/**
 * 段落逐行拆分（paragraphPerLine）
 *
 * v1 行为：每个非空行都是一个独立的 <p>。
 * 标准 markdown 会把相邻行合并为一个段落（软换行），
 * 这会改变存量简历的渲染结构。
 *
 * 本插件在 block 解析之后、inline 解析之前，
 * 把顶层段落中含软换行的段落拆分为多个段落，保持 v1 的渲染结构：
 *   第一行
 *   第二行      →  <p>第一行</p><p>第二行</p>
 *
 * 只处理顶层段落：列表项、引用块内部的软换行不受影响
 * （由 breaks: true 渲染为 <br>，与 tiptap 富文本回写 dom2md 的行为对齐）。
 */

// 需要计入嵌套深度的块容器（这些容器内部的段落不拆分）
const DEPTH_TOKENS = new Set([
  "blockquote_open",
  "blockquote_close",
  "bullet_list_open",
  "bullet_list_close",
  "ordered_list_open",
  "ordered_list_close",
  "list_item_open",
  "list_item_close",
])

interface Insertion {
  index: number // paragraph_open 的下标
  parts: string[]
  source: any
}

function paragraphPerLineRule(state: any) {
  const tokens = state.tokens
  const insertions: Insertion[] = []
  let depth = 0

  for (let i = 0; i < tokens.length; i++) {
    const t = tokens[i]
    if (t.nesting === 1 && DEPTH_TOKENS.has(t.type)) {
      depth++
      continue
    }
    if (t.nesting === -1 && DEPTH_TOKENS.has(t.type)) {
      depth--
      continue
    }
    if (depth === 0 && t.type === "inline" && t.content.includes("\n")) {
      const prev = tokens[i - 1]
      const next = tokens[i + 1]
      if (prev?.type === "paragraph_open" && next?.type === "paragraph_close") {
        insertions.push({ index: i - 1, parts: t.content.split("\n"), source: t })
      }
    }
  }

  // 从后往前替换，避免下标失效
  for (let k = insertions.length - 1; k >= 0; k--) {
    const { index, parts, source } = insertions[k]
    const replacement: any[] = []
    for (const part of parts) {
      const open = new state.Token("paragraph_open", "p", 1)
      open.block = true
      open.hidden = source.hidden
      if (source.map) open.map = source.map
      const inline = new state.Token("inline", "", 0)
      inline.content = part
      inline.children = [] // 核心链路的 inline 规则要求 children 为数组
      inline.hidden = false
      const close = new state.Token("paragraph_close", "p", -1)
      close.block = true
      replacement.push(open, inline, close)
    }
    tokens.splice(index, 3, ...replacement)
  }
}

export function paragraphPerLinePlugin(md: any) {
  md.core.ruler.after("block", "resume_paragraph_per_line", paragraphPerLineRule)
}