import React, { useState, useEffect } from 'react'
import { Sparkles, ArrowRight, X, RefreshCw, Check, Eraser } from 'lucide-react'
import ReactMarkdown from 'react-markdown'
import { chatService } from '../services/chatService'
import { useLanguage } from '../contexts/LanguageContext'

interface AICommandDrawerProps {
    isOpen: boolean
    onClose: () => void
    context: string
    onApply: (content: string) => void
    authToken: string
}

const PRESET_COMMANDS = [
    { label: 'polishContent', valueKey: 'aiCommandInstructPolish' },
    { label: 'expandContent', valueKey: 'aiCommandInstructExpand' },
    { label: 'summarizeContent', valueKey: 'aiCommandInstructSummarize' },
    { label: 'translateToEnglish', valueKey: 'aiCommandInstructTranslateToEn' },
    { label: 'fixGrammar', valueKey: 'aiCommandInstructFixGrammar' },
]

export const AICommandDrawer: React.FC<AICommandDrawerProps> = ({ isOpen, onClose, context, onApply, authToken }) => {
    const { t } = useLanguage()
    const [instruction, setInstruction] = useState('')
    const [result, setResult] = useState('')
    const [isGenerating, setIsGenerating] = useState(false)
    const [mode, setMode] = useState<'input' | 'preview'>('input')

    useEffect(() => {
        if (isOpen) {
            setInstruction('')
            setResult('')
            setMode('input')
            setIsGenerating(false)
        }
    }, [isOpen])

    const handleGenerate = async () => {
        if (!instruction) return

        setMode('preview')
        setIsGenerating(true)
        setResult('')

        try {
            const stream = chatService.streamAssist(instruction, context, authToken)

            for await (const chunk of stream) {
                if (chunk.type === 'content') {
                    setResult(prev => prev + chunk.data)
                } else if (chunk.type === 'error') {
                    setResult(prev => prev + `\n\n[Error: ${chunk.data}]`)
                }
            }
        } catch (error) {
            console.error(error)
            setResult(prev => prev + '\n\n[' + t('aiCommandsError') + ']')
        } finally {
            setIsGenerating(false)
        }
    }

    // Drawer Styles
    const drawerClasses = `fixed inset-y-0 right-0 z-50 w-96 bg-white shadow-2xl transform transition-transform duration-300 ease-in-out ${isOpen ? 'translate-x-0' : 'translate-x-full'
        }`

    // Overlay for closing on click outside (optional, but good UX)
    // Using a transparent overlay that allows interaction with the editor might be desired?
    // Usually drawers have a backdrop. User said "Show AI assistant page in right drawer", likely implies a standard drawer behavior.

    return (
        <>
            {/* Backdrop */}
            {isOpen && (
                <div
                    className="fixed inset-0 bg-black/20 z-40 backdrop-blur-none transition-opacity"
                    onClick={onClose}
                />
            )}

            <div className={drawerClasses}>
                <div className="flex flex-col h-full">
                    {/* Header */}
                    <div className="bg-gradient-to-r from-purple-600 to-blue-600 p-4 shrink-0 flex justify-between items-center text-white shadow-md">
                        <div className="flex items-center gap-2">
                            <Sparkles size={20} className="animate-pulse" />
                            <h3 className="font-bold text-lg">{t('aiAssistant')}</h3>
                        </div>
                        <button onClick={onClose} className="p-1 hover:bg-white/20 rounded-lg transition-colors">
                            <X size={20} />
                        </button>
                    </div>

                    {/* Content */}
                    <div className="flex-1 overflow-y-auto p-4">

                        {mode === 'input' ? (
                            <div className="space-y-6">
                                <div>
                                    <label className="block text-sm font-medium text-slate-700 mb-2">{t('aiCommandsPreset')}</label>
                                    <div className="flex flex-wrap gap-2">
                                        {PRESET_COMMANDS.map(cmd => (
                                            <button
                                                key={cmd.label}
                                                onClick={() => setInstruction(t(cmd.valueKey as any))}
                                                className={`px-3 py-1.5 text-xs rounded-full border transition-all ${instruction === t(cmd.valueKey as any)
                                                    ? 'bg-purple-100 border-purple-300 text-purple-700'
                                                    : 'bg-white border-slate-200 text-slate-600 hover:border-purple-300 hover:text-purple-600'
                                                    }`}
                                            >
                                                {t(cmd.label as keyof typeof t)}
                                            </button>
                                        ))}
                                    </div>
                                </div>

