import { useState } from 'react'
import { CustomValueResponse } from '../services/customFields'

interface Task {
  id: string
  project_id: string
  title: string
  description: string | null
  priority: string
  status_id: string | null
  status_name: string | null
  status_color: string | null
  assignee_id: string | null
  assignee_name: string | null
  due_date: string | null
  start_date: string | null
  time_estimate: number | null
  subtask_count: number
  custom_values?: CustomValueResponse[]
}

interface TaskStatus {
  id: string
  name: string
  color: string
  is_done: boolean
}

interface KanbanBoardProps {
  tasks: Task[]
  statuses: TaskStatus[]
  onStatusChange: (taskId: string, statusId: string) => void
  onTaskClick: (task: Task) => void
}

export function KanbanBoard({
  tasks,
  statuses,
  onStatusChange,
  onTaskClick,
}: KanbanBoardProps) {
  const [draggedTaskId, setDraggedTaskId] = useState<string | null>(null)
  const [dragOverColumnId, setDragOverColumnId] = useState<string | null>(null)

  // Group tasks by status
  const tasksByStatus: Record<string, Task[]> = {}
  statuses.forEach((status) => {
    tasksByStatus[status.id] = tasks.filter((task) => task.status_id === status.id)
  })
  // Tasks without status
  const unassignedTasks = tasks.filter((task) => !task.status_id)

  const handleDragStart = (e: React.DragEvent, taskId: string) => {
    setDraggedTaskId(taskId)
    e.dataTransfer.effectAllowed = 'move'
    e.dataTransfer.setData('text/plain', taskId)
    // Add a slight delay to allow the drag image to be captured
    const target = e.target as HTMLElement
    setTimeout(() => {
      target.style.opacity = '0.5'
    }, 0)
  }

  const handleDragEnd = (e: React.DragEvent) => {
    const target = e.target as HTMLElement
    target.style.opacity = '1'
    setDraggedTaskId(null)
    setDragOverColumnId(null)
  }

  const handleDragOver = (e: React.DragEvent, statusId: string) => {
    e.preventDefault()
    e.dataTransfer.dropEffect = 'move'
    if (dragOverColumnId !== statusId) {
      setDragOverColumnId(statusId)
    }
  }

  const handleDragLeave = (e: React.DragEvent) => {
    e.preventDefault()
    setDragOverColumnId(null)
  }

  const handleDrop = (e: React.DragEvent, statusId: string) => {
    e.preventDefault()
    const taskId = e.dataTransfer.getData('text/plain')
    if (taskId && draggedTaskId) {
      const task = tasks.find((t) => t.id === taskId)
      if (task && task.status_id !== statusId) {
        onStatusChange(taskId, statusId)
      }
    }
    setDraggedTaskId(null)
    setDragOverColumnId(null)
  }

  const getPriorityColor = (priority: string): string => {
    const colors: Record<string, string> = {
      low: '#808080',
      medium: '#0066cc',
      high: '#ff9800',
      urgent: '#f44336',
    }
    return colors[priority] || colors.medium
  }

  const renderTaskCard = (task: Task) => (
    <div
      key={task.id}
      style={{
        ...styles.taskCard,
        borderLeftColor: getPriorityColor(task.priority),
        opacity: draggedTaskId === task.id ? 0.5 : 1,
      }}
      draggable
      onDragStart={(e) => handleDragStart(e, task.id)}
      onDragEnd={handleDragEnd}
      onClick={() => onTaskClick(task)}
    >
      <div style={styles.taskTitle}>{task.title}</div>
      {task.description && (
        <div style={styles.taskDescription}>
          {task.description.length > 80
            ? task.description.substring(0, 80) + '...'
            : task.description}
        </div>
      )}
      <div style={styles.taskMeta}>
        {task.assignee_name && (
          <span style={styles.assigneeBadge}>{task.assignee_name}</span>
        )}
        {task.due_date && (
          <span style={styles.dueDate}>
            {new Date(task.due_date).toLocaleDateString()}
          </span>
        )}
        {task.subtask_count > 0 && (
          <span style={styles.subtaskBadge}>{task.subtask_count} subtasks</span>
        )}
        {/* Display custom field values (limit to first 2 for compact display) */}
        {task.custom_values?.slice(0, 2).map((cv) => (
          <span key={cv.field_id} style={styles.customValueBadge}>
            {cv.field_name}: {cv.display_value || cv.value || '-'}
          </span>
        ))}
      </div>
    </div>
  )

  return (
    <div style={styles.board}>
      {/* Unassigned column (if there are tasks without status) */}
      {unassignedTasks.length > 0 && (
        <div style={styles.column}>
          <div
            style={{
              ...styles.columnHeader,
              backgroundColor: '#9e9e9e',
            }}
          >
            <span style={styles.columnTitle}>No Status</span>
            <span style={styles.taskCount}>{unassignedTasks.length}</span>
          </div>
          <div style={styles.taskList}>
            {unassignedTasks.map(renderTaskCard)}
          </div>
        </div>
      )}

