/*
 * Function to create a child table in a time-based partition set
 */
CREATE FUNCTION create_time_partition (p_parent_table text, p_control text, p_interval interval, p_datetime_string text, p_partition_times timestamp[]) RETURNS text
    LANGUAGE plpgsql SECURITY DEFINER
    AS $$
DECLARE

v_all                           text[] := ARRAY['SELECT', 'INSERT', 'UPDATE', 'DELETE', 'TRUNCATE', 'REFERENCES', 'TRIGGER'];
v_grantees                      text[];
v_job_id                        bigint;
v_jobmon_schema                 text;
v_old_search_path               text;
v_parent_grant                  record;
v_parent_owner                  text;
v_partition_name                text;
v_partition_timestamp_end       timestamp;
v_partition_timestamp_start     timestamp;
v_quarter                       text;
v_revoke                        text[];
v_step_id                       bigint;
v_tablename                     text;
v_trunc_value                   text;
v_time                          timestamp;
v_year                          text;

BEGIN

SELECT nspname INTO v_jobmon_schema FROM pg_namespace n, pg_extension e WHERE e.extname = 'pg_jobmon' AND e.extnamespace = n.oid;
IF v_jobmon_schema IS NOT NULL THEN
    SELECT current_setting('search_path') INTO v_old_search_path;
    EXECUTE 'SELECT set_config(''search_path'',''@extschema@,'||v_jobmon_schema||''',''false'')';
END IF;

SELECT tableowner INTO v_parent_owner FROM pg_tables WHERE schemaname ||'.'|| tablename = p_parent_table;

FOREACH v_time IN ARRAY p_partition_times LOOP    

    v_partition_name := p_parent_table || '_p';

    IF p_interval = '1 year' OR p_interval = '1 month' OR p_interval = '1 day' OR p_interval = '1 hour' OR p_interval = '30 mins' OR p_interval = '15 mins' THEN
        v_partition_name := v_partition_name || to_char(v_time, 'YYYY');
        v_trunc_value := 'year';

        IF p_interval = '1 month' OR p_interval = '1 day' OR p_interval = '1 hour' OR p_interval = '30 mins' OR p_interval = '15 mins' THEN
            v_partition_name := v_partition_name || '_' || to_char(v_time, 'MM');
            v_trunc_value := 'month';

            IF p_interval = '1 day' OR p_interval = '1 hour' OR p_interval = '30 mins' OR p_interval = '15 mins' THEN
                v_partition_name := v_partition_name || '_' || to_char(v_time, 'DD');
                    v_trunc_value := 'day';

                IF p_interval = '1 hour' OR p_interval = '30 mins' OR p_interval = '15 mins' THEN
                    v_partition_name := v_partition_name || '_' || to_char(v_time, 'HH24');
                    IF p_interval <> '30 mins' AND p_interval <> '15 mins' THEN
                        v_partition_name := v_partition_name || '00';
                        v_trunc_value := 'hour';
                    ELSIF p_interval = '15 mins' THEN
                        IF date_part('minute', v_time) < 15 THEN
                            v_partition_name := v_partition_name || '00';
                        ELSIF date_part('minute', v_time) >= 15 AND date_part('minute', v_time) < 30 THEN
                            v_partition_name := v_partition_name || '15';
                        ELSIF date_part('minute', v_time) >= 30 AND date_part('minute', v_time) < 45 THEN
                            v_partition_name := v_partition_name || '30';
                        ELSE
                            v_partition_name := v_partition_name || '45';
                        END IF;
                        v_trunc_value := 'minute';
                    ELSIF p_interval = '30 mins' THEN
                        IF date_part('minute', v_time) < 30 THEN
                            v_partition_name := v_partition_name || '00';
                        ELSE
                            v_partition_name := v_partition_name || '30';
                        END IF;
                        v_trunc_value := 'minute';
                    END IF;
                END IF; -- end hour IF      
            END IF; -- end day IF
        END IF; -- end month IF
    ELSIF p_interval = '1 week' THEN
        v_partition_name := v_partition_name || to_char(v_time, 'IYYY') || 'w' || to_char(v_time, 'IW');
        v_trunc_value := 'week';
    END IF; -- end year/week IF

    -- pull out datetime portion of last partition's tablename if it matched one of the above partitioning intervals
    IF v_trunc_value IS NOT NULL THEN
        v_partition_timestamp_start := date_trunc(v_trunc_value, to_timestamp(substring(v_partition_name from char_length(p_parent_table||'_p')+1), p_datetime_string));
        v_partition_timestamp_end := date_trunc(v_trunc_value, to_timestamp(substring(v_partition_name from char_length(p_parent_table||'_p')+1), p_datetime_string) + p_interval);
    END IF;

