From c8135d811d8930e06f32cb7e0d5a8f46d507b25c Mon Sep 17 00:00:00 2001
From: Dave Morriss <Dave.Morriss@gmail.com>
Date: Fri, 20 Oct 2023 13:37:37 +0100
Subject: [PATCH] Bug fix of query to find days to next free slot

templates/queries-index-mysql.tpl.html,
templates/queries-index-sqlite.tpl.html:
    Rather than driving the search from the eps table itself, this
    version makes a counter that generates slot numbers from the current
    show number to the highest show number in the system. The counter is
    used to interrogate the eps table to find the first empty slot. This
    sems to be a more reliable approach (but time will tell).
---
 templates/queries-index-mysql.tpl.html  | 44 +++++++++++++------------
 templates/queries-index-sqlite.tpl.html |  4 +--
 2 files changed, 25 insertions(+), 23 deletions(-)

diff --git a/templates/queries-index-mysql.tpl.html b/templates/queries-index-mysql.tpl.html
index 9172907..5c4ad9b 100644
--- a/templates/queries-index-mysql.tpl.html
+++ b/templates/queries-index-mysql.tpl.html
@@ -1,29 +1,31 @@
 <!--% query_next_available_episode = '
-    WITH next_id AS (
-	SELECT id, id + 1 AS id_next, date as last_date
-	    FROM eps
-	    WHERE eps.date > NOW()
+    WITH RECURSIVE
+    min_id AS (
+	SELECT max(id) AS start_id FROM eps WHERE date <= NOW()
     ),
-    free_slot AS (
+    max_id AS (
+	SELECT max(id) AS end_id FROM eps
+    ),
+    cnt(x) AS (
+	SELECT start_id from min_id
+	UNION ALL
+	SELECT x+1 FROM cnt
+	WHERE x+1 <= (SELECT end_id FROM max_id)
+    ),
+    first_empty AS (
 	SELECT
-	    last_date AS prev_date,
-	    CASE
-		WHEN DAYOFWEEK(last_date) = 6
-		    THEN 3
-		ELSE 1
-	    END AS date_offset,
-	    next_id.id_next AS empty_slot
-	FROM next_id
-	LEFT JOIN eps ON next_id.id_next = eps.id
-	WHERE eps.id IS NULL
-	ORDER BY next_id.id
-	LIMIT 1
+	    cnt.x AS id
+	FROM cnt
+	LEFT JOIN eps e ON cnt.x = e.id
+	WHERE e.id IS NULL
     )
     SELECT
-	empty_slot AS next_id,
-	ADDDATE(prev_date,date_offset) AS next_date,
-	DATEDIFF(ADDDATE(prev_date,date_offset),NOW()) AS delta_days
-    FROM free_slot
+	fe.id as next_id,
+	(SELECT DATE(ADDDATE(e2.date,1)) from eps e2 where e2.id = fe.id-1) as next_date,
+	DATEDIFF((SELECT ADDDATE(e3.date,1) from eps e3 where e3.id = fe.id-1),now()) AS delta_days
+    FROM first_empty AS fe
+    LEFT JOIN eps e1 ON fe.id = e1.id
+    LIMIT 1
 '
 %-->
 <!--% query_latest_episodes = '
diff --git a/templates/queries-index-sqlite.tpl.html b/templates/queries-index-sqlite.tpl.html
index a68b526..0674bdb 100644
--- a/templates/queries-index-sqlite.tpl.html
+++ b/templates/queries-index-sqlite.tpl.html
@@ -20,8 +20,8 @@
 	WHERE e.id IS NULL
     )
     SELECT
-	fe.id as empty_slot,
-	(SELECT date(eps.date,\'+1 day\') from eps where id = fe.id-1) as slot_date,
+	fe.id as next_id,
+	(SELECT date(eps.date,\'+1 day\') from eps where id = fe.id-1) as next_date,
 	printf(\'%i\',abs(julianday((SELECT date(eps.date,\'+1 day\') from eps where id = fe.id-1)) - julianday(\'now\') + 1)) AS delta_days
     FROM first_empty AS fe
     LEFT JOIN eps e ON fe.id = e.id