OpenTally/src/stv/wasm.rs

/*  OpenTally: Open-source election vote counting
 *  Copyright © 2021–2022 Lee Yingtong Li (RunasSudo)
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */

#![allow(rustdoc::private_intra_doc_links)]
#![allow(unused_unsafe)] // Confuses cargo check

use crate::constraints::{self, Constraints};
use crate::election::{CandidateState, CountState, Election};
//use crate::numbers::{DynNum, Fixed, GuardedFixed, NativeFloat64, Number, NumKind, Rational};
use crate::numbers::{Fixed, GuardedFixed, NativeFloat64, Number, Rational};
use crate::parser::blt;
use crate::stv;
use crate::ties;

extern crate console_error_panic_hook;

use js_sys::Array;
use wasm_bindgen::{JsValue, prelude::wasm_bindgen};

use std::cmp::max;

// Error handling

#[wasm_bindgen]
extern "C" {
	fn wasm_error(message: String);
}

macro_rules! wasm_error {
	($type:expr, $err:expr) => { {
		unsafe { wasm_error(format!("{}: {}", $type, $err)); }
		panic!("{}: {}", $type, $err);
	} }
}

// Init

// Wrapper for [DynNum::set_kind]
//#[wasm_bindgen]
//pub fn dynnum_set_kind(kind: NumKind) {
//	DynNum::set_kind(kind);
//}

/// Wrapper for [Fixed::set_dps]
#[cfg_attr(feature = "wasm", wasm_bindgen)]
pub fn fixed_set_dps(dps: usize) {
	Fixed::set_dps(dps);
}

/// Wrapper for [GuardedFixed::set_dps]
#[cfg_attr(feature = "wasm", wasm_bindgen)]
pub fn gfixed_set_dps(dps: usize) {
	GuardedFixed::set_dps(dps);
}

// Helper macros for making functions

macro_rules! impl_type {
	($type:ident) => { paste::item! {
		// Counting
		
		/// Wrapper for [blt::parse_iterator]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<election_from_blt_$type>](text: String) -> [<Election$type>] {
			// Install panic! hook
			console_error_panic_hook::set_once();
			
			let election: Election<$type> = match blt::parse_iterator(text.chars().peekable()) {
				Ok(e) => e,
				Err(err) => wasm_error!("Syntax Error", err),
			};
			return [<Election$type>](election);
		}
		
		/// Call [Constraints::from_con] and set [Election::constraints]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<election_load_constraints_$type>](election: &mut [<Election$type>], text: String, opts: &STVOptions) {
			election.0.constraints = match Constraints::from_con(text.lines()) {
				Ok(c) => Some(c),
				Err(err) => wasm_error!("Constraint Syntax Error", err),
			};
			
			// Validate constraints
			if let Err(err) = election.0.constraints.as_ref().unwrap().validate_constraints(election.0.candidates.len(), opts.0.constraint_mode) {
				wasm_error!("Constraint Validation Error", err);
			}
			
			// Add dummy candidates if required
			if opts.0.constraint_mode == stv::ConstraintMode::RepeatCount {
				constraints::init_repeat_count(&mut election.0);
			}
		}
		
		/// Wrapper for [stv::preprocess_election]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<preprocess_election_$type>](election: &mut [<Election$type>], opts: &STVOptions) {
			stv::preprocess_election(&mut election.0, &opts.0);
		}
		
		/// Wrapper for [stv::count_init]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<count_init_$type>](state: &mut [<CountState$type>], opts: &STVOptions) {
			match stv::count_init(&mut state.0, opts.as_static()) {
				Ok(_) => (),
				Err(err) => wasm_error!("Error", err),
			}
		}
		
		/// Wrapper for [stv::count_one_stage]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<count_one_stage_$type>](state: &mut [<CountState$type>], opts: &STVOptions) -> bool {
			match stv::count_one_stage::<[<$type>]>(&mut state.0, &opts.0) {
				Ok(v) => v,
				Err(err) => wasm_error!("Error", err),
			}
		}
		
		// Reporting
		
		/// Wrapper for [init_results_table]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<init_results_table_$type>](election: &[<Election$type>], opts: &STVOptions, report_style: &str) -> String {
			return init_results_table(&election.0, &opts.0, report_style);
		}
		
