use std::cmp::Ordering;
use std::fmt;

use lazy_static::lazy_static;
use num_traits::{abs, Num};
use serde::{de, Deserialize, Deserializer, Serialize, Serializer};
use serde::de::{SeqAccess, Visitor};
use serde::ser::SerializeTupleStruct;

use crate::bitfield;
use crate::texture_set::G_MAG;

/// Multiply cave story degrees (0-255, which corresponds to 0°-360°) with this to get
/// respective value in radians.
pub const CDEG_RAD: f64 = std::f64::consts::PI / 128.0;
lazy_static! {
    pub static ref VERSION_BANNER: String = {
        let version = option_env!("DRS_BUILD_VERSION_OVERRIDE").unwrap_or(env!("CARGO_PKG_VERSION"));
        format!("doukutsu-rs {}", version)
    };
}

bitfield! {
  #[derive(Clone, Copy)]
  #[repr(C)]
  pub struct Flag(u32);
  impl Debug;

  /// Set if left wall was hit. (corresponds to flag & 0x01)
  pub hit_left_wall, set_hit_left_wall: 0;
  /// Set if top wall was hit. (corresponds to flag & 0x02)
  pub hit_top_wall, set_hit_top_wall: 1;
  /// Set if right wall was hit. (corresponds to flag & 0x04)
  pub hit_right_wall, set_hit_right_wall: 2;
  /// Set if bottom wall was hit. (corresponds to flag & 0x08)
  pub hit_bottom_wall, set_hit_bottom_wall: 3;
  /// Set if entity stays on right slope. (corresponds to flag & 0x10)
  pub hit_right_slope, set_hit_right_slope: 4;
  /// Set if entity stays on left slope. (corresponds to flag & 0x20)
  pub hit_left_slope, set_hit_left_slope: 5;
  /// Unknown purpose (corresponds to flag & 0x40)
  pub flag_x40, set_flag_x40: 6;
  /// Unknown purpose (corresponds to flag & 0x80)
  pub flag_x80, set_flag_x80: 7;
  /// Set if entity is in water. (corresponds to flag & 0x100)
  pub in_water, set_in_water: 8;
  pub weapon_hit_block, set_weapon_hit_block: 9; // 0x200
  pub hit_by_spike, set_hit_by_spike: 10; // 0x400
  pub water_splash_facing_right, set_water_splash_facing_right: 11; // 0x800
  pub force_left, set_force_left: 12; // 0x1000
  pub force_up, set_force_up: 13; // 0x2000
  pub force_right, set_force_right: 14; // 0x4000
  pub force_down, set_force_down: 15; // 0x8000
  pub hit_left_higher_half, set_hit_left_higher_half: 16; // 0x10000
  pub hit_left_lower_half, set_hit_left_lower_half: 17; // 0x20000
  pub hit_right_lower_half, set_hit_right_lower_half: 18; // 0x40000
  pub hit_right_higher_half, set_hit_right_higher_half: 19; // 0x80000
}

impl Flag {
    pub fn hit_anything(&self) -> bool {
        (self.0 & 0x2ff) != 0
    }
}

bitfield! {
  #[derive(Clone, Copy)]
  #[repr(C)]
  pub struct Equipment(u16);
  impl Debug;

  pub has_booster_0_8, set_booster_0_8: 0; // 0x01 / 0001
  pub has_map, set_map: 1; // 0x02 / 0002
  pub has_arms_barrier, set_arms_barrier: 2; // 0x04 / 0004
  pub has_turbocharge, set_turbocharge: 3; // 0x08 / 0008
  pub has_air_tank, set_air_tank: 4; // 0x10 / 0016
  pub has_booster_2_0, set_booster_2_0: 5; // 0x20 / 0032
  pub has_mimiga_mask, set_mimiga_mask: 6; // 0x40 / 0064
  pub has_whimsical_star, set_whimsical_star: 7; // 0x080 / 0128
  pub has_nikumaru, set_nikumaru: 8; // 0x100 / 0256
  // for custom equips
  pub unused_1, set_unused_1: 9; // 0x200 / 0512
  pub unused_2, set_unused_2: 10; // 0x400 / 1024
  pub unused_3, set_unused_3: 11; // 0x800 / 2048
  pub unused_4, set_unused_4: 12; // 0x1000 / 4096
  pub unused_5, set_unused_5: 13; // 0x2000 / 8192
  // bit 14 and 15 aren't accessible via TSC without abusing overflows (won't work in strict mode)
  pub unused_6, set_unused_6: 14; // 0x4000 / @384
  pub unused_7, set_unused_7: 15; // 0x8000 / P768
}

