"use client";

import { useState, useEffect, forwardRef, useImperativeHandle, useCallback } from "react";
import { getConversations, type Idea } from "@/lib/api/ideas";
import { useAuth } from "@/lib/auth/auth-context";

type ConversationSummary = {
  id: string;
  title: string | null;
  projectId: string | null;
  updatedAt: string;
  messageCount: number;
};

export interface ConversationSidebarRef {
  refresh: () => Promise<void>;
  addConversation: (conversation: ConversationSummary) => void;
}

interface ConversationSidebarProps {
  isOpen: boolean;
  onClose: () => void;
  currentConversationId: string | null;
  onSelectConversation: (conversationId: string | null) => Promise<void>;
  onNewConversation: (projectId?: string | null) => void;
}

export const ConversationSidebar = forwardRef<ConversationSidebarRef, ConversationSidebarProps>(function ConversationSidebar({
  isOpen,
  onClose,
  currentConversationId,
  onSelectConversation,
  onNewConversation,
}, ref) {
  const [searchQuery, setSearchQuery] = useState("");
  const [conversations, setConversations] = useState<ConversationSummary[]>([]);
  const [isLoading, setIsLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);
  const { user } = useAuth();

  /**
   * Convert Idea to ConversationSummary
   */
  const ideaToConversation = useCallback((idea: Idea): ConversationSummary => {
    // Count messages from the stored JSON content
    let messageCount = 0;
    try {
      const messages = JSON.parse(idea.content);
      messageCount = Array.isArray(messages) ? messages.length : 0;
    } catch {
      // If parsing fails, assume 0 messages
      messageCount = 0;
    }

    return {
      id: idea.id,
      title: idea.title,
      projectId: idea.projectId,
      updatedAt: idea.updatedAt,
      messageCount,
    };
  }, []);

  /**
   * Fetch conversations from backend
   */
  const fetchConversations = useCallback(async (): Promise<void> => {
    if (!user) {
      setConversations([]);
      return;
    }

    try {
      setIsLoading(true);
      setError(null);

      const response = await getConversations({
        limit: 50,
        page: 1,
      });

      const summaries = response.data.map(ideaToConversation);
      setConversations(summaries);
    } catch (err) {
      const errorMsg = err instanceof Error ? err.message : "Failed to load conversations";
      setError(errorMsg);
      console.error("Error fetching conversations:", err);
    } finally {
      setIsLoading(false);
    }
  }, [user, ideaToConversation]);

  // Load conversations on mount and when user changes
  useEffect(() => {
    void fetchConversations();
  }, [fetchConversations]);

  // Expose methods to parent via ref
  useImperativeHandle(ref, () => ({
    refresh: async () => {
      await fetchConversations();
    },
    addConversation: (conversation: ConversationSummary) => {
      setConversations((prev) => [conversation, ...prev]);
    },
  }));

  const filteredConversations = conversations.filter((conv) => {
    if (!searchQuery.trim()) return true;
    const title = conv.title || "Untitled conversation";
    return title.toLowerCase().includes(searchQuery.toLowerCase());
  });

  const formatRelativeTime = (dateString: string): string => {
    const date = new Date(dateString);
    const now = new Date();
    const diffMs = now.getTime() - date.getTime();
    const diffMins = Math.floor(diffMs / 60000);
    const diffHours = Math.floor(diffMs / 3600000);
    const diffDays = Math.floor(diffMs / 86400000);

    if (diffMins < 1) return "Just now";
    if (diffMins < 60) return `${diffMins}m ago`;
    if (diffHours < 24) return `${diffHours}h ago`;
    if (diffDays < 7) return `${diffDays}d ago`;
    return date.toLocaleDateString(undefined, { month: "short", day: "numeric" });
  };

  const truncateTitle = (title: string | null, maxLength = 32): string => {
    const displayTitle = title || "Untitled conversation";
    if (displayTitle.length <= maxLength) return displayTitle;
    return displayTitle.substring(0, maxLength - 1) + "…";
  };

  return (
    <>
      {/* Mobile overlay */}
      {isOpen && (
        <div
          className="fixed inset-0 z-40 md:hidden animate-fade-in"
          style={{ backgroundColor: "rgb(0 0 0 / 0.6)" }}
          onClick={onClose}
          aria-hidden="true"
        />
      )}

      {/* Sidebar */}
      <aside
        className={`
          fixed left-0 top-0 z-50 h-screen transform border-r transition-all duration-200 ease-out flex flex-col
          md:sticky md:top-0 md:z-auto md:h-screen md:transform-none md:transition-[width]
          ${isOpen ? "translate-x-0 w-72" : "-translate-x-full md:translate-x-0 md:w-16"}
        `}
        style={{
          backgroundColor: "rgb(var(--surface-0))",
          borderColor: "rgb(var(--border-default))",
        }}
        aria-label="Conversation history"
      >
        {/* Collapsed view */}
        {!isOpen && (
          <div className="hidden md:flex flex-col items-center py-3 h-full">
            <button
              onClick={() => onNewConversation()}
              className="p-3 rounded-lg transition-colors hover:bg-[rgb(var(--surface-1))]"
              title="New Conversation"
            >
              <svg className="h-5 w-5" style={{ color: "rgb(var(--text-muted))" }} fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
                <path d="M12 4v16m8-8H4" />
              </svg>
            </button>
          </div>
        )}