		/// Wrapper for [describe_count]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<describe_count_$type>](filename: String, election: &[<Election$type>], opts: &STVOptions) -> String {
			return stv::html::describe_count(&filename, &election.0, &opts.0);
		}
		
		/// Wrapper for [update_results_table]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<update_results_table_$type>](stage_num: usize, state: &[<CountState$type>], opts: &STVOptions, report_style: &str) -> Array {
			return update_results_table(stage_num, &state.0, &opts.0, report_style);
		}
		
		/// Wrapper for [update_stage_comments]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<update_stage_comments_$type>](state: &[<CountState$type>], stage_num: usize) -> String {
			return update_stage_comments(&state.0, stage_num);
		}
		
		/// Wrapper for [finalise_results_table]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<finalise_results_table_$type>](state: &[<CountState$type>], report_style: &str) -> Array {
			return finalise_results_table(&state.0, report_style);
		}
		
		/// Wrapper for [final_result_summary]
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		#[allow(non_snake_case)]
		pub fn [<final_result_summary_$type>](state: &[<CountState$type>], opts: &STVOptions) -> String {
			return final_result_summary(&state.0, &opts.0);
		}
		
		// Wrapper structs
		
		/// Wrapper for [CountState]
		///
		/// This is required as `&'static` cannot be specified in wasm-bindgen: see [issue 1187](https://github.com/rustwasm/wasm-bindgen/issues/1187).
		///
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		pub struct [<CountState$type>](CountState<'static, $type>);
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		impl [<CountState$type>] {
			/// Create a new [CountState] wrapper
			pub fn new(election: &[<Election$type>]) -> Self {
				return [<CountState$type>](CountState::new(election.as_static()));
			}
			
			/// Call [render_text](crate::stv::gregory::TransferTable::render_text) (as HTML) on [CountState::transfer_table]
			pub fn transfer_table_render_html(&self, opts: &STVOptions) -> Option<String> {
				return self.0.transfer_table.as_ref().map(|tt| tt.render_text(&opts.0));
			}
		}
		
		/// Wrapper for [Election]
		///
		/// This is required as `&'static` cannot be specified in wasm-bindgen: see [issue 1187](https://github.com/rustwasm/wasm-bindgen/issues/1187).
		///
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		pub struct [<Election$type>](Election<$type>);
		#[cfg_attr(feature = "wasm", wasm_bindgen)]
		impl [<Election$type>] {
			/// Return [Election::seats]
			pub fn seats(&self) -> usize { self.0.seats }
			
			/// Return the underlying [Election] as a `&'static Election`
			///
			/// # Safety
			/// This assumes that the underlying [Election] is valid for the `'static` lifetime, as it would be if the [Election] were created from Javascript.
			///
			fn as_static(&self) -> &'static Election<$type> {
				unsafe {
					let ptr = &self.0 as *const Election<$type>;
					&*ptr
				}
			}
		}
	}}
}

//impl_type!(DynNum);
impl_type!(Fixed);
impl_type!(GuardedFixed);
impl_type!(NativeFloat64);
impl_type!(Rational);

/// Wrapper for [stv::STVOptions]
#[cfg_attr(feature = "wasm", wasm_bindgen)]
pub struct STVOptions(stv::STVOptions);

