// Copyright 2019-2021 Parity Technologies (UK) Ltd.
//
// Permission is hereby granted, free of charge, to any
// person obtaining a copy of this software and associated
// documentation files (the "Software"), to deal in the
// Software without restriction, including without
// limitation the rights to use, copy, modify, merge,
// publish, distribute, sublicense, and/or sell copies of
// the Software, and to permit persons to whom the Software
// is furnished to do so, subject to the following
// conditions:
//
// The above copyright notice and this permission notice
// shall be included in all copies or substantial portions
// of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
// ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
// TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
// PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
// SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
// CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
// OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
// IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
// DEALINGS IN THE SOFTWARE.

//! Types to handle JSON-RPC request parameters according to the [spec](https://www.jsonrpc.org/specification#parameter_structures).
//! Some types come with a "*Ser" variant that implements [`serde::Serialize`]; these are used in the client.

use std::borrow::Cow;
use std::fmt;

use serde::de::{self, Deserializer, Unexpected, Visitor};
use serde::ser::Serializer;
use serde::{Deserialize, Serialize};
use serde_json::Value as JsonValue;

use crate::error::{ErrorCode, INVALID_PARAMS_MSG};
use crate::{ErrorObject, ErrorObjectOwned};

/// JSON-RPC v2 marker type.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq)]
pub struct TwoPointZero;

struct TwoPointZeroVisitor;

impl<'de> Visitor<'de> for TwoPointZeroVisitor {
	type Value = TwoPointZero;

	fn expecting(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
		formatter.write_str(r#"a string "2.0""#)
	}

	fn visit_str<E>(self, s: &str) -> Result<Self::Value, E>
	where
		E: de::Error,
	{
		match s {
			"2.0" => Ok(TwoPointZero),
			_ => Err(de::Error::invalid_value(Unexpected::Str(s), &self)),
		}
	}
}

impl<'de> Deserialize<'de> for TwoPointZero {
	fn deserialize<D>(deserializer: D) -> Result<TwoPointZero, D::Error>
	where
		D: Deserializer<'de>,
	{
		deserializer.deserialize_str(TwoPointZeroVisitor)
	}
}

impl Serialize for TwoPointZero {
	fn serialize<S>(&self, serializer: S) -> Result<S::Ok, S::Error>
	where
		S: Serializer,
	{
		serializer.serialize_str("2.0")
	}
}

/// Parameters sent with an incoming JSON-RPC request.
///
/// The data containing the params is a `Cow<&str>` and can either be a borrowed `&str` of JSON from an incoming
/// [`super::request::Request`] (which in turn borrows it from the input buffer that is shared between requests);
/// or, it can be an owned [`String`].
#[derive(Clone, Debug)]
pub struct Params<'a>(Option<Cow<'a, str>>);

impl<'a> Params<'a> {
	/// Create params
	pub fn new(raw: Option<&'a str>) -> Self {
		Self(raw.map(|r| r.trim().into()))
	}

	/// Returns true if the contained JSON is an object
	pub fn is_object(&self) -> bool {
		let json: &str = match self.0 {
			Some(ref cow) => cow,
			None => return false,
		};
		json.starts_with('{')
	}

	/// Obtain a sequence parser, [`ParamsSequence`].
	///
	/// This allows sequential parsing of the incoming params, using an `Iterator`-style API and is useful when the RPC
	/// request has optional parameters at the tail that may or may not be present.
	pub fn sequence(&self) -> ParamsSequence {
		let json = match self.0.as_ref() {
			// It's assumed that params is `[a,b,c]`, if empty regard as no params.
			Some(json) if json == "[]" => "",
			Some(json) => json,
			None => "",
		};
		ParamsSequence(json)
	}

	/// Attempt to parse all parameters as an array or map into type `T`.
	pub fn parse<T>(&'a self) -> Result<T, ErrorObjectOwned>
	where
		T: Deserialize<'a>,
	{
		// NOTE(niklasad1): Option::None is serialized as `null` so we provide that here.
		let params = self.0.as_ref().map(AsRef::as_ref).unwrap_or("null");
		serde_json::from_str(params).map_err(invalid_params)
	}

