import { existsSync, readFileSync } from 'node:fs'
import { dirname, resolve } from 'node:path'
import { fileURLToPath } from 'node:url'

function parseEnvLine(line) {
  const trimmed = line.trim()
  if (!trimmed || trimmed.startsWith('#')) return null

  const equalsIndex = trimmed.indexOf('=')
  if (equalsIndex === -1) return null

  const key = trimmed.slice(0, equalsIndex).trim()
  let value = trimmed.slice(equalsIndex + 1).trim()
  if (!/^[A-Za-z_][A-Za-z0-9_]*$/.test(key)) return null

  if (
    (value.startsWith('"') && value.endsWith('"')) ||
    (value.startsWith("'") && value.endsWith("'"))
  ) {
    value = value.slice(1, -1)
  }

  return { key, value }
}

function loadEnvFile(path) {
  if (!existsSync(path)) return

  const content = readFileSync(path, 'utf8')
  for (const line of content.split(/\r?\n/)) {
    const parsed = parseEnvLine(line)
    if (!parsed || process.env[parsed.key] !== undefined) continue
    process.env[parsed.key] = parsed.value
  }
}

export function loadEnv() {
  const moduleDir = dirname(fileURLToPath(import.meta.url))
  const candidatePaths = [
    resolve(process.cwd(), '.env'),
    resolve(process.cwd(), '..', '.env'),
    resolve(moduleDir, '..', '.env'),
    resolve(moduleDir, '..', '..', '.env')
  ]

  for (const path of [...new Set(candidatePaths)]) {
    loadEnvFile(path)
  }
}