1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
// This file is part of Substrate.

// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: GPL-3.0-or-later WITH Classpath-exception-2.0

// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.

// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.

// You should have received a copy of the GNU General Public License
// along with this program. If not, see <https://www.gnu.org/licenses/>.

//! Chain Spec extensions helpers.

use std::{
	any::{Any, TypeId},
	fmt::Debug,
};

use std::collections::BTreeMap;

use serde::{de::DeserializeOwned, Deserialize, Serialize};

/// A `ChainSpec` extension.
///
/// This trait is implemented automatically by `ChainSpecGroup` macro.
pub trait Group: Clone + Sized {
	/// An associated type containing fork definition.
	type Fork: Fork<Base = Self>;

	/// Convert to fork type.
	fn to_fork(self) -> Self::Fork;
}

/// A `ChainSpec` extension fork definition.
///
/// Basically should look the same as `Group`, but
/// all parameters are optional. This allows changing
/// only one parameter as part of the fork.
/// The forks can be combined (summed up) to specify
/// a complete set of parameters
pub trait Fork: Serialize + DeserializeOwned + Clone + Sized {
	/// A base `Group` type.
	type Base: Group<Fork = Self>;

	/// Combine with another struct.
	///
	/// All parameters set in `other` should override the
	/// ones in the current struct.
	fn combine_with(&mut self, other: Self);

	/// Attempt to convert to the base type if all parameters are set.
	fn to_base(self) -> Option<Self::Base>;
}

macro_rules! impl_trivial {
	() => {};
	($A : ty) => {
		impl_trivial!($A ,);
	};
	($A : ty , $( $B : ty ),*) => {
		impl_trivial!($( $B ),*);

		impl Group for $A {
			type Fork = $A;

			fn to_fork(self) -> Self::Fork {
				self
			}
		}

		impl Fork for $A {
			type Base = $A;

			fn combine_with(&mut self, other: Self) {
				*self = other;
			}

			fn to_base(self) -> Option<Self::Base> {
				Some(self)
			}
		}
	}
}

impl_trivial!((), u8, u16, u32, u64, usize, String, Vec<u8>);

impl<T: Group> Group for Option<T> {
	type Fork = Option<T::Fork>;

	fn to_fork(self) -> Self::Fork {
		self.map(|a| a.to_fork())
	}
}

impl<T: Fork> Fork for Option<T> {
	type Base = Option<T::Base>;

	fn combine_with(&mut self, other: Self) {
		*self = match (self.take(), other) {
			(Some(mut a), Some(b)) => {
				a.combine_with(b);
				Some(a)
			},
			(a, b) => a.or(b),
		};
	}

	fn to_base(self) -> Option<Self::Base> {
		self.map(|x| x.to_base())
	}
}

/// A collection of `ChainSpec` extensions.
///
/// This type can be passed around and allows the core
/// modules to request a strongly-typed, but optional configuration.
pub trait Extension: Serialize + DeserializeOwned + Clone {
	type Forks: IsForks;

	/// Get an extension of specific type.
	fn get<T: 'static>(&self) -> Option<&T>;
	/// Get an extension of specific type as reference to `Any`.
	fn get_any(&self, t: TypeId) -> &dyn Any;
	/// Get an extension of specific type as mutable reference to `Any`.
	fn get_any_mut(&mut self, t: TypeId) -> &mut dyn Any;

	/// Get forkable extensions of specific type.
	fn forks<BlockNumber, T>(&self) -> Option<Forks<BlockNumber, T>>
	where
		BlockNumber: Ord + Clone + 'static,
		T: Group + 'static,
		<Self::Forks as IsForks>::Extension: Extension,
		<<Self::Forks as IsForks>::Extension as Group>::Fork: Extension,
	{
		self.get::<Forks<BlockNumber, <Self::Forks as IsForks>::Extension>>()?
			.for_type()
	}
}

impl Extension for crate::NoExtension {
	type Forks = Self;

	fn get<T: 'static>(&self) -> Option<&T> {
		None
	}
	fn get_any(&self, _t: TypeId) -> &dyn Any {
		self
	}
	fn get_any_mut(&mut self, _: TypeId) -> &mut dyn Any {
		self
	}
}

pub trait IsForks {
	type BlockNumber: Ord + 'static;
	type Extension: Group + 'static;
}

