import type { Ref } from 'react'
import type { Issue } from '../types'
import { useSortable } from '@dnd-kit/sortable'
import { CSS } from '@dnd-kit/utilities'
import { Lock } from 'lucide-react'
import { forwardRef } from 'react'
import { cn } from '@/lib/utils'
import { Card } from './ui/card'

interface IssueCardProps {
  issue: Issue
  selected?: boolean
  onSelect?: (id: string) => void
  /**
   * Visual nesting level for prerequisite-chain rendering in the todo column.
   * Each level adds 16px of left margin. Defaults to 0 (flat).
   */
  depth?: number
  /** 锁定态：前置工单尚未完成。显示锁图标 + tooltip。 */
  locked?: boolean
  /** 锁定时关联的前置工单号，用于 tooltip 文案 "等待 #N 完成"。 */
  lockedPrerequisite?: number
  /** 只读态：同事的工单。禁止拖拽，并在右上角贴归属人头像。 */
  readOnly?: boolean
  /** 归属人 Gitea login（只读卡片才显示）。 */
  ownerLogin?: string
  /** 归属人头像 data URI；缺失时回退首字母圆点。 */
  ownerAvatar?: string
}

/** 同事工单的归属人标记：有头像用头像，没有就用 login 首字母。 */
function OwnerBadge({ login, avatar }: { login: string, avatar?: string }) {
  return avatar
    ? (
        <img
          src={avatar}
          alt={login}
          title={`${login} 的工单（只读）`}
          className="size-4 shrink-0 rounded-full ring-1 ring-[var(--vscode-panel-border)]"
        />
      )
    : (
        <span
          title={`${login} 的工单（只读）`}
          className="grid size-4 shrink-0 place-items-center rounded-full bg-[var(--vscode-badge-background)] text-[8px] uppercase text-[var(--vscode-badge-foreground)]"
        >
          {login.slice(0, 1)}
        </span>
      )
}

export const IssueCard = forwardRef<HTMLDivElement, IssueCardProps>(
  ({ issue, selected, onSelect, depth = 0, locked, lockedPrerequisite, readOnly, ownerLogin, ownerAvatar }, ref) => {
    const { attributes, listeners, setNodeRef, transform, transition, isDragging }
      = useSortable({ id: issue.id, data: { column: issue.column }, disabled: readOnly })

    const style: React.CSSProperties = {
      transform: CSS.Transform.toString(transform),
      transition,
      opacity: isDragging ? 0.4 : 1,
      marginLeft: depth * 16,
    }

    // Merge dnd-kit's ref with the forwarded ref so the parent can scrollIntoView.
    function setRefs(node: HTMLDivElement | null): void {
      setNodeRef(node)
      if (typeof ref === 'function')
        ref(node)
      else if (ref)
        (ref as React.MutableRefObject<HTMLDivElement | null>).current = node
    }

    return (
      <Card
        ref={setRefs as unknown as Ref<HTMLDivElement>}
        style={style}
        {...attributes}
        {...listeners}
        onClick={() => onSelect?.(issue.id)}
        className={cn(
          'relative select-none px-3 py-2 text-xs',
          readOnly ? 'cursor-default' : 'cursor-grab active:cursor-grabbing',
          locked && 'opacity-75',
          selected
          && 'ring-2 ring-[var(--vscode-focusBorder)] ring-offset-1 ring-offset-[var(--vscode-sideBar-background)]',
        )}
      >
        <div className="absolute right-1.5 top-1.5 flex items-center gap-1">
          {locked
            ? (
                <span
                  className="grid place-items-center text-[var(--vscode-disabledForeground)]"
                  title={lockedPrerequisite != null ? `等待 #${lockedPrerequisite} 完成` : '等待前置工单完成'}
                  aria-label={lockedPrerequisite != null ? `等待 #${lockedPrerequisite} 完成` : '等待前置工单完成'}
                >
                  <Lock className="size-3.5" />
                </span>
              )
            : null}
          {readOnly && ownerLogin ? <OwnerBadge login={ownerLogin} avatar={ownerAvatar} /> : null}
        </div>
        {issue.handoffAttachmentId
          ? (
              <span
                className="absolute bottom-1 right-1.5 rounded border border-blue-400/50 bg-blue-400/10 px-1 text-[9px] text-blue-400"
                title={`${issue.handoffFrom ?? '?'} 已移交，待接管`}
              >
                待接管
              </span>
            )
          : null}
        <div className={cn('truncate', (locked || (readOnly && ownerLogin)) && 'pr-5', locked && readOnly && ownerLogin && 'pr-10')}>
          <span className="font-mono opacity-60">
            {issue.source === 'youtrack' ? issue.externalId : `#${issue.number}`}
          </span>
          {' '}
          <span>{issue.title}</span>
        </div>
      </Card>
    )
  },
)

IssueCard.displayName = 'IssueCard'