/*
 * Create the trigger function for the parent table of an id-based partition set
 */
CREATE FUNCTION create_function_id(p_parent_table text, p_job_id bigint DEFAULT NULL) RETURNS void
    LANGUAGE plpgsql SECURITY DEFINER
    AS $$
DECLARE

ex_context                      text;
ex_detail                       text;
ex_hint                         text;
ex_message                      text;
v_control                       text;
v_count                         int;
v_current_partition_name        text;
v_current_partition_id          bigint;
v_datetime_string               text;
v_final_partition_id            bigint;
v_function_name                 text;
v_higher_parent                 text := p_parent_table;
v_id_position                   int;
v_job_id                        bigint;
v_jobmon                        text;
v_jobmon_schema                 text;
v_last_partition                text;
v_max                           bigint;
v_next_partition_id             bigint;
v_next_partition_name           text;
v_old_search_path               text;
v_parent_schema                 text;
v_parent_tablename              text;
v_partition_interval            bigint;
v_premake                       int;
v_prev_partition_id             bigint;
v_prev_partition_name           text;
v_row_max_id                    record;
v_run_maint                     boolean;
v_step_id                       bigint;
v_top_parent                    text := p_parent_table;
v_trig_func                     text;

BEGIN

SELECT partition_interval::bigint
    , control
    , premake
    , use_run_maintenance
    , jobmon
INTO v_partition_interval
    , v_control
    , v_premake
    , v_run_maint
    , v_jobmon
FROM @extschema@.part_config 
WHERE parent_table = p_parent_table
AND partition_type = 'id';

IF NOT FOUND THEN
    RAISE EXCEPTION 'ERROR: no config found for %', p_parent_table;
END IF;

SELECT partition_tablename INTO v_last_partition FROM @extschema@.show_partitions(p_parent_table, 'DESC') LIMIT 1;

IF v_jobmon THEN
    SELECT nspname INTO v_jobmon_schema FROM pg_catalog.pg_namespace n, pg_catalog.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 format('SELECT set_config(%L, %L, %L)', 'search_path', '@extschema@,'||v_jobmon_schema, 'false');
    END IF;
END IF;

IF v_jobmon_schema IS NOT NULL THEN
    IF p_job_id IS NULL THEN
        v_job_id := add_job(format('PARTMAN CREATE FUNCTION: %s', p_parent_table));
    ELSE
        v_job_id = p_job_id;
    END IF;
    v_step_id := add_step(v_job_id, format('Creating partition function for table %s', p_parent_table));
END IF;

SELECT schemaname, tablename INTO v_parent_schema, v_parent_tablename FROM pg_catalog.pg_tables WHERE schemaname ||'.'|| tablename = p_parent_table;
v_function_name := @extschema@.check_name_length(v_parent_tablename, '_part_trig_func', FALSE);

-- Get the highest level top parent if multi-level partitioned in order to get proper max() value below
WHILE v_higher_parent IS NOT NULL LOOP -- initially set in DECLARE
    WITH top_oid AS (
        SELECT i.inhparent AS top_parent_oid
        FROM pg_catalog.pg_inherits i
        JOIN pg_catalog.pg_class c ON c.oid = i.inhrelid
        JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
        WHERE n.nspname||'.'||c.relname = v_higher_parent
    ) SELECT n.nspname||'.'||c.relname
    INTO v_higher_parent
    FROM pg_catalog.pg_class c
    JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace
    JOIN top_oid t ON c.oid = t.top_parent_oid
    JOIN @extschema@.part_config p ON p.parent_table = n.nspname||'.'||c.relname
    WHERE p.partition_type = 'id';

    IF v_higher_parent IS NOT NULL THEN
        -- initially set in DECLARE
        v_top_parent := v_higher_parent;
    END IF;

END LOOP;

