///<reference path="../../../headers/common.d.ts" />

import {PrometheusDatasource} from "./datasource";
import _ from 'lodash';

export class PromCompleter {
  labelQueryCache: any;
  labelNameCache: any;
  labelValueCache: any;

  identifierRegexps = [/\[/, /[a-zA-Z0-9_:]/];

  constructor(private datasource: PrometheusDatasource) {
    this.labelQueryCache = {};
    this.labelNameCache = {};
    this.labelValueCache = {};
  }

  getCompletions(editor, session, pos, prefix, callback) {
    let token = session.getTokenAt(pos.row, pos.column);

    var metricName;
    switch (token.type) {
      case 'entity.name.tag':
        metricName = this.findMetricName(session, pos.row, pos.column);
        if (!metricName) {
          callback(null, this.transformToCompletions(['__name__', 'instance', 'job'], 'label name'));
          return;
        }

        if (this.labelNameCache[metricName]) {
          callback(null, this.labelNameCache[metricName]);
          return;
        }

        return this.getLabelNameAndValueForMetric(metricName).then(result => {
          var labelNames = this.transformToCompletions(
            _.uniq(_.flatten(result.map(r => {
              return Object.keys(r.metric);
            })))
          , 'label name');
          this.labelNameCache[metricName] = labelNames;
          callback(null, labelNames);
        });
      case 'string.quoted':
        metricName = this.findMetricName(session, pos.row, pos.column);
        if (!metricName) {
          callback(null, []);
          return;
        }

        var labelNameToken = this.findToken(session, pos.row, pos.column, 'entity.name.tag', null, 'paren.lparen');
        if (!labelNameToken) {
          callback(null, []);
          return;
        }
        var labelName = labelNameToken.value;

        if (this.labelValueCache[metricName] && this.labelValueCache[metricName][labelName]) {
          callback(null, this.labelValueCache[metricName][labelName]);
          return;
        }

        return this.getLabelNameAndValueForMetric(metricName).then(result => {
          var labelValues = this.transformToCompletions(
            _.uniq(result.map(r => {
              return r.metric[labelName];
            }))
          , 'label value');
          this.labelValueCache[metricName] = this.labelValueCache[metricName] || {};
          this.labelValueCache[metricName][labelName] = labelValues;
          callback(null, labelValues);
        });
    }

    if (token.type === 'paren.lparen' && token.value === '[') {
      var vectors = [];
      for (let unit of ['s', 'm', 'h']) {
        for (let value of [1,5,10,30]) {
         vectors.push({caption: value+unit, value: '['+value+unit, meta: 'range vector'});
        }
      }
      vectors.push({caption: '$__interval', value: '[$__interval', meta: 'range vector'});
      vectors.push({caption: '$__interval_ms', value: '[$__interval_ms', meta: 'range vector'});
      callback(null, vectors);
      return;
    }

    var query = prefix;

    return this.datasource.performSuggestQuery(query, true).then(metricNames => {
      callback(null, metricNames.map(name => {
        let value = name;
        if (prefix === '(') {
          value = '(' + name;
        }

        return {
          caption: name,
          value: value,
          meta: 'metric',
        };
      }));
    });
  }

  getLabelNameAndValueForMetric(metricName) {
    if (this.labelQueryCache[metricName]) {
      return Promise.resolve(this.labelQueryCache[metricName]);
    }
    var op = '=~';
    if (/[a-zA-Z_:][a-zA-Z0-9_:]*/.test(metricName)) {
      op = '=';
    }
    var expr = '{__name__' + op + '"' + metricName + '"}';
    return this.datasource.performInstantQuery({ expr: expr }, new Date().getTime() / 1000).then(response => {
      this.labelQueryCache[metricName] = response.data.data.result;
      return response.data.data.result;
    });
  }

  transformToCompletions(words, meta) {
    return words.map(name => {
      return {
        caption: name,
        value: name,
        meta: meta,
        score: Number.MAX_VALUE
      };
    });
  }

  findMetricName(session, row, column) {
    var metricName = '';

    var tokens;
    var nameLabelNameToken = this.findToken(session, row, column, 'entity.name.tag', '__name__', 'paren.lparen');
    if (nameLabelNameToken) {
      tokens = session.getTokens(nameLabelNameToken.row);
      var nameLabelValueToken = tokens[nameLabelNameToken.index + 2];
      if (nameLabelValueToken && nameLabelValueToken.type === 'string.quoted') {
        metricName = nameLabelValueToken.value.slice(1, -1); // cut begin/end quotation
      }
    } else {
      var metricNameToken = this.findToken(session, row, column, 'identifier', null, null);
      if (metricNameToken) {
        tokens = session.getTokens(metricNameToken.row);
        if (tokens[metricNameToken.index + 1].type === 'paren.lparen') {
          metricName = metricNameToken.value;
        }
      }
    }

    return metricName;
  }

  findToken(session, row, column, target, value, guard) {
    var tokens, idx;
    for (var r = row; r >= 0; r--) {
      tokens = session.getTokens(r);
      if (r === row) { // current row
        var c = 0;
        for (idx = 0; idx < tokens.length; idx++) {
          c += tokens[idx].value.length;
          if (c >= column) {
            break;
          }
        }
      } else {
        idx = tokens.length - 1;
      }

      for (; idx >= 0; idx--) {
        if (tokens[idx].type === guard) {
          return null;
        }

        if (tokens[idx].type === target
          && (!value || tokens[idx].value === value)) {
          tokens[idx].row = r;
          tokens[idx].index = idx;
          return tokens[idx];
        }
      }
    }

    return null;
  }

}