const express = require("express");
const mongoose = require("mongoose");
const Post = require("../models/Post");
const auth = require("../middleware/auth");
const { asyncHandler } = require("../middleware/errorHandler");
const {
  createPostValidation,
  postIdValidation,
} = require("../middleware/validators/postValidator");
const { upload, handleUploadError } = require("../middleware/upload");
const { uploadImage, deleteImage } = require("../config/cloudinary");
const { paginate, buildPaginatedResponse } = require("../middleware/pagination");
const {
  awardPostCreationPoints,
  checkAndAwardBadges,
} = require("../services/gamificationService");

const router = express.Router();

// Get all posts (with pagination)
router.get(
  "/",
  paginate,
  asyncHandler(async (req, res) => {
    const { skip, limit, page } = req.pagination;

    const posts = await Post.find()
      .sort({ createdAt: -1 })
      .skip(skip)
      .limit(limit)
      .populate("user", ["name", "profilePicture"]);

    const totalCount = await Post.countDocuments();

    res.json(buildPaginatedResponse(posts, totalCount, page, limit));
  }),
);

// Create a post with optional image
router.post(
  "/",
  auth,
  upload.single("image"),
  handleUploadError,
  asyncHandler(async (req, res) => {
    const { content } = req.body;
    const session = await mongoose.startSession();
    session.startTransaction();

    try {
      if (!content) {
        await session.abortTransaction();
        session.endSession();
        return res.status(400).json({ msg: "Content is required" });
      }

      const postData = {
        user: req.user.id,
        content,
      };

      // Upload image if provided
      if (req.file) {
        const result = await uploadImage(
          req.file.buffer,
          "adopt-a-street/posts",
        );
        postData.imageUrl = result.url;
        postData.cloudinaryPublicId = result.publicId;
      }

      const newPost = new Post(postData);
      const post = await newPost.save({ session });

      // Award points for post creation
      const { transaction } = await awardPostCreationPoints(
        req.user.id,
        post._id,
        session
      );

      // Check and award badges
      const newBadges = await checkAndAwardBadges(req.user.id, session);

      await session.commitTransaction();
      session.endSession();

      // Populate user data before sending response
      await post.populate("user", ["name", "profilePicture"]);

      res.json({
        post,
        pointsAwarded: transaction.amount,
        newBalance: transaction.balanceAfter,
        badgesEarned: newBadges,
      });
    } catch (err) {
      await session.abortTransaction();
      session.endSession();
      throw err;
    }
  }),
);

// Add image to existing post
router.post(
  "/:id/image",
  auth,
  upload.single("image"),
  handleUploadError,
  postIdValidation,
  asyncHandler(async (req, res) => {
    const post = await Post.findById(req.params.id);
    if (!post) {
      return res.status(404).json({ msg: "Post not found" });
    }

    // Verify user owns the post
    if (post.user.toString() !== req.user.id) {
      return res.status(403).json({ msg: "Not authorized" });
    }

    if (!req.file) {
      return res.status(400).json({ msg: "No image file provided" });
    }

    // Delete old image if exists
    if (post.cloudinaryPublicId) {
      await deleteImage(post.cloudinaryPublicId);
    }

    // Upload new image
    const result = await uploadImage(
      req.file.buffer,
      "adopt-a-street/posts",
    );

    post.imageUrl = result.url;
    post.cloudinaryPublicId = result.publicId;
    await post.save();

    res.json(post);
  }),
);

// Like a post
router.put(
  "/like/:id",
  auth,
  postIdValidation,
  asyncHandler(async (req, res) => {
    const post = await Post.findById(req.params.id);
    if (!post) {
      return res.status(404).json({ msg: "Post not found" });
    }

    // Check if the post has already been liked by this user
    if (
      post.likes.filter((like) => like.toString() === req.user.id).length > 0
    ) {
      return res.status(400).json({ msg: "Post already liked" });
    }

    post.likes.unshift(req.user.id);

    await post.save();

    res.json(post.likes);
  }),
);

module.exports = router;