-- Loop through child tables starting from highest to get current max value in partition set
-- Avoids doing a scan on entire partition set and/or getting any values accidentally in parent.
FOR v_row_max_id IN
    SELECT partition_schemaname, partition_tablename FROM @extschema@.show_partitions(v_top_parent, 'DESC')
LOOP
        EXECUTE format('SELECT max(%I) FROM %I.%I', v_control, v_row_max_id.partition_schemaname, v_row_max_id.partition_tablename) INTO v_max;
        IF v_max IS NOT NULL THEN
            EXIT;
        END IF;
END LOOP;
IF v_max IS NULL THEN
    v_max := 0;
END IF;
v_current_partition_id = v_max - (v_max % v_partition_interval);
v_next_partition_id := v_current_partition_id + v_partition_interval;
v_current_partition_name := @extschema@.check_name_length(v_parent_tablename, v_current_partition_id::text, TRUE);

v_trig_func := format('CREATE OR REPLACE FUNCTION %I.%I() RETURNS trigger LANGUAGE plpgsql AS $t$ 
    DECLARE
        v_count                     int;
        v_current_partition_id      bigint;
        v_current_partition_name    text;
        v_id_position               int;
        v_last_partition            text := %L;
        v_next_partition_id         bigint;
        v_next_partition_name       text;
        v_partition_created         boolean;
    BEGIN
    IF TG_OP = ''INSERT'' THEN 
        IF NEW.%I >= %s AND NEW.%I < %s THEN '
            , v_parent_schema
            , v_function_name
            , v_last_partition
            , v_control
            , v_current_partition_id
            , v_control
            , v_next_partition_id
        );
        SELECT count(*) INTO v_count FROM pg_catalog.pg_tables WHERE schemaname = v_parent_schema AND tablename = v_current_partition_name;
        IF v_count > 0 THEN
            v_trig_func := v_trig_func || format(' 
            INSERT INTO %I.%I VALUES (NEW.*); ', v_parent_schema, v_current_partition_name);
        ELSE
            v_trig_func := v_trig_func || '
            -- Child table for current values does not exist in this partition set, so write to parent
            RETURN NEW;';
        END IF;

    FOR i IN 1..v_premake LOOP
        v_prev_partition_id := v_current_partition_id - (v_partition_interval * i);
        v_next_partition_id := v_current_partition_id + (v_partition_interval * i);
        v_final_partition_id := v_next_partition_id + v_partition_interval;
        v_prev_partition_name := @extschema@.check_name_length(v_parent_tablename, v_prev_partition_id::text, TRUE);
        v_next_partition_name := @extschema@.check_name_length(v_parent_tablename, v_next_partition_id::text, TRUE);

        -- Check that child table exist before making a rule to insert to them.
        -- Handles edge case of changing premake immediately after running create_parent(). 
        SELECT count(*) INTO v_count FROM pg_catalog.pg_tables WHERE schemaname = v_parent_schema AND tablename = v_prev_partition_name;
        IF v_count > 0 THEN
            -- Only handle previous partitions if they're starting above zero
            IF v_prev_partition_id >= 0 THEN
                v_trig_func := v_trig_func ||format('
        ELSIF NEW.%I >= %s AND NEW.%I < %s THEN 
            INSERT INTO %I.%I VALUES (NEW.*); '
                , v_control
                , v_prev_partition_id
                , v_control
                , v_prev_partition_id + v_partition_interval
                , v_parent_schema
                , v_prev_partition_name
            );
            END IF;
        END IF;

        SELECT count(*) INTO v_count FROM pg_catalog.pg_tables WHERE schemaname ||'.'||tablename = v_next_partition_name;
        IF v_count > 0 THEN
            v_trig_func := v_trig_func ||format('
        ELSIF NEW.%I >= %s AND NEW.%I < %s THEN 
            INSERT INTO %I.%I VALUES (NEW.*);'
                , v_control
                , v_next_partition_id
                , v_control
                , v_final_partition_id
                , v_parent_schema
                , v_next_partition_name
            );
        END IF;
    END LOOP;
    v_trig_func := v_trig_func ||format('
        ELSE
            v_current_partition_id := NEW.%I - (NEW.%I %% %s);
            v_current_partition_name := @extschema@.check_name_length(%L, v_current_partition_id::text, TRUE);
            SELECT count(*) INTO v_count FROM pg_catalog.pg_tables WHERE schemaname = %L AND tablename = v_current_partition_name;
            IF v_count > 0 THEN 
                EXECUTE format(''INSERT INTO %%I.%%I VALUES($1.*)'', %L, v_current_partition_name) USING NEW;
            ELSE
                RETURN NEW;
            END IF;
        END IF;'
            , v_control
            , v_control
            , v_partition_interval
            , v_parent_tablename
            , v_parent_schema
            , v_parent_schema
        );