        {/* Full sidebar content */}
        {isOpen && (
          <>
            {/* Header */}
            <div
              className="flex items-center justify-between border-b px-4 py-3"
              style={{ borderColor: "rgb(var(--border-default))" }}
            >
              <div className="flex items-center gap-2">
                <svg
                  className="h-5 w-5"
                  style={{ color: "rgb(var(--text-muted))" }}
                  fill="none"
                  viewBox="0 0 24 24"
                  stroke="currentColor"
                  strokeWidth={1.5}
                >
                  <path d="M8 12h.01M12 12h.01M16 12h.01M21 12c0 4.418-4.03 8-9 8a9.863 9.863 0 01-4.255-.949L3 20l1.395-3.72C3.512 15.042 3 13.574 3 12c0-4.418 4.03-8 9-8s9 3.582 9 8z" />
                </svg>
                <span className="text-sm font-semibold" style={{ color: "rgb(var(--text-primary))" }}>
                  Conversations
                </span>
              </div>

              <button onClick={onClose} className="btn-ghost rounded-md p-1.5" aria-label="Close sidebar">
                <svg className="h-5 w-5" style={{ color: "rgb(var(--text-muted))" }} fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={1.5}>
                  <path d="M6 18L18 6M6 6l12 12" />
                </svg>
              </button>
            </div>

            {/* New Chat Button */}
            <div className="px-3 pt-3">
              <button
                onClick={() => onNewConversation()}
                className="w-full flex items-center justify-center gap-2 rounded-lg border border-dashed py-2.5 text-sm font-medium transition-all duration-150 hover:border-solid"
                style={{
                  borderColor: "rgb(var(--border-strong))",
                  color: "rgb(var(--text-secondary))",
                }}
              >
                <svg className="h-4 w-4" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
                  <path d="M12 4v16m8-8H4" />
                </svg>
                <span>New Conversation</span>
              </button>
            </div>

            {/* Search */}
            <div className="px-3 pt-3">
              <div className="relative">
                <svg
                  className="absolute left-3 top-1/2 h-4 w-4 -translate-y-1/2"
                  style={{ color: "rgb(var(--text-muted))" }}
                  fill="none"
                  viewBox="0 0 24 24"
                  stroke="currentColor"
                  strokeWidth={2}
                >
                  <circle cx="11" cy="11" r="8" />
                  <path d="M21 21l-4.35-4.35" />
                </svg>
                <input
                  type="text"
                  placeholder="Search conversations..."
                  value={searchQuery}
                  onChange={(e) => setSearchQuery(e.target.value)}
                  className="input pl-9 pr-10 py-2 text-sm"
                  style={{ backgroundColor: "rgb(var(--surface-1))" }}
                />
              </div>
            </div>

            {/* Conversations List */}
            <div className="flex-1 overflow-y-auto px-3 pt-3 pb-3 space-y-1">
              {isLoading ? (
                <div className="text-center py-8" style={{ color: "rgb(var(--text-muted))" }}>
                  <div className="h-5 w-5 mx-auto animate-spin rounded-full border-2 border-t-transparent" style={{ borderColor: "rgb(var(--accent-primary))", borderTopColor: "transparent" }} />
                  <p className="text-xs mt-2">Loading conversations...</p>
                </div>
              ) : error ? (
                <div className="text-center py-8" style={{ color: "rgb(var(--semantic-error))" }}>
                  <svg className="h-8 w-8 mx-auto mb-2" fill="none" viewBox="0 0 24 24" stroke="currentColor" strokeWidth={2}>
                    <circle cx="12" cy="12" r="10" />
                    <line x1="12" y1="8" x2="12" y2="12" />
                    <line x1="12" y1="16" x2="12.01" y2="16" />
                  </svg>
                  <p className="text-xs">{error}</p>
                  <button
                    onClick={() => void fetchConversations()}
                    className="text-xs mt-2 underline"
                    style={{ color: "rgb(var(--accent-primary))" }}
                  >
                    Retry
                  </button>
                </div>
              ) : filteredConversations.length === 0 ? (
                <div className="text-center py-8" style={{ color: "rgb(var(--text-muted))" }}>
                  <p className="text-sm">
                    {searchQuery ? "No matching conversations" : "No conversations yet"}
                  </p>
                  <p className="text-xs mt-1">
                    {searchQuery ? "Try a different search" : "Start a new chat to begin"}
                  </p>
                </div>
              ) : (
                filteredConversations.map((conv) => (
                  <button
                    key={conv.id}
                    onClick={() => void onSelectConversation(conv.id)}
                    className={`w-full text-left px-3 py-2 rounded-lg transition-colors ${
                      conv.id === currentConversationId
                        ? "bg-[rgb(var(--accent-primary-light))]"
                        : "hover:bg-[rgb(var(--surface-2))]"
                    }`}
                  >
                    <p
                      className="text-sm font-medium truncate"
                      style={{
                        color: conv.id === currentConversationId
                          ? "rgb(var(--accent-primary))"
                          : "rgb(var(--text-primary))",
                      }}
                    >
                      {truncateTitle(conv.title)}
                    </p>
                    <div className="flex items-center gap-2 mt-0.5" style={{ color: "rgb(var(--text-muted))" }}>
                      <span className="text-xs">{formatRelativeTime(conv.updatedAt)}</span>
                      {conv.messageCount > 0 && (
                        <>
                          <span className="text-xs">·</span>
                          <span className="text-xs">
                            {conv.messageCount} msg{conv.messageCount !== 1 ? "s" : ""}
                          </span>
                        </>
                      )}
                    </div>
                  </button>
                ))
              )}
            </div>
          </>
        )}
      </aside>
    </>
  );
});