import { basename } from 'node:path'
import type { CodeIntelligenceConfig } from '../config.ts'
import { matchesAnyGlob, normalizeRelativePath } from './glob.ts'

export type GeneratedDetection = {
  isGenerated: boolean
  reason?: string
}

const GENERATED_DIR_SEGMENTS = new Set(['generated', '__generated__', 'gen', 'autogen'])
const GENERATED_FILE_NAMES = new Set([
  'package-lock.json',
  'pnpm-lock.yaml',
  'yarn.lock',
  'bun.lockb',
  'composer.lock',
  'poetry.lock',
  'cargo.lock',
])

const HEADER_MARKERS = [
  '@generated',
  'this file is generated',
  'code generated by',
  'do not edit',
  'generated by openapi',
  'generated by prisma',
]

export function detectGeneratedFile(
  relativePath: string,
  content: string,
  config: Pick<CodeIntelligenceConfig, 'generatedPaths'>
): GeneratedDetection {
  const rel = normalizeRelativePath(relativePath)

  if (matchesAnyGlob(rel, config.generatedPaths)) {
    return { isGenerated: true, reason: 'configured generatedPaths match' }
  }

  const segments = rel.toLowerCase().split('/')
  if (segments.some((segment) => GENERATED_DIR_SEGMENTS.has(segment))) {
    return { isGenerated: true, reason: 'generated directory path' }
  }

  if (GENERATED_FILE_NAMES.has(basename(rel).toLowerCase())) {
    return { isGenerated: true, reason: 'lockfile/generated artifact' }
  }

  const header = content.slice(0, 4096).toLowerCase()
  const marker = HEADER_MARKERS.find((candidate) => header.includes(candidate))
  if (marker) {
    return { isGenerated: true, reason: `header marker: ${marker}` }
  }

  return { isGenerated: false }
}