import type { CSSProperties, ReactElement } from 'react'
import type { BlockView } from './types'
import { ChevronDown, ChevronRight, Eye, EyeOff, Pencil } from 'lucide-react'
import { Fragment } from 'react'
import { cn } from '@/lib/utils'
import { CodeEditor } from './CodeEditor'
import { PropertyGrid } from './PropertyGrid'
import { TextPreview } from './TextPreview'

export interface BlockTreeState {
  version: number
  editing: ReadonlySet<string>
  /** 眼下折叠着的块 id、属性行 id 和子行 id（propertyRowId、propertyItemId）：用户的选择叠在默认上，见 collapsedIds */
  collapsed: ReadonlySet<string>
  /** 按筛选不画的块（连同子孙），见 applyFilter */
  hidden: ReadonlySet<string>
  /** 本来被筛掉、跳到定义时临时显示的块 */
  temporary: ReadonlySet<string>
  /** 种类标签上写什么：翻译插件给种类起的名字（库规则的种类是规则给的标签），没给就是 id */
  kindName: (kind: string) => string
  /** 刚点了「编辑」、要把光标放进去的块 */
  focusId: string | null
  onFocused: () => void
  onToggleEdit: (id: string) => void
  onToggleFold: (id: string) => void
}

/** 块下面有没有画出来的子块：子块都被筛掉时不留空的一层、不给折叠箭头。 */
function hasShownChildren(block: BlockView, tree: BlockTreeState): boolean {
  return block.children.some(child => !tree.hidden.has(child.id))
}

/**
 * 块的种类色写在哪：内置种类按 data-kind 取 CSS 里的配色；库规则认领的块（带 badge）按规则给的颜色，
 * 暗色、亮色两个都写在 style 上，CSS 按主题挑一个（见 [data-badge]）。
 */
function kindProps(block: BlockView | undefined): { 'data-kind'?: string, 'data-badge'?: '', 'style'?: CSSProperties } {
  if (!block)
    return {}
  if (!block.badge)
    return { 'data-kind': block.kind }
  const { dark, light } = block.badge.color
  return { 'data-kind': block.kind, 'data-badge': '', 'style': { '--kind-dark': dark, '--kind-light': light } as CSSProperties }
}

/**
 * 一层代码块：左边一条竖线标出这一层，每块的子块紧跟在它下面、再往右缩进一层。被筛掉的块不画，不留空位，竖线跟着变短。
 * owner 是这一层所属的块（顶层没有），悬停它时竖线换成它的种类色。
 */
export function BlockLevel({ blocks, owner, tree }: { blocks: BlockView[], owner?: BlockView, tree: BlockTreeState }): ReactElement {
  return (
    <div className="cr-level flex gap-2" {...kindProps(owner)}>
      <div className="flex w-3 shrink-0 justify-center">
        <div className="cr-guide w-px" />
      </div>
      <div className="flex min-w-0 flex-1 flex-col gap-2">
        {blocks.filter(block => !tree.hidden.has(block.id)).map(block => (
          <Fragment key={block.id}>
            <BlockCard block={block} tree={tree} />
            {hasShownChildren(block, tree) && !tree.collapsed.has(block.id) && (
              <BlockLevel blocks={block.children} owner={block} tree={tree} />
            )}
          </Fragment>
        ))}
      </div>
    </div>
  )
}

/** 预览状态的内容：函数、类、导入、常量、变量块和库规则认领的块是属性表，其余是一行译文，带说明的译文下面接着说明。 */
function BlockPreview({ block, tree }: { block: BlockView, tree: BlockTreeState }): ReactElement {
  if ('properties' in block)
    return <PropertyGrid blockId={block.id} rows={block.properties} collapsed={tree.collapsed} onToggleFold={tree.onToggleFold} />
  return (
    <>
      <TextPreview text={block.translation} />
      {block.doc && <TextPreview text={block.doc} className="mt-0.5" />}
    </>
  )
}

/** 一块：折叠箭头、种类标签、预览内容或源码、右边的「编辑 / 预览」切换。 */
function BlockCard({ block, tree }: { block: BlockView, tree: BlockTreeState }): ReactElement {
  const editing = tree.editing.has(block.id)
  const collapsed = tree.collapsed.has(block.id)
  const hasChildren = hasShownChildren(block, tree)
  const Chevron = collapsed ? ChevronRight : ChevronDown
  return (
    <div
      className="cr-block flex items-start gap-2.5 rounded-lg py-2 pr-2.5 pl-2"
      {...kindProps(block)}
      data-id={block.id}
      data-line={block.startLine}
      data-editing={editing ? '' : undefined}
    >
      {hasChildren
        ? (
            <button
              type="button"
              className="flex h-5 w-3.5 shrink-0 items-center justify-center rounded-sm text-[var(--vscode-descriptionForeground)] hover:text-[var(--vscode-foreground)]"
              aria-label={collapsed ? '展开子块' : '折叠子块'}
              aria-expanded={!collapsed}
              onClick={() => tree.onToggleFold(block.id)}
            >
              <Chevron size={14} strokeWidth={1.8} />
            </button>
          )
        : <span className="w-3.5 shrink-0" />}
      <span className="cr-badge flex h-5 min-w-11 shrink-0 items-center justify-center rounded px-1 text-[11px] leading-[14px] font-medium whitespace-nowrap">
        {tree.kindName(block.kind)}
      </span>
      <div className="min-w-0 flex-1">
        {editing
          ? (
              <CodeEditor
                block={block}
                version={tree.version}
                autoFocus={tree.focusId === block.id}
                onAutoFocused={tree.onFocused}
                onExit={() => tree.onToggleEdit(block.id)}
              />
            )
          : <BlockPreview block={block} tree={tree} />}
      </div>
      {tree.temporary.has(block.id) && (
        <span className="cr-temporary flex h-5 shrink-0 items-center gap-1 rounded px-1.5 text-[11px] whitespace-nowrap">
          <EyeOff size={12} strokeWidth={1.8} aria-hidden />
          已被筛选隐藏，临时显示
        </span>
      )}
      <button
        type="button"
        className={cn(
          'flex shrink-0 items-center gap-1 rounded px-2 py-0.5 text-xs leading-4 text-[var(--vscode-descriptionForeground)] hover:bg-[var(--vscode-toolbar-hoverBackground)]',
          editing && 'bg-[var(--vscode-toolbar-activeBackground)]',
        )}
        onClick={() => tree.onToggleEdit(block.id)}
      >
        {editing ? <Eye size={13} strokeWidth={1.8} /> : <Pencil size={13} strokeWidth={1.8} />}
        {editing ? '预览' : '编辑'}
      </button>
    </div>
  )
}