import { useState, useEffect, useRef, useCallback } from 'react'
import { UserWorkloadDetail, LoadLevel, workloadApi } from '../services/workload'
import { SkeletonList } from './Skeleton'

interface WorkloadUserDetailProps {
  userId: string
  userName: string
  weekStart: string
  isOpen: boolean
  onClose: () => void
}

// Color mapping for load levels
const loadLevelColors: Record<LoadLevel, string> = {
  normal: '#4caf50',
  warning: '#ff9800',
  overloaded: '#f44336',
  unavailable: '#9e9e9e',
}

const loadLevelLabels: Record<LoadLevel, string> = {
  normal: 'Normal',
  warning: 'Warning',
  overloaded: 'Overloaded',
  unavailable: 'Unavailable',
}

export function WorkloadUserDetail({
  userId,
  userName,
  weekStart,
  isOpen,
  onClose,
}: WorkloadUserDetailProps) {
  const [loading, setLoading] = useState(true)
  const [error, setError] = useState<string | null>(null)
  const [detail, setDetail] = useState<UserWorkloadDetail | null>(null)
  const modalOverlayRef = useRef<HTMLDivElement>(null)

  // A11Y: Handle Escape key to close modal
  useEffect(() => {
    const handleKeyDown = (e: KeyboardEvent) => {
      if (e.key === 'Escape' && isOpen) {
        onClose()
      }
    }

    if (isOpen) {
      document.addEventListener('keydown', handleKeyDown)
      modalOverlayRef.current?.focus()
    }

    return () => {
      document.removeEventListener('keydown', handleKeyDown)
    }
  }, [isOpen, onClose])

  const loadUserDetail = useCallback(async () => {
    setLoading(true)
    setError(null)
    try {
      const data = await workloadApi.getUserWorkload(userId, weekStart)
      setDetail(data)
    } catch (err) {
      console.error('Failed to load user workload:', err)
      setError('Failed to load workload details')
    } finally {
      setLoading(false)
    }
  }, [userId, weekStart])

  useEffect(() => {
    if (isOpen && userId) {
      loadUserDetail()
    }
  }, [isOpen, userId, weekStart, loadUserDetail])

  const formatDate = (dateStr: string | null) => {
    if (!dateStr) return '-'
    const date = new Date(dateStr)
    return date.toLocaleDateString('zh-TW', { month: 'short', day: 'numeric' })
  }

  if (!isOpen) return null

  return (
    <div
      ref={modalOverlayRef}
      style={styles.overlay}
      onClick={onClose}
      tabIndex={-1}
      role="dialog"
      aria-modal="true"
      aria-labelledby="workload-detail-title"
    >
      <div style={styles.modal} onClick={(e) => e.stopPropagation()}>
        <div style={styles.header}>
          <div>
            <h2 id="workload-detail-title" style={styles.title}>{userName}</h2>
            <span style={styles.subtitle}>Workload Details</span>
          </div>
          <button style={styles.closeButton} onClick={onClose} aria-label="Close">
            ×
          </button>
        </div>

        {loading ? (
          <div style={{ padding: '16px' }}>
            <SkeletonList count={5} showAvatar={false} />
          </div>
        ) : error ? (
          <div style={styles.error}>{error}</div>
        ) : detail ? (
          <>
            {/* Summary Section */}
            <div style={styles.summarySection}>
              <div style={styles.summaryCard}>
                <span style={styles.summaryLabel}>Allocated Hours</span>
                <span style={styles.summaryValue}>{detail.summary.allocated_hours}h</span>
              </div>
              <div style={styles.summaryCard}>
                <span style={styles.summaryLabel}>Capacity</span>
                <span style={styles.summaryValue}>{detail.summary.capacity_hours}h</span>
              </div>
              <div style={styles.summaryCard}>
                <span style={styles.summaryLabel}>Load</span>
                <span
                  style={{
                    ...styles.summaryValue,
                    color: loadLevelColors[detail.summary.load_level],
                  }}
                >
                  {detail.summary.load_percentage}%
                </span>
              </div>
              <div style={styles.summaryCard}>
                <span style={styles.summaryLabel}>Status</span>
                <span
                  style={{
                    ...styles.statusBadge,
                    backgroundColor: loadLevelColors[detail.summary.load_level],
                  }}
                >
                  {loadLevelLabels[detail.summary.load_level]}
                </span>
              </div>
            </div>

            {/* Tasks Section */}
            <div style={styles.tasksSection}>
              <h3 style={styles.sectionTitle}>Tasks This Week</h3>
              {detail.tasks.length === 0 ? (
                <div style={styles.emptyTasks}>No tasks assigned for this week.</div>
              ) : (
                <div style={styles.taskList}>
                  {detail.tasks.map((task) => (
                    <div key={task.task_id} style={styles.taskItem}>
                      <div style={styles.taskMain}>
                        <span style={styles.taskTitle}>{task.task_title}</span>
                        <span style={styles.projectName}>{task.project_name}</span>
                      </div>
                      <div style={styles.taskMeta}>
                        <span style={styles.timeEstimate}>{task.time_estimate}h</span>
                        {task.due_date && (
                          <span style={styles.dueDate}>Due: {formatDate(task.due_date)}</span>
                        )}
                        {task.status_name && (
                          <span style={styles.status}>{task.status_name}</span>
                        )}
                      </div>
                    </div>
                  ))}
                </div>
              )}
            </div>

