import id from UnitJS.Fun;
import size from Config;
import {asAFunction, iter, map, set, square} from Grid.Util;
import {diagonal, zero} from Geometry.Vector;
import * as CellSet from Geometry.CellSet;

return {
	fork: fork,
	setCells: setCells,
	start: start,
	zoneNames: zoneNames
};

function start(coloring) {
	var empty = Array.from({length: size});
	return {
		constellation: square(size),
		getColor: asAFunction(coloring),
		missing: CellSet.rectangle(zero(), diagonal(size)),
		zones: {
			colors: getColors(coloring),
			rows: empty.map(function(_, i) {return CellSet.row(i);}),
			columns: empty.map(function(_, i) {return CellSet.column(i);})
		}
	};
}

function getColors(grid) {
	var colors = Array.from({length: size});
	iter(grid, function(color, cell) {
		if(colors[color] == undefined) {
			colors[color] = new CellSet.CellSet();
		}
		colors[color].add(cell);
	});
	return colors;
}

function fork(state) {
	var zones = {};
	for(var name in state.zones) {
		zones[name] = state.zones[name].map(function(s) {return s.copy();});
	}
	return {
		constellation: map(state.constellation, id),
		getColor: state.getColor,
		missing: state.missing.copy(),
		zones: zones
	};
}

function setCells(solvingState, value, cellSet) {
	var forgetList = allZones(solvingState).concat(solvingState.missing);
	cellSet.iter(function(cell) {
		set(solvingState.constellation, cell, value);
		forgetList.forEach(function(solverSet) {
			solverSet.remove(cell);
		});
	});
}

function zoneNames(solvingState) {
	return Object.keys(solvingState.zones);
}

function allZones(solvingState) {
	return zoneNames(solvingState).flatMap(function(name) {
		return solvingState.zones[name];
	});
}