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#![no_std]

extern crate no_std_compat as std;

use node::NodePath;
use node::NodePathHash;

use std::collections::hash_map::DefaultHasher;
use std::sync::Mutex;
use std::sync::MutexGuard;

use core::cmp::Ord;
use core::cmp::Ordering;
use core::cmp::PartialOrd;
use core::hash::Hash;
use core::hash::Hasher;

pub mod app;
pub mod bitmap;
pub mod flexbox;
pub mod geometry;
pub mod node;

#[cfg(feature = "text")]
pub mod text;

#[cfg(feature = "xml")]
pub mod xml;

#[cfg(feature = "png")]
pub mod png;

#[cfg(feature = "railway")]
pub mod railway;

/// General-purpose position structure
pub type Point = geometry::Point;

/// General-purpose size structure
pub type Size = geometry::Size;

/// Type representing a rectangle
pub type Spot = geometry::Spot;

/// Non-verbose result
pub type Status = Result<(), ()>;

/// Platforms must publicly expose a `log`
/// function which matches this signature.
///
/// ```rust
/// pub fn log(s: &str) {
///     println!("{}", s);
/// }
/// ```
pub type PlatformLog = &'static dyn Fn(&str);

// todo: allow partial renders
/// Platforms must publicly expose a `blit`
/// function which matches this signature.
///
/// On success, the return value is a tuple containing:
/// 1. the buffer slice
/// 2. the pitch (number of bytes between lines in the spot)
/// 3. false if this buffer is shared between nodes at this spot, true otherwise
///
/// ```rust
/// pub fn blit<'a>(spot: &'a Spot, path: Option<&'a NodePath>) -> Option<(&'a mut [u8], usize, bool)> {
///     let slice = /* maybe allocate memory */;
///     let pitch = /* can be zero for non-shared buffers */;
///     let not_shared = /* true if you allocated memory for that node */;
///     (slice, pitch, not_shared)
/// }
/// ```
pub type PlatformBlit = &'static dyn Fn(Spot, BlitKey) -> Option<(&'static mut [u8], usize, bool)>;

/// Used by platforms as an index of pixel buffers
#[derive(Debug, Copy, Clone, Hash, PartialEq, Eq)]
pub enum BlitKey {
    /// (depth, hash)
    Node(usize, NodePathHash),
    Background,
    Overlay,
}

/// Used by platforms as an index of pixel buffers
#[derive(Debug, Copy, Clone)]
pub enum BlitPath<'a> {
    Node(&'a NodePath),
    Background,
    Overlay,
}

impl<'a> BlitPath<'a> {
    pub fn to_key(&self) -> BlitKey {
        match self {
            BlitPath::Node(path) => BlitKey::Node(path.len() + 1, single_hash(path)),
            BlitPath::Background => BlitKey::Background,
            BlitPath::Overlay => BlitKey::Overlay,
        }
    }
}

/// Compute the hash of anything which implements [`Hash`]
pub fn single_hash(hashable: impl Hash) -> u64 {
    let mut hasher = DefaultHasher::new();
    hashable.hash(&mut hasher);
    hasher.finish()
}

/// `no_std`-friendly wrapper for `mutex.lock()`
pub fn lock<T: ?Sized>(mutex: &Mutex<T>) -> Option<MutexGuard<T>> {
    #[cfg(feature = "std")]
    let result = mutex.lock().ok();
    #[cfg(not(feature = "std"))]
    let result = Some(mutex.lock());
    result
}

/// Transforms an `Option<T>` to a `Result<T, ()>`
/// which is compatible with [`Status`]
pub fn status<T>(option: Option<T>) -> Result<T, ()> {
    option.ok_or(())
}

/// `no_std`-friendly [`std::format`](https://doc.rust-lang.org/std/macro.format.html)
#[macro_export]
macro_rules! format {
	($($arg:tt)*) => {{
		let mut string = String::new();
		core::fmt::write(&mut string, core::format_args!($($arg)*)).unwrap();
		string
	}}
}

impl Ord for BlitKey {
    fn cmp(&self, other: &Self) -> Ordering {
        match (self, other) {
            (BlitKey::Node(d1, _), BlitKey::Node(d2, _)) => d2.cmp(d1),

            (BlitKey::Background, BlitKey::Node(_, _)) => Ordering::Less,
            (BlitKey::Node(_, _), BlitKey::Background) => Ordering::Greater,

            (BlitKey::Overlay, BlitKey::Node(_, _)) => Ordering::Greater,
            (BlitKey::Node(_, _), BlitKey::Overlay) => Ordering::Less,

            (BlitKey::Background, BlitKey::Overlay) => Ordering::Less,
            (BlitKey::Overlay, BlitKey::Background) => Ordering::Greater,

            (BlitKey::Background, BlitKey::Background) => Ordering::Equal,
            (BlitKey::Overlay, BlitKey::Overlay) => Ordering::Equal,
        }
    }
}

impl PartialOrd for BlitKey {
    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}