package database

import (
	"database/sql"
)

type Post struct {
	Uid         int    `json:"uid"`
	Author      string `json:"author"`
	TimeUpdated int    `json:"time_updated"`
	Subreact    string `json:"subreact"`
	Title       string `json:"title"`
	Contents    string `json:"contents"`
}

func GetPosts(subreact string, page int, amount int) ([]Post, error) {
	var db = GetDb()

	// This gets posts without parents (threads) and its latest updated time,
	// which could be the post itself.
    const query = "SELECT Parent.uid, Parent.author, COALESCE(Latest.updated_time, Parent.time) AS bump_time, Parent.subreact, " +
        "Parent.title, Parent.contents " +
        "FROM Posts as Parent " +
        "    LEFT OUTER JOIN ( " +
        "        SELECT Posts.parent, Posts.uid, MAX(Posts.time) AS updated_time " +
        "        FROM Posts " +
        "        WHERE Posts.parent IS NOT NULL " +
        "        ORDER BY Posts.time " +
        "    ) AS LATEST " +
        "    ON Latest.parent = Parent.uid " +
        "WHERE Parent.subreact = (CASE WHEN (? = \"\") then Parent.subreact ELSE ? END) " +
        "ORDER BY bump_time DESC " +
        "LIMIT ? " +
        "OFFSET ?;"

	rows, err := db.Query(query, subreact, subreact, amount, page*amount)
	if err != nil {
		return nil, err
	}
	defer rows.Close()

	posts := make([]Post, 0)
	for rows.Next() {
		var post Post
		if err = rows.Scan(
			&post.Uid,
			&post.Author,
			&post.TimeUpdated,
			&post.Subreact,
			&post.Title,
			&post.Contents); err != nil {

			if err == sql.ErrNoRows {
				return posts, nil
			}

			return nil, err
		}
		posts = append(posts, post)
	}

	return posts, nil
}