use serde::{Deserialize, Serialize};
use sha2::Sha256;
use std::{collections::HashMap, fmt::Display, hash, rc::Rc};

use crate::util::cjson;

#[derive(Clone, Copy, PartialEq, Eq, Hash)]
pub struct StringHash(pub [u8; 32]);

impl Display for StringHash {
	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
		f.write_str(&hex::encode(self.0))
	}
}

impl std::fmt::Debug for StringHash {
	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
		write!(f, "\"{}\"", self)
	}
}

impl Serialize for StringHash {
	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
	where
		S: serde::Serializer,
	{
		hex::serialize(self.0, serializer)
	}
}
impl<'de> Deserialize<'de> for StringHash {
	fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
	where
		D: serde::Deserializer<'de>,
	{
		Ok(StringHash(hex::deserialize(deserializer)?))
	}
}

macro_rules! stringhash_newtype {
	($id:ident) => {
		#[derive(Clone, Copy, Debug, PartialEq, Eq, Hash, Deserialize, Serialize)]
		pub struct $id(pub StringHash);

		impl Display for $id {
			fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
				self.0.fmt(f)
			}
		}
	};
}

pub type InputHasher = Sha256;
stringhash_newtype!(InputHash);

pub type DependencyHasher = Sha256;
stringhash_newtype!(DependencyHash);

pub type ArchiveHasher = Sha256;
stringhash_newtype!(ArchiveHash);

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub struct TaskID(pub String);

impl Display for TaskID {
	fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
		self.0.fmt(f)
	}
}

#[derive(Clone, Debug, Deserialize, Serialize, PartialEq, Eq)]
pub struct TaskArgs(pub HashMap<String, Rc<serde_json::Value>>);

impl hash::Hash for TaskArgs {
	fn hash<H: hash::Hasher>(&self, _state: &mut H) {
		// Don't do anything: Properly hashing the task args is likely to cost
		// much more performance than the hash collisions caused by TaskRefs
		// that only differ by the args
	}
}

#[derive(Clone, Debug, Deserialize, Serialize)]
#[serde(rename_all = "snake_case")]
pub enum Dependency {
	Fetch { name: String, sha256: StringHash },
	BuildTask { output: ArchiveHash },
	TargetTask { output: ArchiveHash },
}

impl Dependency {
	pub fn dependency_hash(&self) -> DependencyHash {
		DependencyHash(StringHash(
			cjson::digest::<DependencyHasher, _>(self).unwrap().into(),
		))
	}
}