use fantoccini::{Client, ClientBuilder, Locator};
use log::info;
use log::warn;
use serde::{Deserialize, Serialize};

macro_rules! skip_fail {
    ($res:expr) => {
        match $res {
            Ok(val) => val,
            Err(e) => {
                warn!("An error: {}; skipped.", e);
                continue;
            }
        }
    };
}

macro_rules! skip_fail_opt {
    ($res:expr) => {
        match $res {
            Some(val) => val,
            None => {
                warn!("Unexpected empty value; skipped.");
                continue;
            }
        }
    };
}

/// Holds data about stackoverflow answers
#[derive(Debug, Serialize, Deserialize, Clone)]
pub struct Answer {
    upvotes: u32,
    author: String,
    pub content: String,
}

/// Get all answers from a stackoverflow domain. No error handling is done so get ready to either
/// check your input or "note: run with `RUST_BACKTRACE=1` environment variable to display a
/// backtrace"
pub async fn get_answers(
    c: &Client,
    url: &str,
    i: usize,
    links_size: usize,
) -> anyhow::Result<Vec<Answer>> {
    // first, go to the Wikipedia page for Foobar
    c.goto(url).await?;

    let answer_loc = c.find_all(Locator::Css(".answer")).await?;
    let mut out_answers = vec![];
    for (j, answer) in answer_loc.iter().enumerate() {
        info!("Getting answer {} on link {} of {}", j, i, links_size);
        let text = skip_fail!(answer.text().await);

        let score =
            skip_fail!(
                skip_fail_opt!(text.clone().split('\n').collect::<Vec<&str>>().get(0))
                    .parse::<u32>()
            );
        let content = text
            .split("Share\nImprove this answer")
            .collect::<Vec<&str>>()[0]
            .to_string()
            .replace("\\n", "\n");

        out_answers.push(Answer {
            upvotes: score,
            content: content,
            author: "unimplemented".to_string(),
        });
    }

    Ok(out_answers)
}

pub async fn get_top_links(c: &Client, pages: u16) -> anyhow::Result<Vec<String>> {
    let mut answers = vec![];
    for page in 1..=pages {
        skip_fail!(
            c.goto(
                format!(
                    "https://stackoverflow.com/questions?tab=votes&page={}",
                    page
                )
                .as_str(),
            )
            .await
        );

        let finds = c.find_all(Locator::Css(".s-link")).await?;
        for find in finds {
            if skip_fail_opt!(skip_fail!(find.attr("href").await)).contains("/questions/") {
                answers.push(find.attr("href").await.unwrap().unwrap());
            }
        }
    }

    Ok(answers)
}