import {isPresent} from 'angular2/src/facade/lang';

import {List, ListWrapper, Map, MapWrapper} from 'angular2/src/facade/collection';

import {RECORD_TYPE_SELF, ProtoRecord} from './proto_record';

/**

* Removes "duplicate" records. It assuming that record evaluation does not

* have side-effects.

*

* Records that are not last in bindings are removed and all the indices

* of the records that depend on them are updated.

*

* Records that are last in bindings CANNOT be removed, and instead are

* replaced with very cheap SELF records.

*/

export function coalesce(records:List<ProtoRecord>):List<ProtoRecord> {

var res = ListWrapper.create();

var indexMap = MapWrapper.create();

for (var i = 0; i < records.length; ++i) {

var r = records[i];

var record = _replaceIndices(r, res.length + 1, indexMap);

var matchingRecord = _findMatching(record, res);

if (isPresent(matchingRecord) && record.lastInBinding) {

ListWrapper.push(res, _selfRecord(record, matchingRecord.selfIndex, res.length + 1));

MapWrapper.set(indexMap, r.selfIndex, matchingRecord.selfIndex);

} else if (isPresent(matchingRecord) && !record.lastInBinding) {

MapWrapper.set(indexMap, r.selfIndex, matchingRecord.selfIndex);

} else {

ListWrapper.push(res, record);

MapWrapper.set(indexMap, r.selfIndex, record.selfIndex);

}

}

return res;

}

function _selfRecord(r:ProtoRecord, contextIndex:number, selfIndex:number):ProtoRecord {

return new ProtoRecord(

RECORD_TYPE_SELF,

"self",

null,

[],

r.fixedArgs,

contextIndex,

selfIndex,

r.bindingRecord,

r.expressionAsString,

r.lastInBinding,

r.lastInDirective

);

}

function _findMatching(r:ProtoRecord, rs:List<ProtoRecord>){

return ListWrapper.find(rs, (rr) =>

rr.mode === r.mode &&

rr.funcOrValue === r.funcOrValue &&

rr.contextIndex === r.contextIndex &&

ListWrapper.equals(rr.args, r.args)

);

}

function _replaceIndices(r:ProtoRecord, selfIndex:number, indexMap:Map) {

var args = ListWrapper.map(r.args, (a) => _map(indexMap, a));

var contextIndex = _map(indexMap, r.contextIndex);

return new ProtoRecord(

r.mode,

r.name,

r.funcOrValue,

args,

r.fixedArgs,

contextIndex,

selfIndex,

r.bindingRecord,

r.expressionAsString,

r.lastInBinding,

r.lastInDirective

);

}

function _map(indexMap:Map, value:number) {

var r = MapWrapper.get(indexMap, value)

return isPresent(r) ? r : value;

}