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import { Collector } from "./collector.ts";import { Labels, Metric, Observe } from "./metric.ts";import { Registry } from "./registry.ts";
class Sample {  private timestamp: number;  private value: number;
  constructor(value: number) {    this.timestamp = new Date().getTime();    this.value = value;  }
  getTimestamp(): number {    return this.timestamp;  }
  getValue(): number {    return this.value;  }}
export class Summary extends Metric implements Observe {  private collector: Collector;  private percentiles: number[];  private values: Sample[];  private maxAge?: number;  private ageBuckets?: number;
  static with(    config: {      name: string;      help: string;      labels?: string[];      percentiles?: number[];      maxAge?: number;      ageBuckets?: number;      registry?: Registry[];    },  ): Summary {    const collector = new Collector(      config.name,      config.help,      "summary",      config.registry,    );    const labels = config.labels || [];    const percentiles = config.percentiles || [.01, .05, .9, .95, .99];    percentiles.forEach((v) => {      if (v < 0 || v > 1) {        throw new Error(`invalid percentile: ${v} not in [0,1]`);      }    });    return new Summary(      collector,      labels,      percentiles,      config.maxAge,      config.ageBuckets,    );  }
  private constructor(    collector: Collector,    labels: string[],    percentiles: number[],    maxAge?: number,    ageBuckets?: number,  ) {    super(labels, new Array(labels.length).fill(undefined));    this.collector = collector;    this.percentiles = percentiles.sort((a, b) => a < b ? -1 : 1);    this.values = [];    this.maxAge = maxAge;    this.ageBuckets = ageBuckets;    this.collector.getOrSetMetric(this);  }
  get description(): string {    const labels = this.getLabelsAsString();    return `${this.collector.name}${labels}`;  }
  private clean() {    // Remove older than maxAge    if (this.maxAge !== undefined) {      const limit = new Date().getTime() - this.maxAge;      let i = 0;      while (i < this.values.length) {        if (this.values[i].getTimestamp() > limit) {          break;        }        i++;      }      this.values = this.values.slice(i);    }    // Remove extra values    if (this.ageBuckets !== undefined) {      const index = this.values.length - this.ageBuckets;      this.values = this.values.splice(index);    }  }
  expose(): string | undefined {    if (this.values.length === 0) {      return undefined;    }
    let text = "";
    this.clean();    const sorted = this.values.slice().sort((a, b) =>      a.getValue() - b.getValue()    );
    for (const p of this.percentiles) {      const labels = this.getLabelsAsString({ percentile: p.toString() });      let index = Math.ceil(p * sorted.length);      index = index == 0 ? 0 : index - 1;      const value = sorted[index].getValue();      text += `${this.collector.name}${labels} ${value}\n`;    }
    const sum = this.values.reduce((sum, v) => sum + v.getValue(), 0);    text += `${this.collector.name}_sum ${sum}\n`;    text += `${this.collector.name}_count ${sorted.length}`;
    return text;  }
  labels(labels: Labels): Observe {    let child = new Summary(this.collector, this.labelNames, this.percentiles);    for (const key of Object.keys(labels)) {      const index = child.labelNames.indexOf(key);      if (index === -1) {        throw new Error(`label with name ${key} not defined`);      }      child.labelValues[index] = labels[key];    }    child = child.collector.getOrSetMetric(child) as Summary;
    return {      observe: (n) => {        child.observe(n);      },    };  }
  observe(n: number) {    this.values.push(new Sample(n));  }
  getCount(): number {    this.clean();    return this.values.length;  }
  getSum(): number {    this.clean();    return this.values.reduce((sum, v) => sum + v.getValue(), 0);  }
  getValues(): number[] {    this.clean();    return this.values.map((s) => s.getValue());  }}