-- =============================================================
-- V016: Add platform identity columns and platform_messages table
-- =============================================================
-- Scope: Prepare schema for multi-platform support (Discord, etc).
-- Legacy telegram_* columns are retained for backward compatibility.
-- =============================================================

-- -- Players: platform-agnostic identity
ALTER TABLE players
    ADD COLUMN platform          VARCHAR(50),
    ADD COLUMN external_user_id  VARCHAR(255),
    ADD COLUMN external_username VARCHAR(255);

CREATE UNIQUE INDEX ix_players_platform_external_user_id
    ON players (platform, external_user_id)
    WHERE platform IS NOT NULL AND external_user_id IS NOT NULL;

-- -- Game groups: platform-agnostic identity
ALTER TABLE game_groups
    ADD COLUMN platform           VARCHAR(50),
    ADD COLUMN external_group_id  VARCHAR(255),
    ADD COLUMN external_channel_id VARCHAR(255);

CREATE UNIQUE INDEX ix_game_groups_platform_external_group_id
    ON game_groups (platform, external_group_id)
    WHERE platform IS NOT NULL AND external_group_id IS NOT NULL;

-- -- Backfill existing Telegram data
UPDATE players
   SET platform          = 'Telegram',
       external_user_id  = telegram_id::TEXT,
       external_username = telegram_username
 WHERE platform IS NULL;

UPDATE game_groups
   SET platform          = 'Telegram',
       external_group_id = telegram_chat_id::TEXT
 WHERE platform IS NULL;

-- -- Platform messages: store per-platform message references
CREATE TABLE platform_messages (
    id                   UUID PRIMARY KEY DEFAULT gen_random_uuid(),
    platform             VARCHAR(50) NOT NULL,
    group_id             UUID REFERENCES game_groups(id) ON DELETE CASCADE,
    batch_id             UUID,
    session_id           UUID REFERENCES sessions(id) ON DELETE CASCADE,
    external_channel_id  VARCHAR(255),
    external_thread_id   VARCHAR(255),
    external_message_id  VARCHAR(255) NOT NULL,
    purpose              VARCHAR(50) NOT NULL,
    created_at           TIMESTAMPTZ NOT NULL DEFAULT now()
);

CREATE INDEX ix_platform_messages_group_id     ON platform_messages(group_id);
CREATE INDEX ix_platform_messages_batch_id     ON platform_messages(batch_id);
CREATE INDEX ix_platform_messages_session_id   ON platform_messages(session_id);
CREATE INDEX ix_platform_messages_platform_message
    ON platform_messages (platform, external_message_id);

-- -- Recreate attendance stats function for new columns (prod back-compat)
CREATE OR REPLACE FUNCTION get_group_attendance_stats(p_group_id UUID)
RETURNS TABLE (
    player_id           UUID,
    display_name        VARCHAR,
    telegram_username   VARCHAR,
    total_sessions      BIGINT,
    confirmed_count     BIGINT,
    declined_count      BIGINT,
    no_response_count   BIGINT,
    waitlisted_count    BIGINT,
    cancellation_affected_count BIGINT,
    attendance_rate     NUMERIC
) AS $$
BEGIN
    RETURN QUERY
    WITH player_sessions AS (
        SELECT
            sp.player_id,
            s.id                AS session_id,
            sp.rsvp_status,
            sp.registration_status,
            s.status            AS session_status,
            s.scheduled_at
        FROM session_participants sp
        JOIN sessions s ON s.id = sp.session_id
        WHERE s.group_id = p_group_id
    ),
    player_totals AS (
        SELECT
            ps.player_id,
            COUNT(*) FILTER (WHERE ps.session_status <> 'Cancelled')                      AS total_sessions,
            COUNT(*) FILTER (WHERE ps.rsvp_status = 'Confirmed' AND ps.session_status <> 'Cancelled') AS confirmed_count,
            COUNT(*) FILTER (WHERE ps.rsvp_status = 'Declined' AND ps.session_status <> 'Cancelled')  AS declined_count,
            COUNT(*) FILTER (WHERE ps.rsvp_status = 'Pending' AND ps.scheduled_at < NOW() AND ps.session_status <> 'Cancelled') AS no_response_count,
            COUNT(*) FILTER (WHERE ps.registration_status = 'Waitlisted' AND ps.session_status <> 'Cancelled') AS waitlisted_count,
            COUNT(*) FILTER (WHERE ps.session_status = 'Cancelled')                        AS cancellation_affected_count
        FROM player_sessions ps
        GROUP BY ps.player_id
    )
    SELECT
        pt.player_id,
        p.display_name,
        COALESCE(p.external_username, p.telegram_username) AS telegram_username,
        pt.total_sessions,
        pt.confirmed_count,
        pt.declined_count,
        pt.no_response_count,
        pt.waitlisted_count,
        pt.cancellation_affected_count,
        ROUND(
            100.0 * pt.confirmed_count
            / NULLIF(pt.total_sessions, 0),
            1
        ) AS attendance_rate
    FROM player_totals pt
    JOIN players p ON p.id = pt.player_id
    ORDER BY pt.confirmed_count DESC, pt.total_sessions DESC;
END;
$$ LANGUAGE plpgsql STABLE;