import { useState, useCallback, useRef, useEffect } from 'react'
import { useNavigate } from 'react-router-dom'
import { ChevronLeft, Save, Download, FileJson, FileCode, Image, FileText, Undo2, Redo2, MousePointer2, Hand, FileOutput, Upload, Cable } from 'lucide-react'
import { cn } from '@/lib/utils'

export type InteractionMode = 'select' | 'pan' | 'connect'

interface DiagramHeaderProps {
  name: string
  clientName: string | null
  isDirty: boolean
  isSaving: boolean
  lastSavedAt: Date | null
  diagramId: string | null
  onNameChange: (name: string) => void
  onSave: () => void
  onExportPng: () => void
  onExportSvg: () => void
  onExportPdf: () => void
  onExportJson: () => void
  onExportDrawio: () => void
  onImportDrawio: () => void  // draw.io import — triggered from Export menu
  onUndo: () => void
  onRedo: () => void
  canUndo: boolean
  canRedo: boolean
  interactionMode: InteractionMode
  onModeChange: (mode: InteractionMode) => void
}

export function DiagramHeader({
  name,
  clientName,
  isDirty,
  isSaving,
  lastSavedAt,
  diagramId,
  onNameChange,
  onSave,
  onExportPng,
  onExportSvg,
  onExportPdf,
  onExportJson,
  onExportDrawio,
  onImportDrawio,
  onUndo,
  onRedo,
  canUndo,
  canRedo,
  interactionMode,
  onModeChange,
}: DiagramHeaderProps) {
  const navigate = useNavigate()
  const [editing, setEditing] = useState(false)
  const [editValue, setEditValue] = useState(name)
  const [showExportMenu, setShowExportMenu] = useState(false)
  const inputRef = useRef<HTMLInputElement>(null)
  const exportMenuRef = useRef<HTMLDivElement>(null)

  useEffect(() => {
    if (editing && inputRef.current) {
      inputRef.current.focus()
      inputRef.current.select()
    }
  }, [editing])

  useEffect(() => {
    setEditValue(name)
  }, [name])

  useEffect(() => {
    if (!showExportMenu) return
    const handleClick = (e: MouseEvent) => {
      if (exportMenuRef.current && !exportMenuRef.current.contains(e.target as HTMLElement)) {
        setShowExportMenu(false)
      }
    }
    document.addEventListener('mousedown', handleClick)
    return () => document.removeEventListener('mousedown', handleClick)
  }, [showExportMenu])

  const handleConfirmName = useCallback(() => {
    setEditing(false)
    if (editValue.trim() && editValue !== name) {
      onNameChange(editValue.trim())
    } else {
      setEditValue(name)
    }
  }, [editValue, name, onNameChange])

  const formatLastSaved = () => {
    if (!lastSavedAt) return null
    // eslint-disable-next-line react-hooks/purity
    const diff = Date.now() - lastSavedAt.getTime()
    if (diff < 60_000) return 'Saved just now'
    const mins = Math.floor(diff / 60_000)
    return `Saved ${mins}m ago`
  }

  return (
    <div className="flex h-14 items-center gap-3 border-b border-default bg-card px-4">
      <button
        onClick={() => navigate('/network-diagrams')}
        className="flex items-center gap-1 text-xs text-muted-foreground hover:text-primary"
      >
        <ChevronLeft size={16} />
        Network Maps
      </button>

      <div className="mx-2 h-5 w-px bg-border-default" />

      <div className="flex items-center gap-1">
        <button
          onClick={onUndo}
          disabled={!canUndo}
          title="Undo (Ctrl+Z)"
          className="p-1.5 rounded text-muted-foreground hover:text-primary hover:bg-elevated disabled:opacity-30 disabled:cursor-not-allowed transition-colors"
        >
          <Undo2 size={16} />
        </button>
        <button
          onClick={onRedo}
          disabled={!canRedo}
          title="Redo (Ctrl+Y)"
          className="p-1.5 rounded text-muted-foreground hover:text-primary hover:bg-elevated disabled:opacity-30 disabled:cursor-not-allowed transition-colors"
        >
          <Redo2 size={16} />
        </button>
      </div>

