// Copyright (C) 2020 The Android Open Source Project
//
// 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 {Duration} from '../../base/time';
import {ColumnDef, Sorting} from '../../public/aggregation';
import {AreaSelection} from '../../public/selection';
import {COUNTER_TRACK_KIND} from '../../public/track_kinds';
import {Engine} from '../../trace_processor/engine';
import {AreaSelectionAggregator} from '../../public/selection';
import {LONG, NUM} from '../../trace_processor/query_result';

export class CounterSelectionAggregator implements AreaSelectionAggregator {
  readonly id = 'counter_aggregation';

  // This just describes which counters we match, we don't actually use the
  // resulting datasets, but it's a useful too to show what we actually match.
  readonly trackKind = COUNTER_TRACK_KIND;
  readonly schema = {
    id: NUM,
    ts: LONG,
    value: NUM,
  };

  async createAggregateView(engine: Engine, area: AreaSelection) {
    const trackIds: (string | number)[] = [];
    for (const trackInfo of area.tracks) {
      if (trackInfo?.tags?.kind === COUNTER_TRACK_KIND) {
        trackInfo.tags?.trackIds && trackIds.push(...trackInfo.tags.trackIds);
      }
    }
    if (trackIds.length === 0) return false;
    const duration = area.end - area.start;
    const durationSec = Duration.toSeconds(duration);

    await engine.query(`include perfetto module counters.intervals`);

    // TODO(lalitm): Rewrite this query in a way that is both simpler and faster
    let query;
    if (trackIds.length === 1) {
      // Optimized query for the special case where there is only 1 track id.
      query = `CREATE OR REPLACE PERFETTO TABLE ${this.id} AS
      WITH
        res AS (
          select c.*
          from counter_leading_intervals!((
            SELECT counter.*
            FROM counter
            WHERE counter.track_id = ${trackIds[0]}
              AND counter.ts <= ${area.end}
          )) c
          WHERE c.ts + c.dur >= ${area.start}
        ),
        aggregated AS (
          SELECT
            COUNT(1) AS count,
            ROUND(SUM(
              (MIN(ts + dur, ${area.end}) - MAX(ts,${area.start}))*value)/${duration},
              2
            ) AS avg_value,
            value_at_max_ts(ts, value) AS last_value,
            value_at_max_ts(-ts, value) AS first_value,
            MIN(value) AS min_value,
            MAX(value) AS max_value
          FROM res
        )
      SELECT
        (SELECT name FROM counter_track WHERE id = ${trackIds[0]}) AS name,
        *,
        MAX(last_value) - MIN(first_value) AS delta_value,
        ROUND((MAX(last_value) - MIN(first_value))/${durationSec}, 2) AS rate
      FROM aggregated`;
    } else {
      // Slower, but general purspose query that can aggregate multiple tracks
      query = `CREATE OR REPLACE PERFETTO TABLE ${this.id} AS
      WITH
        res AS (
          select c.*
          from counter_leading_intervals!((
            SELECT counter.*
            FROM counter
            WHERE counter.track_id in (${trackIds})
              AND counter.ts <= ${area.end}
          )) c
          where c.ts + c.dur >= ${area.start}
        ),
        aggregated AS (
          SELECT track_id,
            COUNT(1) AS count,
            ROUND(SUM(
              (MIN(ts + dur, ${area.end}) - MAX(ts,${area.start}))*value)/${duration},
              2
            ) AS avg_value,
            value_at_max_ts(-ts, value) AS first,
            value_at_max_ts(ts, value) AS last,
            MIN(value) AS min_value,
            MAX(value) AS max_value
          FROM res
          GROUP BY track_id
        )
      SELECT
        name,
        count,
        avg_value,
        last AS last_value,
        first AS first_value,
        last - first AS delta_value,
        ROUND((last - first)/${durationSec}, 2) AS rate,
        min_value,
        max_value
      FROM aggregated JOIN counter_track ON
        track_id = counter_track.id
      GROUP BY track_id`;
    }
    await engine.query(query);
    return true;
  }

  getColumnDefinitions(): ColumnDef[] {
    return [
      {
        title: 'Name',
        kind: 'STRING',
        columnConstructor: Uint16Array,
        columnId: 'name',
      },
      {
        title: 'Delta value',
        kind: 'NUMBER',
        columnConstructor: Float64Array,
        columnId: 'delta_value',
      },
      {
        title: 'Rate /s',
        kind: 'Number',
        columnConstructor: Float64Array,
        columnId: 'rate',
      },
      {
        title: 'Weighted avg value',
        kind: 'Number',
        columnConstructor: Float64Array,
        columnId: 'avg_value',
      },
      {
        title: 'Count',
        kind: 'Number',
        columnConstructor: Float64Array,
        columnId: 'count',
        sum: true,
      },
      {
        title: 'First value',
        kind: 'NUMBER',
        columnConstructor: Float64Array,
        columnId: 'first_value',
      },
      {
        title: 'Last value',
        kind: 'NUMBER',
        columnConstructor: Float64Array,
        columnId: 'last_value',
      },
      {
        title: 'Min value',
        kind: 'NUMBER',
        columnConstructor: Float64Array,
        columnId: 'min_value',
      },
      {
        title: 'Max value',
        kind: 'NUMBER',
        columnConstructor: Float64Array,
        columnId: 'max_value',
      },
    ];
  }

  async getExtra() {}

  getTabName() {
    return 'Counters';
  }

  getDefaultSorting(): Sorting {
    return {column: 'name', direction: 'DESC'};
  }
}