      {/* Status columns */}
      {statuses.map((status) => (
        <div
          key={status.id}
          style={{
            ...styles.column,
            ...(dragOverColumnId === status.id ? styles.columnDragOver : {}),
          }}
          onDragOver={(e) => handleDragOver(e, status.id)}
          onDragLeave={handleDragLeave}
          onDrop={(e) => handleDrop(e, status.id)}
        >
          <div
            style={{
              ...styles.columnHeader,
              backgroundColor: status.color || '#e0e0e0',
            }}
          >
            <span style={styles.columnTitle}>{status.name}</span>
            <span style={styles.taskCount}>
              {tasksByStatus[status.id]?.length || 0}
            </span>
          </div>
          <div style={styles.taskList}>
            {tasksByStatus[status.id]?.map(renderTaskCard)}
            {(!tasksByStatus[status.id] || tasksByStatus[status.id].length === 0) && (
              <div style={styles.emptyColumn}>
                Drop tasks here
              </div>
            )}
          </div>
        </div>
      ))}
    </div>
  )
}

const styles: Record<string, React.CSSProperties> = {
  board: {
    display: 'flex',
    gap: '16px',
    overflowX: 'auto',
    paddingBottom: '16px',
    minHeight: '500px',
  },
  column: {
    flex: '0 0 280px',
    backgroundColor: '#f5f5f5',
    borderRadius: '8px',
    display: 'flex',
    flexDirection: 'column',
    maxHeight: 'calc(100vh - 200px)',
    transition: 'background-color 0.2s ease',
  },
  columnDragOver: {
    backgroundColor: '#e3f2fd',
    boxShadow: 'inset 0 0 0 2px #0066cc',
  },
  columnHeader: {
    display: 'flex',
    justifyContent: 'space-between',
    alignItems: 'center',
    padding: '12px 16px',
    borderRadius: '8px 8px 0 0',
    color: 'white',
    fontWeight: 600,
  },
  columnTitle: {
    fontSize: '14px',
  },
  taskCount: {
    fontSize: '12px',
    backgroundColor: 'rgba(255, 255, 255, 0.3)',
    padding: '2px 8px',
    borderRadius: '10px',
  },
  taskList: {
    flex: 1,
    padding: '12px',
    overflowY: 'auto',
    display: 'flex',
    flexDirection: 'column',
    gap: '8px',
  },
  taskCard: {
    backgroundColor: 'white',
    borderRadius: '6px',
    padding: '12px',
    boxShadow: '0 1px 3px rgba(0, 0, 0, 0.1)',
    cursor: 'grab',
    borderLeft: '4px solid',
    transition: 'box-shadow 0.2s ease, transform 0.2s ease',
  },
  taskTitle: {
    fontSize: '14px',
    fontWeight: 500,
    marginBottom: '6px',
    lineHeight: 1.4,
  },
  taskDescription: {
    fontSize: '12px',
    color: '#666',
    marginBottom: '8px',
    lineHeight: 1.4,
  },
  taskMeta: {
    display: 'flex',
    flexWrap: 'wrap',
    gap: '6px',
    fontSize: '11px',
  },
  assigneeBadge: {
    backgroundColor: '#e3f2fd',
    color: '#1565c0',
    padding: '2px 6px',
    borderRadius: '4px',
  },
  dueDate: {
    color: '#666',
  },
  subtaskBadge: {
    color: '#767676', // WCAG AA compliant
  },
  customValueBadge: {
    backgroundColor: '#f3e5f5',
    color: '#7b1fa2',
    padding: '2px 6px',
    borderRadius: '4px',
    fontSize: '10px',
    maxWidth: '100px',
    overflow: 'hidden',
    textOverflow: 'ellipsis',
    whiteSpace: 'nowrap',
  },
  emptyColumn: {
    textAlign: 'center',
    padding: '24px',
    color: '#767676', // WCAG AA compliant
    fontSize: '13px',
    border: '2px dashed #ddd',
    borderRadius: '6px',
  },
}

export default KanbanBoard