impl IsForks for Option<()> {
	type BlockNumber = u64;
	type Extension = Self;
}

#[derive(Clone, Debug, Serialize, Deserialize, PartialEq)]
#[serde(deny_unknown_fields)]
pub struct Forks<BlockNumber: Ord, T: Group> {
	forks: BTreeMap<BlockNumber, T::Fork>,
	#[serde(flatten)]
	base: T,
}

impl<B: Ord, T: Group + Default> Default for Forks<B, T> {
	fn default() -> Self {
		Self { base: Default::default(), forks: Default::default() }
	}
}

impl<B: Ord, T: Group> Forks<B, T>
where
	T::Fork: Debug,
{
	/// Create new fork definition given the base and the forks.
	pub fn new(base: T, forks: BTreeMap<B, T::Fork>) -> Self {
		Self { base, forks }
	}

	/// Return a set of parameters for `Group` including all forks up to `block` (inclusive).
	pub fn at_block(&self, block: B) -> T {
		let mut start = self.base.clone().to_fork();

		for (_, fork) in self.forks.range(..=block) {
			start.combine_with(fork.clone());
		}

		start
			.to_base()
			.expect("We start from the `base` object, so it's always fully initialized; qed")
	}
}

impl<B, T> IsForks for Forks<B, T>
where
	B: Ord + 'static,
	T: Group + 'static,
{
	type BlockNumber = B;
	type Extension = T;
}

impl<B: Ord + Clone, T: Group + Extension> Forks<B, T>
where
	T::Fork: Extension,
{
	/// Get forks definition for a subset of this extension.
	///
	/// Returns the `Forks` struct, but limited to a particular type
	/// within the extension.
	pub fn for_type<X>(&self) -> Option<Forks<B, X>>
	where
		X: Group + 'static,
	{
		let base = self.base.get::<X>()?.clone();
		let forks = self
			.forks
			.iter()
			.filter_map(|(k, v)| Some((k.clone(), v.get::<Option<X::Fork>>()?.clone()?)))
			.collect();

		Some(Forks { base, forks })
	}
}

impl<B, E> Extension for Forks<B, E>
where
	B: Serialize + DeserializeOwned + Ord + Clone + 'static,
	E: Extension + Group + 'static,
{
	type Forks = Self;

	fn get<T: 'static>(&self) -> Option<&T> {
		if TypeId::of::<T>() == TypeId::of::<E>() {
			<dyn Any>::downcast_ref(&self.base)
		} else {
			self.base.get()
		}
	}

	fn get_any(&self, t: TypeId) -> &dyn Any {
		if t == TypeId::of::<E>() {
			&self.base
		} else {
			self.base.get_any(t)
		}
	}

	fn get_any_mut(&mut self, t: TypeId) -> &mut dyn Any {
		if t == TypeId::of::<E>() {
			&mut self.base
		} else {
			self.base.get_any_mut(t)
		}
	}

	fn forks<BlockNumber, T>(&self) -> Option<Forks<BlockNumber, T>>
	where
		BlockNumber: Ord + Clone + 'static,
		T: Group + 'static,
		<Self::Forks as IsForks>::Extension: Extension,
		<<Self::Forks as IsForks>::Extension as Group>::Fork: Extension,
	{
		if TypeId::of::<BlockNumber>() == TypeId::of::<B>() {
			<dyn Any>::downcast_ref(&self.for_type::<T>()?).cloned()
		} else {
			self.get::<Forks<BlockNumber, <Self::Forks as IsForks>::Extension>>()?
				.for_type()
		}
	}
}

/// A subset of the `Extension` trait that only allows for querying extensions.
pub trait GetExtension {
	/// Get an extension of specific type.
	fn get_any(&self, t: TypeId) -> &dyn Any;

	/// Get an extension of specific type with mutable access.
	fn get_any_mut(&mut self, t: TypeId) -> &mut dyn Any;
}

impl<E: Extension> GetExtension for E {
	fn get_any(&self, t: TypeId) -> &dyn Any {
		Extension::get_any(self, t)
	}

	fn get_any_mut(&mut self, t: TypeId) -> &mut dyn Any {
		Extension::get_any_mut(self, t)
	}
}