    -- "Q" is ignored in to_timestamp, so handle special case
    IF p_interval = '3 months' THEN
        v_year := to_char(v_time, 'YYYY');
        v_quarter := to_char(v_time, 'Q');
        v_partition_name := v_partition_name || v_year || 'q' || v_quarter;
        v_trunc_value := 'quarter';
        CASE 
            WHEN v_quarter = '1' THEN
                v_partition_timestamp_start := date_trunc(v_trunc_value, to_timestamp(v_year || '-01-01', 'YYYY-MM-DD'));
            WHEN v_quarter = '2' THEN
                v_partition_timestamp_start := date_trunc(v_trunc_value, to_timestamp(v_year || '-04-01', 'YYYY-MM-DD'));
            WHEN v_quarter = '3' THEN
                v_partition_timestamp_start := date_trunc(v_trunc_value, to_timestamp(v_year || '-07-01', 'YYYY-MM-DD'));
            WHEN v_quarter = '4' THEN
                v_partition_timestamp_start := date_trunc(v_trunc_value, to_timestamp(v_year || '-10-01', 'YYYY-MM-DD'));
        END CASE;
        v_partition_timestamp_end := date_trunc(v_trunc_value, (v_partition_timestamp_start + p_interval));
    END IF;

    SELECT schemaname ||'.'|| tablename INTO v_tablename FROM pg_catalog.pg_tables WHERE schemaname ||'.'|| tablename = v_partition_name;
    IF v_tablename IS NOT NULL THEN
        CONTINUE;
    END IF;

    IF v_jobmon_schema IS NOT NULL THEN
        v_job_id := add_job('PARTMAN CREATE TABLE: '||p_parent_table);
        v_step_id := add_step(v_job_id, 'Creating new partition '||v_partition_name||' with interval from '||v_partition_timestamp_start||' to '||(v_partition_timestamp_end-'1sec'::interval));
    END IF;

    IF position('.' in p_parent_table) > 0 THEN 
        v_tablename := substring(v_partition_name from position('.' in v_partition_name)+1);
    END IF;

    EXECUTE 'CREATE TABLE '||v_partition_name||' (LIKE '||p_parent_table||' INCLUDING DEFAULTS INCLUDING INDEXES)';
    EXECUTE 'ALTER TABLE '||v_partition_name||' ADD CONSTRAINT '||v_tablename||'_partition_check
        CHECK ('||p_control||'>='||quote_literal(v_partition_timestamp_start)||' AND '||p_control||'<'||quote_literal(v_partition_timestamp_end)||')';
    EXECUTE 'ALTER TABLE '||v_partition_name||' INHERIT '||p_parent_table;

    FOR v_parent_grant IN 
        SELECT array_agg(DISTINCT privilege_type::text ORDER BY privilege_type::text) AS types, grantee
        FROM information_schema.table_privileges 
        WHERE table_schema ||'.'|| table_name = p_parent_table
        GROUP BY grantee 
    LOOP
        EXECUTE 'GRANT '||array_to_string(v_parent_grant.types, ',')||' ON '||v_partition_name||' TO '||v_parent_grant.grantee;
        SELECT array_agg(r) INTO v_revoke FROM (SELECT unnest(v_all) AS r EXCEPT SELECT unnest(v_parent_grant.types)) x;
        IF v_revoke IS NOT NULL THEN
            EXECUTE 'REVOKE '||array_to_string(v_revoke, ',')||' ON '||v_partition_name||' FROM '||v_parent_grant.grantee||' CASCADE';
        END IF;
        v_grantees := array_append(v_grantees, v_parent_grant.grantee::text);
    END LOOP;
    -- Revoke all privileges from roles that have none on the parent
    IF v_grantees IS NOT NULL THEN
        SELECT array_agg(r) INTO v_revoke FROM (
            SELECT DISTINCT grantee::text AS r FROM information_schema.table_privileges WHERE table_schema ||'.'|| table_name = v_partition_name
            EXCEPT
            SELECT unnest(v_grantees)) x;
        IF v_revoke IS NOT NULL THEN
            EXECUTE 'REVOKE ALL ON '||v_partition_name||' FROM '||array_to_string(v_revoke, ',');
        END IF;
    END IF;

    EXECUTE 'ALTER TABLE '||v_partition_name||' OWNER TO '||v_parent_owner;

    IF v_jobmon_schema IS NOT NULL THEN
        PERFORM update_step(v_step_id, 'OK', 'Done');
        PERFORM close_job(v_job_id);
    END IF;

END LOOP;

IF v_jobmon_schema IS NOT NULL THEN
    EXECUTE 'SELECT set_config(''search_path'','''||v_old_search_path||''',''false'')';
END IF;

RETURN v_partition_name;

EXCEPTION
    WHEN OTHERS THEN
        IF v_jobmon_schema IS NOT NULL THEN
            EXECUTE 'SELECT set_config(''search_path'',''@extschema@,'||v_jobmon_schema||''',''false'')';
            IF v_job_id IS NULL THEN
                v_job_id := add_job('PARTMAN CREATE TABLE: '||p_parent_table);
                v_step_id := add_step(v_job_id, 'Partition maintenance for table '||p_parent_table||' failed');
            ELSIF v_step_id IS NULL THEN
                v_step_id := add_step(v_job_id, 'EXCEPTION before first step logged');
            END IF;
            PERFORM update_step(v_step_id, 'CRITICAL', 'ERROR: '||coalesce(SQLERRM,'unknown'));
            PERFORM fail_job(v_job_id);
            EXECUTE 'SELECT set_config(''search_path'','''||v_old_search_path||''',''false'')';
        END IF;
        RAISE EXCEPTION '%', SQLERRM;
END
$$;