import type { CSSProperties } from 'vue'
import trim from './trim'
import test from './test'

export function isValidValue(value: any): boolean {
  if (test.isEmpty(value))
    return false
  if (typeof value === 'string') {
    const trimmed = trim(value).toLowerCase()
    return trimmed !== 'null' && trimmed !== 'undefined' && trimmed !== ''
  }
  return true
}

/**
 * 将 CSS 字符串解析为对象
 */
export function cssStrToObj(str: string): object {
  const result = {}
  if (!isValidValue(str))
    return result
  const styleStr = trim(String(str))
  if (!isValidValue(styleStr))
    return result
  const declarations = styleStr.split(';')
  declarations.forEach((decl) => {
    const [prop, ...values] = decl.split(':').map(s => s.trim())
    const value = values.join(':')
    if (prop && value) {
      const camelProp = prop.replace(/-([a-z])/g, (match, letter) => letter.toUpperCase());
      (result as Record<string, string>)[camelProp] = value
    }
  })
  return result
}

/**
 * 将 CSS 对象转换为 CSS 字符串
 */
export function cssObjToStr(obj: object): string {
  if (!isValidValue(obj) || typeof obj !== 'object')
    return ''
  return (
    `${Object.entries(obj)
      .map(([key, value]) => {
        if (!isValidValue(value))
          return ''
        // 驼峰转短横线
        const kebab = key.replace(/([A-Z])/g, '-$1').toLowerCase()
        return `${kebab}: ${value}`
      })
      .filter(Boolean)
      .join('; ')};`
  )
}

/**
 * 合并多个 CSS 输入（对象或字符串），返回一个 CSS 对象
 */
export function mergeStyles(...args: (object | string)[]): CSSProperties {
  const result = {} as Record<string, any>
  for (let i = 0; i < args.length; i++) {
    const arg = args[i]
    if (!isValidValue(arg))
      return result as CSSProperties
    if (typeof arg === 'string') {
      Object.assign(result, cssStrToObj(arg))
    }
    else if (test.object(arg)) {
      const cleanedObj: Record<string, any> = {}
      Object.keys(arg).forEach((key) => {
        const value = (arg as Record<string, any>)[key]
        if (isValidValue(value)) {
          // 有效
          cleanedObj[key] = value
        }
      })
      Object.assign(result, cleanedObj)
    }
  }
  return result
}

/**
 * 合并为 CSS 字符串
 */
export function mergeCssStrings(...args: (object | string)[]): string {
  const obj = mergeStyles(...args)
  return cssObjToStr(obj)
}