import _ from 'lodash';
import { actionReverse } from '../actions/reverse';
import { osmIsInterestingTag } from './tags';


// For fixing up rendering of multipolygons with tags on the outer member.
// https://github.com/openstreetmap/iD/issues/613
export function osmIsSimpleMultipolygonOuterMember(entity, graph) {
    if (entity.type !== 'way' || Object.keys(entity.tags).filter(osmIsInterestingTag).length === 0)
        return false;

    var parents = graph.parentRelations(entity);
    if (parents.length !== 1)
        return false;

    var parent = parents[0];
    if (!parent.isMultipolygon() || Object.keys(parent.tags).filter(osmIsInterestingTag).length > 1)
        return false;

    var members = parent.members, member;
    for (var i = 0; i < members.length; i++) {
        member = members[i];
        if (member.id === entity.id && member.role && member.role !== 'outer')
            return false; // Not outer member
        if (member.id !== entity.id && (!member.role || member.role === 'outer'))
            return false; // Not a simple multipolygon
    }

    return parent;
}


export function osmSimpleMultipolygonOuterMember(entity, graph) {
    if (entity.type !== 'way')
        return false;

    var parents = graph.parentRelations(entity);
    if (parents.length !== 1)
        return false;

    var parent = parents[0];
    if (!parent.isMultipolygon() || Object.keys(parent.tags).filter(osmIsInterestingTag).length > 1)
        return false;

    var members = parent.members, member, outerMember;
    for (var i = 0; i < members.length; i++) {
        member = members[i];
        if (!member.role || member.role === 'outer') {
            if (outerMember)
                return false; // Not a simple multipolygon
            outerMember = member;
        }
    }

    if (!outerMember)
        return false;

    var outerEntity = graph.hasEntity(outerMember.id);
    if (!outerEntity || !Object.keys(outerEntity.tags).filter(osmIsInterestingTag).length)
        return false;

    return outerEntity;
}


// Join `array` into sequences of connecting ways.
//
// Segments which share identical start/end nodes will, as much as possible,
// be connected with each other.
//
// The return value is a nested array. Each constituent array contains elements
// of `array` which have been determined to connect. Each consitituent array
// also has a `nodes` property whose value is an ordered array of member nodes,
// with appropriate order reversal and start/end coordinate de-duplication.
//
// Members of `array` must have, at minimum, `type` and `id` properties.
// Thus either an array of `osmWay`s or a relation member array may be
// used.
//
// If an member has a `tags` property, its tags will be reversed via
// `actionReverse` in the output.
//
// Incomplete members (those for which `graph.hasEntity(element.id)` returns
// false) and non-way members are ignored.
//
export function osmJoinWays(array, graph) {
    var joined = [], member, current, nodes, first, last, i, how, what;

    array = array.filter(function(member) {
        return member.type === 'way' && graph.hasEntity(member.id);
    });

    function resolve(member) {
        return graph.childNodes(graph.entity(member.id));
    }

    function reverse(member) {
        return member.tags ? actionReverse(member.id, { reverseOneway: true })(graph).entity(member.id) : member;
    }

    while (array.length) {
        member = array.shift();
        current = [member];
        current.nodes = nodes = resolve(member).slice();
        joined.push(current);

        while (array.length && _.first(nodes) !== _.last(nodes)) {
            first = _.first(nodes);
            last  = _.last(nodes);

            for (i = 0; i < array.length; i++) {
                member = array[i];
                what = resolve(member);

                if (last === _.first(what)) {
                    how  = nodes.push;
                    what = what.slice(1);
                    break;
                } else if (last === _.last(what)) {
                    how  = nodes.push;
                    what = what.slice(0, -1).reverse();
                    member = reverse(member);
                    break;
                } else if (first === _.last(what)) {
                    how  = nodes.unshift;
                    what = what.slice(0, -1);
                    break;
                } else if (first === _.first(what)) {
                    how  = nodes.unshift;
                    what = what.slice(1).reverse();
                    member = reverse(member);
                    break;
                } else {
                    what = how = null;
                }
            }

            if (!what)
                break; // No more joinable ways.

            how.apply(current, [member]);
            how.apply(nodes, what);

            array.splice(i, 1);
        }
    }

    return joined;
}