// This script is a local dev helper to identify functions likely violating ESLint `max-lines-per-function`
// without running ESLint. It uses the TypeScript AST to compute line spans.
//
// Usage:
//   node scripts/findLongFunctions.js [--max 40] [--limit 50]
//
// Notes:
// - Counts *raw* line span (endLine - startLine + 1). ESLint uses a different metric
//   (skipBlankLines/skipComments). This script is used to pick candidates efficiently.
//
// It is intentionally plain JS to avoid requiring a TS build step.
const fs = require('fs')
const path = require('path')
const ts = require('typescript')

/**
 * @typedef {Readonly<{ file: string; name: string; startLine: number; endLine: number; span: number }>} LongFn
 */

/**
 * @param {string} value
 * @returns {number | undefined}
 */
function readNumberArg(value) {
  const n = Number(value)
  if (Number.isFinite(n) && n > 0) {
    return n
  }
  return undefined
}

/**
 * @param {string[]} argv
 * @returns {{ max: number; limit: number }}
 */
function readArgs(argv) {
  let max = 40
  let limit = 50

  for (let i = 0; i < argv.length; i += 1) {
    const token = argv[i]
    const next = argv[i + 1]
    if (token === '--max' && next) {
      max = readNumberArg(next) ?? max
      i += 1
      continue
    }
    if (token === '--limit' && next) {
      limit = readNumberArg(next) ?? limit
      i += 1
    }
  }

  return { max, limit }
}

/**
 * @param {string} p
 * @returns {boolean}
 */
function isIgnoredPath(p) {
  const normalized = p.split(path.sep).join('/')
  return (
    normalized.includes('/node_modules/') ||
    normalized.includes('/.next/') ||
    normalized.includes('/dist/') ||
    normalized.includes('/out/')
  )
}

/**
 * @param {string} dir
 * @param {string[]} out
 * @returns {void}
 */
function collectSourceFiles(dir, out) {
  const entries = fs.readdirSync(dir, { withFileTypes: true })
  for (const entry of entries) {
    const full = path.join(dir, entry.name)
    if (isIgnoredPath(full)) {
      continue
    }
    if (entry.isDirectory()) {
      collectSourceFiles(full, out)
      continue
    }
    if (!entry.isFile()) {
      continue
    }
    if (full.endsWith('.ts') || full.endsWith('.tsx')) {
      out.push(full)
    }
  }
}

/**
 * @param {ts.Node} node
 * @returns {string}
 */
function getReadableName(node) {
  if (ts.isFunctionDeclaration(node) && node.name) {
    return node.name.getText()
  }
  if (ts.isMethodDeclaration(node) && node.name) {
    return node.name.getText()
  }
  if (ts.isConstructorDeclaration(node)) {
    return 'constructor'
  }
  if (ts.isGetAccessorDeclaration(node) && node.name) {
    return `get ${node.name.getText()}`
  }
  if (ts.isSetAccessorDeclaration(node) && node.name) {
    return `set ${node.name.getText()}`
  }
  if (ts.isArrowFunction(node) || ts.isFunctionExpression(node)) {
    const parent = node.parent
    if (ts.isVariableDeclaration(parent) && ts.isIdentifier(parent.name)) {
      return parent.name.text
    }
    if (ts.isPropertyAssignment(parent) && ts.isIdentifier(parent.name)) {
      return parent.name.text
    }
    return '<anonymous>'
  }
  return '<unknown>'
}

/**
 * @param {ts.Node} node
 * @returns {node is (ts.FunctionDeclaration | ts.FunctionExpression | ts.ArrowFunction | ts.MethodDeclaration | ts.ConstructorDeclaration | ts.GetAccessorDeclaration | ts.SetAccessorDeclaration)}
 */
function isFunctionLikeWithBody(node) {
  if (!ts.isFunctionLike(node)) {
    return false
  }
  // Arrow functions may have expression bodies. We only flag block bodies for line spans.
  // Function/method declarations use block bodies.
  return Boolean(node.body)
}

/**
 * @param {string} filename
 * @param {number} max
 * @returns {LongFn[]}
 */
function findLongFunctionsInFile(filename, max) {
  const sourceText = fs.readFileSync(filename, 'utf8')
  const sourceFile = ts.createSourceFile(
    filename,
    sourceText,
    ts.ScriptTarget.Latest,
    true,
    filename.endsWith('.tsx') ? ts.ScriptKind.TSX : ts.ScriptKind.TS
  )

  /** @type {LongFn[]} */
  const results = []

  /**
   * @param {ts.Node} node
   * @returns {void}
   */
  function visit(node) {
    if (isFunctionLikeWithBody(node)) {
      const start = sourceFile.getLineAndCharacterOfPosition(node.getStart(sourceFile, false))
      const end = sourceFile.getLineAndCharacterOfPosition(node.getEnd())
      const startLine = start.line + 1
      const endLine = end.line + 1
      const span = endLine - startLine + 1
      if (span > max) {
        results.push({
          file: filename,
          name: getReadableName(node),
          startLine,
          endLine,
          span,
        })
      }
    }
    ts.forEachChild(node, visit)
  }

  visit(sourceFile)
  return results
}

/**
 * @param {LongFn} fn
 * @returns {string}
 */
function formatFn(fn) {
  const rel = path.relative(process.cwd(), fn.file).split(path.sep).join('/')
  return `${fn.span.toString().padStart(4, ' ')}  ${rel}:${fn.startLine}-${fn.endLine}  ${fn.name}`
}

function main() {
  const { max, limit } = readArgs(process.argv.slice(2))
  /** @type {string[]} */
  const files = []
  for (const dir of ['components', 'hooks', 'lib', 'pages', 'types', 'scripts']) {
    const full = path.join(process.cwd(), dir)
    if (fs.existsSync(full)) {
      collectSourceFiles(full, files)
    }
  }

  /** @type {LongFn[]} */
  const all = []
  for (const file of files) {
    const found = findLongFunctionsInFile(file, max)
    all.push(...found)
  }

  all.sort((a, b) => b.span - a.span || a.file.localeCompare(b.file) || a.startLine - b.startLine)
  const top = all.slice(0, limit)

  console.log(`Found ${all.length} function-like nodes with raw span > ${max} lines.`)
  console.log(`Showing top ${top.length} (sorted by span desc):\n`)
  for (const fn of top) {
    console.log(formatFn(fn))
  }
}

main()