/// Helper function that queries an extension by type from `GetExtension` trait object.
pub fn get_extension<T: 'static>(e: &dyn GetExtension) -> Option<&T> {
	<dyn Any>::downcast_ref(GetExtension::get_any(e, TypeId::of::<T>()))
}

/// Helper function that queries an extension by type from `GetExtension` trait object.
pub fn get_extension_mut<T: 'static>(e: &mut dyn GetExtension) -> Option<&mut T> {
	<dyn Any>::downcast_mut(GetExtension::get_any_mut(e, TypeId::of::<T>()))
}

#[cfg(test)]
mod tests {
	use super::*;
	use sc_chain_spec_derive::{ChainSpecExtension, ChainSpecGroup};
	// Make the proc macro work for tests and doc tests.
	use crate as sc_chain_spec;

	#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, ChainSpecGroup)]
	#[serde(deny_unknown_fields)]
	pub struct Extension1 {
		pub test: u64,
	}

	#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, ChainSpecGroup)]
	#[serde(deny_unknown_fields)]
	pub struct Extension2 {
		pub test: u8,
	}

	#[derive(
		Debug, Clone, PartialEq, Serialize, Deserialize, ChainSpecGroup, ChainSpecExtension,
	)]
	#[serde(deny_unknown_fields)]
	pub struct Extensions {
		pub ext1: Extension1,
		pub ext2: Extension2,
	}

	#[derive(Debug, Clone, PartialEq, Serialize, Deserialize, ChainSpecExtension)]
	#[serde(deny_unknown_fields)]
	pub struct Ext2 {
		#[serde(flatten)]
		ext1: Extension1,
		#[forks]
		forkable: Forks<u64, Extensions>,
	}

	#[test]
	fn forks_should_work_correctly() {
		use super::Extension as _;

		// We first need to deserialize into a `Value` because of the following bug:
		// https://github.com/serde-rs/json/issues/505
		let ext_val: serde_json::Value = serde_json::from_str(
			r#"
{
	"test": 11,
	"forkable": {
		"ext1": {
			"test": 15
		},
		"ext2": {
			"test": 123
		},
		"forks": {
			"1": {
				"ext1": { "test": 5 }
			},
			"2": {
				"ext2": { "test": 5 }
			},
			"5": {
				"ext2": { "test": 1 }
			}
		}
	}
}
		"#,
		)
		.unwrap();

		let ext: Ext2 = serde_json::from_value(ext_val).unwrap();

		assert_eq!(ext.get::<Extension1>(), Some(&Extension1 { test: 11 }));

		// get forks definition
		let forks = ext.get::<Forks<u64, Extensions>>().unwrap();
		assert_eq!(
			forks.at_block(0),
			Extensions { ext1: Extension1 { test: 15 }, ext2: Extension2 { test: 123 } }
		);
		assert_eq!(
			forks.at_block(1),
			Extensions { ext1: Extension1 { test: 5 }, ext2: Extension2 { test: 123 } }
		);
		assert_eq!(
			forks.at_block(2),
			Extensions { ext1: Extension1 { test: 5 }, ext2: Extension2 { test: 5 } }
		);
		assert_eq!(
			forks.at_block(4),
			Extensions { ext1: Extension1 { test: 5 }, ext2: Extension2 { test: 5 } }
		);
		assert_eq!(
			forks.at_block(5),
			Extensions { ext1: Extension1 { test: 5 }, ext2: Extension2 { test: 1 } }
		);
		assert_eq!(
			forks.at_block(10),
			Extensions { ext1: Extension1 { test: 5 }, ext2: Extension2 { test: 1 } }
		);
		assert!(forks.at_block(10).get::<Extension2>().is_some());

		// filter forks for `Extension2`
		let ext2 = forks.for_type::<Extension2>().unwrap();
		assert_eq!(ext2.at_block(0), Extension2 { test: 123 });
		assert_eq!(ext2.at_block(2), Extension2 { test: 5 });
		assert_eq!(ext2.at_block(10), Extension2 { test: 1 });

		// make sure that it can return forks correctly
		let ext2_2 = forks.forks::<u64, Extension2>().unwrap();
		assert_eq!(ext2, ext2_2);

		// also ext should be able to return forks correctly:
		let ext2_3 = ext.forks::<u64, Extension2>().unwrap();
		assert_eq!(ext2_2, ext2_3);
	}
}