mod structs;

use std::env;
use std::io::{stdin, BufRead};
use std::process::{exit, Command};
use std::os::unix::process::CommandExt;
use reqwest::Client;
use quick_xml::Reader;
use quick_xml::events::Event;
extern crate tokio;

fn main() {
    let view_image_command = ["xdg-open", "{}"];
    let nitter_instance = "https://nitter.nixnet.services";
    let twitter_accounts = [
        structs::TwitterAccount { display_name: "calli", twitter_username: "moricalliope", schedule_keyword: "schedule" },
        structs::TwitterAccount { display_name: "kiara", twitter_username: "takanashikiara", schedule_keyword: "schedule" },
    ];

    let mut args = env::args();
    args.next();
    let mut preselect = String::new();
    for arg in args {
        preselect.push_str(&format!("{} ", arg));
    }
    let mut preselect = preselect.trim().to_lowercase();
    if preselect.is_empty() {
        let mut index = 0;
        for account in &twitter_accounts {
            eprintln!("{}. {}", index, &account.display_name);
            index += 1;
        }
        eprint!("> ");
        // https://www.programming-idioms.org/idiom/120/read-integer-from-stdin/1906/rust
        preselect = stdin()
            .lock()
            .lines()
            .next()
            .expect("stdin is not avaliable")
            .expect("can't read from stdin")
            .trim()
            .to_lowercase();
    }
    let mut account_index = 0;
    match preselect.parse::<usize>() {
        Ok(index) => {
            if twitter_accounts.len() > index {
                account_index = index;
            } else {
                eprintln!("Invalid index");
                exit(1);
            }
        },
        Err(_) => {
            let mut exhausted = true;
            for account in &twitter_accounts {
                if &account.display_name.to_lowercase() == &preselect {
                    exhausted = false;
                    break;
                }
                account_index += 1;
            }
            if exhausted {
                eprintln!("Cannot find account");
                exit(1);
            }
        }
    };
    let account = &twitter_accounts[account_index];
    let text = tokio::runtime::Builder::new_current_thread()
        .enable_all()
        .build()
        .unwrap()
        .block_on(get_feed_text(nitter_instance, &account));
    let mut is_inside_item = false;
    let mut is_inside_title = false;
    let mut is_inside_description = false;
    let mut title: Option<String> = None;
    let mut url: Option<String> = None;
    let mut reader = Reader::from_str(&text);
    let mut buf = Vec::new();
    loop {
        match reader.read_event(&mut buf) {
            Ok(Event::Start(ref e)) => {
                match e.name() {
                    b"item" => {
                        is_inside_item = true;
                        title = None;
                        url = None;
                    },
                    b"title" => is_inside_title = true,
                    b"description" => is_inside_description = true,
                    _ => ()
                };
            },
            Ok(Event::Text(e)) => {
                if is_inside_item && is_inside_title {
                    title = Some(e.unescape_and_decode(&reader).unwrap());
                }
            },
            Ok(Event::CData(e)) => {
                if is_inside_item && is_inside_description {
                    let description_text = e.unescape_and_decode(&reader).unwrap();
                    let mut description_reader = Reader::from_str(&description_text);
                    let mut description_buf = Vec::new();
                    loop {
                        match description_reader.read_event(&mut description_buf) {
                            Ok(Event::Empty(ref e)) => {
                                if e.name() == b"img" {
                                    url = Some(e.attributes()
                                        .find(|attribute| attribute.as_ref().unwrap().key == b"src")
                                        .unwrap()
                                        .unwrap()
                                        .unescape_and_decode_value(&description_reader)
                                        .unwrap());
                                }
                            },
                            Err(err) => panic!("Error at position {}: {:?}", description_reader.buffer_position(), err),
                            Ok(Event::Eof) => break,
                            _ => ()
                        }
                    }
                }
            },
            Ok(Event::End(ref e)) => {
                match e.name() {
                    b"item" => {
                        is_inside_item = false;
                        if title.is_some() && url.is_some() {
                            break;
                        }
                    },
                    b"description" => {
                        is_inside_description = false;
                        if title.is_some() && url.is_some() {
                            break;
                        }
                    },
                    b"title" => is_inside_title = false,
                    _ => ()
                };
            },
            Err(err) => panic!("Error at position {}: {:?}", reader.buffer_position(), err),
            Ok(Event::Eof) => {
                if title.is_none() || url.is_none() {
                    eprintln!("Cannot find tweet");
                    exit(1);
                }
                break;
            },
            _ => ()
        };
        buf.clear();
    }
    drop(buf);
    println!("{}", title.unwrap());
    let mut args = view_image_command.to_vec().split_off(1);
    let url = url.unwrap();
    for i in 0..args.len() {
        if args[i] == "{}" {
            args[i] = url.as_str();
        }
    }
    Command::new(&view_image_command[0])
        .args(args)
        .exec();
}

async fn get_feed_text(nitter_instance: &str, account: &structs::TwitterAccount) -> String {
    let mut url = nitter_instance.to_string();
    url.push_str("/search/rss");
    match Client::new().get(&url)
        .query(&[
            ("f", "tweets"),
            ("f-images", "on"),
            ("q", &format!("{} from:{}", &account.schedule_keyword, &account.twitter_username))
        ])
        .send()
        .await {
            Ok(resp) => {
                match resp.text().await {
                    Ok(text) => text,
                    Err(err) => {
                        eprintln!("Failed to get text due to {}", err);
                        exit(1);
                    }
                }
            },
            Err(err) => {
                eprintln!("Failed to connect to Nitter due to {}", err);
                exit(1);
            }
        }
}