use async_std::fs::read_to_string;
use std::env;
use std::ffi::OsStr;
use std::fs::{read_dir, File};
use std::io::{Error, ErrorKind, Write};
use std::path::PathBuf;

use crate::post::Post;

pub async fn get_all_posts() -> Result<Vec<Post>, Error> {
    let mut posts: Vec<Post> = vec![];

    for file in post_directory_contents()? {
        let file = file?;
        if let Some("json") = file.path().extension().and_then(OsStr::to_str) {
            let contents = read_post_from_disk(&file.path()).await?;
            let post = Post::from_str(&contents)?;
            posts.push(post);
        }
    }

    posts.sort_by_key(|el| el.date.clone());
    posts.reverse();

    Ok(posts)
}

pub async fn get_one_post(post_id: String) -> Result<Post, Error> {
    let posts_dir = get_posts_directory_path()?;
    let path = posts_dir.join(format!("{}.json", post_id));
    let contents = read_post_from_disk(&path).await?;
    let post = Post::from_str(&contents)?;

    Ok(post)
}

pub fn delete_post(post_id: String) -> Result<(), Error> {
    let posts_dir = get_posts_directory_path()?;
    let path = posts_dir.join(format!("{}.json", post_id));
    std::fs::remove_file(path)?;
    Ok(())
}

async fn read_post_from_disk(path: &PathBuf) -> Result<String, Error> {
    match read_to_string(&path).await {
        Ok(c) => Ok(c),
        Err(_) => Err(Error::new(
            ErrorKind::NotFound,
            format!(
                "Can't find post with the id '{}'",
                path.file_stem().unwrap().to_str().unwrap()
            ),
        )),
    }
}

pub fn write_post_to_disk(post: &Post) -> Result<(), Error> {
    let mut path: PathBuf = get_posts_directory_path()?;
    let filename = format!("{}.json", post.id);
    path = path.join(&filename);
    let mut file = File::create(&path)?;
    file.write_all(serde_json::to_string(&post)?.as_bytes())?;
    Ok(())
}

fn post_directory_contents() -> Result<std::fs::ReadDir, Error> {
    let path = get_posts_directory_path()?;

    match read_dir(path) {
        Ok(f) => Ok(f),
        Err(_) => Err(Error::new(
            ErrorKind::Other,
            "Posts directory does not exist",
        )),
    }
}

fn get_posts_directory_path() -> Result<PathBuf, Error> {
    match env::var("POSTS_DIR") {
        Ok(dir) => Ok(dir.into()),
        Err(_) => Err(Error::new(
            ErrorKind::Other,
            "Posts directory environment variable not set",
        )),
    }
}