/**
 * Copyright (c) 2019 mol* contributors, licensed under MIT, See LICENSE file for more info.
 *
 * @author David Sehnal <david.sehnal@gmail.com>
 */

import Expression from '../../mol-script/language/expression';
import { QueryFn, Structure, StructureSelection as Sel, QueryContext } from '../../mol-model/structure';
import { Script } from '../../mol-script/script';
import { compile } from '../../mol-script/runtime/query/compiler';
import { PluginStateObject as SO } from '../state/objects';

export { StructureQueryHelper }
namespace StructureQueryHelper {
    export interface CacheEntry {
        script?: Script,
        expression: Expression,
        compiled: QueryFn<Sel>,
        originalStructure: Structure,
        currentStructure: Structure
    }

    export function isUnchanged(entry: CacheEntry, query: Script | Expression, structure: Structure) {
        if (entry.currentStructure !== structure) return false;
        if (Script.is(query)) {
            return !!entry.script && Script.areEqual(entry.script, query);
        }
        return entry.expression === query;
    }

    export function create(structure: Structure, query: Script | Expression): CacheEntry {
        const script = Script.is(query) ? query : void 0;
        const expression = Script.is(query) ? Script.toExpression(query) : query;
        const compiled = compile<Sel>(expression);

        return { script, expression, compiled, originalStructure: structure, currentStructure: structure };
    }

    export function run(entry: CacheEntry, structure: Structure) {
        return entry.compiled(new QueryContext(structure))
    }

    export function createAndRun(structure: Structure, query: Script | Expression) {
        const entry = create(structure, query);
        return { entry, selection: run(entry, structure) };
    }

    export function updateStructure(entry: CacheEntry, structure: Structure) {
        entry.currentStructure = structure;
        return entry.compiled(new QueryContext(structure));
    }

    export function updateStructureObject(obj: SO.Molecule.Structure, selection: Sel, label?: string) {
        const s = Sel.unionStructure(selection);
        obj.label = `${label || 'Selection'}`;
        obj.description = Structure.elementDescription(s);
        obj.data = s;
    }
}