            {/* Total hours breakdown */}
            <div style={styles.totalSection}>
              <span style={styles.totalLabel}>Total Estimated Hours:</span>
              <span style={styles.totalValue}>
                {detail.tasks.reduce((sum, task) => sum + task.time_estimate, 0)}h
              </span>
            </div>
          </>
        ) : null}
      </div>
    </div>
  )
}

const styles: { [key: string]: React.CSSProperties } = {
  overlay: {
    position: 'fixed',
    top: 0,
    left: 0,
    right: 0,
    bottom: 0,
    backgroundColor: 'rgba(0, 0, 0, 0.5)',
    display: 'flex',
    justifyContent: 'center',
    alignItems: 'center',
    zIndex: 1000,
  },
  modal: {
    backgroundColor: 'white',
    borderRadius: '8px',
    width: '600px',
    maxWidth: '90%',
    maxHeight: '80vh',
    overflow: 'hidden',
    display: 'flex',
    flexDirection: 'column',
  },
  header: {
    display: 'flex',
    justifyContent: 'space-between',
    alignItems: 'flex-start',
    padding: '20px 24px',
    borderBottom: '1px solid #eee',
  },
  title: {
    fontSize: '20px',
    fontWeight: 600,
    margin: 0,
    color: '#333',
  },
  subtitle: {
    fontSize: '14px',
    color: '#666',
  },
  closeButton: {
    background: 'none',
    border: 'none',
    fontSize: '28px',
    cursor: 'pointer',
    color: '#767676', // WCAG AA compliant
    padding: '0',
    lineHeight: 1,
  },
  loading: {
    padding: '48px',
    textAlign: 'center',
    color: '#666',
  },
  error: {
    padding: '48px',
    textAlign: 'center',
    color: '#f44336',
  },
  summarySection: {
    display: 'grid',
    gridTemplateColumns: 'repeat(4, 1fr)',
    gap: '12px',
    padding: '20px 24px',
    backgroundColor: '#f9f9f9',
  },
  summaryCard: {
    display: 'flex',
    flexDirection: 'column',
    alignItems: 'center',
    gap: '4px',
  },
  summaryLabel: {
    fontSize: '12px',
    color: '#666',
    textTransform: 'uppercase',
    letterSpacing: '0.5px',
  },
  summaryValue: {
    fontSize: '20px',
    fontWeight: 600,
    color: '#333',
  },
  statusBadge: {
    display: 'inline-block',
    padding: '4px 10px',
    borderRadius: '4px',
    fontSize: '12px',
    fontWeight: 500,
    color: 'white',
  },
  tasksSection: {
    flex: 1,
    overflowY: 'auto',
    padding: '20px 24px',
  },
  sectionTitle: {
    fontSize: '14px',
    fontWeight: 600,
    color: '#666',
    margin: '0 0 12px 0',
    textTransform: 'uppercase',
    letterSpacing: '0.5px',
  },
  emptyTasks: {
    textAlign: 'center',
    padding: '24px',
    color: '#767676', // WCAG AA compliant
    fontSize: '14px',
  },
  taskList: {
    display: 'flex',
    flexDirection: 'column',
    gap: '8px',
  },
  taskItem: {
    display: 'flex',
    justifyContent: 'space-between',
    alignItems: 'center',
    padding: '12px 16px',
    backgroundColor: '#f9f9f9',
    borderRadius: '6px',
    borderLeft: '3px solid #0066cc',
  },
  taskMain: {
    display: 'flex',
    flexDirection: 'column',
    gap: '2px',
  },
  taskTitle: {
    fontSize: '14px',
    fontWeight: 500,
    color: '#333',
  },
  projectName: {
    fontSize: '12px',
    color: '#666',
  },
  taskMeta: {
    display: 'flex',
    alignItems: 'center',
    gap: '12px',
  },
  timeEstimate: {
    fontSize: '14px',
    fontWeight: 600,
    color: '#0066cc',
  },
  dueDate: {
    fontSize: '12px',
    color: '#666',
  },
  status: {
    fontSize: '11px',
    padding: '2px 8px',
    backgroundColor: '#e0e0e0',
    borderRadius: '4px',
    color: '#666',
  },
  totalSection: {
    display: 'flex',
    justifyContent: 'flex-end',
    alignItems: 'center',
    gap: '8px',
    padding: '16px 24px',
    borderTop: '1px solid #eee',
    backgroundColor: '#f9f9f9',
  },
  totalLabel: {
    fontSize: '14px',
    color: '#666',
  },
  totalValue: {
    fontSize: '18px',
    fontWeight: 600,
    color: '#333',
  },
}

export default WorkloadUserDetail