/*
 * age-circs.sql - a script to age/anonymize patrons' circ history.
 *
 * Copyright (C) 2008 Equinox Software, Inc.
 * Copyright (C) 2014 BC Libraries Cooperative
 * Author: Jeff Davis <jdavis@sitka.bclibraries.ca>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 */

BEGIN;

\echo 'utility function for testing interval'
CREATE OR REPLACE FUNCTION sitka.is_valid_interval(TEXT) RETURNS BOOL AS $$
BEGIN
  RETURN CASE WHEN $1::INTERVAL IS NULL THEN FALSE ELSE TRUE END;
EXCEPTION WHEN OTHERS THEN
  RETURN FALSE;
END;
$$ LANGUAGE plpgsql;

\echo 'exception matrix table'
CREATE TABLE IF NOT EXISTS sitka.age_circ_exception_matrix (
  id SERIAL NOT NULL,
  active BOOLEAN NOT NULL DEFAULT TRUE,
  org_unit INT REFERENCES actor.org_unit (id) ON DELETE CASCADE DEFERRABLE INITIALLY DEFERRED,
  grp INT REFERENCES permission.grp_tree (id) ON DELETE CASCADE DEFERRABLE INITIALLY DEFERRED
);

\echo 'function for finding exceptions'
CREATE OR REPLACE FUNCTION sitka.has_age_circ_exception(circ_id BIGINT) RETURNS BOOL AS $$
DECLARE
  potential_aged_circ  action.circulation%ROWTYPE;
  usr                  actor.usr%ROWTYPE;
  matching_exceptions  INT;
BEGIN
  matching_exceptions := 0;
  -- TODO: should we match exceptions against the entire circ chain?
  SELECT * INTO potential_aged_circ FROM action.circulation WHERE id = circ_id;
  SELECT * INTO usr FROM actor.usr WHERE id = potential_aged_circ.usr;
  SELECT count(*) INTO matching_exceptions
    FROM sitka.age_circ_exception_matrix m
      LEFT JOIN permission.grp_ancestors_distance( usr.profile ) upgad ON m.grp = upgad.id
      LEFT JOIN actor.org_unit_ancestors_distance( potential_aged_circ.circ_lib ) ctoua ON m.org_unit = ctoua.id
    WHERE m.active
      AND (m.grp IS NULL      OR upgad.id IS NOT NULL)
      AND (m.org_unit IS NULL OR ctoua.id IS NOT NULL);
  IF matching_exceptions > 0 THEN
    RETURN TRUE;
  END IF;
  RETURN FALSE;
END;
$$ LANGUAGE plpgsql;


-- function for testing whether circ should be aged
CREATE OR REPLACE FUNCTION sitka.age_circ_test(circ_id BIGINT, cutoff DATE, skip_basic_tests BOOL DEFAULT FALSE) RETURNS BOOLEAN AS $$
DECLARE
  potential_aged_circ  action.circulation%ROWTYPE;
  balance              NUMERIC;
  circ_chain_finish    TIMESTAMP WITH TIME ZONE;
  usr_keep_start       TEXT;
  usr_keep_age         TEXT;
  usr_keep_date        DATE;
  circ_cutoff          DATE;
  has_exception        BOOL;
BEGIN

  -- use the cutoff param as the default cutoff date for the current circ
  circ_cutoff := cutoff;

  -- grab our circ
  SELECT * INTO potential_aged_circ FROM action.circulation WHERE id = circ_id;

  -- When you are batch-deleting old circs, you would normally gather a list of
  -- closed circs with no outstanding balance, and then pass each of those
  -- circs through the age_circ_test function to check for further exceptions.
  -- In that situation, we don't want to waste time and processing power
  -- re-checking whether the circs are closed or have outstanding balances,
  -- so we provide an option to skip those basic tests.
  IF skip_basic_tests IS FALSE THEN
    IF potential_aged_circ.xact_finish IS NULL THEN
      RETURN FALSE;
    END IF;
    SELECT balance_owed INTO balance FROM money.materialized_billable_xact_summary WHERE id = circ_id;
    IF balance != 0 THEN
      RETURN FALSE;
    END IF;
  END IF;
    
  -- renewals create a "chain" of circs; find the last circ in the current chain
  SELECT MAX(xact_finish) INTO circ_chain_finish FROM action.circ_chain(potential_aged_circ.id);

  -- user's history.circ.retention_start setting, if any, overrides default cutoff date
  SELECT value INTO usr_keep_start FROM actor.usr_setting WHERE usr = potential_aged_circ.usr AND name = 'history.circ.retention_start'; IF usr_keep_start IS NOT NULL THEN
    circ_cutoff := oils_json_to_text(usr_keep_start)::DATE;
  END IF;

