use std::iter;
use std::str::FromStr;

use evtclib::{Log, Outcome};
use itertools::Itertools;

/// A [`LogBag`] is a struct that holds multiple logs in their categories.
///
/// This is similar to hash map mapping a category to a list of logs, but the [`LogBag`] saves its
/// insertion order. The logs are saved as a line, that way we don't have to re-parse or re-upload
/// them and we can just handle arbitrary data.
#[derive(Default, Debug, Clone, PartialEq, Eq, Hash)]
pub struct LogBag {
    data: Vec<(String, Vec<String>)>,
}

impl LogBag {
    /// Construct a new, empty [`LogBag`].
    pub fn new() -> Self {
        LogBag { data: Vec::new() }
    }

    /// Return an iterator over all available categories.
    pub fn categories(&self) -> impl Iterator<Item = &str> {
        self.data.iter().map(|x| &x.0 as &str)
    }

    /// Return an iterator over (category, items).
    pub fn iter(&self) -> impl Iterator<Item = (&str, impl Iterator<Item = &str>)> {
        self.data
            .iter()
            .map(|(cat, lines)| (cat as &str, lines.iter().map(|l| l as &str)))
    }

    /// Insert an item into the given category.
    ///
    /// If the category does not exist yet, it will be appended at the bottom.
    pub fn insert(&mut self, category: &str, line: String) {
        for (cat, lines) in self.data.iter_mut() {
            if cat == category {
                lines.push(line);
                return;
            }
        }

        // When we reach here, we don't have the category yet, so we gotta insert it.
        self.data.push((String::from(category), vec![line]));
    }

    /// Tries to parse the given text as a plain [`LogBag`].
    pub fn parse_plain(input: &str) -> Option<LogBag> {
        input.parse().ok()
    }

    pub fn parse_markdown(input: &str) -> Option<LogBag> {
        let plain = input
            .split('\n')
            .map(|line| line.trim_matches('*'))
            .join("\n");
        LogBag::parse_plain(&plain)
    }

    /// Renders the contents of this [`LogBag`] as plain text.
    ///
    /// The output of this can be fed back into [`LogBag::parse_plain`] to round-trip.
    pub fn render_plain(&self) -> String {
        self.iter()
            .map(|(category, lines)| iter::once(category).chain(lines).join("\n"))
            .join("\n\n")
    }

    /// Renders the contents of this [`LogBag`] as HTML.
    ///
    /// Useful for posting to Matrix chats.
    pub fn render_html(&self) -> String {
        self.iter()
            .map(|(category, mut lines)| {
                format!("<b>{}</b><br>\n{}", category, lines.join("<br>\n"))
            })
            .join("<br>\n<br>\n")
    }

    /// Renders the contents of this [`LogBag`] as Markdown.
    ///
    /// Useful for posting to Discord chats.
    pub fn render_markdown(&self) -> String {
        self.iter()
            .map(|(category, mut lines)| format!("**{}**\n{}", category, lines.join("\n")))
            .join("\n\n")
    }
}

impl FromStr for LogBag {
    type Err = ();

    fn from_str(s: &str) -> Result<Self, Self::Err> {
        let data = s
            .trim()
            .split("\n\n")
            .map(|chunk| {
                let mut lines = chunk.split('\n');
                let category = lines.next().unwrap();
                (
                    category.to_string(),
                    lines.map(ToString::to_string).collect::<Vec<_>>(),
                )
            })
            .filter(|(cat, lines)| !cat.is_empty() && !lines.is_empty())
            .collect();
        Ok(LogBag { data })
    }
}

impl From<Vec<(String, Vec<String>)>> for LogBag {
    fn from(data: Vec<(String, Vec<String>)>) -> Self {
        LogBag { data }
    }
}

/// A helper function to return the right emoji for a given log.
pub fn state_emoji(log: &Log) -> &'static str {
    let outcome = log.analyzer().and_then(|a| a.outcome());
    match outcome {
        Some(Outcome::Success) => "✅",
        Some(Outcome::Failure) => "❌",
        None => "❓",
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn insert() {
        let mut logbag = LogBag::new();
        logbag.insert("cat 1", "line 1".to_string());
        assert_eq!(logbag.categories().count(), 1);
        logbag.insert("cat 1", "line 2".to_string());
        assert_eq!(logbag.categories().count(), 1);
        logbag.insert("cat 2", "line 1".to_string());
        assert_eq!(logbag.categories().count(), 2);

        assert_eq!(
            logbag.categories().collect::<Vec<_>>(),
            vec!["cat 1", "cat 2"]
        );
    }

