Migration for skill persistence fixes (no hash yet).

server/src/migrations/V46__skill_persistence.sql

@@ -1 +1,46 @@
--- Do skill group change of storing (available_exp, available_sp, and earned_sp) to earned_exp
+-- Temp table relating earned_sp to the experience required to earn that amount
+CREATE TEMP TABLE _sp_series
+(
+	earned_sp INT NOT NULL,
+	exp INT NOT NULL
+);
+
+-- Inserts exp values corresponding to the sp value
+INSERT INTO _sp_series
+WITH RECURSIVE sp_series(earned_sp, exp) AS (
+    SELECT 0, 0
+    UNION ALL
+    -- Function is the same as function in skillset/mod.rs in fn skill_point_cost as of time of this migration
+    -- though slightly modified to account for sqlite lacking functions for floor and exp
+    -- Floor modification is replacing floor(a) with round(a - 0.5)
+    -- Exp mofidication is replacing exp(-a) with 1 / (2^(a*1.442695)) where 1.442695 = log(e)/log(2)
+    SELECT earned_sp + 1,
+           exp +
+			CASE
+				WHEN earned_sp < 300
+					THEN (10 * ROUND(((1000.0 / 10.0) / (1.0 + 1.0 / (1 << ROUND((0.125 * (earned_sp + 1) * 1.442695) - 0.1)) * (1000.0 / 70.0 - 1.0))) - 0.5))
+				ELSE
+					1000
+			END
+    FROM sp_series
+    -- Only create table up to maximum value of earned_sp in database
+    WHERE earned_sp <= (SELECT MAX(earned_sp) FROM skill_group)
+)
+SELECT	earned_sp,
+		exp
+FROM sp_series;
+
+-- Update exp column with new values, add the leftover exp to this value
+UPDATE skill_group
+SET exp = skill_group.exp + (SELECT exp FROM _sp_series WHERE earned_sp = skill_group.earned_sp);
+
+-- Progress in earned_sp is tracked in exp now
+ALTER TABLE skill_group DROP COLUMN earned_sp;
+-- available_sp is now useless to track, automatically recalculated when loading persisted skill groups
+ALTER TABLE skill_group DROP COLUMN available_sp;
+-- Skills are now tracked in skill_group table as a json blob. Json blob fine since we can just invalidate and let people respec if it doesn't deserialize
+ALTER TABLE skill_group ADD COLUMN skills TEXT DEFAULT "" NOT NULL;
+-- Skills now tracked in skill_group table, can ust drop
+DROP TABLE skill;
+-- Temp table no longer needed, drop it
+DROP TABLE _sp_series;