use crate::Result;
use reqwest::Url;
use chrono::{DateTime, Utc};
use std::hash::{Hash, Hasher};

pub struct FetchedRSSItem {
  guid: String,
  title: String,
  description: String,
  content: String,
}
impl FetchedRSSItem {
  pub fn guid(&self) -> &str { &self.guid }
  pub fn title(&self) -> &str { &self.title }
  pub fn description(&self) -> &str { &self.description }
  pub fn content(&self) -> &str { &self.content }

  fn parse(item: rss::Item) -> Self {
    FetchedRSSItem {
      guid: Self::get_or_create_guid(&item),
      title: item.title().unwrap_or("").to_string(), 
      description: item.description().unwrap_or("").to_string(),
      content: item.content().unwrap_or("").to_string(),
    }
  }

  fn get_or_create_guid(item: &rss::Item) -> String {
    if let Some(guid) = item.guid() {
      return guid.value().to_string();
    }

    let mut hasher = std::collections::hash_map::DefaultHasher::new();
    item.link().unwrap_or("").hash(&mut hasher);
    item.title().unwrap_or("").hash(&mut hasher);
    item.description().unwrap_or("").hash(&mut hasher);

    format!("gen-{:x}", hasher.finish())
  }
}
pub struct FetchedRSSChannel {
  title: String,
  link: Url,
  description: String,

  items: Vec<FetchedRSSItem>,

  fetched_at: DateTime<Utc>,
}
impl FetchedRSSChannel {
  pub fn title(&self) -> &str { &self.title }
  pub fn link(&self) -> &Url { &self.link }
  pub fn description(&self) -> &str { &self.description }
  pub fn items(&self) -> &[FetchedRSSItem] { &self.items }
  pub fn fetched_at(&self) -> &DateTime<Utc> { &self.fetched_at }

  pub fn parse(rss: rss::Channel) -> Result<Self> {
    Ok(FetchedRSSChannel {
      title: rss.title,
      link: Url::parse(&rss.link)?,
      description: rss.description,

      items: rss.items.into_iter().map(FetchedRSSItem::parse).collect(),

      fetched_at: Utc::now(),
    })
  }
}