use once_cell::sync::Lazy;
use regex::Regex;
use reqwest::{IntoUrl, Url};
use serde::{Deserialize, Serialize};

use crate::error::Result;
use crate::models::{Album, Band, Feed, SearchFilter, SearchResult, TrAlbumType};
use crate::{util, Bandcamp, Error, API_URL};

static BAND_ID_REGEX: Lazy<Regex> = Lazy::new(|| {
    Regex::new(
        r#"<script\stype="text/javascript"\s[^>]*data-band="\{[^"]*&quot;id&quot;:(\d+)[,}]"#,
    )
    .unwrap()
});

#[derive(Serialize)]
struct BandRequest {
    band_id: u64,
}

#[derive(Serialize)]
struct AlbumRequest {
    band_id: u64,
    tralbum_id: u64,
    tralbum_type: TrAlbumType,
}

#[derive(Serialize)]
struct SearchRequest<'a> {
    search_text: &'a str,
    search_filter: SearchFilter,
    full_page: bool,
}

#[derive(Deserialize)]
struct SearchResultWrapper {
    auto: SearchResult,
}

#[derive(Deserialize)]
#[serde(untagged)]
enum ResponseWrapper<T> {
    Ok(T),
    Error { error_message: String },
}

impl<T> ResponseWrapper<T> {
    fn convert(self) -> Result<T> {
        match self {
            ResponseWrapper::Ok(data) => Ok(data),
            ResponseWrapper::Error { error_message } => {
                if error_message.starts_with("No such ") || error_message.ends_with(" not found") {
                    Err(Error::NotFound(error_message.into()))
                } else {
                    Err(Error::Bandcamp(error_message.into()))
                }
            }
        }
    }
}

impl Bandcamp {
    /// Get a band from the Bandcamp API
    pub async fn band(&self, band_id: u64) -> Result<Band> {
        let req = BandRequest { band_id };

        let resp = self
            .client
            .post(format!("{}mobile/24/band_details", API_URL))
            .json(&req)
            .send()
            .await?
            .error_for_status()?;

        resp.json::<ResponseWrapper<Band>>().await?.convert()
    }

    /// Get a album (or a track) from the Bandcamp API
    ///
    /// # Parameters
    /// - `band_id` The Band ID of the album/track
    /// - `tralbum_id` Album/Track ID
    /// - `tralbum_type` Track/Album
    pub async fn album(
        &self,
        band_id: u64,
        tralbum_id: u64,
        tralbum_type: TrAlbumType,
    ) -> Result<Album> {
        let req = AlbumRequest {
            band_id,
            tralbum_id,
            tralbum_type,
        };

        let resp = self
            .client
            .post(format!("{}mobile/25/tralbum_details", API_URL))
            .json(&req)
            .send()
            .await?
            .error_for_status()?;

        resp.json::<ResponseWrapper<Album>>().await?.convert()
    }

    /// Get an album (or a track) from the Bandcamp API using a unified ID string
    ///
    /// # Examples
    /// - Album: `3760769193a1493086082`
    /// - Track: `2464198920t716010980`
    pub async fn album_uid<S: AsRef<str>>(&self, uid: S) -> Result<Album> {
        let (band_id, tralbum_type, tralbum_id) = util::parse_album_uid(uid)?;
        self.album(band_id, tralbum_id, tralbum_type).await
    }

    /// Search Bandcamp for bands, albums or tracks
    pub async fn search<S: AsRef<str>>(
        &self,
        query: S,
        filter: SearchFilter,
    ) -> Result<SearchResult> {
        let req = SearchRequest {
            search_text: query.as_ref(),
            search_filter: filter,
            full_page: false,
        };

        let resp = self
            .client
            .post(format!(
                "{}bcsearch_public_api/1/autocomplete_elastic",
                API_URL
            ))
            .json(&req)
            .send()
            .await?
            .error_for_status()?;

        Ok(resp
            .json::<ResponseWrapper<SearchResultWrapper>>()
            .await?
            .convert()?
            .auto)
    }

    /// Get the current Bandcamp feed containing featured works.
    pub async fn feed(&self) -> Result<Feed> {
        let resp = self
            .client
            .get(format!(
                "{}mobile/25/feed_older_logged_out?story_groups=featured",
                API_URL
            ))
            .send()
            .await?
            .error_for_status()?;

        resp.json::<ResponseWrapper<Feed>>().await?.convert()
    }

    /// Get a continuation page for the Bandcamp feed
    pub async fn feed_cont<S: AsRef<str>>(&self, token: S) -> Result<Feed> {
        let resp = self
            .client
            .get(
                Url::parse_with_params(
                    &format!("{}mobile/25/feed_older_logged_out", API_URL),
                    &[("story_groups", &format!("featured:{}", token.as_ref()))],
                )
                .unwrap(),
            )
            .send()
            .await?
            .error_for_status()?;

        resp.json::<ResponseWrapper<Feed>>().await?.convert()
    }

    /// Get the numeric band id from their bandcamp URL
    pub async fn band_id_from_url<U: IntoUrl>(&self, url: U) -> Result<u64> {
        let mut url = url.into_url().map_err(|_| Error::InvalidUrl)?;
        let host = url.host_str().ok_or(Error::InvalidUrl)?;
        if !host.ends_with(".bandcamp.com") {
            return Err(Error::InvalidUrl);
        }
        url.set_path("");
        url.set_query(None);

        let resp = self.client.get(url).send().await?.error_for_status()?;
        let html = resp.text().await?;
        BAND_ID_REGEX
            .captures(&html)
            .ok_or_else(|| Error::WebsiteParsing("could not find band id".into()))?
            .get(1)
            .unwrap()
            .as_str()
            .parse()
            .map_err(|_| Error::WebsiteParsing("could not parse band id".into()))
    }
}