foundry.gradle.util.charting.ChartCreator.kt Maven / Gradle / Ivy

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/*
 * Copyright (C) 2022 Slack Technologies, LLC
 *
 * 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
 *
 *    https://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.
 */
package foundry.gradle.util.charting

import foundry.gradle.util.charting.ChartData.SimpleData
import foundry.gradle.util.charting.ChartFill.FillType.BACKGROUND
import foundry.gradle.util.charting.ChartType.LineChart
import foundry.gradle.util.charting.Color.Companion.BLACK
import foundry.gradle.util.charting.Color.Companion.WHITE
import foundry.gradle.util.charting.VisibleAxis.XAxis
import foundry.gradle.util.charting.VisibleAxis.YAxis
import okhttp3.HttpUrl

/**
 * Simple API for Google Charts.
 *
 * https://developers.google.com/chart/image/docs/making_charts
 *
 * Models shared with us from our friends at Square.
 */
internal object ChartCreator {
  private val RED = Color(0xF8696A)
  private val YELLOW = Color(0xFEE783)
  private val GREEN = Color(0x75C37C)

  fun createChartUrl(
    data: List,
    xRange: IntRange = 1..data.size,
    yRange: IntRange = 0..(data.maxOrNull() ?: 0),
  ): String {
    check(data.isNotEmpty()) { "Empty data!" }
    var currentColor = colorForValue(data.first())

    val colorRanges = mutableListOf()
    var startIndex = 0

    data.forEachIndexed { index, value ->
      val color = colorForValue(value)
      if (currentColor != color) {
        colorRanges += ColorRange(currentColor, startIndex, index - 1)
        currentColor = color
        startIndex = index - 1
      }
    }

    colorRanges += ColorRange(currentColor, startIndex, data.size - 1)

    val chartProperties = buildList {
      add(LineChart)
      add(ChartSize(1000, 300))
      add(ChartFill(BACKGROUND, BLACK))
      add(XAxis + YAxis)
      add(AxisStyle(0, WHITE) + AxisStyle(1, WHITE))
      add(AxisRange(0, xRange.first, xRange.last) + AxisRange(1, yRange.first, yRange.last))
      add(SimpleData(data))
      add(SeriesColors(WHITE))
      add(colorRanges.collapse())
    }

    return HttpUrl.Builder()
      .scheme("https")
      .host("chart.googleapis.com")
      .addPathSegment("chart")
      .apply {
        for (prop in chartProperties) {
          addQueryParameter(prop.key, prop.value)
        }
      }
      .build()
      .toString()
  }

  private fun colorForValue(value: Int): Color {
    return when {
      value <= 70 -> RED
      value <= 90 -> YELLOW
      else -> GREEN
    }
  }
}