	/// Attempt to parse parameters as an array of a single value of type `T`, and returns that value.
	pub fn one<T>(&'a self) -> Result<T, ErrorObjectOwned>
	where
		T: Deserialize<'a>,
	{
		self.parse::<[T; 1]>().map(|[res]| res)
	}

	/// Convert `Params<'a>` to `Params<'static>` so that it can be moved across threads.
	///
	/// This will cause an allocation if the params internally are using a borrowed JSON slice.
	pub fn into_owned(self) -> Params<'static> {
		Params(self.0.map(|s| Cow::Owned(s.into_owned())))
	}

	/// Return the length of underlying JSON string in number of bytes.
	pub fn len_bytes(&self) -> usize {
		match self.0 {
			Some(ref cow) => cow.len(),
			None => 0,
		}
	}

	/// Return the underlying JSON string as a `&str`.
	pub fn as_str(&self) -> Option<&str> {
		match self.0 {
			Some(ref cow) => Some(cow.as_ref()),
			None => None,
		}
	}
}

/// An `Iterator`-like parser for a sequence of [`Params`].
///
/// This will parse the params one at a time, and allows for graceful handling of optional parameters at the tail; other
/// use cases are likely better served by [`Params::parse`]. The reason this is not an actual [`Iterator`] is that
/// params parsing (often) yields values of different types.
///
/// Regards empty array `[]` as no parameters provided.
#[derive(Debug, Copy, Clone)]
pub struct ParamsSequence<'a>(&'a str);

impl<'a> ParamsSequence<'a> {
	fn next_inner<T>(&mut self) -> Option<Result<T, ErrorObjectOwned>>
	where
		T: Deserialize<'a>,
	{
		let mut json = self.0;
		match json.as_bytes().first()? {
			b']' => {
				self.0 = "";
				return None;
			}
			b'[' | b',' => json = &json[1..],
			_ => {
				let errmsg = format!("Invalid params. Expected one of '[', ']' or ',' but found {json:?}");
				return Some(Err(invalid_params(errmsg)));
			}
		}

		let mut iter = serde_json::Deserializer::from_str(json).into_iter::<T>();

		match iter.next()? {
			Ok(value) => {
				self.0 = json[iter.byte_offset()..].trim_start();

				Some(Ok(value))
			}
			Err(e) => {
				self.0 = "";
				Some(Err(invalid_params(e)))
			}
		}
	}

	/// Parse the next parameter to type `T`
	///
	/// ```
	/// # use jsonrpsee_types::params::Params;
	/// let params = Params::new(Some(r#"[true, 10, "foo"]"#));
	/// let mut seq = params.sequence();
	///
	/// let a: bool = seq.next().unwrap();
	/// let b: i32 = seq.next().unwrap();
	/// let c: &str = seq.next().unwrap();
	///
	/// assert_eq!(a, true);
	/// assert_eq!(b, 10);
	/// assert_eq!(c, "foo");
	/// ```
	#[allow(clippy::should_implement_trait)]
	pub fn next<T>(&mut self) -> Result<T, ErrorObjectOwned>
	where
		T: Deserialize<'a>,
	{
		match self.next_inner() {
			Some(result) => result,
			None => Err(invalid_params("No more params")),
		}
	}

	/// Parse the next optional parameter to type `Option<T>`.
	///
	/// The result will be `None` for `null`, and for missing values in the supplied JSON array.
	///
	/// ```
	/// # use jsonrpsee_types::params::Params;
	/// let params = Params::new(Some(r#"[1, 2, null]"#));
	/// let mut seq = params.sequence();
	///
	/// let params: [Option<u32>; 4] = [
	///     seq.optional_next().unwrap(),
	///     seq.optional_next().unwrap(),
	///     seq.optional_next().unwrap(),
	///     seq.optional_next().unwrap(),
	/// ];
	///
	/// assert_eq!(params, [Some(1), Some(2), None, None]);
	/// ```
	pub fn optional_next<T>(&mut self) -> Result<Option<T>, ErrorObjectOwned>
	where
		T: Deserialize<'a>,
	{
		match self.next_inner::<Option<T>>() {
			Some(result) => result,
			None => Ok(None),
		}
	}
}

