//! Discussion types: a per-repo forum next to issues. Storage lives in `store/discussions.rs`.
//! Titles and bodies are checked with the issue validators, since the limits are the same.

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

/// Categories a discussion can be filed under. The `as_str` names are stored.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum DiscussionCategory {
    General,
    Ideas,
    Qa,
    /// Only Maintain or higher may post here.
    Announcements,
}

/// Every category, in the order the chooser shows them.
pub const DISCUSSION_CATEGORIES: &[DiscussionCategory] = &[
    DiscussionCategory::General,
    DiscussionCategory::Ideas,
    DiscussionCategory::Qa,
    DiscussionCategory::Announcements,
];

impl DiscussionCategory {
    /// The stored and URL name.
    pub fn as_str(self) -> &'static str {
        match self {
            DiscussionCategory::General => "general",
            DiscussionCategory::Ideas => "ideas",
            DiscussionCategory::Qa => "qa",
            DiscussionCategory::Announcements => "announcements",
        }
    }

    /// The label people read.
    pub fn label(self) -> &'static str {
        match self {
            DiscussionCategory::General => "General",
            DiscussionCategory::Ideas => "Ideas",
            DiscussionCategory::Qa => "Q&A",
            DiscussionCategory::Announcements => "Announcements",
        }
    }

    /// The category with this stored name, if any.
    pub fn parse(name: &str) -> Option<DiscussionCategory> {
        DISCUSSION_CATEGORIES
            .iter()
            .copied()
            .find(|c| c.as_str() == name)
    }
}

/// One discussion. `answer_comment_id` is set only in Q&A, and names the accepted reply.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct Discussion {
    pub id: String,
    pub repo_id: String,
    pub number: i64,
    pub category: DiscussionCategory,
    pub title: String,
    pub body: String,
    pub author_id: String,
    pub answer_comment_id: Option<String>,
    pub locked: bool,
    pub comment_count: i64,
    pub created_at: String,
    pub updated_at: String,
}

/// A discussion with its author's username, for the list.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DiscussionListItem {
    pub discussion: Discussion,
    pub author: String,
}

/// Why a discussion is in a user's inbox. The `as_str` names are stored in `discussion_notifications`.
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum DiscussionReason {
    /// The user was @mentioned in the discussion or one of its comments.
    Mention,
    /// Someone commented on the user's discussion.
    Reply,
}

impl DiscussionReason {
    /// The stored name.
    pub fn as_str(self) -> &'static str {
        match self {
            DiscussionReason::Mention => "mention",
            DiscussionReason::Reply => "reply",
        }
    }

    /// The reason with this stored name, if any.
    pub fn parse(name: &str) -> Option<DiscussionReason> {
        match name {
            "mention" => Some(DiscussionReason::Mention),
            "reply" => Some(DiscussionReason::Reply),
            _ => None,
        }
    }
}

/// One inbox row for a discussion, joined with its repo and title for the notifications page.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DiscussionNotification {
    pub discussion_id: String,
    pub repo_id: String,
    pub repo_owner: String,
    pub repo_name: String,
    pub number: i64,
    pub title: String,
    pub reason: DiscussionReason,
    /// Username of the last person who acted, if the account still exists.
    pub last_actor_name: Option<String>,
    pub unread: bool,
    pub updated_at: String,
}

/// One comment. A top-level comment has no `parent_id`; a reply names a top-level comment of the
/// same discussion. A deleted comment has `deleted` set and an empty body.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DiscussionComment {
    pub id: String,
    pub discussion_id: String,
    pub parent_id: Option<String>,
    pub author_id: String,
    pub body: String,
    pub created_at: String,
    pub updated_at: String,
    pub deleted: bool,
}

/// Filters and paging for the discussion list. `category: None` lists every category.
#[derive(Debug, Clone, PartialEq, Eq)]
pub struct DiscussionFilter {
    pub category: Option<DiscussionCategory>,
    pub page: u32,
    pub per_page: u32,
}

/// Validates a discussion title (trimmed, returned) and body.
pub fn validate_discussion(title: &str, body: &str) -> Result<String> {
    let title = crate::issues::validate_title(title)?;
    crate::issues::validate_body(body)?;
    Ok(title)
}

/// Validates a comment body: not blank, and within the body limit.
pub fn validate_comment(body: &str) -> Result<()> {
    crate::issues::validate_body(body)?;
    if body.trim().is_empty() {
        return Err(Error::Invalid("comment is empty".into()));
    }
    Ok(())
}