bitfield! {
  #[derive(Clone, Copy)]
  #[repr(C)]
  pub struct Condition(u16);
  impl Debug;

  pub interacted, set_interacted: 0; // 0x01
  pub hidden, set_hidden: 1; // 0x02
  pub fallen, set_fallen: 2; // 0x04
  pub explode_die, set_explode_die: 3; // 0x08
  pub damage_boss, set_damage_boss: 4; // 0x10
  pub increase_acceleration, set_increase_acceleration: 5; // 0x20
  pub cond_x40, set_cond_x40: 6; // 0x40
  pub alive, set_alive: 7; // 0x80

  // engine specific flags
  pub drs_boss, set_drs_boss: 15;
}

bitfield! {
  #[derive(Clone, Copy, Serialize, Deserialize)]
  #[repr(C)]
  pub struct ControlFlags(u16);
  impl Debug;

  pub tick_world, set_tick_world: 0; // 0x01
  pub control_enabled, set_control_enabled: 1; // 0x02
  pub interactions_disabled, set_interactions_disabled: 2; // 0x04
  pub credits_running, set_credits_running: 3; // 0x08

  // engine specific flags
  pub friendly_fire, set_friendly_fire: 14;
  pub wind, set_wind: 15;
}

bitfield! {
  #[derive(Clone, Copy)]
  #[repr(C)]
  pub struct BulletFlag(u16);
  impl Debug;
  pub flag_x01, set_flag_x01: 0; // 0x01
  pub flag_x02, set_flag_x02: 1; // 0x02
  pub no_collision_checks, set_no_collision_checks: 2; // 0x04
  pub bounce_from_walls, set_bounce_from_walls: 3; // 0x08
  pub flag_x10, set_flag_x10: 4; // 0x10
  pub flag_x20, set_flag_x20: 5; // 0x20
  pub can_destroy_snack, set_can_destroy_snack: 6; // 0x40
  pub flag_x80, set_flag_x80: 7; // 0x80
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
pub enum FadeDirection {
    Left = 0,
    Up,
    Right,
    Down,
    Center,
}

impl FadeDirection {
    pub fn from_int(val: usize) -> Option<FadeDirection> {
        match val {
            0 => { Some(FadeDirection::Left) }
            1 => { Some(FadeDirection::Up) }
            2 => { Some(FadeDirection::Right) }
            3 => { Some(FadeDirection::Down) }
            4 => { Some(FadeDirection::Center) }
            _ => { None }
        }
    }

    pub fn opposite(&self) -> FadeDirection {
        match self {
            FadeDirection::Left => { FadeDirection::Right }
            FadeDirection::Up => { FadeDirection::Down }
            FadeDirection::Right => { FadeDirection::Left }
            FadeDirection::Down => { FadeDirection::Up }
            FadeDirection::Center => { FadeDirection::Center }
        }
    }
}

#[derive(Debug, PartialEq, Copy, Clone)]
#[repr(u8)]
pub enum FadeState {
    Visible,
    FadeIn(i8, FadeDirection),
    Hidden,
    FadeOut(i8, FadeDirection),
}

