mod clap_wrap;
mod errors;
mod filters;
mod user_input;

pub use clap_wrap::*;
pub use errors::*;
pub use filters::*;
pub use search_result::SearchResult;
pub use user_input::Pager;

use lazy_regex::Lazy;
use reqwest::blocking as reqwest;
use scraper::{Html, Selector};

pub type HtmlFragments = Vec<String>;

const URL_START: &str = "https://www.imdb.com/find?s=tt&q=";
static RESULT_SELECTOR: Lazy<Selector> = Lazy::new(|| Selector::parse("td.result_text").unwrap());

// Upper limit on things we'll bother to parse... just in case
#[cfg(not(debug_assertions))]
const MAX_FRAGMENTS: usize = 200;
#[cfg(debug_assertions)]
const MAX_FRAGMENTS: usize = 50;

pub fn request_and_scrape(search_term: &str) -> Result<HtmlFragments> {
    let html = reqwest::get(format!("{}{}", URL_START, search_term))?.text()?;
    let document = Html::parse_document(&html);
    let fragments = document
        .select(&RESULT_SELECTOR)
        .take(MAX_FRAGMENTS)
        .map(|er| er.inner_html())
        .collect();
    Ok(fragments)
}

mod search_result {
    use crate::SearchResultWarning::*;
    use crate::{Filters, HtmlFragments, SearchResultWarning};
    use lazy_regex::*;
    use std::convert::TryFrom;
    use std::fmt;

    /*
    The DIRT_MARGIN_* constants refer to the amount of unwanted characters captured by the regex.
    For example, to capture the movie name we have to also find the > character to know we're at the start of the name, and the </a> tag to know we're at the end of the movie name.
    This gives movie names a 'dirt margin' of (1, 4): 1 character at the start, 4 characters at the end
     */

    // Matches something like "tt6856242"
    static ID_REGEX: Lazy<Regex> = lazy_regex!("tt[0-9]+");
    // Matches something like ">Kingsman: The Secret Service</a>"
    // +? means 1 or more, not greedily
    static NAME_REGEX: Lazy<Regex> = lazy_regex!(">.+?</a>");
    const DIRT_MARGIN_NAME: (usize, usize) = (1, 4);
    // Matches something like "(TV Series)"
    static GENRE_REGEX: Lazy<Regex> = lazy_regex!("\\([A-z]+(\\s[A-z]+)?\\)");
    const DIRT_MARGIN_GENRE: (usize, usize) = (1, 1);
    // Matches something like "(1989)"
    static YEAR_REGEX: Lazy<Regex> = lazy_regex!("\\([0-9]{4}\\)");
    const DIRT_MARGIN_YEAR: (usize, usize) = (1, 1);

    #[derive(Debug)]
    pub struct SearchResult {
        pub name: String,
        pub id: String,
        pub genre: String,
        pub year: Option<u16>,
    }

    impl SearchResult {
        pub fn try_many_lossy(fragments: HtmlFragments, filters: &Filters) -> Vec<Self> {
            fragments
                .into_iter()
                .filter_map(|a| match Self::try_from(a.as_str()) {
                    Ok(sr) => Some(sr),
                    Err(why) => {
                        eprintln!("Warning: {}", why);
                        None
                    }
                })
                .filter(|sr| filters.allows(sr))
                .collect()
        }

        fn find_name_in_fragment(fragment: &str) -> Result<&str, SearchResultWarning> {
            let m = NAME_REGEX
                .find(fragment)
                .ok_or(NameNotFound(fragment.into()))?;
            let dirty_name = m.as_str();
            let clean_name = &dirty_name[DIRT_MARGIN_NAME.0..dirty_name.len() - DIRT_MARGIN_NAME.1];
            Ok(clean_name)
        }
    }

    impl TryFrom<&str> for SearchResult {
        type Error = SearchResultWarning;

        fn try_from(fragment: &str) -> Result<Self, SearchResultWarning> {
            let id = ID_REGEX
                .find(fragment)
                .ok_or(ImdbIdNotFound(fragment.into()))?
                .as_str()
                .into();
            let name = SearchResult::find_name_in_fragment(fragment)?.to_string();

            let genre = match GENRE_REGEX.find(fragment) {
                Some(m) => {
                    let s = m.as_str();
                    String::from(&s[DIRT_MARGIN_GENRE.0..s.len() - DIRT_MARGIN_GENRE.1])
                }
                None => String::from("Movie"),
            };

            let year = YEAR_REGEX.find(fragment).and_then(|m| {
                let year = m.as_str();
                let year = year[DIRT_MARGIN_YEAR.0..year.len() - DIRT_MARGIN_YEAR.1]
                    .parse()
                    .expect("Failed to parse a year that matched YEAR_REGEX");
                Some(year)
            });

            Ok(SearchResult {
                name,
                id,
                genre,
                year,
            })
        }
    }

    impl fmt::Display for SearchResult {
        fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
            match self.year {
                Some(y) => write!(f, "{} ({}, {})", self.name, self.genre, y),
                None => write!(f, "{} ({})", self.name, self.genre),
            }
        }
    }
}

