repo_description: the package manager for JavaScript
repo_topics: javascript nodejs npm npm-cli package-manager tools
code: // this is called when an ERESOLVE error is caught in the exit-handler, or when there's a log.warn('eresolve', msg, explanation), to turn it into a human-intelligible explanation of what's wrong and how to fix.
  const { explainEdge, explainNode, printNode } = require('./explain-dep.js')
  
  // expl is an explanation object that comes from Arborist.
  // Depth is how far we want to want to descend into the object making a report.
  // The full report (ie, depth=Infinity) is always written to the cache folder at ${cache}/eresolve-report.txt along with full json.
  const explain = (expl, chalk, depth) => {
    const { edge, dep, current, peerConflict, currentEdge } = expl
  
    const out = []
    const whileInstalling = dep && dep.whileInstalling ||
      current && current.whileInstalling ||
      edge && edge.from && edge.from.whileInstalling
    if (whileInstalling) {
      out.push('While resolving: ' + printNode(whileInstalling, chalk))
    }
  
    // it "should" be impossible for an ERESOLVE explanation to lack both current and currentEdge, but better to have a less helpful error than a crashing failure.
    if (current) {
      out.push('Found: ' + explainNode(current, depth, chalk))
    } else if (peerConflict && peerConflict.current) {
      out.push('Found: ' + explainNode(peerConflict.current, depth, chalk))
    } else if (currentEdge) {
      out.push('Found: ' + explainEdge(currentEdge, depth, chalk))
    } else /* istanbul ignore else - should always have one */ if (edge) {
      out.push('Found: ' + explainEdge(edge, depth, chalk))
    }
  
    out.push('\nCould not resolve dependency:\n' +
      explainEdge(edge, depth, chalk))
  
    if (peerConflict) {
      const heading = '\nConflicting peer dependency:'
      const pc = explainNode(peerConflict.peer, depth, chalk)
      out.push(heading + ' ' + pc)
    }
  
    return out.join('\n')
  }
  
  // generate a full verbose report and tell the user how to fix it
  const report = (expl, chalk, noColorChalk) => {
    const flags = [
      expl.strictPeerDeps ? '--no-strict-peer-deps' : '',
      '--force',
      '--legacy-peer-deps',
    ].filter(Boolean)
  
    const or = (arr) => arr.length <= 2
      ? arr.join(' or ') :
      arr.map((v, i, l) => i + 1 === l.length ? `or ${v}` : v).join(', ')
  
    const fix = `Fix the upstream dependency conflict, or retry this command with ${or(flags)} to accept an incorrect (and potentially broken) dependency resolution.`
  
    return {
      explanation: `${explain(expl, chalk, 4)}\n\n${fix}`,
      file: `# npm resolution error report\n\n${explain(expl, noColorChalk, Infinity)}\n\n${fix}`,
    }
  }
  
  module.exports = {
    explain,
    report,
  }
  