#[derive(Debug, Clone, Copy, PartialEq, Eq)]
#[repr(u8)]
pub enum Direction {
    Left = 0,
    Up,
    Right,
    Bottom,
    FacingPlayer,
}

pub const FILE_TYPES: [&str; 3] = [".png", ".bmp", ".pbm"];

impl Direction {
    pub fn from_int(val: usize) -> Option<Direction> {
        match val {
            0 => { Some(Direction::Left) }
            1 => { Some(Direction::Up) }
            2 => { Some(Direction::Right) }
            3 => { Some(Direction::Bottom) }
            _ => { None }
        }
    }

    pub fn from_int_facing(val: usize) -> Option<Direction> {
        match val {
            0 => { Some(Direction::Left) }
            1 => { Some(Direction::Up) }
            2 => { Some(Direction::Right) }
            3 => { Some(Direction::Bottom) }
            4 => { Some(Direction::FacingPlayer) }
            _ => { None }
        }
    }

    pub fn opposite(&self) -> Direction {
        match self {
            Direction::Left => { Direction::Right }
            Direction::Up => { Direction::Bottom }
            Direction::Right => { Direction::Left }
            Direction::Bottom => { Direction::Up }
            Direction::FacingPlayer => unreachable!(),
        }
    }

    pub fn vector_x(&self) -> i32 {
        match self {
            Direction::Left => { -1 }
            Direction::Up => { 0 }
            Direction::Right => { 1 }
            Direction::Bottom => { 0 }
            Direction::FacingPlayer => unreachable!(),
        }
    }

    pub fn vector_y(&self) -> i32 {
        match self {
            Direction::Left => { 0 }
            Direction::Up => { -1 }
            Direction::Right => { 0 }
            Direction::Bottom => { 1 }
            Direction::FacingPlayer => unreachable!(),
        }
    }
}

#[derive(Debug, Clone, Copy)]
pub struct Point<T: Num + PartialOrd + Copy = isize> {
    pub x: T,
    pub y: T,
}

impl<T: Num + PartialOrd + Copy> Point<T> {
    #[inline(always)]
    pub fn new(x: T, y: T) -> Point<T> {
        Point {
            x,
            y,
        }
    }
}

#[derive(Debug, Clone, Copy)]
#[repr(C)]
pub struct Rect<T: Num + PartialOrd + Copy = isize> {
    pub left: T,
    pub top: T,
    pub right: T,
    pub bottom: T,
}

impl<T: Num + PartialOrd + Copy> Rect<T> {
    #[inline(always)]
    pub fn new(left: T, top: T, right: T, bottom: T) -> Rect<T> {
        Rect {
            left,
            top,
            right,
            bottom,
        }
    }

    #[inline(always)]
    pub fn new_size(x: T, y: T, width: T, height: T) -> Rect<T> {
        Rect {
            left: x,
            top: y,
            right: x.add(width),
            bottom: y.add(height),
        }
    }

    pub fn width(&self) -> T {
        if let Some(Ordering::Greater) = self.left.partial_cmp(&self.right) {
            self.left.sub(self.right)
        } else {
            self.right.sub(self.left)
        }
    }

    pub fn height(&self) -> T {
        if let Some(Ordering::Greater) = self.top.partial_cmp(&self.bottom) {
            self.top.sub(self.bottom)
        } else {
            self.bottom.sub(self.top)
        }
    }
}

impl<T: Num + PartialOrd + Copy + Serialize> Serialize for Rect<T> {
    fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
        where
            S: Serializer,
    {
        let mut state = serializer.serialize_tuple_struct("Rect", 4)?;
        state.serialize_field(&self.left)?;
        state.serialize_field(&self.top)?;
        state.serialize_field(&self.right)?;
        state.serialize_field(&self.bottom)?;
        state.end()
    }
}
macro_rules! rect_deserialze {
    ($num_type: ident) => {
        impl<'de> Deserialize<'de> for Rect<$num_type> {
            fn deserialize<D>(deserializer: D) -> Result<Rect<$num_type>, D::Error>
                where
                    D: Deserializer<'de>,
            {
                struct RectVisitor;

                impl<'de> Visitor<'de> for RectVisitor {
                    type Value = Rect<$num_type>;

                    fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
                        formatter.write_str("Expected Rect structure.")
                    }

                    fn visit_seq<V>(self, mut seq: V) -> Result<Self::Value, V::Error>
                        where
                            V: SeqAccess<'de>
                    {
                        let invalid_length = || {
                            de::Error::invalid_length(0, &self)
                        };

