import { EthGasReporterOutput } from './types';

/**
 * Try to merge several gas reporter output objects into one. It will also
 * validate that the config are the same to make sure that the reports were
 * generated by the same source.
 */
export function mergeReports(reports: EthGasReporterOutput[]): EthGasReporterOutput {
  const result: EthGasReporterOutput = {
    namespace: null,
    config: null,
    info: {
      methods: {},
      deployments: [],
      blockLimit: null,
    },
  };

  for (const report of reports) {
    if (!result.config) result.config = report.config;

    if (!result.namespace) {
      result.namespace = report.namespace;
    }

    if (result.namespace !== report.namespace) {
      throw new Error('Cannot merge reports with different namespaces');
    }

    // Update config.gasPrice only if the newer one has a bigger number
    if (typeof report.config.gasPrice === 'number') {
      if (
        typeof result.config.gasPrice !== 'number' ||
        result.config.gasPrice < report.config.gasPrice
      ) {
        result.config.gasPrice = report.config.gasPrice;
      }
    } else {
      result.config.gasPrice = report.config.gasPrice;
    }

    if (!report.info || typeof report.info.blockLimit !== 'number') {
      throw new Error(`Invalid "info" property for given report`);
    }

    if (!result.info.blockLimit) {
      result.info.blockLimit = report.info.blockLimit;
    } else if (result.info.blockLimit !== report.info.blockLimit) {
      throw new Error('"info.blockLimit" should be the same on all reports');
    }

    if (!report.info.methods) {
      throw new Error(`Missing "info.methods" property on given report`);
    }

    // Merge info.methods objects
    Object.entries(report.info.methods).forEach(([key, value]) => {
      if (!result.info.methods[key]) {
        result.info.methods[key] = value;
        return;
      }

      result.info.methods[key].gasData = [
        ...result.info.methods[key].gasData,
        ...report.info.methods[key].gasData,
      ].sort((a, b) => a - b);

      result.info.methods[key].numberOfCalls += report.info.methods[key].numberOfCalls;
    });

    if (!Array.isArray(report.info.deployments)) {
      throw new Error(`Invalid "info.deployments" property on given report`);
    }

    // Merge info.deployments objects
    report.info.deployments.forEach(deployment => {
      const current = result.info.deployments.find(d => d.name === deployment.name);

      if (current) {
        current.gasData = [...current.gasData, ...deployment.gasData].sort((a, b) => a - b);
      } else {
        result.info.deployments.push(deployment);
      }
    });
  }

  return result
}