  -- trim cutoff to user's history.circ.retention_age, if set
  SELECT oils_json_to_text(value) INTO usr_keep_age FROM actor.usr_setting WHERE usr = potential_aged_circ.usr AND name = 'history.circ.retention_age';
  IF usr_keep_age IS NOT NULL AND sitka.is_valid_interval(usr_keep_age) IS TRUE THEN
    SELECT (now() - usr_keep_age::INTERVAL)::DATE INTO usr_keep_date;
    IF usr_keep_date IS NOT NULL AND usr_keep_date < circ_cutoff THEN
      circ_cutoff := usr_keep_date;
    END IF;
  END IF;

  -- don't age the chain if the last circ is later than the cutoff
  IF circ_chain_finish IS NULL OR circ_chain_finish > circ_cutoff THEN
    RETURN FALSE;
  END IF;

  -- don't age the circ if it matches a defined exception
  has_exception := FALSE;
  SELECT * INTO has_exception FROM sitka.has_age_circ_exception(potential_aged_circ.id);
  IF has_exception IS TRUE THEN
    RETURN FALSE;
  END IF;

  -- this circ passes all our tests
  RETURN TRUE;

EXCEPTION WHEN OTHERS THEN
  RAISE WARNING 'Cannot age circ %, error during age circ test', circ_id;
  RETURN FALSE;
END;
$$ LANGUAGE plpgsql;


\echo 'table for aged circs'
CREATE TABLE IF NOT EXISTS sitka.aged_circs (
  id BIGINT NOT NULL,
  delete_date DATE NOT NULL
);

\echo 'table for aged circ count'
CREATE TABLE IF NOT EXISTS sitka.aged_circs_by_user (
  usr BIGINT NOT NULL,
  month INT NOT NULL,
  year INT NOT NULL,
  count INT NOT NULL DEFAULT 0,
  UNIQUE (usr, month, year)
);

CREATE OR REPLACE FUNCTION sitka.age_circs(cutoff DATE, max_circ_count BIGINT) RETURNS INT AS $$
DECLARE
  today                DATE;
  potential_aged_circ  BIGINT;
  can_age_circ         BOOL;
  circs_aged           INT;
BEGIN
  today := now()::DATE;

  -- TODO: more strictness here?
  CREATE TEMPORARY TABLE circs_to_age AS
    SELECT c.id FROM action.circulation c
    JOIN money.materialized_billable_xact_summary m ON c.id = m.id
    WHERE c.xact_finish IS NOT NULL AND c.xact_finish < cutoff
    AND m.balance_owed = 0
    ORDER BY c.xact_start
    LIMIT max_circ_count;

  -- for each circ that we might want to age...
  FOR potential_aged_circ IN
    SELECT id FROM circs_to_age
  LOOP

    can_age_circ := NULL;

    -- test whether we can age each circ
    SELECT * INTO can_age_circ FROM sitka.age_circ_test(potential_aged_circ, cutoff, TRUE);
    IF can_age_circ IS FALSE OR can_age_circ IS NULL THEN
      DELETE FROM circs_to_age WHERE id = potential_aged_circ;
    END IF;

  END LOOP;

  -- update user circ counts
  CREATE TEMPORARY TABLE usr_circ_totals AS
    SELECT a.usr, (EXTRACT(month FROM a.xact_start)) AS month,
      (EXTRACT(year FROM a.xact_start)) AS year, count(*) AS fresh_circs
    FROM action.circulation a 
    JOIN circs_to_age b ON a.id = b.id
    GROUP BY 1,2,3;
  UPDATE sitka.aged_circs_by_user a SET count = count + b.fresh_circs
    FROM usr_circ_totals b WHERE a.usr = b.usr
    AND a.month = b.month AND a.year = b.year;
  INSERT INTO sitka.aged_circs_by_user (usr, month, year, count)
    SELECT usr, month, year, fresh_circs FROM usr_circ_totals
    WHERE (usr, month, year) NOT IN (SELECT usr, month, year FROM sitka.aged_circs_by_user);
  DROP TABLE usr_circ_totals;

  -- old circs may have a null copy_location, but action.aged_circulation doesn't allow that
  UPDATE action.circulation a SET copy_location = 1
    FROM circs_to_age b WHERE a.id = b.id
    AND a.copy_location IS NULL;

  -- this will set off the age_circs trigger on action.circulation
  DELETE FROM action.circulation WHERE id IN (SELECT id FROM circs_to_age);

  UPDATE action.aged_circulation
  SET usr_post_code = NULL, usr_birth_year = NULL
  WHERE usr_post_code IS NOT NULL OR usr_birth_year IS NOT NULL;

  INSERT INTO sitka.aged_circs (id, delete_date)
    SELECT id, today FROM circs_to_age;

  SELECT count(*) INTO circs_aged FROM circs_to_age;
  DROP TABLE circs_to_age;
  RETURN circs_aged;
END; $$ LANGUAGE plpgsql;

SAVEPOINT ready;

---- To actually age circs, do something like the following:
--SELECT count(*) FROM action.aged_circulation;
--SELECT * FROM sitka.age_circs( (now() - '2 years'::INTERVAL)::DATE, NULL );
--SELECT count(*) FROM action.aged_circulation;
--
--\echo 'SAVEPOINT done:'
--SAVEPOINT done;
--
--COMMIT;