                        let left = seq.next_element()?.ok_or_else(invalid_length)?;
                        let top = seq.next_element()?.ok_or_else(invalid_length)?;
                        let right = seq.next_element()?.ok_or_else(invalid_length)?;
                        let bottom = seq.next_element()?.ok_or_else(invalid_length)?;

                        Ok(Rect { left, top, right, bottom })
                    }
                }

                deserializer.deserialize_tuple_struct("Rect", 4, RectVisitor)
            }
        }
    };
}

rect_deserialze!(u8);
rect_deserialze!(u16);
rect_deserialze!(i32);
rect_deserialze!(isize);
rect_deserialze!(usize);

#[inline(always)]
pub fn fix9_scale(val: i32) -> f32 {
    unsafe {
        let mag = G_MAG as f32;
        (val as f32 * mag / 512.0).floor() / mag
    }
}

#[inline(always)]
fn lerp_f64(v1: f64, v2: f64, t: f64) -> f64 {
    v1 * (1.0 - t) + v2 * t
}

#[inline(always)]
fn lerp_f32(v1: f32, v2: f32, t: f32) -> f32 {
    v1 * (1.0 - t) + v2 * t
}

pub fn interpolate_fix9_scale(old_val: i32, val: i32, frame_delta: f64) -> f32 {
    if abs(old_val - val) > 0x1800 {
        return val as f32 / 512.0;
    }

    unsafe {
        let interpolated = lerp_f64(old_val as f64, val as f64, frame_delta) as f32;
        let mag = G_MAG as f32;
        (interpolated * mag / 512.0).floor() / mag
    }
}


/// A RGBA color in the `sRGB` color space represented as `f32`'s in the range `[0.0-1.0]`
///
/// For convenience, [`WHITE`](constant.WHITE.html) and [`BLACK`](constant.BLACK.html) are provided.
#[derive(Copy, Clone, PartialEq, Debug, Serialize, Deserialize)]
pub struct Color {
    /// Red component
    pub r: f32,
    /// Green component
    pub g: f32,
    /// Blue component
    pub b: f32,
    /// Alpha component
    pub a: f32,
}

impl Color {
    /// Create a new `Color` from four `f32`'s in the range `[0.0-1.0]`
    pub const fn new(r: f32, g: f32, b: f32, a: f32) -> Self {
        Color { r, g, b, a }
    }

    /// Create a new `Color` from four `u8`'s in the range `[0-255]`
    pub fn from_rgba(r: u8, g: u8, b: u8, a: u8) -> Color {
        Color::from((r, g, b, a))
    }

    /// Create a new `Color` from three u8's in the range `[0-255]`,
    /// with the alpha component fixed to 255 (opaque)
    pub fn from_rgb(r: u8, g: u8, b: u8) -> Color {
        Color::from((r, g, b))
    }

    /// Return a tuple of four `u8`'s in the range `[0-255]` with the `Color`'s
    /// components.
    pub fn to_rgba(self) -> (u8, u8, u8, u8) {
        self.into()
    }

    /// Return a tuple of three `u8`'s in the range `[0-255]` with the `Color`'s
    /// components.
    pub fn to_rgb(self) -> (u8, u8, u8) {
        self.into()
    }

    /// Convert a packed `u32` containing `0xRRGGBBAA` into a `Color`
    pub fn from_rgba_u32(c: u32) -> Color {
        let c = c.to_be_bytes();

