctm.last_mut().unwrap() *= affine_transform
            }
            Statement::Transform(affine_transform) => {
                *context_ctm.last_mut().unwrap() = affine_transform
            }
            Statement::Unknown(s, _items) => {
                eprintln!("Unknown statement: {s}")
            }
            Statement::Camera(c) => {
                if camera.is_some() {
                    return Err(miette!("The camera can only be set once."));
                }
                camera = Some((c, *context_ctm.last().unwrap()));
                named_transforms.insert(String::from("\"camera\""), *context_ctm.last().unwrap());
            }
            Statement::CoordinateSystem(s) => {
                named_transforms.insert(s, *context_ctm.last().unwrap());
            }
            Statement::CoordSysTransform(s) => {
                *context_ctm.last_mut().unwrap() = *named_transforms
                    .get(&s)
                    .ok_or_else(|| miette!("unknown transform"))?;
            }
            Statement::WorldBegin => break,
            s => bail!("unexpected statemnet in global settings: {s:?}"),
        }
    }

    let (camera, camera_ctm) = camera.ok_or(miette!("A camera has to be specified"))?;

    let mut pbrt = Pbrt::new(PbrtWorldSettings { camera, camera_ctm });

    let mut context_ctm = vec![AffineTransform::identity()];

    // let mut context_material = vec![];

    while let Some(p) = parser.next(&textures).transpose()? {
        match p {
            Statement::AttributeBegin => context_ctm.push(*context_ctm.last().unwrap()),
            Statement::AttributeEnd => {
                context_ctm.pop();
            }
            Statement::Include(_) => unreachable!(),
            Statement::ConcatTransform(affine_transform) => {
                *context_ctm.last_mut().unwrap() *= affine_transform
            }
            Statement::Transform(affine_transform) => {
                *context_ctm.last_mut().unwrap() = affine_transform
            }
            Statement::Shape(shape_type, shape_alpha) => {
                pbrt.scene.shapes.push(Shape {
                    ctm: *context_ctm.last().unwrap(),
                    material: 0,
                    obj: shape_type,
                    alpha: shape_alpha,
                });
            }
            Statement::CoordinateSystem(s) => {
                named_transforms.insert(s, *context_ctm.last().unwrap());
            }
            Statement::CoordSysTransform(s) => {
                *context_ctm.last_mut().unwrap() = *named_transforms
                    .get(&s)
                    .ok_or_else(|| miette!("unknown transform"))?;
            }
            Statement::Unknown(s, _items) => {
                eprintln!("Unknown statement: {s}")
            }
            s => bail!("unexpected statemnet in world settings: {s:?}"),
        }
    }

    Ok(pbrt)
}

pub fn parse_pbrt_v4(path: impl AsRef<Path> + std::fmt::Debug) -> Result<Pbrt> {
    inner_parse_pbrt(path)
}