Under-the-hood improvements around Speed and Years (#13482)

* Mini-refactor: YearsPerTurn can be immutable, support destructuring

* Lint: Replace non-rendering unicode points with escapes

* Wiki: Describe `Speed.turns` better

* A unit test for turn-to-year conversion

* Faster turn-to-year math

* Readability changes

core/src/com/unciv/logic/GameInfo.kt

@@ -304,21 +304,7 @@ class GameInfo : IsPartOfGameInfoSerialization, HasGameInfoSerializationVersion
         return turns + (totalTurns * startPercent / 100)
     }
 
-    fun getYear(turnOffset: Int = 0): Int {
-        val turn = getEquivalentTurn() + turnOffset
-        val yearsToTurn = speed.yearsPerTurn
-        var year = speed.startYear
-        var i = 0
-        var yearsPerTurn: Float
-
-        while (i < turn) {
-            yearsPerTurn = (yearsToTurn.firstOrNull { i < it.untilTurn }?.yearInterval ?: yearsToTurn.last().yearInterval)
-            year += yearsPerTurn
-            ++i
-        }
-
-        return year.toInt()
-    }
+    fun getYear(turnOffset: Int = 0) = speed.turnToYear(getEquivalentTurn() + turnOffset).toInt()
 
     fun calculateChecksum(): String {
         val oldChecksum = checksum

core/src/com/unciv/models/ruleset/Speed.kt

@@ -29,11 +29,39 @@ class Speed : RulesetObject(), IsPartOfGameInfoSerialization {
     var startYear: Float = -4000f
     var turns: ArrayList<HashMap<String, Float>> = ArrayList()
 
-    data class YearsPerTurn(val yearInterval: Float, val untilTurn: Int)
-    val yearsPerTurn: ArrayList<YearsPerTurn> by lazy {
-        ArrayList<YearsPerTurn>().apply {
-            turns.forEach { this.add(YearsPerTurn(it["yearsPerTurn"]!!, it["untilTurn"]!!.toInt())) }
+    // These could be private but for RulesetValidator checking it
+    data class YearsPerTurn(val yearInterval: Float, val untilTurn: Int) {
+        internal constructor(rawRow: HashMap<String, Float>) : this(rawRow["yearsPerTurn"]!!, rawRow["untilTurn"]!!.toInt())
+    }
+    val yearsPerTurn: ArrayList<YearsPerTurn> by lazy { turns.mapTo(ArrayList()) { YearsPerTurn(it) } }
+
+    /** End of defined turn range, used for starting Era's `startPercent` calculation */
+    fun numTotalTurns(): Int = yearsPerTurn.last().untilTurn
+
+    /** Calculate a Year from a turn number.
+     *
+     *  Note that years can have fractional parts and the integer part of the year for two consecutive turns _can_ be equal,
+     *  but Unciv currently has no way to display that. This is left as Float to enable such display in the future,
+     *  maybe as months, or even the 18+1 'months' of the mayan Haab'.
+     *
+     *  @param turn The logical turn number, any offset from starting in an advanced Era already added in
+     */
+    fun turnToYear(turn: Int): Float {
+        var year = startYear
+        var intervalStartTurn = 0
+        val lastIntervalEndTurn = numTotalTurns()
+        for ((turnLength, intervalEndTurn) in yearsPerTurn) {
+            if (intervalStartTurn >= turn) break // ensure year isn't projected backwards for negative `turn`
+            if (turn <= intervalEndTurn || intervalEndTurn == lastIntervalEndTurn) {
+                // We can interpolate linearly within this interval and are done
+                year += (turn - intervalStartTurn) * turnLength
+                break
+            }
+            // Accumulate total length in years of this interval and move on to the following intervals.
+            year += (intervalEndTurn - intervalStartTurn) * turnLength
+            intervalStartTurn = intervalEndTurn
         }
+        return year
     }
 
     val statCostModifiers: EnumMap<Stat, Float> by lazy {
@@ -81,6 +109,4 @@ class Speed : RulesetObject(), IsPartOfGameInfoSerialization {
         yield(FormattedLine("Start year: [" + ("{[${abs(startYear).toInt()}] " + (if (startYear < 0) "BC" else "AD") + "}]").tr()))
     }.toList()
     override fun getSortGroup(ruleset: Ruleset): Int = (modifier * 1000).toInt()
-
-    fun numTotalTurns(): Int = yearsPerTurn.last().untilTurn
 }

core/src/com/unciv/ui/screens/worldscreen/topbar/WorldScreenTopBarResources.kt

@@ -84,7 +84,7 @@ internal class WorldScreenTopBarResources(topbar: WorldScreenTopBar) : ScalingTa
         val yearText = YearTextUtil.toYearText(
             civInfo.gameInfo.getYear(), civInfo.isLongCountDisplay()
         )
-        turnsLabel.setText(Fonts.turn + " " + civInfo.gameInfo.turns.tr() + " | " + yearText)
+        turnsLabel.setText(Fonts.turn + "\u2004" + civInfo.gameInfo.turns.tr() + "\u2004|\u2004" + yearText) // U+2004: Three-Per-Em Space
 
         resourcesWrapper.clearChildren()
         val civResources = civInfo.getCivResourcesByName()

core/src/com/unciv/ui/screens/worldscreen/topbar/WorldScreenTopBarStats.kt

@@ -60,7 +60,7 @@ internal class WorldScreenTopBarStats(topbar: WorldScreenTopBar) : ScalingTableW
         isTransform = false
 
         defaults().pad(defaultTopPad, defaultHorizontalPad, defaultBottomPad, defaultHorizontalPad)
-        
+
         fun addStat(
             icon: String,
             label: Label,
@@ -124,7 +124,7 @@ internal class WorldScreenTopBarStats(topbar: WorldScreenTopBar) : ScalingTableW
         resetScale()
 
         val nextTurnStats = civInfo.stats.statsForNextTurn
-        
+
         goldLabel.setText(civInfo.gold.tr())
         goldPerTurnLabel.setText(rateLabel(nextTurnStats.gold))
 
