import getRange from Solver.SingleCell;
import CellSet from Geometry.CellSet;
import * as State from Solver.State;
import * as Strategy from Solver.Strategy;

return {
	find: find
};

function find(solvingState) {
	return Strategy.tryEach(
		solvingState.missing.map(findContradiction(solvingState))
	);
}

function findContradiction(solvingState) {
	return function(cell) {
		return function() {
			var forked = State.fork(solvingState);
			State.setCells(forked, false, getRange(forked, cell));
			return getContradiction(solvingState, forked, cell);
		};
	};
}

function stepOfContradiction(cell, name, i) {
	var step = {
		reason: 'noStarLeft',
		empty: new CellSet(cell),
	};
	step['in_' + name] = i;
	return step;
}

function getContradiction(beforeState, afterState, cell) {
	for(var name in beforeState.zones) {
		var zones = beforeState.zones[name];
		for(var i = 0; i < zones.length; i++) {
			if(zones[i].size() > 0 && afterState.zones[name][i].size() < 1) {
				return stepOfContradiction(cell, name, i);
			}
		}
	}
}