use anyhow::{anyhow, Context, Result};
use redis;
use redis::AsyncCommands;
use serde::{Deserialize, Serialize};
use std::collections::HashMap;
use std::fs::File;

#[derive(Default, Serialize, Deserialize)]
struct PyindieblogData {
    posts: Vec<serde_json::Value>,
    cards: Vec<serde_json::Value>,
}

#[async_std::main]
async fn main() -> Result<()> {
    let mut args = std::env::args();
    args.next(); // skip argv[0] which is the name
    let redis_uri = args
        .next()
        .ok_or_else(|| anyhow!("No Redis URI provided"))?;
    let client = redis::Client::open(redis_uri.as_str())
        .with_context(|| format!("Failed to construct Redis client on {}", redis_uri))?;

    let filename = args
        .next()
        .ok_or_else(|| anyhow!("No filename provided for export"))?;

    let mut data: Vec<serde_json::Value>;

    let file = File::create(filename)?;

    let mut conn = client
        .get_async_std_connection()
        .await
        .with_context(|| "Failed to connect to the Redis server")?;

    data = conn
        .hgetall::<&str, HashMap<String, String>>("posts")
        .await?
        .values()
        .map(|s| {
            serde_json::from_str::<serde_json::Value>(s)
                .with_context(|| format!("Failed to parse the following entry: {:?}", s))
        })
        .collect::<std::result::Result<Vec<serde_json::Value>, anyhow::Error>>()
        .with_context(|| "Failed to export h-entries from pyindieblog")?;
    data.extend(
        conn.hgetall::<&str, HashMap<String, String>>("hcards")
            .await?
            .values()
            .map(|s| {
                serde_json::from_str::<serde_json::Value>(s)
                    .with_context(|| format!("Failed to parse the following card: {:?}", s))
            })
            .collect::<std::result::Result<Vec<serde_json::Value>, anyhow::Error>>()
            .with_context(|| "Failed to export h-cards from pyindieblog")?,
    );

    data.sort_by_key(|v| {
        v["properties"]["published"][0]
            .as_str()
            .map(|s| s.to_string())
    });

    serde_json::to_writer(file, &data)?;

    Ok(())
}