'use client'

import { useState, useEffect, useRef, useCallback } from 'react'
import { EXAMPLE_QUESTIONS, AdvisorEmptyState, AdvisorMessageList, type Message } from './ComplianceAdvisorParts'

// =============================================================================
// TYPES
// =============================================================================

interface ComplianceAdvisorWidgetProps {
  currentStep?: string
}

type Country = 'DE' | 'AT' | 'CH' | 'EU'

const COUNTRIES: { code: Country; label: string }[] = [
  { code: 'DE', label: 'DE' },
  { code: 'AT', label: 'AT' },
  { code: 'CH', label: 'CH' },
  { code: 'EU', label: 'EU' },
]

// =============================================================================
// COMPONENT
// =============================================================================

export function ComplianceAdvisorWidget({ currentStep = 'default' }: ComplianceAdvisorWidgetProps) {
  const [isOpen, setIsOpen] = useState(false)
  const [isExpanded, setIsExpanded] = useState(false)
  const [messages, setMessages] = useState<Message[]>([])
  const [inputValue, setInputValue] = useState('')
  const [isTyping, setIsTyping] = useState(false)
  const [selectedCountry, setSelectedCountry] = useState<Country>('DE')
  const messagesEndRef = useRef<HTMLDivElement>(null)
  const abortControllerRef = useRef<AbortController | null>(null)

  const exampleQuestions = EXAMPLE_QUESTIONS[currentStep] || EXAMPLE_QUESTIONS.default

  useEffect(() => {
    messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' })
  }, [messages])

  useEffect(() => {
    return () => {
      abortControllerRef.current?.abort()
    }
  }, [])

  const handleSendMessage = useCallback(
    async (content: string) => {
      if (!content.trim() || isTyping) return

      const userMessage: Message = {
        id: `msg-${Date.now()}`,
        role: 'user',
        content: content.trim(),
        timestamp: new Date(),
      }

      setMessages((prev) => [...prev, userMessage])
      setInputValue('')
      setIsTyping(true)

      const agentMessageId = `msg-${Date.now()}-agent`
      abortControllerRef.current = new AbortController()

      try {
        const history = messages.map((m) => ({
          role: m.role === 'user' ? 'user' : 'assistant',
          content: m.content,
        }))

        const response = await fetch('/api/sdk/compliance-advisor/chat', {
          method: 'POST',
          headers: { 'Content-Type': 'application/json' },
          body: JSON.stringify({
            message: content.trim(),
            history,
            currentStep,
            country: selectedCountry,
          }),
          signal: abortControllerRef.current.signal,
        })

        if (!response.ok) {
          const errorData = await response.json().catch(() => ({ error: 'Unbekannter Fehler' }))
          throw new Error(errorData.error || `Server-Fehler (${response.status})`)
        }

        setMessages((prev) => [
          ...prev,
          { id: agentMessageId, role: 'agent', content: '', timestamp: new Date() },
        ])

        const reader = response.body!.getReader()
        const decoder = new TextDecoder()
        let accumulated = ''

        while (true) {
          const { done, value } = await reader.read()
          if (done) break

          accumulated += decoder.decode(value, { stream: true })
          const currentText = accumulated
          setMessages((prev) =>
            prev.map((m) => (m.id === agentMessageId ? { ...m, content: currentText } : m))
          )
          requestAnimationFrame(() => {
            messagesEndRef.current?.scrollIntoView({ behavior: 'smooth' })
          })
        }

        setIsTyping(false)
      } catch (error) {
        if ((error as Error).name === 'AbortError') {
          setIsTyping(false)
          return
        }

        const errorMessage = error instanceof Error ? error.message : 'Verbindung fehlgeschlagen'
        setMessages((prev) => {
          const hasAgent = prev.some((m) => m.id === agentMessageId)
          if (hasAgent) {
            return prev.map((m) =>
              m.id === agentMessageId ? { ...m, content: `Fehler: ${errorMessage}` } : m
            )
          }
          return [
            ...prev,
            { id: agentMessageId, role: 'agent' as const, content: `Fehler: ${errorMessage}`, timestamp: new Date() },
          ]
        })
        setIsTyping(false)
      }
    },
    [isTyping, messages, currentStep, selectedCountry]
  )

  const handleStopGeneration = useCallback(() => {
    abortControllerRef.current?.abort()
    setIsTyping(false)
  }, [])

  const handleKeyDown = (e: React.KeyboardEvent) => {
    if (e.key === 'Enter' && !e.shiftKey) {
      e.preventDefault()
      handleSendMessage(inputValue)
    }
  }