        Color::from((c[0], c[1], c[2], c[3]))
    }

    /// Convert a packed `u32` containing `0x00RRGGBB` into a `Color`.
    /// This lets you do things like `Color::from_rgb_u32(0xCD09AA)` easily if you want.
    pub fn from_rgb_u32(c: u32) -> Color {
        let c = c.to_be_bytes();

        Color::from((c[1], c[2], c[3]))
    }

    /// Convert a `Color` into a packed `u32`, containing `0xRRGGBBAA` as bytes.
    pub fn to_rgba_u32(self) -> u32 {
        let (r, g, b, a): (u8, u8, u8, u8) = self.into();

        u32::from_be_bytes([r, g, b, a])
    }

    /// Convert a `Color` into a packed `u32`, containing `0x00RRGGBB` as bytes.
    pub fn to_rgb_u32(self) -> u32 {
        let (r, g, b, _a): (u8, u8, u8, u8) = self.into();

        u32::from_be_bytes([0, r, g, b])
    }
}

impl From<(u8, u8, u8, u8)> for Color {
    /// Convert a `(R, G, B, A)` tuple of `u8`'s in the range `[0-255]` into a `Color`
    fn from(val: (u8, u8, u8, u8)) -> Self {
        let (r, g, b, a) = val;
        let rf = (f32::from(r)) / 255.0;
        let gf = (f32::from(g)) / 255.0;
        let bf = (f32::from(b)) / 255.0;
        let af = (f32::from(a)) / 255.0;
        Color::new(rf, gf, bf, af)
    }
}

impl From<(u8, u8, u8)> for Color {
    /// Convert a `(R, G, B)` tuple of `u8`'s in the range `[0-255]` into a `Color`,
    /// with a value of 255 for the alpha element (i.e., no transparency.)
    fn from(val: (u8, u8, u8)) -> Self {
        let (r, g, b) = val;
        Color::from((r, g, b, 255))
    }
}

impl From<[f32; 4]> for Color {
    /// Turns an `[R, G, B, A] array of `f32`'s into a `Color` with no format changes.
    /// All inputs should be in the range `[0.0-1.0]`.
    fn from(val: [f32; 4]) -> Self {
        Color::new(val[0], val[1], val[2], val[3])
    }
}

impl From<(f32, f32, f32)> for Color {
    /// Convert a `(R, G, B)` tuple of `f32`'s in the range `[0.0-1.0]` into a `Color`,
    /// with a value of 1.0 to for the alpha element (ie, no transparency.)
    fn from(val: (f32, f32, f32)) -> Self {
        let (r, g, b) = val;
        Color::new(r, g, b, 1.0)
    }
}

impl From<(f32, f32, f32, f32)> for Color {
    /// Convert a `(R, G, B, A)` tuple of `f32`'s in the range `[0.0-1.0]` into a `Color`
    fn from(val: (f32, f32, f32, f32)) -> Self {
        let (r, g, b, a) = val;
        Color::new(r, g, b, a)
    }
}

impl From<Color> for (u8, u8, u8, u8) {
    /// Convert a `Color` into a `(R, G, B, A)` tuple of `u8`'s in the range of `[0-255]`.
    fn from(color: Color) -> Self {
        let r = (color.r * 255.0) as u8;
        let g = (color.g * 255.0) as u8;
        let b = (color.b * 255.0) as u8;
        let a = (color.a * 255.0) as u8;
        (r, g, b, a)
    }
}

impl From<Color> for (u8, u8, u8) {
    /// Convert a `Color` into a `(R, G, B)` tuple of `u8`'s in the range of `[0-255]`,
    /// ignoring the alpha term.
    fn from(color: Color) -> Self {
        let (r, g, b, _) = color.into();
        (r, g, b)
    }
}

impl From<Color> for [f32; 4] {
    /// Convert a `Color` into an `[R, G, B, A]` array of `f32`'s in the range of `[0.0-1.0]`.
    fn from(color: Color) -> Self {
        [color.r, color.g, color.b, color.a]
    }
}