//! Per-user read state — maps to `message_read_state` table.
//!
//! Tracks the last message each user has read in each channel.
//! Used for unread badges, "mark as read", and notification suppression.
//! One row per (channel_id, user_id), upserted on each read.

use chrono::{DateTime, Utc};
use serde::{Deserialize, Serialize};
use uuid::Uuid;

/// A user's read progress in one channel.
#[derive(Debug, Clone, Serialize, Deserialize, sqlx::FromRow)]
pub struct MessageReadState {
    pub id: Uuid,
    pub channel_id: Uuid,
    pub user_id: Uuid,
    /// The last message id the user has read (cursor).
    pub last_read_message_id: Option<Uuid>,
    /// When the user last opened / scrolled through this channel.
    pub last_read_at: Option<DateTime<Utc>>,
    /// Total unread message count (denormalized for fast badge display).
    pub unread_count: i64,
    /// Total unread @mentions for this channel (denormalized).
    pub unread_mentions: i64,
    pub created_at: DateTime<Utc>,
    pub updated_at: DateTime<Utc>,
}

/// Summary of a user's read state for the client-side channel list.
///
/// Includes unread badge count and mention count for a single channel.
#[derive(Debug, Clone, Serialize, Deserialize)]
pub struct ReadStateSummary {
    pub channel_id: Uuid,
    pub unread_count: i64,
    pub unread_mentions: i64,
    pub has_unread: bool,
}

impl From<MessageReadState> for ReadStateSummary {
    fn from(s: MessageReadState) -> Self {
        Self {
            channel_id: s.channel_id,
            unread_count: s.unread_count,
            unread_mentions: s.unread_mentions,
            has_unread: s.unread_count > 0,
        }
    }
}

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

    #[test]
    fn test_read_state_summary_conversion() {
        let state = MessageReadState {
            id: Uuid::now_v7(),
            channel_id: Uuid::now_v7(),
            user_id: Uuid::now_v7(),
            last_read_message_id: None,
            last_read_at: None,
            unread_count: 5,
            unread_mentions: 2,
            created_at: Utc::now(),
            updated_at: Utc::now(),
        };

        let summary: ReadStateSummary = state.into();
        assert!(summary.has_unread);
        assert_eq!(summary.unread_count, 5);
        assert_eq!(summary.unread_mentions, 2);
    }

    #[test]
    fn test_read_state_summary_no_unread() {
        let state = MessageReadState {
            id: Uuid::now_v7(),
            channel_id: Uuid::now_v7(),
            user_id: Uuid::now_v7(),
            last_read_message_id: None,
            last_read_at: None,
            unread_count: 0,
            unread_mentions: 0,
            created_at: Utc::now(),
            updated_at: Utc::now(),
        };

        let summary: ReadStateSummary = state.into();
        assert!(!summary.has_unread);
    }
}