use core::panic;
use std::str::FromStr;

use serde::{Deserialize, Deserializer, Serialize};
use serde_yaml::Value;

use crate::prelude::*;

#[derive(Serialize, Deserialize)]
pub struct Challenge {
    pub japanese: Vec<Vec<Vec<ChallengeWord>>>,
    pub english: Option<Vec<String>>,
    pub song: Option<Song>,
    pub youtube: Option<String>,
    pub spotify: Option<String>,
    pub translation: Option<Translation>,
    pub suggester: Option<String>,
    pub date: chrono::NaiveDate,
}

impl Challenge {
    pub fn get(number: u32) -> Self {
        use comrak::{parse_document, Arena, ComrakOptions};
        use std::fs;

        let options = {
            let mut options = ComrakOptions::default();
            options.extension.front_matter_delimiter = Some("---".to_owned());
            options
        };
        let arena = Arena::new();
        let root = parse_document(
            &arena,
            &fs::read_to_string(format!("content/challenges/{number}.md")).expect("Couldn't find challenge file"),
            &options,
        );
        if let Some(node) = root.children().next() {
            if let comrak::nodes::NodeValue::FrontMatter(frontmatter) = &node.data.borrow().value {
                let frontmatter = {
                    // Trim starting and ending fences
                    let lines: Vec<&str> = frontmatter.trim().lines().collect();
                    lines[1..lines.len() - 1].join("\n")
                };
                let challenge: Challenge = serde_yaml::from_str(&frontmatter).unwrap();
                challenge
            } else {
                panic!("No frontmatter!")
            }
        } else {
            panic!("Empty document!")
        }   
    }
}

#[derive(Serialize, Deserialize)]
pub struct Song {
    pub japanese: Option<String>,
    pub english: Option<String>,
}

#[derive(Serialize)]
pub struct ChallengeWord {
    pub dictionary: Option<String>,
    pub pos: Option<PartOfSpeech>,
    pub text: Option<Vec<Furigana>>,
}

impl<'de> Deserialize<'de> for ChallengeWord {
    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
    where
        D: Deserializer<'de>,
    {
        let value = Deserialize::deserialize(deserializer)?;
        let map = if let Value::Mapping(map) = value {
            map
        } else {
            return Err(serde::de::Error::invalid_type(
                serde::de::Unexpected::Other("not a string or map"),
                &"a string or map",
            ));
        };
        let text = map.get("text").map(|value| match value {
            Value::String(string) => vec![Furigana::new(string.clone(), None)],
            Value::Sequence(sequence) => sequence
                .iter()
                .map(|value| match value {
                    Value::String(kanji) => Furigana::new(kanji.to_owned(), None),
                    Value::Mapping(mapping) => {
                        let (kanji, furigana) = mapping.iter().next().unwrap();
                        Furigana::new(
                            kanji.as_str().unwrap().to_owned(),
                            Some(furigana.as_str().unwrap().to_owned()),
                        )
                    }
                    _ => panic!(),
                })
                .collect(),
            _ => panic!(),
        });
        let dictionary = match map.get("dictionary") {
            Some(value) => match value {
                Value::Null => None,
                Value::String(dictionary) => Some(if !dictionary.starts_with("http") {
                    format!("https://jisho.org/word/{dictionary}")
                } else {
                    dictionary.to_owned()
                }),
                _ => panic!("dictionary must be string!"),
            },
            None => text.as_ref().map(|furigana| {
                furigana
                    .iter()
                    .map(|segment| segment.kanji.clone())
                    .collect()
            }),
        };
        let pos: Option<PartOfSpeech> = map
            .get("pos")
            .map(|value| value.as_str().unwrap().parse().unwrap());
        Ok(ChallengeWord {
            dictionary,
            pos,
            text,
        })
    }
}
#[derive(Serialize, Deserialize)]
#[serde(rename_all = "camelCase")]
pub enum PartOfSpeech {
    Noun,
    Adjective,
    Verb,
    Adverb,
    Particle,
    Phrase,
}

#[derive(Debug, PartialEq, Eq)]
pub struct ParsePartOfSpeechError;

impl FromStr for PartOfSpeech {
    type Err = ParsePartOfSpeechError;
    fn from_str(s: &str) -> Result<Self, Self::Err> {
        use PartOfSpeech::*;
        Ok(match s {
            "noun" => Noun,
            "adjective" => Adjective,
            "verb" => Verb,
            "adverb" => Adverb,
            "particle" => Particle,
            "phrase" => Phrase,
            _ => return Err(ParsePartOfSpeechError),
        })
    }
}

#[derive(Serialize, Deserialize)]
pub struct Furigana {
    pub kanji: String,
    pub kyujitai: Option<String>,
    pub furigana: Option<String>,
}

impl Furigana {
    fn new(kanji: String, furigana: Option<String>) -> Self {
        Self {
            kyujitai: match kanji.to_kyujitai() {
                kyujitai if kyujitai.eq(&kanji) => None,
                kyujitai => Some(kyujitai),
            },
            kanji,
            furigana,
        }
    }
}

#[derive(Serialize, Deserialize)]
pub struct Translation {
    pub author: Option<String>,
    pub site: TranslationSite,
}

#[derive(Serialize, Deserialize)]
pub struct TranslationSite {
    pub name: String,
    pub link: String,
}