  if (!isOpen) {
    return (
      <button
        onClick={() => setIsOpen(true)}
        className="fixed bottom-6 right-[5.5rem] w-14 h-14 bg-indigo-600 hover:bg-indigo-700 text-white rounded-full shadow-lg flex items-center justify-center transition-all duration-200 hover:scale-110 z-50"
        aria-label="Compliance Advisor oeffnen"
      >
        <svg className="w-6 h-6" fill="none" stroke="currentColor" viewBox="0 0 24 24">
          <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M8 10h.01M12 10h.01M16 10h.01M9 16H5a2 2 0 01-2-2V6a2 2 0 012-2h14a2 2 0 012 2v8a2 2 0 01-2 2h-5l-5 5v-5z" />
        </svg>
      </button>
    )
  }

  return (
    <div className={`fixed bottom-6 right-6 ${isExpanded ? 'w-[700px] h-[80vh]' : 'w-[400px] h-[500px]'} max-h-screen bg-white rounded-2xl shadow-2xl flex flex-col z-50 border border-gray-200 transition-all duration-200`}>
      {/* Header */}
      <div className="bg-gradient-to-r from-purple-600 to-indigo-600 text-white px-4 py-3 rounded-t-2xl flex items-center justify-between">
        <div className="flex items-center gap-2">
          <div className="w-8 h-8 bg-white/20 rounded-full flex items-center justify-center">
            <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9.663 17h4.673M12 3v1m6.364 1.636l-.707.707M21 12h-1M4 12H3m3.343-5.657l-.707-.707m2.828 9.9a5 5 0 117.072 0l-.548.547A3.374 3.374 0 0014 18.469V19a2 2 0 11-4 0v-.531c0-.895-.356-1.754-.988-2.386l-.548-.547z" />
            </svg>
          </div>
          <div>
            <div className="font-semibold text-sm">Compliance Advisor</div>
            <div className="flex items-center gap-1 mt-0.5">
              {COUNTRIES.map(({ code, label }) => (
                <button
                  key={code}
                  onClick={() => setSelectedCountry(code)}
                  className={`px-1.5 py-0.5 text-[10px] font-medium rounded transition-colors ${selectedCountry === code ? 'bg-white text-indigo-700' : 'bg-white/15 text-white/80 hover:bg-white/25'}`}
                >
                  {label}
                </button>
              ))}
            </div>
          </div>
        </div>
        <div className="flex items-center gap-1">
          <button
            onClick={() => setIsExpanded(!isExpanded)}
            className="text-white/80 hover:text-white transition-colors"
            aria-label={isExpanded ? 'Verkleinern' : 'Vergroessern'}
          >
            <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              {isExpanded ? (
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9 9L4 4m0 0v4m0-4h4m6 6l5 5m0 0v-4m0 4h-4" />
              ) : (
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M4 8V4m0 0h4M4 4l5 5m11-1V4m0 0h-4m4 0l-5 5M4 16v4m0 0h4m-4 0l5-5m11 5v-4m0 4h-4m4 0l-5-5" />
              )}
            </svg>
          </button>
          <button onClick={() => setIsOpen(false)} className="text-white/80 hover:text-white transition-colors" aria-label="Schliessen">
            <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
              <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M6 18L18 6M6 6l12 12" />
            </svg>
          </button>
        </div>
      </div>

      {/* Messages Area */}
      <div className="flex-1 overflow-y-auto p-4 space-y-4 bg-gray-50">
        {messages.length === 0 ? (
          <AdvisorEmptyState
            exampleQuestions={exampleQuestions}
            onExampleClick={(q) => handleSendMessage(q)}
          />
        ) : (
          <AdvisorMessageList
            messages={messages}
            isTyping={isTyping}
            messagesEndRef={messagesEndRef}
          />
        )}
      </div>

      {/* Input Area */}
      <div className="border-t border-gray-200 p-3 bg-white rounded-b-2xl">
        <div className="flex gap-2">
          <input
            type="text"
            value={inputValue}
            onChange={(e) => setInputValue(e.target.value)}
            onKeyDown={handleKeyDown}
            placeholder="Frage eingeben..."
            disabled={isTyping}
            className="flex-1 px-3 py-2 text-sm border border-gray-300 rounded-lg focus:outline-none focus:ring-2 focus:ring-purple-500 focus:border-transparent disabled:opacity-50"
          />
          {isTyping ? (
            <button
              onClick={handleStopGeneration}
              className="px-4 py-2 bg-red-500 text-white rounded-lg hover:bg-red-600 transition-colors"
              title="Generierung stoppen"
            >
              <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M6 6h12v12H6z" />
              </svg>
            </button>
          ) : (
            <button
              onClick={() => handleSendMessage(inputValue)}
              disabled={!inputValue.trim()}
              className="px-4 py-2 bg-indigo-600 text-white rounded-lg hover:bg-indigo-700 disabled:opacity-50 disabled:cursor-not-allowed transition-colors"
            >
              <svg className="w-5 h-5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 19l9 2-9-18-9 18 9-2zm0 0v-8" />
              </svg>
            </button>
          )}
        </div>
      </div>
    </div>
  )
}