    IF v_run_maint IS FALSE THEN
        v_trig_func := v_trig_func ||format('
        v_current_partition_id := NEW.%I - (NEW.%I %% %s);
        IF (NEW.%I %% %s) > (%s / 2) THEN
            v_id_position := (length(v_last_partition) - position(''p_'' in reverse(v_last_partition))) + 2;
            v_next_partition_id := (substring(v_last_partition from v_id_position)::bigint) + %s;
            WHILE ((v_next_partition_id - v_current_partition_id) / %s) <= %s LOOP 
                v_partition_created := @extschema@.create_partition_id(%L, ARRAY[v_next_partition_id]);
                IF v_partition_created THEN
                    PERFORM @extschema@.create_function_id(%L);
                    PERFORM @extschema@.apply_constraints(%L);
                END IF;
                v_next_partition_id := v_next_partition_id + %s;
            END LOOP;
        END IF;'
            , v_control
            , v_control
            , v_partition_interval
            , v_control
            , v_partition_interval
            , v_partition_interval
            , v_partition_interval
            , v_partition_interval
            , v_premake
            , p_parent_table
            , p_parent_table
            , p_parent_table
            , v_partition_interval
        );
    END IF;

    v_trig_func := v_trig_func ||'
    END IF; 
    RETURN NULL; 
    END $t$;';

EXECUTE v_trig_func;

IF v_jobmon_schema IS NOT NULL THEN
    PERFORM update_step(v_step_id, 'OK', format('Added function for current id interval: %s to %s', v_current_partition_id, v_final_partition_id-1));
END IF;

IF v_jobmon_schema IS NOT NULL THEN
    PERFORM close_job(v_job_id);
    EXECUTE format('SELECT set_config(%L, %L, %L)', 'search_path', v_old_search_path, 'false');
END IF;

EXCEPTION
    WHEN OTHERS THEN
        GET STACKED DIAGNOSTICS ex_message = MESSAGE_TEXT,
                                ex_context = PG_EXCEPTION_CONTEXT,
                                ex_detail = PG_EXCEPTION_DETAIL,
                                ex_hint = PG_EXCEPTION_HINT;
        IF v_jobmon_schema IS NOT NULL THEN
            IF v_job_id IS NULL THEN
                EXECUTE format('SELECT %I.add_job(''PARTMAN CREATE FUNCTION: %s'')', v_jobmon_schema, p_parent_table) INTO v_job_id;
                EXECUTE format('SELECT %I.add_step(%s, ''Partition function maintenance for table %s failed'')', v_jobmon_schema, v_job_id, p_parent_table) INTO v_step_id;
            ELSIF v_step_id IS NULL THEN
                EXECUTE format('SELECT %I.add_step(%s, ''EXCEPTION before first step logged'')', v_jobmon_schema, v_job_id) INTO v_step_id;
            END IF;
            EXECUTE format('SELECT %I.update_step(%s, ''CRITICAL'', %L)', v_jobmon_schema, v_step_id, 'ERROR: '||coalesce(SQLERRM,'unknown'));
            EXECUTE format('SELECT %I.fail_job(%s)', v_jobmon_schema, v_job_id);
        END IF;
        RAISE EXCEPTION '%
CONTEXT: %
DETAIL: %
HINT: %', ex_message, ex_context, ex_detail, ex_hint;
END
$$;