@@ -155,9 +155,9 @@ internal class WorldScreenTopBarStats(topbar: WorldScreenTopBar) : ScalingTableW
         // kotlin Float division by Zero produces `Float.POSITIVE_INFINITY`, not an exception
         val turnsToNextPolicy = (civInfo.policies.getCultureNeededForNextPolicy() - civInfo.policies.storedCulture) / nextTurnStats.culture
         cultureString += when {
-            turnsToNextPolicy <= 0f -> " (!)" // Can choose policy right now
-            nextTurnStats.culture <= 0 -> " (${Fonts.infinity})" // when you start the game, you're not producing any culture
-            else -> " (" + Fonts.turn + " " + ceil(turnsToNextPolicy).toInt().tr() + ")"
+            turnsToNextPolicy <= 0f -> "\u2004(!)" // Can choose policy right now
+            nextTurnStats.culture <= 0 -> "\u2004(${Fonts.infinity})" // when you start the game, you're not producing any culture
+            else -> "\u2004(" + Fonts.turn + "\u2009" + ceil(turnsToNextPolicy).toInt().tr() + ")" // U+2004: Three-Per-Em Space, U+2009: Thin Space
         }
         return cultureString
     }

docs/Modders/Mod-file-structure/5-Miscellaneous-JSON-files.md

@@ -105,12 +105,16 @@ Each speed can have the following attributes:
 
 ### Time interval per turn
 
-The "turns" attribute defines the number of years passed between turns. The attribute consists of a list of hashmaps, each hashmaps in turn having 2 required attributes: "yearsPerTurn" (Float) and "untilTurn" (Integer)
+The "turns" attribute defines the number of years passing between turns. The attribute consists of a list of objects, each having 2 required attributes: "yearsPerTurn" (Float) and "untilTurn" (Integer)
 
-| Attribute    | Type    | Default  | Notes                                                                                    |
-|--------------|---------|----------|------------------------------------------------------------------------------------------|
-| yearsPerTurn | Integer | Required | Number of years passed between turns                                                     |
-| untilTurn    | Integer | Required | Which turn that this "speed" is active until (if it is the last object, this is ignored) |
+| Attribute    | Type    | Default  | Notes                                                      |
+|--------------|---------|----------|------------------------------------------------------------|
+| yearsPerTurn | Integer | Required | Number of years passing between turns                      |
+| untilTurn    | Integer | Required | End of this interval (if it is the last object, see below) |
+
+For each row, "yearsPerTurn" is applied up to the "untilTurn"-1 to "untilTurn" step.
+The last "untilTurn" in the list is ignored for year calculation, that is, if a game passes that turn number, years continue to increment by the "yearsPerTurn" of the last entry.
+However, this is used when starting a game in a later Era: Era.startPercent is relative to the last "untilTurn".
 
 The code below is an example of a valid "turns" definition and it specifies that the first 50 turns of a game last for 60 years each, then the next 30 turns (and any played after the 80th) last for 40 years each.
 

tests/src/com/unciv/testing/BasicTests.kt

@@ -4,6 +4,7 @@ package com.unciv.testing
 import com.badlogic.gdx.Gdx
 import com.unciv.Constants
 import com.unciv.UncivGame
+import com.unciv.logic.GameInfo
 import com.unciv.models.metadata.BaseRuleset
 import com.unciv.models.metadata.GameSettings
 import com.unciv.models.ruleset.Ruleset
@@ -328,4 +329,50 @@ class BasicTests {
         }
         return stats
     }
+
+    @Test
+    fun turnToYearTest() {
+        // Pretty random choice, but ensures 'turn > last definition' and 'float to int rounding' is tested
+        val testData = mapOf(
+            "Quick" to mapOf(
+                0 to -4000,
+                100 to 800,
+                200 to 1860,
+                300 to 2020,
+                5000 to 6720
+            ),
+            "Standard" to mapOf(
+                99 to -400,
+                479 to 2039,
+                999 to 2299
+            ),
+            "Epic" to mapOf(
+                66 to -2350,
+                666 to 2008,
+                4242 to 3796
+            ),
+            "Marathon" to mapOf(
+                222 to -1280,
+                1111 to 1978,
+                1400 to 2041
+            ),
+        )
+        val gameInfo = GameInfo()
+        gameInfo.ruleset = ruleset
+        Assert.assertEquals(0, ruleset.eras[gameInfo.gameParameters.startingEra]!!.startPercent)
+        var fails = 0
+
+        for ((speedName, tests) in testData) {
+            val speed = ruleset.speeds[speedName]!!
+            gameInfo.speed = speed
+            for ((turn, expected) in tests) {
+                val actual = gameInfo.getYear(turn)
+                if (actual == expected) continue
+                println("speed: $speedName, turn: $turn, expected: $expected, actual: $actual")
+                fails++
+            }
+        }
+
+        Assert.assertEquals("Some turn to year conversions do not match", 0, fails)
+    }
 }