use std::collections::HashSet;
use std::time::{SystemTime, UNIX_EPOCH};

use rusqlite::{OptionalExtension, Row};

use crate::types::post::Post;
use crate::database;

pub fn init() -> Result<(), rusqlite::Error> {
    let sql = "
        CREATE TABLE IF NOT EXISTS posts (
            post_id     INTEGER PRIMARY KEY AUTOINCREMENT,
            user_id     INTEGER NOT NULL,
            content     TEXT NOT NULL,
            likes       TEXT NOT NULL,
            comments    TEXT NOT NULL,
            date        INTEGER NOT NULL,
            FOREIGN KEY(user_id) REFERENCES users(user_id)
        );
    ";
    let conn = database::connect()?;
    conn.execute(sql, ())?;
    Ok(())
}

fn post_from_row(row: &Row) -> Result<Post, rusqlite::Error> {
    let post_id = row.get(0)?;
    let user_id = row.get(1)?;
    let content = row.get(2)?;
    let likes_json: String = row.get(3)?;
    let comments_json: String = row.get(4)?;
    let date = row.get(5)?;

    let Ok(likes) = serde_json::from_str(&likes_json) else {
        return Err(rusqlite::Error::InvalidQuery)
    };

    let Ok(comments) = serde_json::from_str(&comments_json) else {
        return Err(rusqlite::Error::InvalidQuery)
    };

    Ok(Post{post_id, user_id, content, likes, comments, date})
}

pub fn get_post(post_id: u64) -> Result<Option<Post>, rusqlite::Error> {
    let conn = database::connect()?;
    let mut stmt = conn.prepare("SELECT * FROM posts WHERE post_id = ?")?;
    let row = stmt.query_row([post_id], |row| Ok(post_from_row(row)?)).optional()?;
    Ok(row)
}

pub fn get_post_page(page: u64) -> Result<Vec<Post>, rusqlite::Error> {
    let page_size = 10;
    let conn = database::connect()?;
    let mut stmt = conn.prepare("SELECT * FROM posts ORDER BY post_id DESC LIMIT ? OFFSET ?")?;
    let row = stmt.query_map([page_size, page_size * page], |row| Ok(post_from_row(row)?))?;
    Ok(row.into_iter().flatten().collect())
}

pub fn get_users_posts(user_id: u64) -> Result<Vec<Post>, rusqlite::Error> {
    let conn = database::connect()?;
    let mut stmt = conn.prepare("SELECT * FROM posts WHERE user_id = ? ORDER BY post_id DESC")?;
    let row = stmt.query_map([user_id], |row| Ok(post_from_row(row)?))?;
    Ok(row.into_iter().flatten().collect())
}

pub fn add_post(user_id: u64, content: &str) -> Result<Post, rusqlite::Error> {
    let likes: HashSet<u64> = HashSet::new();
    let comments: Vec<(u64, String)> = Vec::new();
    let Ok(likes_json) = serde_json::to_string(&likes) else {
        return Err(rusqlite::Error::InvalidQuery)
    };
    let Ok(comments_json) = serde_json::to_string(&comments) else {
        return Err(rusqlite::Error::InvalidQuery)
    };
    let date = SystemTime::now().duration_since(UNIX_EPOCH).unwrap().as_millis() as u64;
    let conn = database::connect()?;
    let mut stmt = conn.prepare("INSERT INTO posts (user_id, content, likes, comments, date) VALUES(?,?,?,?,?) RETURNING *;")?;
    let post = stmt.query_row((user_id, content, likes_json, comments_json, date), |row| Ok(post_from_row(row)?))?;
    Ok(post)
}

pub fn update_post(post_id: u64, likes: &HashSet<u64>, comments: &Vec<(u64, String)>) -> Result<(), rusqlite::Error> {
    let Ok(likes_json) = serde_json::to_string(&likes) else {
        return Err(rusqlite::Error::InvalidQuery)
    };
    let Ok(comments_json) = serde_json::to_string(&comments) else {
        return Err(rusqlite::Error::InvalidQuery)
    };
    let conn = database::connect()?;
    let sql = "UPDATE posts SET likes = ?, comments = ? WHERE post_id = ?";
    conn.execute(sql, (likes_json, comments_json, post_id))?;
    Ok(())
}