                                <div>
                                    <label className="block text-sm font-medium text-slate-700 mb-2">{t('aiCommandsCustom')}</label>
                                    <textarea
                                        className="w-full h-32 p-3 border border-slate-300 rounded-lg focus:ring-2 focus:ring-purple-500 focus:border-transparent outline-none resize-none text-sm"
                                        placeholder={t('aiCommandsCustomPlaceholder')}
                                        value={instruction}
                                        onChange={e => setInstruction(e.target.value)}
                                        autoFocus
                                    />
                                </div>

                                {context && (
                                    <div className="bg-slate-50 p-3 rounded-lg border border-slate-200">
                                        <p className="text-xs text-slate-400 mb-1">{t('aiCommandsReferenceContext')}</p>
                                        <p className="text-xs text-slate-600 line-clamp-3 font-mono">{context.slice(0, 200)}</p>
                                    </div>
                                )}
                            </div>
                        ) : (
                            <div className="h-full flex flex-col">
                                <div className="flex justify-between items-center mb-2">
                                    <h4 className="font-bold text-slate-700 text-sm">{t('aiCommandsResult')}</h4>
                                    {isGenerating && (
                                        <span className="text-xs text-purple-600 flex items-center gap-1">
                                            <RefreshCw size={12} className="animate-spin" /> {t('aiCommandsGenerating')}
                                        </span>
                                    )}
                                </div>
                                <div className="flex-1 bg-slate-50 border border-slate-200 rounded-lg p-3 overflow-y-auto markdown-body text-sm relative">
                                    {result ? <ReactMarkdown>{result}</ReactMarkdown> : <span className="text-slate-400 italic text-xs">Thinking...</span>}
                                </div>
                            </div>
                        )}
                    </div>

                    {/* Footer */}
                    <div className="p-4 border-t border-slate-200 bg-slate-50 shrink-0 flex flex-col gap-3">
                        {mode === 'input' ? (
                            <button
                                onClick={handleGenerate}
                                disabled={!instruction}
                                className="w-full flex justify-center items-center gap-2 px-4 py-2 bg-gradient-to-r from-purple-600 to-blue-600 text-white rounded-lg hover:shadow-lg disabled:opacity-50 disabled:shadow-none transition-all font-medium text-sm"
                            >
                                <Sparkles size={16} />
                                {t('aiCommandsStartGeneration')}
                            </button>
                        ) : (
                            <div className="flex gap-2">
                                <button
                                    onClick={() => setMode('input')}
                                    className="flex-1 px-3 py-2 text-slate-600 bg-white border border-slate-200 hover:bg-slate-50 rounded-lg text-sm"
                                    disabled={isGenerating}
                                >
                                    {t('aiCommandsGoBack')}
                                </button>
                                <button
                                    onClick={() => {
                                        onApply(result)
                                        // Optional: Don't close drawer immediately to allow multiple edits?
                                        // Usually "Apply" implies "Done". User can reopen if needed.
                                        onClose()
                                    }}
                                    disabled={isGenerating || !result}
                                    className="flex-1 flex justify-center items-center gap-2 px-3 py-2 bg-green-600 text-white rounded-lg hover:bg-green-700 disabled:opacity-50 shadow-sm text-sm"
                                >
                                    <Check size={16} />
                                    {t('aiCommandsApplyResult')}
                                </button>
                            </div>
                        )}
                        <div className="text-center">
                            <button onClick={() => {
                                setInstruction('')
                                setResult('')
                                setMode('input')
                            }} className="text-xs text-slate-400 hover:text-slate-600 flex items-center justify-center gap-1 mx-auto">
                                <Eraser size={12} /> {t('aiCommandsReset')}
                            </button>
                        </div>
                    </div>
                </div>
            </div>
        </>
    )
}