SET FOREIGN_KEY_CHECKS = 0;

-- Tables no longer needed as old dashboard is decomm.
DROP TABLE IF EXISTS guild_users;
DROP TABLE IF EXISTS events;

CREATE TABLE users_new
(
    id                     BIGINT UNSIGNED,
    dm_channel             INT UNSIGNED UNIQUE              NOT NULL,
    timezone               VARCHAR(32)                      NOT NULL DEFAULT 'UTC',
    meridian_time          BOOLEAN                          NOT NULL DEFAULT 0,
    allowed_dm             BOOLEAN                          NOT NULL DEFAULT 1,
    reset_inputs_on_create BOOLEAN                          NOT NULL DEFAULT 0,
    use_browser_timezone   BOOLEAN                          NOT NULL DEFAULT 1,
    dashboard_color_scheme ENUM ('system', 'light', 'dark') NOT NULL DEFAULT 'system',

    PRIMARY KEY (id),
    FOREIGN KEY `fk_user_dm_channel` (dm_channel) REFERENCES channels (id) ON DELETE RESTRICT,
    -- Useful for bot startup times
    INDEX `index_timezone` (timezone)
);

-- Drop some dodgy user entries
CREATE TEMPORARY TABLE dupe_users
SELECT dm_channel
FROM users u1
WHERE (SELECT COUNT(1) FROM users u2 WHERE u2.dm_channel = u1.dm_channel) > 1;

DELETE
FROM users
WHERE dm_channel IN (SELECT * FROM dupe_users);

INSERT INTO users_new (id, dm_channel, timezone, meridian_time, allowed_dm)
SELECT `user`, dm_channel, IFNULL(timezone, 'UTC'), meridian_time, allowed_dm
FROM users;

-- Add new user ID column
ALTER TABLE todos
    ADD COLUMN user_id_new BIGINT UNSIGNED;
-- Reference new table with new column
ALTER TABLE todos
    ADD CONSTRAINT `todos_user_fk` FOREIGN KEY (user_id_new) REFERENCES users_new (id) ON DELETE SET NULL ON UPDATE CASCADE;
-- Populate new column
UPDATE todos
SET user_id_new = (SELECT user FROM users WHERE id = user_id);
-- Prepare a statement to drop the old constraint
SELECT @todo_query := CONCAT('ALTER TABLE todos DROP FOREIGN KEY ', constraint_name)
FROM information_schema.key_column_usage
WHERE constraint_schema = DATABASE()
  AND table_name = 'todos'
  AND column_name = 'user_id';
PREPARE todo_stmt FROM @todo_query;
EXECUTE todo_stmt;
-- Drop old column
ALTER TABLE todos
    DROP COLUMN user_id;
-- Rename new column
ALTER TABLE todos RENAME COLUMN user_id_new TO user_id;

-- Add new set by column
ALTER TABLE reminders
    ADD COLUMN set_by_new BIGINT UNSIGNED;
-- Reference new table with new column
ALTER TABLE reminders
    ADD CONSTRAINT `reminders_set_by_fk` FOREIGN KEY (set_by_new) REFERENCES users_new (id) ON DELETE SET NULL ON UPDATE CASCADE;
-- Populate new column
UPDATE reminders
SET set_by_new = (SELECT user FROM users WHERE id = set_by);
-- Prepare a statement to drop the old constraint
SELECT @reminders_query := CONCAT('ALTER TABLE reminders DROP FOREIGN KEY ', constraint_name)
FROM information_schema.key_column_usage
WHERE constraint_schema = DATABASE()
  AND table_name = 'reminders'
  AND column_name = 'set_by';
PREPARE reminders_stmt FROM @reminders_query;
EXECUTE reminders_stmt;
-- Drop old column
ALTER TABLE reminders
    DROP COLUMN set_by;
ALTER TABLE reminders RENAME COLUMN set_by_new TO set_by;

-- Swap the tables
DROP TABLE users;
RENAME TABLE users_new TO users;

SET FOREIGN_KEY_CHECKS = 1;