//! Emoji reactions: the fixed set a user can put on an issue, a pull request or a comment, and
//! the summaries the pages show. Stored as the short name (`+1`, `heart`, ...).

use crate::error::{Error, Result};
use crate::model::Id;

/// The fixed reaction set, in the order the pages list them.
#[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord, Hash)]
pub enum Reaction {
    PlusOne,
    MinusOne,
    Laugh,
    Hooray,
    Confused,
    Heart,
    Rocket,
    Eyes,
}

impl Reaction {
    /// Every reaction, in display order.
    pub const ALL: [Reaction; 8] = [
        Reaction::PlusOne,
        Reaction::MinusOne,
        Reaction::Laugh,
        Reaction::Hooray,
        Reaction::Confused,
        Reaction::Heart,
        Reaction::Rocket,
        Reaction::Eyes,
    ];

    /// The short name stored in the database and sent in forms.
    pub fn name(self) -> &'static str {
        match self {
            Reaction::PlusOne => "+1",
            Reaction::MinusOne => "-1",
            Reaction::Laugh => "laugh",
            Reaction::Hooray => "hooray",
            Reaction::Confused => "confused",
            Reaction::Heart => "heart",
            Reaction::Rocket => "rocket",
            Reaction::Eyes => "eyes",
        }
    }

    /// The glyph shown for the reaction.
    pub fn emoji(self) -> &'static str {
        match self {
            Reaction::PlusOne => "\u{1f44d}",
            Reaction::MinusOne => "\u{1f44e}",
            Reaction::Laugh => "\u{1f604}",
            Reaction::Hooray => "\u{1f389}",
            Reaction::Confused => "\u{1f615}",
            Reaction::Heart => "\u{2764}\u{fe0f}",
            Reaction::Rocket => "\u{1f680}",
            Reaction::Eyes => "\u{1f440}",
        }
    }

    /// The reaction with this short name, or `None` for anything outside the set.
    pub fn parse(name: &str) -> Option<Reaction> {
        Reaction::ALL.into_iter().find(|r| r.name() == name)
    }
}

impl std::str::FromStr for Reaction {
    type Err = Error;

    fn from_str(s: &str) -> Result<Self> {
        Reaction::parse(s).ok_or_else(|| Error::Invalid(format!("unknown reaction: {s}")))
    }
}

/// What a reaction is attached to. Pull requests are issue rows, so they use `Issue`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ReactionTarget {
    Issue,
    Comment,
    /// A discussion (store/discussions.rs).
    Discussion,
    /// A discussion comment or reply.
    DiscussionComment,
}

impl ReactionTarget {
    /// The `target_kind` column value.
    pub fn as_str(self) -> &'static str {
        match self {
            ReactionTarget::Issue => "issue",
            ReactionTarget::Comment => "comment",
            ReactionTarget::Discussion => "discussion",
            ReactionTarget::DiscussionComment => "discussion_comment",
        }
    }
}

/// One reaction on one target: how many users chose it, whether the viewer did, and the first
/// usernames (at most ten, earliest reaction first).
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct ReactionSummary {
    pub reaction: Reaction,
    pub count: usize,
    pub reacted_by_viewer: bool,
    pub users: Vec<String>,
}

/// Usernames kept per summary.
pub const SUMMARY_USERS: usize = 10;

/// Summaries of one target, keyed by the target id.
pub type ReactionMap = std::collections::HashMap<Id, Vec<ReactionSummary>>;