use std::{
    collections::{BTreeMap, BTreeSet},
    convert::TryFrom,
    vec::IntoIter,
};

use thiserror::Error;

use crate::model::{lint, Lint};

/// A collection of lints
#[derive(Debug, Eq, PartialEq, Clone)]
pub struct Lints {
    lints: BTreeSet<Lint>,
}

lazy_static! {
    /// All the available lints
    static ref AVAILABLE: Lints = {
        let set = Lint::all_lints().collect();
        Lints::new(set)
    };
}

impl Lints {
    /// Create a new lint
    ///
    /// # Examples
    ///
    /// ```rust
    /// use std::collections::BTreeSet;
    ///
    /// use mit_lint::Lints;
    /// Lints::new(BTreeSet::new());
    /// ```
    #[must_use]
    pub fn new(lints: BTreeSet<Lint>) -> Lints {
        Lints { lints }
    }

    /// Get the available lints
    ///
    /// # Examples
    ///
    /// ```rust
    /// use mit_lint::{Lint, Lints};
    ///
    /// let lints = Lints::available().clone();
    /// assert!(lints.into_iter().count() > 0);
    /// ```
    #[must_use]
    pub fn available() -> &'static Lints {
        &AVAILABLE
    }

    /// Get all the names of these lints
    ///
    /// # Examples
    ///
    /// ```rust
    /// use mit_lint::{Lint, Lints};
    ///
    /// let names = Lints::available().clone().names();
    /// assert!(names.contains(&Lint::SubjectNotSeparateFromBody.name()));
    /// ```
    #[must_use]
    pub fn names(self) -> Vec<&'static str> {
        self.lints.iter().map(|lint| lint.name()).collect()
    }

    /// Get all the config keys of these lints
    ///
    /// # Examples
    ///
    /// ```rust
    /// use mit_lint::{Lint, Lints};
    ///
    /// let names = Lints::available().clone().config_keys();
    /// assert!(names.contains(&Lint::SubjectNotSeparateFromBody.config_key()));
    /// ```
    #[must_use]
    pub fn config_keys(self) -> Vec<String> {
        self.lints.iter().map(|lint| lint.config_key()).collect()
    }

    /// Create the union of two lints
    ///
    /// # Examples
    ///
    /// ```rust
    /// use mit_lint::{Lint, Lints};
    ///
    /// let to_add = Lints::new(vec![Lint::NotEmojiLog].into_iter().collect());
    /// let actual = Lints::available().clone().merge(&to_add).names();
    /// assert!(actual.contains(&Lint::NotEmojiLog.name()));
    /// ```
    #[must_use]
    pub fn merge(&self, other: &Lints) -> Lints {
        Lints::new(self.lints.union(&other.lints).copied().collect())
    }

    /// Get the lints that are in self, but not in other
    ///
    /// # Examples
    ///
    /// ```rust
    /// use mit_lint::{Lint, Lints};
    ///
    /// let to_remove = Lints::new(vec![Lint::SubjectNotSeparateFromBody].into_iter().collect());
    /// let actual = Lints::available().clone().subtract(&to_remove).names();
    /// assert!(!actual.contains(&Lint::SubjectNotSeparateFromBody.name()));
    /// ```
    #[must_use]
    pub fn subtract(&self, other: &Lints) -> Lints {
        Lints::new(self.lints.difference(&other.lints).copied().collect())
    }
}

impl std::iter::IntoIterator for Lints {
    type IntoIter = IntoIter<Lint>;
    type Item = Lint;

    fn into_iter(self) -> Self::IntoIter {
        self.lints.into_iter().collect::<Vec<_>>().into_iter()
    }
}

impl TryFrom<Lints> for String {
    type Error = Error;

    fn try_from(lints: Lints) -> Result<Self, Self::Error> {
        let enabled: Vec<_> = lints.into();

        let config: BTreeMap<String, bool> = Lint::all_lints()
            .map(|x| (x, enabled.contains(&x)))
            .fold(BTreeMap::new(), |mut acc, (lint, state)| {
                acc.insert(lint.to_string(), state);
                acc
            });

        let mut inner: BTreeMap<String, BTreeMap<String, bool>> = BTreeMap::new();
        inner.insert("lint".into(), config);
        let mut output: BTreeMap<String, BTreeMap<String, BTreeMap<String, bool>>> =
            BTreeMap::new();
        output.insert("mit".into(), inner);

