/* 
 * Apply constraints managed by partman extension
 */
CREATE FUNCTION apply_constraints(p_parent_table text, p_child_table text DEFAULT NULL, p_debug BOOLEAN DEFAULT FALSE) RETURNS void
    LANGUAGE plpgsql
    AS $$
DECLARE

v_child_table                   text;
v_child_tablename               text;
v_col                           text;
v_constraint_cols               text[];
v_constraint_col_type           text;
v_constraint_name               text;
v_datetime_string               text;
v_existing_constraint_name      text;
v_job_id                        bigint;
v_jobmon_schema                 text;
v_last_partition                text;
v_last_partition_id             int; 
v_last_partition_timestamp      timestamp;
v_constraint_values             record;
v_old_search_path               text;
v_parent_schema                 text;
v_parent_tablename              text;
v_part_interval                 text;
v_partition_suffix              text;
v_premake                       int;
v_sql                           text;
v_step_id                       bigint;
v_suffix_position               int;
v_type                          text;

BEGIN

SELECT type
    , part_interval
    , premake
    , datetime_string
    , last_partition
    , constraint_cols
INTO v_type
    , v_part_interval
    , v_premake
    , v_datetime_string
    , v_last_partition
    , v_constraint_cols
FROM @extschema@.part_config
WHERE parent_table = p_parent_table;

IF v_constraint_cols IS NULL THEN
    IF p_debug THEN
        RAISE NOTICE 'Given parent table (%) not set up for constraint management (constraint_cols is NULL)', p_parent_table;
    END IF;
    -- Returns silently to allow this function to be simply called by maintenance processes without having to check if config options are set.
    RETURN;
END IF;

SELECT schemaname, tablename INTO v_parent_schema, v_parent_tablename FROM pg_tables WHERE schemaname ||'.'|| tablename = p_parent_table;

-- If p_child_table is null, figure out the partition that is the one right before the premake value backwards.
IF p_child_table IS NULL THEN
    
    v_suffix_position := (length(v_last_partition) - position('p_' in reverse(v_last_partition))) + 2;

    IF v_type IN ('time-static', 'time-dynamic') THEN
        v_last_partition_timestamp := to_timestamp(substring(v_last_partition from v_suffix_position), v_datetime_string);
        v_partition_suffix := to_char(v_last_partition_timestamp - (v_part_interval::interval * ((v_premake * 2)+1) ), v_datetime_string);
    ELSIF v_type IN ('id-static', 'id-dynamic') THEN
        v_last_partition_id := substring(v_last_partition from v_suffix_position)::int;
        v_partition_suffix := (v_last_partition_id - (v_part_interval::int * ((v_premake * 2)+1) ))::text; 
    END IF;
    
    v_child_table := @extschema@.check_name_length(v_parent_tablename, v_parent_schema, v_partition_suffix, TRUE);

ELSE
    v_child_table := p_child_table;
END IF;
    
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 'SELECT set_config(''search_path'',''@extschema@,'||v_jobmon_schema||''',''false'')';
END IF;

IF v_jobmon_schema IS NOT NULL THEN
    v_job_id := add_job('PARTMAN CREATE CONSTRAINT: '||p_parent_table);
    v_step_id := add_step(v_job_id, 'Checking if target child table exists');
END IF;

SELECT tablename INTO v_child_tablename FROM pg_catalog.pg_tables WHERE schemaname ||'.'|| tablename = v_child_table;
IF v_child_tablename IS NULL THEN
    IF v_jobmon_schema IS NOT NULL THEN
        PERFORM update_step(v_step_id, 'NOTICE', 'Target child table ('||v_child_table||') does not exist. Skipping constraint creation.');
        PERFORM close_job(v_job_id);
        EXECUTE 'SELECT set_config(''search_path'','''||v_old_search_path||''',''false'')';
    END IF;
    IF p_debug THEN
        RAISE NOTICE 'Target child table (%) does not exist. Skipping constraint creation.', v_child_table;
    END IF;
    RETURN;
ELSE
    IF v_jobmon_schema IS NOT NULL THEN
        PERFORM update_step(v_step_id, 'OK', 'Done');
    END IF;
END IF;

