import React, { useState } from "react";
import { motion, AnimatePresence } from "framer-motion";
import { FileText, ArrowLeft, Calendar, Clock, MessageSquare } from "lucide-react";
import { Card, CardContent } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { Pagination } from "@/components/ui/pagination";
import { ClaudeMemoriesDropdown } from "@/components/ClaudeMemoriesDropdown";
import { cn } from "@/lib/utils";
import { formatUnixTimestamp, formatISOTimestamp, truncateText, getFirstLine } from "@/lib/date-utils";
import type { Session, ClaudeMdFile } from "@/lib/api";

interface SessionListProps {
  /**
   * Array of sessions to display
   */
  sessions: Session[];
  /**
   * The current project path being viewed
   */
  projectPath: string;
  /**
   * Callback to go back to project list
   */
  onBack: () => void;
  /**
   * Callback when a session is clicked
   */
  onSessionClick?: (session: Session) => void;
  /**
   * Callback when a CLAUDE.md file should be edited
   */
  onEditClaudeFile?: (file: ClaudeMdFile) => void;
  /**
   * Optional className for styling
   */
  className?: string;
}

const ITEMS_PER_PAGE = 5;

/**
 * SessionList component - Displays paginated sessions for a specific project
 * 
 * @example
 * <SessionList
 *   sessions={sessions}
 *   projectPath="/Users/example/project"
 *   onBack={() => setSelectedProject(null)}
 *   onSessionClick={(session) => console.log('Selected session:', session)}
 * />
 */
export const SessionList: React.FC<SessionListProps> = ({
  sessions,
  projectPath,
  onBack,
  onSessionClick,
  onEditClaudeFile,
  className,
}) => {
  const [currentPage, setCurrentPage] = useState(1);
  
  // Calculate pagination
  const totalPages = Math.ceil(sessions.length / ITEMS_PER_PAGE);
  const startIndex = (currentPage - 1) * ITEMS_PER_PAGE;
  const endIndex = startIndex + ITEMS_PER_PAGE;
  const currentSessions = sessions.slice(startIndex, endIndex);
  
  // Reset to page 1 if sessions change
  React.useEffect(() => {
    setCurrentPage(1);
  }, [sessions.length]);
  
  return (
    <div className={cn("space-y-4", className)}>
      <motion.div
        initial={{ opacity: 0, x: -20 }}
        animate={{ opacity: 1, x: 0 }}
        transition={{ duration: 0.3 }}
        className="flex items-center space-x-3"
      >
        <Button
          variant="ghost"
          size="icon"
          onClick={onBack}
          className="h-8 w-8"
        >
          <ArrowLeft className="h-4 w-4" />
        </Button>
        <div className="flex-1 min-w-0">
          <h2 className="text-base font-medium truncate">{projectPath}</h2>
          <p className="text-xs text-muted-foreground">
            {sessions.length} session{sessions.length !== 1 ? 's' : ''}
          </p>
        </div>
      </motion.div>

      {/* CLAUDE.md Memories Dropdown */}
      {onEditClaudeFile && (
        <motion.div
          initial={{ opacity: 0, y: 10 }}
          animate={{ opacity: 1, y: 0 }}
          transition={{ duration: 0.3, delay: 0.1 }}
        >
          <ClaudeMemoriesDropdown
            projectPath={projectPath}
            onEditFile={onEditClaudeFile}
          />
        </motion.div>
      )}

      <AnimatePresence mode="popLayout">
        <div className="space-y-2">
          {currentSessions.map((session, index) => (
            <motion.div
              key={session.id}
              initial={{ opacity: 0, y: 20 }}
              animate={{ opacity: 1, y: 0 }}
              exit={{ opacity: 0, y: -20 }}
              transition={{
                duration: 0.3,
                delay: index * 0.05,
                ease: [0.4, 0, 0.2, 1],
              }}
            >
              <Card
                className={cn(
                  "transition-all hover:shadow-md hover:scale-[1.01] active:scale-[0.99] cursor-pointer",
                  session.todo_data && "border-l-4 border-l-primary"
                )}
                onClick={() => {
                  // Emit a special event for Claude Code session navigation
                  const event = new CustomEvent('claude-session-selected', { 
                    detail: { session, projectPath } 
                  });
                  window.dispatchEvent(event);
                  onSessionClick?.(session);
                }}
              >
                <CardContent className="p-3">
                  <div className="space-y-2">
                    <div className="flex items-start justify-between">
                      <div className="flex items-start space-x-3 flex-1 min-w-0">
                        <FileText className="h-4 w-4 text-muted-foreground mt-0.5 flex-shrink-0" />
                        <div className="space-y-1 flex-1 min-w-0">
                          <p className="font-mono text-xs text-muted-foreground">{session.id}</p>
                          
                          {/* First message preview */}
                          {session.first_message && (
                            <div className="space-y-1">
                              <div className="flex items-center space-x-1 text-xs text-muted-foreground">
                                <MessageSquare className="h-3 w-3" />
                                <span>First message:</span>
                              </div>
                              <p className="text-xs line-clamp-2 text-foreground/80">
                                {truncateText(getFirstLine(session.first_message), 100)}
                              </p>
                            </div>
                          )}
                          
                          {/* Metadata */}
                          <div className="flex items-center space-x-3 text-xs text-muted-foreground">
                            {/* Message timestamp if available, otherwise file creation time */}
                            <div className="flex items-center space-x-1">
                              <Clock className="h-3 w-3" />
                              <span>
                                {session.message_timestamp 
                                  ? formatISOTimestamp(session.message_timestamp)
                                  : formatUnixTimestamp(session.created_at)
                                }
                              </span>
                            </div>
                            
                            {session.todo_data && (
                              <div className="flex items-center space-x-1">
                                <Calendar className="h-3 w-3" />
                                <span>Has todo</span>
                              </div>
                            )}
                          </div>
                        </div>
                      </div>
                    </div>
                  </div>
                </CardContent>
              </Card>
            </motion.div>
          ))}
        </div>
      </AnimatePresence>
      
      <Pagination
        currentPage={currentPage}
        totalPages={totalPages}
        onPageChange={setCurrentPage}
      />
    </div>
  );
};