-- name: InsertDMChannel :execresult
INSERT INTO channels (name, type) VALUES ('', 'dm');

-- name: InsertDMParticipants :exec
INSERT INTO dm_participants (channel_id, user_id) VALUES (?, ?), (?, ?);

-- name: InsertDMOpenState :exec
INSERT OR IGNORE INTO dm_open_state (user_id, channel_id) VALUES (?, ?), (?, ?);

-- name: FindExistingDMChannel :one
SELECT dp1.channel_id
FROM dm_participants dp1
JOIN dm_participants dp2 ON dp1.channel_id = dp2.channel_id
JOIN channels c ON c.id = dp1.channel_id
WHERE dp1.user_id = ? AND dp2.user_id = ? AND c.type = 'dm'
LIMIT 1;

-- name: OpenDM :exec
INSERT OR IGNORE INTO dm_open_state (user_id, channel_id) VALUES (?, ?);

-- name: CloseDM :exec
DELETE FROM dm_open_state WHERE user_id = ? AND channel_id = ?;

-- name: IsDMParticipant :one
SELECT user_id FROM dm_participants WHERE user_id = ? AND channel_id = ?;

-- name: GetDMParticipantIDs :many
SELECT user_id FROM dm_participants WHERE channel_id = ?;

-- name: GetUserDMChannels :many
SELECT
    c.id                                          AS channel_id,
    u.id                                          AS recipient_id,
    u.username                                    AS recipient_username,
    COALESCE(u.avatar, '')                        AS recipient_avatar,
    u.status                                      AS recipient_status,
    lm.id                                         AS last_message_id,
    COALESCE(lm.content, '')                      AS last_message,
    COALESCE(lm.timestamp, '')                    AS last_message_at,
    COUNT(CASE WHEN m_unread.id > COALESCE(rs.last_message_id, 0)
               AND m_unread.deleted = 0 THEN 1 END) AS unread_count
FROM dm_open_state dos
JOIN channels c          ON c.id = dos.channel_id AND c.type = 'dm'
JOIN dm_participants dp  ON dp.channel_id = c.id AND dp.user_id != ?
JOIN users u             ON u.id = dp.user_id
LEFT JOIN messages lm    ON lm.id = (
    SELECT MAX(id) FROM messages WHERE channel_id = c.id AND deleted = 0
)
LEFT JOIN messages m_unread ON m_unread.channel_id = c.id
LEFT JOIN read_states rs ON rs.channel_id = c.id AND rs.user_id = ?
WHERE dos.user_id = ?
GROUP BY c.id
ORDER BY COALESCE(lm.timestamp, dos.opened_at) DESC;