import type { ReactNode } from 'react';
import { useRef, useEffect } from 'react';
import { useThemeTokens } from '@/providers/theme-token-provider';
import { useChat } from '@ai-sdk/react';
import { FontAwesomeIcon } from '@fortawesome/react-fontawesome';
import { faPaperPlaneTop, faSparkles, faUserHeadset } from '@fortawesome/pro-duotone-svg-icons';

const API_URL = import.meta.env.VITE_API_URL ?? 'http://localhost:4100';

type CallerContext = {
    type?: string;
    callerPhone?: string;
    leadId?: string;
    leadName?: string;
};

interface AiChatPanelProps {
    callerContext?: CallerContext;
    onChatStart?: () => void;
}

export const AiChatPanel = ({ callerContext, onChatStart }: AiChatPanelProps) => {
    const { tokens } = useThemeTokens();
    const quickActions = tokens.ai.quickActions;
    const messagesEndRef = useRef<HTMLDivElement>(null);
    const chatStartedRef = useRef(false);

    const token = localStorage.getItem('helix_access_token') ?? '';

    const { messages, input, handleSubmit, handleInputChange, isLoading, append } = useChat({
        api: `${API_URL}/api/ai/stream`,
        streamProtocol: 'text',
        headers: {
            'Authorization': `Bearer ${token}`,
        },
        body: {
            context: callerContext,
        },
    });

    useEffect(() => {
        const el = messagesEndRef.current;
        if (el?.parentElement) {
            el.parentElement.scrollTop = el.parentElement.scrollHeight;
        }
        if (messages.length > 0 && !chatStartedRef.current) {
            chatStartedRef.current = true;
            onChatStart?.();
        }
    }, [messages, onChatStart]);

    const handleQuickAction = (prompt: string) => {
        append({ role: 'user', content: prompt });
    };

    return (
        <div className="flex h-full flex-col p-3">
            <div className="flex-1 space-y-3 overflow-y-auto min-h-0">
                {messages.length === 0 && (
                    <div className="flex flex-col items-center justify-center py-6 text-center">
                        <FontAwesomeIcon icon={faSparkles} className="mb-2 size-6 text-fg-brand-primary" />
                        <p className="text-xs text-tertiary">
                            Ask me about doctors, clinics, packages, or patient info.
                        </p>
                        <div className="mt-3 flex flex-wrap justify-center gap-1.5">
                            {quickActions.map((action) => (
                                <button
                                    key={action.label}
                                    onClick={() => handleQuickAction(action.prompt)}
                                    disabled={isLoading}
                                    className="rounded-lg border border-secondary bg-primary px-2.5 py-1.5 text-xs font-medium text-secondary transition duration-100 ease-linear hover:bg-secondary hover:text-primary disabled:opacity-50"
                                >
                                    {action.label}
                                </button>
                            ))}
                        </div>
                    </div>
                )}

                {messages.map((msg) => (
                    <div
                        key={msg.id}
                        className={`flex ${msg.role === 'user' ? 'justify-end' : 'justify-start'}`}
                    >
                        <div
                            className={`max-w-[90%] rounded-xl px-3 py-2 text-xs leading-relaxed ${
                                msg.role === 'user'
                                    ? 'bg-brand-solid text-white'
                                    : 'bg-secondary text-primary'
                            }`}
                        >
                            {msg.role === 'assistant' && (
                                <div className="mb-1 flex items-center gap-1">
                                    <FontAwesomeIcon icon={faSparkles} className="size-2.5 text-fg-brand-primary" />
                                    <span className="text-[10px] font-semibold uppercase tracking-wider text-brand-secondary">AI</span>
                                </div>
                            )}
                            <MessageContent content={msg.content} />
                        </div>
                    </div>
                ))}

                {isLoading && (
                    <div className="flex justify-start">
                        <div className="rounded-xl bg-secondary px-3 py-2">
                            <div className="flex items-center gap-1">
                                <span className="size-1.5 animate-bounce rounded-full bg-fg-quaternary [animation-delay:0ms]" />
                                <span className="size-1.5 animate-bounce rounded-full bg-fg-quaternary [animation-delay:150ms]" />
                                <span className="size-1.5 animate-bounce rounded-full bg-fg-quaternary [animation-delay:300ms]" />
                            </div>
                        </div>
                    </div>
                )}

                <div ref={messagesEndRef} />
            </div>

            <form onSubmit={handleSubmit} className="mt-2 flex items-center gap-2 shrink-0">
                <div className="flex flex-1 items-center rounded-lg border border-secondary bg-primary shadow-xs transition duration-100 ease-linear focus-within:border-brand focus-within:ring-4 focus-within:ring-brand-100">
                    <FontAwesomeIcon icon={faUserHeadset} className="ml-2.5 size-3.5 text-fg-quaternary" />
                    <input
                        type="text"
                        value={input}
                        onChange={handleInputChange}
                        placeholder="Ask the AI assistant..."
                        disabled={isLoading}
                        className="flex-1 bg-transparent px-2 py-2 text-xs text-primary placeholder:text-placeholder outline-none disabled:cursor-not-allowed"
                    />
                </div>
                <button
                    type="submit"
                    disabled={isLoading || input.trim().length === 0}
                    className="flex size-8 shrink-0 items-center justify-center rounded-lg bg-brand-solid text-white transition duration-100 ease-linear hover:bg-brand-solid_hover disabled:cursor-not-allowed disabled:bg-disabled"
                >
                    <FontAwesomeIcon icon={faPaperPlaneTop} className="size-3.5" />
                </button>
            </form>
        </div>
    );
};
// Tool result cards will be added in Phase 2 when SDK versions are aligned for data stream protocol

const parseLine = (text: string): ReactNode[] => {
    const parts: ReactNode[] = [];
    const boldPattern = /\*\*(.+?)\*\*/g;
    let lastIndex = 0;
    let match: RegExpExecArray | null;

    while ((match = boldPattern.exec(text)) !== null) {
        if (match.index > lastIndex) parts.push(text.slice(lastIndex, match.index));
        parts.push(<strong key={match.index} className="font-semibold">{match[1]}</strong>);
        lastIndex = boldPattern.lastIndex;
    }

    if (lastIndex < text.length) parts.push(text.slice(lastIndex));
    return parts.length > 0 ? parts : [text];
};

const MessageContent = ({ content }: { content: string }) => {
    if (!content) return null;
    const lines = content.split('\n');

    return (
        <div className="space-y-1">
            {lines.map((line, i) => {
                if (line.trim().length === 0) return <div key={i} className="h-1" />;
                if (line.trimStart().startsWith('- ')) {
                    return (
                        <div key={i} className="flex gap-1.5 pl-1">
                            <span className="mt-1.5 size-1 shrink-0 rounded-full bg-fg-quaternary" />
                            <span>{parseLine(line.replace(/^\s*-\s*/, ''))}</span>
                        </div>
                    );
                }
                return <p key={i}>{parseLine(line)}</p>;
            })}
        </div>
    );
};