/// Id of a subscription, communicated by the server.
#[derive(Debug, PartialEq, Clone, Hash, Eq, Deserialize, Serialize)]
#[serde(deny_unknown_fields)]
#[serde(untagged)]
pub enum SubscriptionId<'a> {
	/// Numeric id
	Num(u64),
	/// String id
	#[serde(borrow)]
	Str(Cow<'a, str>),
}

impl<'a> From<SubscriptionId<'a>> for JsonValue {
	fn from(sub_id: SubscriptionId) -> Self {
		match sub_id {
			SubscriptionId::Num(n) => n.into(),
			SubscriptionId::Str(s) => s.into_owned().into(),
		}
	}
}

impl<'a> From<u64> for SubscriptionId<'a> {
	fn from(sub_id: u64) -> Self {
		Self::Num(sub_id)
	}
}

impl<'a> From<String> for SubscriptionId<'a> {
	fn from(sub_id: String) -> Self {
		Self::Str(sub_id.into())
	}
}

impl<'a> TryFrom<JsonValue> for SubscriptionId<'a> {
	type Error = ();

	fn try_from(json: JsonValue) -> Result<SubscriptionId<'a>, ()> {
		match json {
			JsonValue::String(s) => Ok(SubscriptionId::Str(s.into())),
			JsonValue::Number(n) => {
				if let Some(n) = n.as_u64() {
					Ok(SubscriptionId::Num(n))
				} else {
					Err(())
				}
			}
			_ => Err(()),
		}
	}
}

impl<'a> SubscriptionId<'a> {
	/// Convert `SubscriptionId<'a>` to `SubscriptionId<'static>` so that it can be moved across threads.
	///
	/// This can cause an allocation if the id is a string.
	pub fn into_owned(self) -> SubscriptionId<'static> {
		match self {
			SubscriptionId::Num(num) => SubscriptionId::Num(num),
			SubscriptionId::Str(s) => SubscriptionId::Str(Cow::Owned(s.into_owned())),
		}
	}
}

/// Represent a request that failed because of an invalid request id.
#[derive(Debug, thiserror::Error)]
pub enum InvalidRequestId {
	/// The request ID was parsed as valid ID but not a pending request.
	#[error("request ID={0} is not a pending call")]
	NotPendingRequest(String),

	/// The request ID was already assigned to a pending call.
	#[error("request ID={0} is already occupied by a pending call")]
	Occupied(String),

	/// The request ID format was invalid.
	#[error("request ID={0} is invalid")]
	Invalid(String),
}

/// Request Id
#[derive(Debug, PartialEq, Clone, Hash, Eq, Deserialize, Serialize, PartialOrd, Ord)]
#[serde(deny_unknown_fields)]
#[serde(untagged)]
pub enum Id<'a> {
	/// Null
	Null,
	/// Numeric id
	Number(u64),
	/// String id
	#[serde(borrow)]
	Str(Cow<'a, str>),
}

impl<'a> Id<'a> {
	/// If the Id is a number, returns the associated number. Returns None otherwise.
	pub fn as_number(&self) -> Option<&u64> {
		match self {
			Self::Number(n) => Some(n),
			_ => None,
		}
	}

	/// If the Id is a String, returns the associated str. Returns None otherwise.
	pub fn as_str(&self) -> Option<&str> {
		match self {
			Self::Str(s) => Some(s.as_ref()),
			_ => None,
		}
	}

	/// If the ID is Null, returns (). Returns None otherwise.
	pub fn as_null(&self) -> Option<()> {
		match self {
			Self::Null => Some(()),
			_ => None,
		}
	}

	/// Convert `Id<'a>` to `Id<'static>` so that it can be moved across threads.
	///
	/// This can cause an allocation if the id is a string.
	pub fn into_owned(self) -> Id<'static> {
		match self {
			Id::Null => Id::Null,
			Id::Number(num) => Id::Number(num),
			Id::Str(s) => Id::Str(Cow::Owned(s.into_owned())),
		}
	}

