"use client";

import { useState, useEffect } from "react";
import { Clock, History, Loader2 } from "lucide-react";
import { Button } from "@/components/ui/button";
import {
  Sheet,
  SheetContent,
  SheetDescription,
  SheetHeader,
  SheetTitle,
  SheetTrigger,
} from "@/components/ui/sheet";
import { ScrollArea } from "@/components/ui/scroll-area";
import { auth, db } from "@/lib/firebase/config";
import { doc, getDoc, collection, query, where, orderBy, getDocs } from "firebase/firestore";
import { formatDistanceToNow } from "date-fns";

interface MissionRevision {
  id: string;
  content: string;
  updatedAt: Date;
  updatedBy: string;
  source: 'ai' | 'user';
}

interface MissionIdeaSectionProps {
  projectId: string;
}

export function MissionIdeaSection({ projectId }: MissionIdeaSectionProps) {
  const [loading, setLoading] = useState(true);
  const [content, setContent] = useState("");
  const [lastUpdated, setLastUpdated] = useState<Date | null>(null);
  const [revisions, setRevisions] = useState<MissionRevision[]>([]);
  const [loadingRevisions, setLoadingRevisions] = useState(false);

  useEffect(() => {
    if (projectId) {
      fetchMissionIdea();
    }
  }, [projectId]);

  const fetchMissionIdea = async () => {
    setLoading(true);
    try {
      const user = auth.currentUser;
      if (!user) return;

      // Fetch current mission idea from project document
      const projectRef = doc(db, 'projects', projectId);
      const projectSnap = await getDoc(projectRef);
      
      if (projectSnap.exists()) {
        const data = projectSnap.data();
        setContent(
          data.missionIdea || 
          "Help solo founders build and launch their products 10x faster by turning conversations into production-ready code, designs, and marketing."
        );
        setLastUpdated(data.missionIdeaUpdatedAt?.toDate() || null);
      }
    } catch (error) {
      console.error('Error fetching mission idea:', error);
    } finally {
      setLoading(false);
    }
  };

  const fetchRevisions = async () => {
    setLoadingRevisions(true);
    try {
      const user = auth.currentUser;
      if (!user) return;

      // Fetch revision history
      const revisionsRef = collection(db, 'missionRevisions');
      const revisionsQuery = query(
        revisionsRef,
        where('projectId', '==', projectId),
        orderBy('updatedAt', 'desc')
      );
      const revisionsSnap = await getDocs(revisionsQuery);
      
      const revisionsList: MissionRevision[] = [];
      revisionsSnap.forEach((doc) => {
        const data = doc.data();
        revisionsList.push({
          id: doc.id,
          content: data.content,
          updatedAt: data.updatedAt?.toDate(),
          updatedBy: data.updatedBy || 'AI',
          source: data.source || 'ai',
        });
      });
      
      setRevisions(revisionsList);
    } catch (error) {
      console.error('Error fetching revisions:', error);
    } finally {
      setLoadingRevisions(false);
    }
  };

  if (loading) {
    return (
      <div className="flex items-center justify-center py-12">
        <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
      </div>
    );
  }

  return (
    <div className="space-y-4">
      {/* Content Card */}
      <div className="rounded-lg border bg-card p-6">
        <p className="text-xl font-medium leading-relaxed">
          {content}
        </p>
      </div>

      {/* Meta Information */}
      <div className="flex items-center justify-between text-sm text-muted-foreground">
        <div className="flex items-center gap-2">
          <Clock className="h-4 w-4" />
          <span>
            {lastUpdated
              ? `Last updated ${formatDistanceToNow(lastUpdated, { addSuffix: true })} by AI`
              : 'Not yet updated'}
          </span>
        </div>

        {/* Revision History */}
        <Sheet>
          <SheetTrigger asChild>
            <Button 
              variant="ghost" 
              size="sm"
              onClick={fetchRevisions}
            >
              <History className="h-4 w-4 mr-2" />
              View History
            </Button>
          </SheetTrigger>
          <SheetContent className="w-[500px] sm:w-[600px]">
            <SheetHeader>
              <SheetTitle>Revision History</SheetTitle>
              <SheetDescription>
                See how your mission idea has evolved over time
              </SheetDescription>
            </SheetHeader>
            
            <ScrollArea className="h-[calc(100vh-120px)] mt-6">
              {loadingRevisions ? (
                <div className="flex items-center justify-center py-12">
                  <Loader2 className="h-6 w-6 animate-spin text-muted-foreground" />
                </div>
              ) : revisions.length === 0 ? (
                <div className="text-center py-12 text-muted-foreground">
                  <History className="h-12 w-12 mx-auto mb-3 opacity-50" />
                  <p className="text-sm">No revision history yet</p>
                </div>
              ) : (
                <div className="space-y-4">
                  {revisions.map((revision, index) => (
                    <div 
                      key={revision.id}
                      className="rounded-lg border bg-card p-4 space-y-2"
                    >
                      <div className="flex items-center justify-between text-xs text-muted-foreground">
                        <div className="flex items-center gap-2">
                          <span className="font-medium">
                            {revision.source === 'ai' ? 'AI Update' : 'Manual Edit'}
                          </span>
                          {index === 0 && (
                            <span className="px-2 py-0.5 rounded-full bg-primary/10 text-primary text-[10px] font-medium">
                              Current
                            </span>
                          )}
                        </div>
                        <span>
                          {formatDistanceToNow(revision.updatedAt, { addSuffix: true })}
                        </span>
                      </div>
                      <p className="text-sm leading-relaxed">
                        {revision.content}
                      </p>
                      <div className="text-xs text-muted-foreground">
                        {revision.updatedAt.toLocaleString()}
                      </div>
                    </div>
                  ))}
                </div>
              )}
            </ScrollArea>
          </SheetContent>
        </Sheet>
      </div>
    </div>
  );
}