        Ok(toml::to_string(&output)?)
    }
}

impl From<Vec<Lint>> for Lints {
    fn from(lints: Vec<Lint>) -> Self {
        Lints::new(lints.into_iter().collect())
    }
}

impl From<Lints> for Vec<Lint> {
    fn from(lints: Lints) -> Self {
        lints.into_iter().collect()
    }
}

impl TryFrom<Vec<&str>> for Lints {
    type Error = Error;

    fn try_from(value: Vec<&str>) -> Result<Self, Self::Error> {
        let lints = value
            .into_iter()
            .try_fold(
                vec![],
                |lints: Vec<Lint>, item_name| -> Result<Vec<Lint>, Error> {
                    let lint = Lint::try_from(item_name)?;

                    Ok(vec![lints, vec![lint]].concat())
                },
            )
            .map(Vec::into_iter)?;

        Ok(Lints::new(lints.collect()))
    }
}

#[cfg(test)]
mod tests {
    use std::{
        collections::BTreeSet,
        convert::{TryFrom, TryInto},
    };

    use indoc::indoc;

    use crate::model::{
        lint::Lint::{
            BodyWiderThan72Characters,
            DuplicatedTrailers,
            JiraIssueKeyMissing,
            PivotalTrackerIdMissing,
            SubjectLongerThan72Characters,
            SubjectNotSeparateFromBody,
        },
        lints::Error,
        Lint,
        Lints,
    };

    #[test]
    fn it_returns_an_error_if_one_of_the_names_is_wrong() {
        let lints = vec![
            "pivotal-tracker-id-missing",
            "broken",
            "jira-issue-key-missing",
        ];
        let actual: Result<Lints, Error> = lints.try_into();

        assert!(actual.is_err());
    }

    #[test]
    fn it_can_construct_itself_from_names() {
        let lints = vec!["pivotal-tracker-id-missing", "jira-issue-key-missing"];

        let mut expected_lints = BTreeSet::new();
        expected_lints.insert(PivotalTrackerIdMissing);
        expected_lints.insert(JiraIssueKeyMissing);

        let expected = Lints::new(expected_lints);
        let actual: Lints = lints.try_into().expect("Lints to have been parsed");

        assert_eq!(expected, actual);
    }

    #[test]
    fn it_can_give_me_an_into_iterator() {
        let mut lints = BTreeSet::new();
        lints.insert(PivotalTrackerIdMissing);
        lints.insert(JiraIssueKeyMissing);
        let input = Lints::new(lints);

        let expected = vec![PivotalTrackerIdMissing, JiraIssueKeyMissing];
        let actual = input.into_iter().collect::<Vec<_>>();

        assert_eq!(expected, actual);
    }

    #[test]
    fn it_can_convert_into_a_vec() {
        let mut lints = BTreeSet::new();
        lints.insert(PivotalTrackerIdMissing);
        lints.insert(JiraIssueKeyMissing);
        let input = Lints::new(lints);

        let expected = vec![PivotalTrackerIdMissing, JiraIssueKeyMissing];
        let actual: Vec<Lint> = input.into();

        assert_eq!(expected, actual);
    }

    #[test]
    fn it_can_give_me_the_names() {
        let mut lints = BTreeSet::new();
        lints.insert(PivotalTrackerIdMissing);
        lints.insert(JiraIssueKeyMissing);
        let input = Lints::new(lints);

        let expected = vec![PivotalTrackerIdMissing.name(), JiraIssueKeyMissing.name()];
        let actual = input.names();

        assert_eq!(expected, actual);
    }

    #[test]
    fn it_can_give_me_the_config_keys() {
        let mut lints = BTreeSet::new();
        lints.insert(PivotalTrackerIdMissing);
        lints.insert(JiraIssueKeyMissing);
        let input = Lints::new(lints);

        let expected = vec![
            PivotalTrackerIdMissing.config_key(),
            JiraIssueKeyMissing.config_key(),
        ];
        let actual = input.config_keys();

        assert_eq!(expected, actual);
    }

    #[test]
    fn can_get_all() {
        let actual = Lints::available();
        let lints = Lint::all_lints().collect();
        let expected = &Lints::new(lints);

        assert_eq!(
            expected, actual,
            "Expected all the lints to be {:?}, instead got {:?}",
            expected, actual
        );
    }