	/// Extract the underlying number from the ID.
	pub fn try_parse_inner_as_number(&self) -> Result<u64, InvalidRequestId> {
		match self {
			Id::Null => Err(InvalidRequestId::Invalid("null".to_string())),
			Id::Number(num) => Ok(*num),
			Id::Str(s) => s.parse().map_err(|_| InvalidRequestId::Invalid(s.as_ref().to_owned())),
		}
	}
}

impl<'a> std::fmt::Display for Id<'a> {
	fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
		match self {
			Id::Null => f.write_str("null"),
			Id::Number(n) => f.write_str(&n.to_string()),
			Id::Str(s) => f.write_str(s),
		}
	}
}

fn invalid_params(e: impl ToString) -> ErrorObjectOwned {
	ErrorObject::owned(ErrorCode::InvalidParams.code(), INVALID_PARAMS_MSG, Some(e.to_string()))
}

#[cfg(test)]
mod test {
	use super::{Cow, Id, JsonValue, Params, SubscriptionId, TwoPointZero};
	use crate::response::SubscriptionPayload;

	#[test]
	fn id_deserialization() {
		let s = r#""2""#;
		let deserialized: Id = serde_json::from_str(s).unwrap();
		match deserialized {
			Id::Str(ref cow) => {
				assert!(matches!(cow, Cow::Borrowed(_)));
				assert_eq!(cow, "2");
			}
			_ => panic!("Expected Id::Str"),
		}

		let s = r#"2"#;
		let deserialized: Id = serde_json::from_str(s).unwrap();
		assert_eq!(deserialized, Id::Number(2));

		let s = r#""2x""#;
		let deserialized: Id = serde_json::from_str(s).unwrap();
		assert_eq!(deserialized, Id::Str(Cow::Borrowed("2x")));

		let s = r#"[1337]"#;
		assert!(serde_json::from_str::<Id>(s).is_err());

		let s = r#"[null, 0, 2, "\"3"]"#;
		let deserialized: Vec<Id> = serde_json::from_str(s).unwrap();
		assert_eq!(deserialized, vec![Id::Null, Id::Number(0), Id::Number(2), Id::Str("\"3".into())]);
	}

	#[test]
	fn id_serialization() {
		let d =
			vec![Id::Null, Id::Number(0), Id::Number(2), Id::Number(3), Id::Str("\"3".into()), Id::Str("test".into())];
		let serialized = serde_json::to_string(&d).unwrap();
		assert_eq!(serialized, r#"[null,0,2,3,"\"3","test"]"#);
	}

	#[test]
	fn params_parse() {
		let none = Params::new(None);
		assert!(none.sequence().next::<u64>().is_err());
		assert!(none.parse::<Option<u64>>().is_ok());
		assert_eq!(none.len_bytes(), 0);

		let array_params = Params::new(Some("[1, 2, 3]"));
		assert_eq!(array_params.len_bytes(), 9);
		let arr: Result<[u64; 3], _> = array_params.parse();
		assert!(arr.is_ok());

		let mut seq = array_params.sequence();

		assert_eq!(seq.next::<u64>().unwrap(), 1);
		assert_eq!(seq.next::<u64>().unwrap(), 2);
		assert_eq!(seq.next::<u64>().unwrap(), 3);
		assert!(seq.next::<u64>().is_err());

		let array_one = Params::new(Some("[1]"));
		assert_eq!(array_one.len_bytes(), 3);
		let one: Result<u64, _> = array_one.one();
		assert!(one.is_ok());

		let object_params = Params::new(Some(r#"{"beef":99,"dinner":0}"#));
		assert_eq!(object_params.len_bytes(), 22);
		let obj: Result<JsonValue, _> = object_params.parse();
		assert!(obj.is_ok());
	}

	#[test]
	fn params_parse_empty_json() {
		let array_params = Params::new(Some("[]"));
		let arr: Result<Vec<u64>, _> = array_params.parse();
		assert!(arr.is_ok());

		let obj_params = Params::new(Some("{}"));
		let obj: Result<JsonValue, _> = obj_params.parse();
		assert!(obj.is_ok());
	}

	#[test]
	fn params_sequence_borrows() {
		let params = Params::new(Some(r#"["foo", "bar"]"#));
		let mut seq = params.sequence();

		assert_eq!(seq.next::<&str>().unwrap(), "foo");
		assert_eq!(seq.next::<&str>().unwrap(), "bar");
		assert!(seq.next::<&str>().is_err());

