use std::io::{Result, Error, ErrorKind::Other};
use serde::Deserialize;
use reqwest::get;
use scraper::{ElementRef, Html, Selector, node::Node::{Text, Element}};

#[derive(Deserialize, Debug)]
struct GeniusApiResponse {
    response: GeniusResponseBlock,
}

#[derive(Deserialize, Debug)]
struct GeniusResponseBlock {
    hits: Vec<GeniusHit>,
}

#[derive(Deserialize, Debug)]
struct GeniusHit {
    #[serde(rename = "type")]
    hit_type: String,
    result: GeniusResult,
}

#[derive(Deserialize, Debug)]
struct GeniusResult {
    url: String,
}

pub async fn search(url: &str) -> Result<String> {
    let response = get(url).await
        .map_err(|_| Error::new(Other, "Could not perform lyrics search in engine."))?
        .json::<GeniusApiResponse>().await
        .map_err(|_| Error::new(Other, "Lyrics engine returned invalid response from search."))?;
    let url = response.response.hits.into_iter()
        .find(|hit| hit.hit_type == "song")
        .map(|hit| hit.result.url)
        .ok_or_else(|| Error::new(Other, "Could not find a matching track in lyrics engine."))?;

    Ok(url)
}

pub async fn get_lyrics(url: &str) -> Result<String> {
    let song_html = get(url).await
        .map_err(|_| Error::new(Other, "Could not fetch lyrics from engine."))?
        .text().await
        .map_err(|_| Error::new(Other, "Lyrics engine returned invalid response."))?;

    let document = Html::parse_document(&song_html);
    let selector = Selector::parse(r#"div[data-lyrics-container="true"]"#).unwrap();
    let lyrics_div = document.select(&selector).next()
        .ok_or_else(|| Error::new(Other, "Could not find lyrics in response."))?;

    let mut lyrics = String::new();
    for node in lyrics_div.children() {
        match node.value() {
            Element(element) => {
                if element.name() == "br" {
                    lyrics.push('\n');
                } else {
                    if let Some(element_ref) = ElementRef::wrap(node) {
                        let text = element_ref.text().collect::<Vec<_>>().join("");
                        lyrics.push_str(&text);
                    }
                }
            },
            Text(text) => {
                lyrics.push_str(text);
            },
            _ => {}
        }
    }

    Ok(lyrics)
}