FOREACH v_col IN ARRAY v_constraint_cols
LOOP
    SELECT c.conname
    INTO v_existing_constraint_name
    FROM pg_catalog.pg_constraint c 
        JOIN pg_catalog.pg_attribute a ON c.conrelid = a.attrelid 
    WHERE conrelid = v_child_table::regclass 
        AND c.conname LIKE 'partmanconstr_%'
        AND c.contype = 'c' 
        AND a.attname = v_col
        AND ARRAY[a.attnum] <@ c.conkey 
        AND a.attisdropped = false;

    IF v_jobmon_schema IS NOT NULL THEN
        v_step_id := add_step(v_job_id, 'Applying new constraint on column: '||v_col);
    END IF;

    IF v_existing_constraint_name IS NOT NULL THEN
        IF v_jobmon_schema IS NOT NULL THEN
            PERFORM update_step(v_step_id, 'NOTICE', 'Partman managed constraint already exists on this table ('||v_child_table||') and column ('||v_col||'). Skipping creation.');
        END IF;
        RAISE WARNING 'Partman managed constraint already exists on this table (%) and column (%). Skipping creation.', v_child_table, v_col ;
        CONTINUE;
    END IF;

    -- Ensure column name gets put on end of constraint name to help avoid naming conflicts 
    v_constraint_name := @extschema@.check_name_length('partmanconstr_'||v_child_tablename, p_suffix := '_'||v_col);

    EXECUTE 'SELECT min('||v_col||')::text AS min, max('||v_col||')::text AS max FROM '||v_child_table INTO v_constraint_values;

    IF v_constraint_values IS NOT NULL THEN
        v_sql := concat('ALTER TABLE ', v_child_table, ' ADD CONSTRAINT ', v_constraint_name
            , ' CHECK (', v_col, ' >= ', quote_literal(v_constraint_values.min), ' AND '
            , v_col, ' <= ', quote_literal(v_constraint_values.max), ')' );
        IF p_debug THEN
            RAISE NOTICE 'Constraint creation query: %', v_sql;
        END IF;
        EXECUTE v_sql;

        IF v_jobmon_schema IS NOT NULL THEN
            PERFORM update_step(v_step_id, 'OK', 'New constraint created: '||v_sql);
        END IF;
    ELSE
        IF p_debug THEN
            RAISE NOTICE 'Given column (%) contains all NULLs. No constraint created', v_col;
        END IF;
        IF v_jobmon_schema IS NOT NULL THEN
            PERFORM update_step(v_step_id, 'NOTICE', 'Given column ('||v_col||') contains all NULLs. No constraint created');
        END IF;
    END IF;

END LOOP;

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

EXCEPTION
    WHEN OTHERS THEN
        IF v_jobmon_schema IS NOT NULL THEN
            IF v_job_id IS NULL THEN
                EXECUTE 'SELECT '||v_jobmon_schema||'.add_job(''PARTMAN CREATE CONSTRAINT: '||p_parent_table||')' INTO v_job_id;
                EXECUTE 'SELECT '||v_jobmon_schema||'.add_step('||v_job_id||', ''Partition constraint maintenance for table '||p_parent_table||' failed'')' INTO v_step_id;
            ELSIF v_step_id IS NULL THEN
                EXECUTE 'SELECT '||v_jobmon_schema||'.add_step('||v_job_id||', ''EXCEPTION before first step logged'')' INTO v_step_id;
            END IF;
            EXECUTE 'SELECT '||v_jobmon_schema||'.update_step('||v_step_id||', ''CRITICAL'', ''ERROR: '||coalesce(SQLERRM,'unknown')||''')';
            EXECUTE 'SELECT '||v_jobmon_schema||'.fail_job('||v_job_id||')';
        END IF;
        RAISE EXCEPTION '%', SQLERRM;
END
$$;