#[cfg_attr(feature = "wasm", wasm_bindgen)]
impl STVOptions {
	/// Wrapper for [stv::STVOptions::new]
	pub fn new(
		round_surplus_fractions: Option<usize>,
		round_values: Option<usize>,
		round_votes: Option<usize>,
		round_quota: Option<usize>,
		round_subtransfers: &str,
		meek_surplus_tolerance: String,
		quota: &str,
		quota_criterion: &str,
		quota_mode: &str,
		ties: Array,
		random_seed: String,
		surplus: &str,
		surplus_order: &str,
		papers: &str,
		exclusion: &str,
		meek_nz_exclusion: bool,
		sample: &str,
		sample_per_ballot: bool,
		early_bulk_elect: bool,
		bulk_exclude: bool,
		defer_surpluses: bool,
		immediate_elect: bool,
		min_threshold: String,
		constraints_path: Option<String>,
		constraint_mode: &str,
		pp_decimals: usize,
	) -> Self {
		Self(stv::STVOptions::new(
			round_surplus_fractions,
			round_values,
			round_votes,
			round_quota,
			round_subtransfers.into(),
			meek_surplus_tolerance,
			quota.into(),
			quota_criterion.into(),
			quota_mode.into(),
			ties::from_strs(ties.iter().map(|v| v.as_string().unwrap()).collect(), Some(random_seed)),
			surplus.into(),
			surplus_order.into(),
			if papers == "transferable" || papers == "subtract_nontransferable" { true } else { false },
			if papers == "subtract_nontransferable" { true } else { false },
			exclusion.into(),
			meek_nz_exclusion,
			sample.into(),
			sample_per_ballot,
			early_bulk_elect,
			bulk_exclude,
			defer_surpluses,
			immediate_elect,
			min_threshold,
			constraints_path,
			constraint_mode.into(),
			false,
			false,
			false,
			pp_decimals,
		))
	}
	
	/// Wrapper for [stv::STVOptions::validate]
	pub fn validate(&self) {
		match self.0.validate() {
			Ok(_) => {}
			Err(err) => { wasm_error!("Error", err) }
		}
	}
}

impl STVOptions {
	/// Return the underlying [stv::STVOptions] as a `&'static stv::STVOptions`
	///
	/// # Safety
	/// This assumes that the underlying [stv::STVOptions] is valid for the `'static` lifetime, as it would be if the [stv::STVOptions] were created from Javascript.
	///
	fn as_static(&self) -> &'static stv::STVOptions {
		unsafe {
			let ptr = &self.0 as *const stv::STVOptions;
			&*ptr
		}
	}
}

// Reporting

/// Generate the first column of the HTML results table
pub fn init_results_table<N: Number>(election: &Election<N>, opts: &stv::STVOptions, report_style: &str) -> String {
	return stv::html::init_results_table(election, opts, report_style).join("");
}

/// Generate subsequent columns of the HTML results table
pub fn update_results_table<N: Number>(stage_num: usize, state: &CountState<N>, opts: &stv::STVOptions, report_style: &str) -> Array {
	return stv::html::update_results_table(stage_num, state, opts, report_style)
		.into_iter()
		.map(|s| JsValue::from(s))
		.collect();
}

/// Get the comment for the current stage
pub fn update_stage_comments<N: Number>(state: &CountState<N>, stage_num: usize) -> String {
	let mut comments = state.logger.render().join(" ");
	if state.transfer_table.is_some() {
		comments.push_str(&format!(r##" <a href="#" class="detailedTransfersLink" onclick="viewDetailedTransfers({});return false;">[View detailed transfers]</a>"##, stage_num));
	}
	return comments;
}

/// Generate the final column of the HTML results table
pub fn finalise_results_table<N: Number>(state: &CountState<N>, report_style: &str) -> Array {
	return stv::html::finalise_results_table(state, report_style)
		.into_iter()
		.map(|s| JsValue::from(s))
		.collect();
}

/// Generate the final lead-out text summarising the result of the election
pub fn final_result_summary<N: Number>(state: &CountState<N>, opts: &stv::STVOptions) -> String {
	let mut result = String::from("<p>Count complete. The winning candidates are, in order of election:</p><ol>");
	
	let mut winners = Vec::new();
	for (candidate, count_card) in state.candidates.iter() {
		if count_card.state == CandidateState::Elected {
			winners.push((candidate, count_card.order_elected, &count_card.keep_value));
		}
	}
	winners.sort_unstable_by(|a, b| a.1.cmp(&b.1));
	
	for (winner, _, kv_opt) in winners.into_iter() {
		if let Some(kv) = kv_opt {
			result.push_str(&format!("<li>{} (<i>kv</i> = {:.dps2$})</li>", winner.name, kv, dps2=max(opts.pp_decimals, 2)));
		} else {
			result.push_str(&format!("<li>{}</li>", winner.name));
		}
	}
	
	result.push_str("</ol>");
	return result;
}