'use client'

import { useRouter } from 'next/navigation'
import { useTransition } from 'react'
import {
  DndContext, DragEndEvent,
  KeyboardSensor, PointerSensor, useSensor, useSensors, closestCenter,
} from '@dnd-kit/core'
import {
  SortableContext, sortableKeyboardCoordinates,
  useSortable, verticalListSortingStrategy,
} from '@dnd-kit/sortable'
import { CSS } from '@dnd-kit/utilities'
import { GripVertical, Plus } from 'lucide-react'
import { toast } from 'sonner'
import { useSelectionStore } from '@/stores/selection-store'
import { useBacklogStore, type BacklogTask } from '@/stores/backlog-store'
import { reorderTasksAction } from '@/actions/tasks'
import { Button } from '@/components/ui/button'
import { DemoTooltip } from '@/components/shared/demo-tooltip'
import { EmptyPanel } from './empty-panel'
import { PRIORITY_BORDER } from './backlog-card'
import { cn } from '@/lib/utils'

const STATUS_COLORS: Record<string, string> = {
  TO_DO: 'bg-status-todo/15 text-status-todo border-status-todo/30',
  IN_PROGRESS: 'bg-status-in-progress/15 text-status-in-progress border-status-in-progress/30',
  REVIEW: 'bg-status-review/15 text-status-review border-status-review/30',
  DONE: 'bg-status-done/15 text-status-done border-status-done/30',
}
const STATUS_LABELS: Record<string, string> = {
  TO_DO: 'To Do',
  IN_PROGRESS: 'Bezig',
  REVIEW: 'Review',
  DONE: 'Klaar',
}

function SortableTaskRow({
  task,
  isDemo,
  onClick,
}: {
  task: BacklogTask
  isDemo: boolean
  onClick: () => void
}) {
  const { attributes, listeners, setNodeRef, transform, transition, isDragging } =
    useSortable({ id: task.id })

  return (
    <div
      ref={setNodeRef}
      style={{ transform: CSS.Transform.toString(transform), transition }}
      className={cn(
        'flex items-center gap-2 px-3 py-2 rounded-lg border cursor-pointer',
        'bg-surface-container hover:bg-surface-container-high transition-colors',
        PRIORITY_BORDER[task.priority],
        isDragging && 'opacity-50 shadow-lg',
      )}
      onClick={onClick}
    >
      <DemoTooltip show={isDemo}>
        <button
          {...attributes}
          {...listeners}
          disabled={isDemo}
          onClick={(e) => e.stopPropagation()}
          className="text-muted-foreground hover:text-foreground cursor-grab disabled:opacity-30 disabled:cursor-not-allowed shrink-0"
          aria-label="Versleep om te herordenen"
        >
          <GripVertical className="size-4" />
        </button>
      </DemoTooltip>

      <span className="flex-1 text-sm truncate">{task.title}</span>

      <span
        className={cn(
          'text-xs px-1.5 py-0.5 rounded border shrink-0',
          STATUS_COLORS[task.status] ?? STATUS_COLORS.TO_DO,
        )}
      >
        {STATUS_LABELS[task.status] ?? task.status}
      </span>
    </div>
  )
}

interface TaskPanelProps {
  productId: string
  isDemo: boolean
  closePath: string
}

export function TaskPanel({ productId, isDemo, closePath }: TaskPanelProps) {
  const router = useRouter()
  const [, startTransition] = useTransition()
  const selectedStoryId = useSelectionStore((s) => s.selectedStoryId)
  const tasksByStory = useBacklogStore((s) => s.tasksByStory)

  const tasks = selectedStoryId ? (tasksByStory[selectedStoryId] ?? []) : null

  const sensors = useSensors(
    useSensor(PointerSensor),
    useSensor(KeyboardSensor, { coordinateGetter: sortableKeyboardCoordinates }),
  )

  function handleDragEnd(event: DragEndEvent) {
    if (!selectedStoryId) return
    const { active, over } = event
    if (!over || active.id === over.id) return

    const ids = tasks!.map((t) => t.id)
    const from = ids.indexOf(active.id as string)
    const to = ids.indexOf(over.id as string)
    if (from === -1 || to === -1) return

    const reordered = [...ids]
    reordered.splice(from, 1)
    reordered.splice(to, 0, active.id as string)

    startTransition(async () => {
      const result = await reorderTasksAction(selectedStoryId, reordered)
      if (result?.error) toast.error(result.error)
    })
  }

  const header = (
    <div className="flex items-center justify-between px-4 py-3 border-b border-border bg-surface-container-low shrink-0">
      <h2 className="text-sm font-medium">Taken</h2>
      <DemoTooltip show={isDemo}>
        <Button
          size="sm"
          variant="outline"
          disabled={isDemo || !selectedStoryId}
          onClick={() => {
            if (!selectedStoryId) return
            router.push(`${closePath}?newTask=1&storyId=${selectedStoryId}`)
          }}
        >
          <Plus className="size-3.5 mr-1" />
          Nieuwe taak
        </Button>
      </DemoTooltip>
    </div>
  )

  if (tasks === null) {
    return (
      <div className="flex flex-col h-full">
        {header}
        <EmptyPanel message="Selecteer een story om de taken te bekijken." />
      </div>
    )
  }

  if (tasks.length === 0) {
    return (
      <div className="flex flex-col h-full">
        {header}
        <EmptyPanel
          message="Nog geen taken voor deze story."
          action={{
            label: 'Nieuwe taak',
            onClick: () => router.push(`${closePath}?newTask=1&storyId=${selectedStoryId}`),
            disabled: isDemo,
          }}
        />
      </div>
    )
  }

  return (
    <div className="flex flex-col h-full">
      {header}
      <div className="flex-1 overflow-y-auto p-3 space-y-1.5">
        <DndContext
          sensors={sensors}
          collisionDetection={closestCenter}
          onDragEnd={handleDragEnd}
        >
          <SortableContext items={tasks.map((t) => t.id)} strategy={verticalListSortingStrategy}>
            {tasks.map((task) => (
              <SortableTaskRow
                key={task.id}
                task={task}
                isDemo={isDemo}
                onClick={() => router.push(`${closePath}?editTask=${task.id}`)}
              />
            ))}
          </SortableContext>
        </DndContext>
      </div>
    </div>
  )
}