// Copyright 2018 The Grin Developers
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

//! Values that should be shared across all modules, without necessarily
//! having to pass them all over the place, but aren't consensus values.
//! should be used sparingly.

/// An enum collecting sets of parameters used throughout the
/// code wherever mining is needed. This should allow for
/// different sets of parameters for different purposes,
/// e.g. CI, User testing, production values

use std::sync::RwLock;
use consensus::PROOFSIZE;
use consensus::DEFAULT_SIZESHIFT;
use consensus::COINBASE_MATURITY;
use consensus::{MEDIAN_TIME_WINDOW, INITIAL_DIFFICULTY, 
	BLOCK_TIME_SEC, DIFFICULTY_ADJUST_WINDOW, CUT_THROUGH_HORIZON};
use core::target::Difficulty;
use consensus::TargetError;

/// Define these here, as they should be developer-set, not really tweakable
/// by users

/// Automated testing sizeshift
pub const AUTOMATED_TESTING_SIZESHIFT: u8 = 10;

/// Automated testing proof size
pub const AUTOMATED_TESTING_PROOF_SIZE: usize = 4;

/// User testing sizeshift
pub const USER_TESTING_SIZESHIFT: u8 = 16;

/// User testing proof size
pub const USER_TESTING_PROOF_SIZE: usize = 42;

/// Automated testing coinbase maturity
pub const AUTOMATED_TESTING_COINBASE_MATURITY: u64 = 3;

/// User testing coinbase maturity
pub const USER_TESTING_COINBASE_MATURITY: u64 = 3;

/// Testing cut through horizon in blocks
pub const TESTING_CUT_THROUGH_HORIZON: u32 = 20;

/// Testing initial block difficulty
pub const TESTING_INITIAL_DIFFICULTY: u64 = 1;

/// Testing initial block difficulty, testnet 2
/// we want to overestimate here as well
/// Setting to 1 for development, but should be 1000 at T2 launch
pub const TESTNET2_INITIAL_DIFFICULTY: u64 = 1;

/// The target is the 32-bytes hash block hashes must be lower than.
pub const MAX_PROOF_TARGET: [u8; 8] = [0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff];
 
/// We want to slow this right down for user testing at cuckoo 16, so pick a smaller max
pub const MAX_PROOF_TARGET_TESTING: [u8; 8] = [0x05, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff];

/// Types of chain a server can run with, dictates the genesis block and
/// and mining parameters used.
#[derive(Debug, Clone, Serialize, Deserialize, PartialEq)]
pub enum ChainTypes {
	/// For CI testing
	AutomatedTesting,

	/// For User testing
	UserTesting,

  /// First test network
	Testnet1,

	/// Second test network
	Testnet2,

  /// Main production network
	Mainnet,
}

impl Default for ChainTypes {
	fn default() -> ChainTypes {
		ChainTypes::UserTesting
	}
}

lazy_static!{
	/// The mining parameter mode
	pub static ref CHAIN_TYPE: RwLock<ChainTypes> =
			RwLock::new(ChainTypes::Mainnet);
}

/// Set the mining mode
pub fn set_mining_mode(mode: ChainTypes) {
	let mut param_ref = CHAIN_TYPE.write().unwrap();
	*param_ref = mode;
}

/// The sizeshift
pub fn sizeshift() -> u8 {
	let param_ref = CHAIN_TYPE.read().unwrap();
	match *param_ref {
		ChainTypes::AutomatedTesting => AUTOMATED_TESTING_SIZESHIFT,
		ChainTypes::UserTesting => USER_TESTING_SIZESHIFT,
		ChainTypes::Testnet1 => USER_TESTING_SIZESHIFT,
		ChainTypes::Testnet2 => DEFAULT_SIZESHIFT,
		ChainTypes::Mainnet => DEFAULT_SIZESHIFT,
	}
}

/// The proofsize
pub fn proofsize() -> usize {
	let param_ref = CHAIN_TYPE.read().unwrap();
	match *param_ref {
		ChainTypes::AutomatedTesting => AUTOMATED_TESTING_PROOF_SIZE,
		ChainTypes::UserTesting => USER_TESTING_PROOF_SIZE,
		ChainTypes::Testnet1 => PROOFSIZE,
		ChainTypes::Testnet2 => PROOFSIZE,
		ChainTypes::Mainnet => PROOFSIZE,
	}
}

/// Coinbase maturity
pub fn coinbase_maturity() -> u64 {
	let param_ref = CHAIN_TYPE.read().unwrap();
	match *param_ref {
		ChainTypes::AutomatedTesting => AUTOMATED_TESTING_COINBASE_MATURITY,
		ChainTypes::UserTesting => USER_TESTING_COINBASE_MATURITY,
		ChainTypes::Testnet1 => COINBASE_MATURITY,
		ChainTypes::Testnet2 => COINBASE_MATURITY,
		ChainTypes::Mainnet => COINBASE_MATURITY,
	}
}

/// Max Proof Target
pub fn max_proof_target() -> [u8; 8] {
	let param_ref = CHAIN_TYPE.read().unwrap();
	match *param_ref {
		ChainTypes::AutomatedTesting => MAX_PROOF_TARGET_TESTING,
		ChainTypes::UserTesting => MAX_PROOF_TARGET_TESTING,
		ChainTypes::Testnet1 => MAX_PROOF_TARGET_TESTING,
		ChainTypes::Testnet2 => MAX_PROOF_TARGET,
		ChainTypes::Mainnet => MAX_PROOF_TARGET,
	}
}

