// -*- mode: typescript; indent-tabs-mode: nil; js-basic-offset: 4 -*-
//
// This file is part of Genie
//
// Copyright 2020 The Board of Trustees of the Leland Stanford Junior University
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//    http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
// Author: Giovanni Campagna <gcampagn@cs.stanford.edu>


import assert from 'assert';

import { Ast, } from 'thingtalk';

import * as C from '../ast_manip';
import { ContextInfo } from '../state_manip';

function contextualAction(ctx : ContextInfo, action : Ast.Invocation) {
    assert(action instanceof Ast.Invocation);
    const ctxInvocation = C.getInvocation(ctx.next!);
    if (!ctxInvocation || !(ctxInvocation instanceof Ast.Invocation))
        return null;
    if (!C.isSameFunction(ctxInvocation.schema!, action.schema!))
        return null;
    if (action.in_params.length === 0) // common case, no new parameters
        return ctxInvocation;

    for (const newParam of action.in_params) {
        if (newParam.value.isUndefined)
            continue;

        // check that we don't change a previous parameter

        // if we're introducing a value for the chain parameter that was not previously provided,
        // it must one of the top 3 results
        const nextInfo = ctx.nextInfo!;
        if (newParam.name === nextInfo.chainParameter &&
           !nextInfo.chainParameterFilled) {
            if (!ctx.results)
                return null;
            const results = ctx.results;
            let good = false;
            for (let i = 0; i < Math.min(results.length, 3); i ++) {
                const id = results[i].value.id;
                if (id && id.equals(newParam.value)) {
                    good = true;
                    break;
                }
            }
            if (!good)
                return null;
        }

        for (const oldParam of ctxInvocation.in_params) {
            if (oldParam.value.isUndefined)
                continue;
            if (newParam.name !== oldParam.name)
                continue;

            if (!newParam.value.equals(oldParam.value))
                return null;
        }
    }

    // semi-shallow clone
    const clone = new Ast.Invocation(null, ctxInvocation.selector, ctxInvocation.channel,
        ctxInvocation.in_params.map((ip) => new Ast.InputParam(null, ip.name, ip.value)),
        ctxInvocation.schema);
    for (const newParam of action.in_params) {
        if (newParam.value.isUndefined)
            continue;

        let found = false;
        for (const oldParam of clone.in_params) {
            if (newParam.name === oldParam.name) {
                if (oldParam.value.isUndefined)
                    oldParam.value = newParam.value;
                found = true;
                break;
            }
        }

        if (!found)
            clone.in_params.push(newParam);
    }

    return clone;
}

export {
    contextualAction
};