import type { CodeBlock, Node } from '../contract'
import { syntaxChildren } from './pythonTree'

/** 库规则共用的挑子块的办法。 */

/** 紧挨在 child 前面的注释块（连着几块都算，中间没隔别的子块），照源码顺序：讲的是它下面的这个 child。 */
export function leadingComments(children: readonly CodeBlock[], child: CodeBlock): CodeBlock[] {
  const at = children.indexOf(child)
  let from = at
  while (from > 0 && children[from - 1].kind === 'comment')
    from--
  return children.slice(from, at)
}

/**
 * 要并进卡片的子块：成员连同各自前面紧挨着的注释块，照源码顺序。成员并进来了，讲它的注释跟着并，不在卡片下面单独留一块；
 * 讲别的子块（方法）的注释、最后一个子块后面的注释照常留下。
 */
export function withLeadingComments(children: readonly CodeBlock[], members: readonly CodeBlock[]): CodeBlock[] {
  return children.filter(child => members.includes(child))
    .flatMap(member => [...leadingComments(children, member), member])
}

/** 注释块里的各条注释（几条行注释连成的一块是好几个节点）；当注释用的字符串是那个字符串。 */
function commentNodes(block: CodeBlock): Node[] {
  if (block.node.type !== 'comment')
    return syntaxChildren(block.node).slice(0, 1)
  const nodes: Node[] = []
  for (let node: Node | null = block.node; node?.type === 'comment' && node.endIndex <= block.header.endIndex; node = node.nextSibling)
    nodes.push(node)
  return nodes
}

/**
 * Python 类主体里一个成员（赋值、只写注解的字段）的说明，照源码顺序：紧挨在它上面的注释块、它这一行行尾的注释、
 * 紧跟在它后面的属性 docstring。
 */
export function memberDocs(children: readonly CodeBlock[], block: CodeBlock): Node[] {
  const trailing = block.node.nextSibling
  const doc = block.kind === 'variable' ? block.facts.doc : block.kind === 'field' ? block.doc : undefined
  return [
    ...leadingComments(children, block).flatMap(commentNodes),
    ...(trailing?.type === 'comment' && trailing.startPosition.row === block.node.endPosition.row ? [trailing] : []),
    ...(doc ? [doc] : []),
  ]
}