#[cfg(test)]
mod unit_tests {
    use super::*;
    use std::convert::TryFrom;

    // Data taken from search term "kingsmen"
    const INPUTS: [&str; 10] = [
        " <a href=\"/title/tt6856242/?ref_=fn_tt_tt_1\">The King's Man</a> (2021) ",
        " <a href=\"/title/tt0405676/?ref_=fn_tt_tt_2\">All the King's Men</a> (2006) ",
        " <a href=\"/title/tt2119547/?ref_=fn_tt_tt_3\">The Kingsmen</a> (2011) (Short) ",
        " <a href=\"/title/tt0041113/?ref_=fn_tt_tt_4\">All the King's Men</a> (1949) ",
        " <a href=\"/title/tt4649466/?ref_=fn_tt_tt_5\">Kingsman: The Golden Circle</a> (2017) ",
        " <a href=\"/title/tt2802144/?ref_=fn_tt_tt_6\">Kingsman: The Secret Service</a> (2014) ",
        " <a href=\"/title/tt0222577/?ref_=fn_tt_tt_7\">King's Men</a> (1975) (TV Series) ",
        " <a href=\"/title/tt14642606/?ref_=fn_tt_tt_8\">The Kingsmen</a> (2017) (TV Episode) <br> <small>- Season 3 <sp
    an class=\"ghost\">|</span> Episode 22 </small> <br><small>- <a href=\"/title/tt3319722/?ref_=fn_tt_tt_8a\">Gosp
    el Music Showcase</a> (2011) (TV Series) </small> ",
        " <a href=\"/title/tt0220969/?ref_=fn_tt_tt_9\">All the King's Men</a> (1999) (TV Movie) ",
        " <a href=\"/title/tt0084793/?ref_=fn_tt_tt_10\">Tian xia di yi</a> ",
    ];
    static SEARCH_RESULTS: Lazy<Vec<SearchResult>> = Lazy::new(|| {
        INPUTS
            .iter()
            .map(|s| match SearchResult::try_from(*s) {
                Ok(sr) => sr,
                Err(why) => panic!("Failed to process test data: {}", why),
            })
            .collect()
    });

    #[test]
    fn name_searching() {
        let names = [
            "The King's Man",
            "All the King's Men",
            "The Kingsmen",
            "All the King's Men",
            "Kingsman: The Golden Circle",
            "Kingsman: The Secret Service",
            "King's Men",
            "The Kingsmen",
            "All the King's Men",
            "Tian xia di yi",
        ];
        names
            .iter()
            .zip(SEARCH_RESULTS.iter())
            .for_each(|(name, sr)| {
                assert_eq!(sr.name, *name);
            });
    }

    #[test]
    fn id_searching() {
        let ids = [
            "tt6856242",
            "tt0405676",
            "tt2119547",
            "tt0041113",
            "tt4649466",
            "tt2802144",
            "tt0222577",
            "tt14642606",
            "tt0220969",
            "tt0084793",
        ];
        ids.iter().zip(SEARCH_RESULTS.iter()).for_each(|(id, sr)| {
            assert_eq!(sr.id, *id);
        });
    }

    #[test]
    fn genre_searching() {
        let genres = [
            "Movie",
            "Movie",
            "Short",
            "Movie",
            "Movie",
            "Movie",
            "TV Series",
            "TV Episode",
            "TV Movie",
            "Movie",
        ];

        genres
            .iter()
            .zip(SEARCH_RESULTS.iter())
            .for_each(|(genre, sr)| {
                assert_eq!(&sr.genre, *genre);
            });
    }

    #[test]
    fn year_searching() {
        let years: [Option<u16>; 10] = [
            Some(2021),
            Some(2006),
            Some(2011),
            Some(1949),
            Some(2017),
            Some(2014),
            Some(1975),
            Some(2017),
            Some(1999),
            None,
        ];

        years
            .iter()
            .zip(SEARCH_RESULTS.iter())
            .for_each(|(year, sr)| {
                assert_eq!(year, &sr.year);
            });
    }

    #[test]
    fn name_not_found() {
        let fragments = [
            "tt1234 (Movie)",
            "The King's Man tt123124 (TV Episode)",
            "<a href=\"/title/tt6856242/?ref_=fn_tt_tt_1\">The King's Man<a> (2021)",
        ];
        for fragment in fragments.iter() {
            match SearchResult::try_from(*fragment).unwrap_err() {
                SearchResultWarning::NameNotFound(_) => {}
                e => panic!("Incorrect error type raised: {:?}", e),
            }
        }
    }

    #[test]
    fn id_not_found() {
        let fragments = [
            "The King's Man (Movie)",
            "The King's Man 123124 (TV Episode)",
            "<a href=\"/title/tta6856242/?ref_=fn_tt_tt_1\">The King's Man</a> (2021)",
        ];
        for fragment in fragments.iter() {
            match SearchResult::try_from(*fragment).unwrap_err() {
                SearchResultWarning::ImdbIdNotFound(_) => {}
                e => panic!("Incorrect error type raised: {:?}", e),
            }
        }
    }
}