/// Initial mining difficulty
pub fn initial_block_difficulty() -> u64 {
	let param_ref = CHAIN_TYPE.read().unwrap();
	match *param_ref {
		ChainTypes::AutomatedTesting => TESTING_INITIAL_DIFFICULTY,
		ChainTypes::UserTesting => TESTING_INITIAL_DIFFICULTY,
		ChainTypes::Testnet1 => TESTING_INITIAL_DIFFICULTY,
		ChainTypes::Testnet2 => TESTNET2_INITIAL_DIFFICULTY,
		ChainTypes::Mainnet => INITIAL_DIFFICULTY,
	}
}

/// Horizon at which we can cut-through and do full local pruning
pub fn cut_through_horizon() -> u32 {
	let param_ref = CHAIN_TYPE.read().unwrap();
	match *param_ref {
		ChainTypes::AutomatedTesting => TESTING_CUT_THROUGH_HORIZON,
		ChainTypes::UserTesting => TESTING_CUT_THROUGH_HORIZON,
		ChainTypes::Testnet1 => CUT_THROUGH_HORIZON,
		ChainTypes::Testnet2 => CUT_THROUGH_HORIZON,
		ChainTypes::Mainnet => CUT_THROUGH_HORIZON,
	}
}

/// Are we in automated testing mode?
pub fn is_automated_testing_mode() -> bool {
	let param_ref = CHAIN_TYPE.read().unwrap();
	ChainTypes::AutomatedTesting == *param_ref
}

/// Are we in user testing mode?
pub fn is_user_testing_mode() -> bool {
	let param_ref = CHAIN_TYPE.read().unwrap();
	ChainTypes::UserTesting == *param_ref
}

/// Are we in production mode (a live public network)?
pub fn is_production_mode() -> bool {
	let param_ref = CHAIN_TYPE.read().unwrap();
	ChainTypes::Testnet1 == *param_ref ||
    ChainTypes::Testnet2 == *param_ref ||
    ChainTypes::Mainnet == *param_ref
}

/// Helper function to get a nonce known to create a valid POW on
/// the genesis block, to prevent it taking ages. Should be fine for now
/// as the genesis block POW solution turns out to be the same for every new
/// block chain at the moment
pub fn get_genesis_nonce() -> u64 {
	let param_ref = CHAIN_TYPE.read().unwrap();
	match *param_ref {
		// won't make a difference
		ChainTypes::AutomatedTesting => 0,
		// Magic nonce for current genesis block at cuckoo16
		ChainTypes::UserTesting => 27944,
		// Magic nonce for genesis block for testnet2 (cuckoo30)

		_ => panic!("Pre-set"),
	}
}

/// Converts an iterator of block difficulty data to more a more mangeable vector and pads 
/// if needed (which will) only be needed for the first few blocks after genesis

pub fn difficulty_data_to_vector<T>(cursor: T) -> Vec<Result<(u64, Difficulty), TargetError>>
	where
	T: IntoIterator<Item = Result<(u64, Difficulty), TargetError>> {
	// Convert iterator to vector, so we can append to it if necessary
	let needed_block_count = (MEDIAN_TIME_WINDOW + DIFFICULTY_ADJUST_WINDOW) as usize;
	let mut last_n: Vec<Result<(u64, Difficulty), TargetError>> = cursor.into_iter()
		.take(needed_block_count)
		.collect();

	// Sort blocks from earliest to latest (to keep conceptually easier)
	last_n.reverse();
	// Only needed just after blockchain launch... basically ensures there's
	// always enough data by simulating perfectly timed pre-genesis
	// blocks at the genesis difficulty as needed.
	let block_count_difference = needed_block_count - last_n.len();
	if block_count_difference > 0 {
		// Collect any real data we have
		let mut live_intervals:Vec<(u64, Difficulty)> = last_n.iter()
			.map(|b| (b.clone().unwrap().0, b.clone().unwrap().1))
			.collect();
		for i in (1..live_intervals.len()).rev() {
			// prevents issues with very fast automated test chains
			if live_intervals[i-1].0 > live_intervals[i].0 {
				live_intervals[i].0 = 0;
			} else {
				live_intervals[i].0=live_intervals[i].0-live_intervals[i-1].0;
			}
		}
		// 
		// Remove genesis "interval"
		if live_intervals.len() > 1 {
			live_intervals.remove(0);
		} else {
			//if it's just genesis, adjust the interval
			live_intervals[0].0 = BLOCK_TIME_SEC;
		}
		let mut interval_index = live_intervals.len() - 1;
		let mut last_ts = last_n.first().as_ref().unwrap().as_ref().unwrap().0;
		// fill in simulated blocks, repeating whatever pattern we've obtained from
		// real data
		// if we have, say, 15 blocks so far with intervals of I1..I15, then
		// the 71-15=56 pre genesis blocks will have
		// intervals/difficulties I1..I15 I1..I15 I1..I15 I1..I11
		for _ in 0..block_count_difference {
			last_ts = last_ts - live_intervals[interval_index].0;
			let last_diff = &live_intervals[interval_index].1;
			last_n.insert(0, Ok((last_ts, last_diff.clone())));
			interval_index = match interval_index {
				0 => live_intervals.len()-1,
				_ => interval_index - 1,
			};
		}
	}
	last_n
}