    #[test]
    fn parse_empty() {
        assert_eq!(LogBag::parse_plain(""), Some(LogBag::new()));
    }

    #[test]
    fn parse_single() {
        let mut logbag = LogBag::new();
        logbag.insert("cat 1", "line 1".to_string());
        logbag.insert("cat 1", "line 2".to_string());

        assert_eq!(
            LogBag::parse_plain(
                "\
cat 1
line 1
line 2"
            ),
            Some(logbag)
        );
    }

    #[test]
    fn parse_multi() {
        let mut logbag = LogBag::new();
        logbag.insert("cat 1", "line 1".to_string());
        logbag.insert("cat 1", "line 2".to_string());
        logbag.insert("cat 2", "line 1".to_string());
        logbag.insert("cat 2", "line 2".to_string());

        assert_eq!(
            LogBag::parse_plain(
                "\
cat 1
line 1
line 2

cat 2
line 1
line 2"
            ),
            Some(logbag)
        );
    }

    #[test]
    fn parse_markdown() {
        let mut logbag = LogBag::new();
        logbag.insert("cat 1", "line 1".to_string());
        logbag.insert("cat 1", "line 2".to_string());
        logbag.insert("cat 2", "line 1".to_string());
        logbag.insert("cat 2", "line 2".to_string());

        assert_eq!(
            LogBag::parse_markdown(
                "\
**cat 1**
line 1
line 2

**cat 2**
line 1
line 2"
            ),
            Some(logbag)
        );
    }

    #[test]
    fn render_plain_single() {
        let mut logbag = LogBag::new();
        logbag.insert("category", "line 1".to_string());
        logbag.insert("category", "line 2".to_string());

        assert_eq!(
            logbag.render_plain(),
            "\
category
line 1
line 2"
        );
    }

    #[test]
    fn render_plain_multi() {
        let mut logbag = LogBag::new();
        logbag.insert("category 1", "line 1".to_string());
        logbag.insert("category 1", "line 2".to_string());
        logbag.insert("category 2", "enil 1".to_string());
        logbag.insert("category 2", "enil 2".to_string());

        assert_eq!(
            logbag.render_plain(),
            "\
category 1
line 1
line 2

category 2
enil 1
enil 2"
        );
    }

    #[test]
    fn render_html_single() {
        let mut logbag = LogBag::new();
        logbag.insert("category", "line 1".to_string());
        logbag.insert("category", "line 2".to_string());

        assert_eq!(
            logbag.render_html(),
            "\
<b>category</b><br>
line 1<br>
line 2"
        );
    }

    #[test]
    fn render_html_multi() {
        let mut logbag = LogBag::new();
        logbag.insert("category 1", "line 1".to_string());
        logbag.insert("category 1", "line 2".to_string());
        logbag.insert("category 2", "enil 1".to_string());
        logbag.insert("category 2", "enil 2".to_string());

        assert_eq!(
            logbag.render_html(),
            "\
<b>category 1</b><br>
line 1<br>
line 2<br>
<br>
<b>category 2</b><br>
enil 1<br>
enil 2"
        );
    }

    #[test]
    fn render_markdown_single() {
        let mut logbag = LogBag::new();
        logbag.insert("category", "line 1".to_string());
        logbag.insert("category", "line 2".to_string());

        assert_eq!(
            logbag.render_markdown(),
            "\
**category**
line 1
line 2"
        );
    }

    #[test]
    fn render_markdown_multi() {
        let mut logbag = LogBag::new();
        logbag.insert("category 1", "line 1".to_string());
        logbag.insert("category 1", "line 2".to_string());
        logbag.insert("category 2", "enil 1".to_string());
        logbag.insert("category 2", "enil 2".to_string());

        assert_eq!(
            logbag.render_markdown(),
            "\
**category 1**
line 1
line 2

**category 2**
enil 1
enil 2"
        );
    }
}