/*
Copyright 2023 The Matrix.org Foundation C.I.C.
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.
*/
import { type StatsReportEmitter } from "./statsReportEmitter.ts";
import { type CallStatsReportSummary } from "./callStatsReportSummary.ts";
import { type SummaryStatsReport } from "./statsReport.ts";
import { type ParticipantState } from "../groupCall.ts";
import { type RoomMember } from "../../matrix.ts";

interface CallStatsReportSummaryCounter {
    receivedAudio: number;
    receivedVideo: number;
    receivedMedia: number;
    concealedAudio: number;
    totalAudio: number;
}

export class SummaryStatsReportGatherer {
    public constructor(private emitter: StatsReportEmitter) {}

    public build(allSummary: CallStatsReportSummary[]): void {
        // Filter all stats which collect the first time webrtc stats.
        // Because stats based on time interval and the first collection of a summery stats has no previous
        // webrtcStats as basement all the calculation are 0. We don't want track the 0 stats.
        const summary = allSummary.filter((s) => !s.isFirstCollection);
        const summaryTotalCount = summary.length;
        // For counting the peer connections we also want to consider the ignored summaries
        const peerConnectionsCount = allSummary.length;
        if (summaryTotalCount === 0) {
            return;
        }

        const summaryCounter: CallStatsReportSummaryCounter = {
            receivedAudio: 0,
            receivedVideo: 0,
            receivedMedia: 0,
            concealedAudio: 0,
            totalAudio: 0,
        };
        let maxJitter = 0;
        let maxPacketLoss = 0;
        summary.forEach((stats) => {
            this.countTrackListReceivedMedia(summaryCounter, stats);
            this.countConcealedAudio(summaryCounter, stats);
            maxJitter = this.buildMaxJitter(maxJitter, stats);
            maxPacketLoss = this.buildMaxPacketLoss(maxPacketLoss, stats);
        });
        const decimalPlaces = 5;
        const report = {
            percentageReceivedMedia: Number((summaryCounter.receivedMedia / summaryTotalCount).toFixed(decimalPlaces)),
            percentageReceivedVideoMedia: Number(
                (summaryCounter.receivedVideo / summaryTotalCount).toFixed(decimalPlaces),
            ),
            percentageReceivedAudioMedia: Number(
                (summaryCounter.receivedAudio / summaryTotalCount).toFixed(decimalPlaces),
            ),
            maxJitter,
            maxPacketLoss,
            percentageConcealedAudio: Number(
                summaryCounter.totalAudio > 0
                    ? (summaryCounter.concealedAudio / summaryCounter.totalAudio).toFixed(decimalPlaces)
                    : 0,
            ),
            peerConnections: peerConnectionsCount,
        } as SummaryStatsReport;
        this.emitter.emitSummaryStatsReport(report);
    }

    public static extendSummaryReport(
        report: SummaryStatsReport,
        callParticipants: Map<RoomMember, Map<string, ParticipantState>>,
    ): void {
        // Calculate the actual number of devices based on the participants state event
        // (this is used, to compare the expected participant count from the room state with the acutal peer connections)
        // const devices = callParticipants.()
        const devices: [string, ParticipantState][] = [];
        const users: [RoomMember, Map<string, ParticipantState>][] = [];
        for (const userEntry of callParticipants) {
            users.push(userEntry);
            for (const device of userEntry[1]) {
                devices.push(device);
            }
        }
        report.opponentDevicesInCall = Math.max(0, devices.length - 1);
        report.opponentUsersInCall = Math.max(0, users.length - 1);
        report.diffDevicesToPeerConnections = Math.max(0, devices.length - 1) - report.peerConnections;
        report.ratioPeerConnectionToDevices =
            Math.max(0, devices.length - 1) == 0 ? 0 : report.peerConnections / (devices.length - 1);
    }

    private countTrackListReceivedMedia(counter: CallStatsReportSummaryCounter, stats: CallStatsReportSummary): void {
        let hasReceivedAudio = false;
        let hasReceivedVideo = false;
        if (stats.receivedAudioMedia > 0 || stats.audioTrackSummary.count === 0) {
            counter.receivedAudio++;
            hasReceivedAudio = true;
        }
        if (stats.receivedVideoMedia > 0 || stats.videoTrackSummary.count === 0) {
            counter.receivedVideo++;
            hasReceivedVideo = true;
        } else {
            if (stats.videoTrackSummary.muted > 0 && stats.videoTrackSummary.muted === stats.videoTrackSummary.count) {
                counter.receivedVideo++;
                hasReceivedVideo = true;
            }
        }

        if (hasReceivedVideo && hasReceivedAudio) {
            counter.receivedMedia++;
        }
    }

    private buildMaxJitter(maxJitter: number, stats: CallStatsReportSummary): number {
        if (maxJitter < stats.videoTrackSummary.maxJitter) {
            maxJitter = stats.videoTrackSummary.maxJitter;
        }

        if (maxJitter < stats.audioTrackSummary.maxJitter) {
            maxJitter = stats.audioTrackSummary.maxJitter;
        }
        return maxJitter;
    }

    private buildMaxPacketLoss(maxPacketLoss: number, stats: CallStatsReportSummary): number {
        if (maxPacketLoss < stats.videoTrackSummary.maxPacketLoss) {
            maxPacketLoss = stats.videoTrackSummary.maxPacketLoss;
        }

        if (maxPacketLoss < stats.audioTrackSummary.maxPacketLoss) {
            maxPacketLoss = stats.audioTrackSummary.maxPacketLoss;
        }
        return maxPacketLoss;
    }

    private countConcealedAudio(summaryCounter: CallStatsReportSummaryCounter, stats: CallStatsReportSummary): void {
        summaryCounter.concealedAudio += stats.audioTrackSummary.concealedAudio;
        summaryCounter.totalAudio += stats.audioTrackSummary.totalAudio;
    }
}