      <div className="mx-2 h-5 w-px bg-border-default" />

      {/* Interaction mode toggle */}
      <div className="flex items-center overflow-hidden rounded border border-default">
        <button
          onClick={() => onModeChange('select')}
          title="Select (V)"
          className={cn(
            'flex items-center gap-1.5 px-2.5 py-1.5 text-xs transition-colors',
            interactionMode === 'select'
              ? 'bg-elevated text-primary'
              : 'text-muted-foreground hover:text-primary hover:bg-elevated/50',
          )}
        >
          <MousePointer2 size={15} />
          <span className="hidden sm:inline">Select</span>
        </button>
        <button
          onClick={() => onModeChange('pan')}
          title="Pan (H)"
          className={cn(
            'flex items-center gap-1.5 border-l border-default px-2.5 py-1.5 text-xs transition-colors',
            interactionMode === 'pan'
              ? 'bg-elevated text-primary'
              : 'text-muted-foreground hover:text-primary hover:bg-elevated/50',
          )}
        >
          <Hand size={15} />
          <span className="hidden sm:inline">Pan</span>
        </button>
        <button
          onClick={() => onModeChange('connect')}
          title="Connect (C)"
          className={cn(
            'flex items-center gap-1.5 border-l border-default px-2.5 py-1.5 text-xs transition-colors',
            interactionMode === 'connect'
              ? 'bg-elevated text-primary'
              : 'text-muted-foreground hover:text-primary hover:bg-elevated/50',
          )}
        >
          <Cable size={15} />
          <span className="hidden sm:inline">Connect</span>
        </button>
      </div>

      <div className="mx-2 h-5 w-px bg-border-default" />

      {editing ? (
        <input
          ref={inputRef}
          value={editValue}
          onChange={e => setEditValue(e.target.value)}
          onBlur={handleConfirmName}
          onKeyDown={e => { if (e.key === 'Enter') handleConfirmName(); if (e.key === 'Escape') { setEditing(false); setEditValue(name) } }}
          className="rounded border border-accent bg-input px-2 py-1 text-sm font-heading font-semibold text-heading focus:outline-none"
        />
      ) : (
        <button
          onClick={() => setEditing(true)}
          className="text-sm font-heading font-semibold text-heading hover:text-accent"
        >
          {name || 'Untitled Diagram'}
        </button>
      )}

      {clientName && (
        <span className="rounded-full bg-elevated px-2 py-0.5 text-[10px] text-muted-foreground">
          {clientName}
        </span>
      )}

      <div className="flex-1" />

      {isDirty && !isSaving ? (
        <span className="text-[10px] text-amber-400">Unsaved changes</span>
      ) : lastSavedAt ? (
        <span className="text-[10px] text-muted-foreground">{formatLastSaved()}</span>
      ) : null}

      <button
        onClick={onSave}
        disabled={isSaving}
        className="flex items-center gap-1.5 rounded bg-accent px-3 py-1.5 text-xs font-medium text-white hover:bg-accent/90 disabled:opacity-50"
      >
        <Save size={14} />
        {isSaving ? 'Saving...' : 'Save'}
      </button>

      <div className="relative" ref={exportMenuRef}>
        <button
          onClick={() => setShowExportMenu(prev => !prev)}
          className="flex items-center gap-1.5 rounded border border-default px-3 py-1.5 text-xs text-primary hover:border-hover"
        >
          <Download size={14} />
          Export / Import
        </button>
        {showExportMenu && (
          <div className="absolute right-0 top-full z-50 mt-1 w-44 rounded border border-default bg-card py-1 shadow-lg">
            <div className="px-3 py-1 text-[10px] font-semibold uppercase tracking-wider text-muted-foreground">Export as</div>
            <button
              onClick={() => { onExportPng(); setShowExportMenu(false) }}
              className="flex w-full items-center gap-2 px-3 py-1.5 text-xs text-primary hover:bg-elevated"
            >
              <Image size={12} /> PNG
            </button>
            <button
              onClick={() => { onExportSvg(); setShowExportMenu(false) }}
              className="flex w-full items-center gap-2 px-3 py-1.5 text-xs text-primary hover:bg-elevated"
            >
              <FileCode size={12} /> SVG
            </button>
            <button
              onClick={() => { onExportPdf(); setShowExportMenu(false) }}
              className="flex w-full items-center gap-2 px-3 py-1.5 text-xs text-primary hover:bg-elevated"
            >
              <FileText size={12} /> PDF
            </button>
            {diagramId && (
              <button
                onClick={() => { onExportJson(); setShowExportMenu(false) }}
                className="flex w-full items-center gap-2 px-3 py-1.5 text-xs text-primary hover:bg-elevated"
              >
                <FileJson size={12} /> JSON
              </button>
            )}
            <button
              onClick={() => { onExportDrawio(); setShowExportMenu(false) }}
              className="flex w-full items-center gap-2 px-3 py-1.5 text-xs text-primary hover:bg-elevated"
            >
              <FileOutput size={12} /> draw.io
            </button>
            <div className="my-1 border-t border-default" />
            <div className="px-3 py-1 text-[10px] font-semibold uppercase tracking-wider text-muted-foreground">Import</div>
            <button
              onClick={() => { onImportDrawio(); setShowExportMenu(false) }}
              className="flex w-full items-center gap-2 px-3 py-1.5 text-xs text-primary hover:bg-elevated"
            >
              <Upload size={12} /> draw.io file…
            </button>
          </div>
        )}
      </div>
    </div>
  )
}