import React, { useState, useMemo } from 'react';
import { Card, Button } from '../components/UiKit';
import { useOrg } from '../contexts/OrgContext';
import { CHAT_STARTERS } from '../constants';

const Chat: React.FC = () => {
    const { employees, reports, generateEmployeeReport } = useOrg();
    const [messages, setMessages] = useState<Array<{ id: string, role: 'user' | 'assistant', text: string }>>([]);
    const [input, setInput] = useState('');
    const [isLoading, setIsLoading] = useState(false);
    const [selectedEmployeeId, setSelectedEmployeeId] = useState<string>('');
    const selectedReport = selectedEmployeeId ? reports[selectedEmployeeId] : undefined;

    const dynamicStarters = useMemo(() => {
        if (!selectedReport) return CHAT_STARTERS.slice(0, 4);
        const strengths = selectedReport.insights.strengths?.slice(0, 2) || [];
        const weaknesses = selectedReport.insights.weaknesses?.slice(0, 1) || [];
        const risk = selectedReport.retentionRisk;
        const starters: string[] = [];
        if (strengths[0]) starters.push(`How can we further leverage ${strengths[0]} for cross-team impact?`);
        if (weaknesses[0]) starters.push(`What is an actionable plan to address ${weaknesses[0]} this quarter?`);
        if (risk) starters.push(`What factors contribute to ${selectedReport.employeeId}'s ${risk} retention risk?`);
        starters.push(`Is ${selectedReport.employeeId} a candidate for expanded scope or leadership?`);
        while (starters.length < 4) starters.push(CHAT_STARTERS[starters.length] || 'Provide an organizational insight.');
        return starters.slice(0, 4);
    }, [selectedReport]);

    const handleSend = async (message?: string) => {
        const textToSend = message || input;
        if (!textToSend.trim()) return;

        const userMessage = { id: Date.now().toString(), role: 'user' as const, text: textToSend };
        setMessages(prev => [...prev, userMessage]);
        setInput('');
        setIsLoading(true);

        // Simulate AI response (placeholder for server /api/chat usage)
        setTimeout(() => {
            const aiResponse = {
                id: (Date.now() + 1).toString(),
                role: 'assistant' as const,
                text: `Based on ${selectedEmployeeId ? 'the selected employee\'s' : 'organizational'} data, here's an insight related to: "${textToSend}".`
            };
            setMessages(prev => [...prev, aiResponse]);
            setIsLoading(false);
        }, 1500);
    };

    return (
        <div className="p-6 max-w-4xl mx-auto h-full flex flex-col">
            <div className="mb-6">
                <h1 className="text-3xl font-bold text-[--text-primary]">Chat with AI</h1>
                <p className="text-[--text-secondary] mt-1">Ask questions about your employees and organization</p>
            </div>

            <div className="mb-4 flex flex-col md:flex-row md:items-center gap-3">
                <div className="flex items-center gap-2">
                    <label className="text-sm text-[--text-secondary]">Focus Employee:</label>
                    <select
                        className="px-2 py-1 text-sm bg-[--background-secondary] border border-[--border-color] rounded"
                        value={selectedEmployeeId}
                        onChange={e => setSelectedEmployeeId(e.target.value)}
                    >
                        <option value="">(Organization)</option>
                        {employees.map(emp => <option key={emp.id} value={emp.id}>{emp.name}</option>)}
                    </select>
                    {selectedEmployeeId && !selectedReport && (
                        <Button size="sm" variant="secondary" onClick={() => generateEmployeeReport(employees.find(e => e.id === selectedEmployeeId)!)}>
                            Generate Report
                        </Button>
                    )}
                </div>
            </div>

            {messages.length === 0 && (
                <Card className="mb-6">
                    <h3 className="text-lg font-semibold text-[--text-primary] mb-4">Get started with these questions:</h3>
                    <div className="grid grid-cols-1 md:grid-cols-2 gap-3">
                        {dynamicStarters.map((starter, idx) => (
                            <Button
                                key={idx}
                                variant="secondary"
                                size="sm"
                                className="text-left justify-start"
                                onClick={() => handleSend(starter)}
                            >
                                {starter}
                            </Button>
                        ))}
                    </div>
                </Card>
            )}

            <div className="flex-1 overflow-y-auto mb-4 space-y-4">
                {messages.map(message => (
                    <div key={message.id} className={`flex ${message.role === 'user' ? 'justify-end' : 'justify-start'}`}>
                        <div className={`max-w-[70%] p-4 rounded-lg ${message.role === 'user'
                            ? 'bg-blue-500 text-white'
                            : 'bg-[--background-secondary] text-[--text-primary]'
                            }`}>
                            {message.text}
                        </div>
                    </div>
                ))}
                {isLoading && (
                    <div className="flex justify-start">
                        <div className="bg-[--background-secondary] text-[--text-primary] p-4 rounded-lg">
                            <div className="flex space-x-1">
                                <div className="w-2 h-2 bg-gray-500 rounded-full animate-bounce"></div>
                                <div className="w-2 h-2 bg-gray-500 rounded-full animate-bounce" style={{ animationDelay: '0.1s' }}></div>
                                <div className="w-2 h-2 bg-gray-500 rounded-full animate-bounce" style={{ animationDelay: '0.2s' }}></div>
                            </div>
                        </div>
                    </div>
                )}
            </div>

            <Card padding="sm">
                <div className="flex space-x-2">
                    <input
                        type="text"
                        value={input}
                        onChange={(e) => setInput(e.target.value)}
                        onKeyPress={(e) => e.key === 'Enter' && handleSend()}
                        placeholder="Ask about employees, reports, or company insights..."
                        className="flex-1 px-3 py-2 border border-[--border-color] rounded-lg bg-[--background-secondary] text-[--text-primary] focus:outline-none focus:ring-2 focus:ring-blue-500"
                    />
                    <Button onClick={() => handleSend()} disabled={isLoading || !input.trim()}>
                        Send
                    </Button>
                </div>
            </Card>
        </div>
    );
};

export default Chat;