		// It's ok to parse the params again.
		let params: (&str, &str) = params.parse().unwrap();
		assert_eq!(params, ("foo", "bar"));
	}

	#[test]
	fn two_point_zero_serde_works() {
		let initial_ser = r#""2.0""#;
		// The fact that it was deserialized is enough.
		let two_point_zero: TwoPointZero = serde_json::from_str(initial_ser).unwrap();
		let serialized = serde_json::to_string(&two_point_zero).unwrap();
		assert_eq!(serialized, initial_ser);
	}

	#[test]
	fn subscription_id_serde_works() {
		let test_vector = &[("42", SubscriptionId::Num(42)), (r#""one""#, SubscriptionId::Str("one".into()))];

		for (initial_ser, expected) in test_vector {
			let id: SubscriptionId = serde_json::from_str(initial_ser).unwrap();
			assert_eq!(&id, expected);
			let serialized = serde_json::to_string(&id).unwrap();
			assert_eq!(&serialized, initial_ser);
		}
	}

	#[test]
	fn subscription_params_serialize_work() {
		let ser = serde_json::to_string(&SubscriptionPayload { subscription: SubscriptionId::Num(12), result: "goal" })
			.unwrap();
		let exp = r#"{"subscription":12,"result":"goal"}"#;
		assert_eq!(ser, exp);
	}

	#[test]
	fn subscription_params_deserialize_work() {
		let ser = r#"{"subscription":"9","result":"offside"}"#;
		assert!(
			serde_json::from_str::<SubscriptionPayload<()>>(ser).is_err(),
			"invalid type should not be deserializable"
		);
		let dsr: SubscriptionPayload<JsonValue> = serde_json::from_str(ser).unwrap();
		assert_eq!(dsr.subscription, SubscriptionId::Str("9".into()));
		assert_eq!(dsr.result, serde_json::json!("offside"));
	}

	#[test]
	fn params_sequence_optional_ignore_empty() {
		let params = Params::new(Some(r#"["foo", "bar"]"#));
		let mut seq = params.sequence();

		assert_eq!(seq.optional_next::<&str>().unwrap(), Some("foo"));
		assert_eq!(seq.optional_next::<&str>().unwrap(), Some("bar"));

		let params = Params::new(Some(r#"[]"#));
		let mut seq = params.sequence();
		assert!(seq.optional_next::<&str>().unwrap().is_none());

		let params = Params::new(Some(r#"   []		"#));
		let mut seq = params.sequence();
		assert!(seq.optional_next::<&str>().unwrap().is_none());

		let params = Params::new(Some(r#"{}"#));
		let mut seq = params.sequence();
		assert!(seq.optional_next::<&str>().is_err(), "JSON object not supported by RpcSequence");

		let params = Params::new(Some(r#"[12, "[]", [], {}]"#));
		let mut seq = params.sequence();
		assert_eq!(seq.optional_next::<u64>().unwrap(), Some(12));
		assert_eq!(seq.optional_next::<&str>().unwrap(), Some("[]"));
		assert_eq!(seq.optional_next::<Vec<u8>>().unwrap(), Some(vec![]));
		assert_eq!(seq.optional_next::<serde_json::Value>().unwrap(), Some(serde_json::json!({})));
	}

	#[test]
	fn params_sequence_optional_nesting_works() {
		let nested = Params::new(Some(r#"[1, [2], [3, 4], [[5], [6,7], []], {"named":7}]"#));
		let mut seq = nested.sequence();
		assert_eq!(seq.optional_next::<i8>().unwrap(), Some(1));
		assert_eq!(seq.optional_next::<[i8; 1]>().unwrap(), Some([2]));
		assert_eq!(seq.optional_next::<Vec<u16>>().unwrap(), Some(vec![3, 4]));
		assert_eq!(seq.optional_next::<Vec<Vec<u32>>>().unwrap(), Some(vec![vec![5], vec![6, 7], vec![]]));
		assert_eq!(seq.optional_next::<serde_json::Value>().unwrap(), Some(serde_json::json!({"named":7})));
	}
}