-- Convert the legacy rollup schema without dropping its data. The explicit
-- transaction makes lock/statement timeout failures leave the old table intact.
BEGIN;
LOCK TABLE reporting_events_rollups IN ACCESS EXCLUSIVE MODE;

DO $$
DECLARE
    invalid_periods BIGINT;
    invalid_dimensions BIGINT;
    invalid_counts BIGINT;
    oversized_dimensions BIGINT;
    collision_groups BIGINT;
BEGIN
    SELECT count(*) INTO invalid_periods
    FROM reporting_events_rollups
    WHERE NOT pg_input_is_valid(period, 'date');
    IF invalid_periods > 0 THEN
        RAISE EXCEPTION 'migration 000048: % rollup period value(s) cannot convert to date', invalid_periods
            USING HINT = 'Repair or remove the reported legacy rows explicitly, then retry the migration.';
    END IF;

    SELECT count(*) INTO invalid_dimensions
    FROM reporting_events_rollups
    WHERE NOT pg_input_is_valid(dimension_value, 'bigint');
    IF invalid_dimensions > 0 THEN
        RAISE EXCEPTION 'migration 000048: % rollup dimension_value(s) cannot convert to bigint', invalid_dimensions
            USING HINT = 'Map non-numeric legacy dimensions explicitly, then retry the migration.';
    END IF;

    SELECT count(*) INTO invalid_counts
    FROM reporting_events_rollups
    WHERE metric_name LIKE '%count%' AND NOT pg_input_is_valid(value::text, 'bigint');
    IF invalid_counts > 0 THEN
        RAISE EXCEPTION 'migration 000048: % count value(s) cannot convert losslessly to bigint', invalid_counts
            USING HINT = 'Repair fractional, non-finite, or out-of-range count values, then retry the migration.';
    END IF;

    SELECT count(*) INTO oversized_dimensions
    FROM reporting_events_rollups
    WHERE length(dimension) > 20;
    IF oversized_dimensions > 0 THEN
        RAISE EXCEPTION 'migration 000048: % dimension value(s) exceed the new 20-character limit', oversized_dimensions
            USING HINT = 'Shorten or explicitly map oversized dimensions, then retry the migration.';
    END IF;

    SELECT count(*) INTO collision_groups
    FROM (
        SELECT 1
        FROM reporting_events_rollups
        GROUP BY account_id, period::date, dimension, dimension_value::BIGINT, metric_name
        HAVING count(*) > 1
    ) collisions;
    IF collision_groups > 0 THEN
        RAISE EXCEPTION 'migration 000048: % unique-key collision group(s) appear after type conversion', collision_groups
            USING HINT = 'Merge or choose one legacy row in each collision group explicitly, then retry the migration.';
    END IF;
END $$;

CREATE TABLE reporting_events_rollups_v2 (
    id SERIAL PRIMARY KEY,
    account_id INTEGER NOT NULL,
    date DATE NOT NULL,
    dimension_type VARCHAR(20) NOT NULL,
    dimension_id BIGINT NOT NULL,
    metric VARCHAR(50) NOT NULL,
    count BIGINT NOT NULL DEFAULT 0,
    sum_value DOUBLE PRECISION NOT NULL DEFAULT 0,
    sum_value_business_hours DOUBLE PRECISION NOT NULL DEFAULT 0,
    created_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    updated_at TIMESTAMP WITH TIME ZONE DEFAULT NOW(),
    deleted_at TIMESTAMP WITH TIME ZONE,
    UNIQUE(account_id, date, dimension_type, dimension_id, metric)
);

INSERT INTO reporting_events_rollups_v2 (
    id, account_id, date, dimension_type, dimension_id, metric, count,
    sum_value, sum_value_business_hours, created_at, updated_at, deleted_at
)
SELECT
    id,
    account_id,
    period::date,
    dimension,
    dimension_value::BIGINT,
    metric_name,
    CASE WHEN metric_name LIKE '%count%' THEN value::BIGINT ELSE 1 END,
    value,
    COALESCE(value_in_business_hours, 0),
    created_at,
    updated_at,
    deleted_at
FROM reporting_events_rollups;

SELECT setval(
    pg_get_serial_sequence('reporting_events_rollups_v2', 'id'),
    COALESCE((SELECT MAX(id) FROM reporting_events_rollups_v2), 1),
    EXISTS (SELECT 1 FROM reporting_events_rollups_v2)
);

DROP TABLE reporting_events_rollups;
ALTER TABLE reporting_events_rollups_v2 RENAME TO reporting_events_rollups;
ALTER INDEX reporting_events_rollups_v2_pkey RENAME TO reporting_events_rollups_pkey;
CREATE INDEX idx_reporting_events_rollups_deleted_at ON reporting_events_rollups(deleted_at);
CREATE INDEX idx_reporting_events_rollups_account_id ON reporting_events_rollups(account_id) WHERE deleted_at IS NULL;
CREATE INDEX idx_reporting_events_rollups_date ON reporting_events_rollups(date) WHERE deleted_at IS NULL;
CREATE INDEX idx_reporting_events_rollups_dimension ON reporting_events_rollups(dimension_type, dimension_id) WHERE deleted_at IS NULL;
COMMIT;