    #[test]
    fn get_toml() {
        let mut lints_on = BTreeSet::new();
        lints_on.insert(DuplicatedTrailers);
        lints_on.insert(SubjectNotSeparateFromBody);
        lints_on.insert(SubjectLongerThan72Characters);
        lints_on.insert(BodyWiderThan72Characters);
        lints_on.insert(PivotalTrackerIdMissing);
        let actual = String::try_from(Lints::new(lints_on)).expect("Failed to serialise");
        let expected = indoc!(
            "
            [mit.lint]
            body-wider-than-72-characters = true
            duplicated-trailers = true
            github-id-missing = false
            jira-issue-key-missing = false
            not-conventional-commit = false
            not-emoji-log = false
            pivotal-tracker-id-missing = true
            subject-line-ends-with-period = false
            subject-line-not-capitalized = false
            subject-longer-than-72-characters = true
            subject-not-separated-from-body = true
            "
        );

        assert_eq!(
            expected, actual,
            "Expected the list of lint identifiers to be {:?}, instead got {:?}",
            expected, actual
        );
    }

    #[test]
    fn two_sets_of_lints_can_be_merged() {
        let mut set_a_lints = BTreeSet::new();
        set_a_lints.insert(PivotalTrackerIdMissing);

        let mut set_b_lints = BTreeSet::new();
        set_b_lints.insert(DuplicatedTrailers);

        let set_a = Lints::new(set_a_lints);
        let set_b = Lints::new(set_b_lints);

        let actual = set_a.merge(&set_b);

        let mut lints = BTreeSet::new();
        lints.insert(DuplicatedTrailers);
        lints.insert(PivotalTrackerIdMissing);
        let expected = Lints::new(lints);

        assert_eq!(
            expected, actual,
            "Expected the list of lint identifiers to be {:?}, instead got {:?}",
            expected, actual
        );
    }

    #[test]
    fn when_merging_overlapping_does_not_lead_to_duplication() {
        let mut set_a_lints = BTreeSet::new();
        set_a_lints.insert(PivotalTrackerIdMissing);

        let mut set_b_lints = BTreeSet::new();
        set_b_lints.insert(DuplicatedTrailers);
        set_b_lints.insert(PivotalTrackerIdMissing);

        let set_a = Lints::new(set_a_lints);
        let set_b = Lints::new(set_b_lints);

        let actual = set_a.merge(&set_b);

        let mut lints = BTreeSet::new();
        lints.insert(DuplicatedTrailers);
        lints.insert(PivotalTrackerIdMissing);
        let expected = Lints::new(lints);

        assert_eq!(
            expected, actual,
            "Expected the list of lint identifiers to be {:?}, instead got {:?}",
            expected, actual
        );
    }

    #[test]
    fn we_can_subtract_lints_from_the_lint_list() {
        let mut set_a_lints = BTreeSet::new();
        set_a_lints.insert(JiraIssueKeyMissing);
        set_a_lints.insert(PivotalTrackerIdMissing);

        let mut set_b_lints = BTreeSet::new();
        set_b_lints.insert(DuplicatedTrailers);
        set_b_lints.insert(PivotalTrackerIdMissing);

        let set_a = Lints::new(set_a_lints);
        let set_b = Lints::new(set_b_lints);

        let actual = set_a.subtract(&set_b);

        let mut lints = BTreeSet::new();
        lints.insert(JiraIssueKeyMissing);
        let expected = Lints::new(lints);

        assert_eq!(
            expected, actual,
            "Expected the list of lint identifiers to be {:?}, instead got {:?}",
            expected, actual
        );
    }
}

#[derive(Error, Debug)]
pub enum Error {
    #[error("{0}")]
    LintNameUnknown(#[from] lint::Error),
    #[error("Failed to parse lint config file: {0}")]
    TomlParse(#[from] toml::de::Error),
    #[error("Failed to read lint config file: {0}")]
    TomlSerialize(#[from] toml::ser::Error),
}