From c75f43589d83938727603be46a971c049a6946de Mon Sep 17 00:00:00 2001
From: Tor Andersson <tor@ccxvii.net>
Date: Tue, 26 Jul 2022 20:28:38 +0200
Subject: retreat rework

---
 rules.js | 71 +++++++++++++++++++++++++++++++++++++++-------------------------
 1 file changed, 43 insertions(+), 28 deletions(-)

diff --git a/rules.js b/rules.js
index 3f4afab..c3e7fb5 100644
--- a/rules.js
+++ b/rules.js
@@ -1129,6 +1129,7 @@ function search_move_retreat(start, speed) {
 }
 
 function search_withdraw(start, speed) {
+	// TODO: who+bonus instead of start+speed
 	update_supply_networks()
 	let sline = is_axis_player() ? game.axis_supply_line : game.allied_supply_line
 	let sdist = is_axis_player() ? distance_to[EL_AGHEILA] : distance_to[ALEXANDRIA]
@@ -1141,6 +1142,7 @@ function search_withdraw(start, speed) {
 }
 
 function search_withdraw_retreat(start, speed) {
+	// TODO: who+bonus instead of start+speed
 	update_supply_networks()
 	let sline = is_axis_player() ? game.axis_supply_line : game.allied_supply_line
 	let sdist = is_axis_player() ? distance_to[EL_AGHEILA] : distance_to[ALEXANDRIA]
@@ -1983,9 +1985,19 @@ function move_unit(who, to, speed) {
 
 // === RETREAT ===
 
-// TODO: check each unit separately to deal with fortress supply
+function friendly_unit_supply_line(who) {
+	update_supply_networks()
+	return is_axis_player() ? game.axis_supply_line : game.allied_supply_line
+}
+
+function friendly_unit_supply_distance(who) {
+	return is_axis_player() ? distance_to[EL_AGHEILA] : distance_to[ALEXANDRIA]
+}
 
-function can_disengage_and_withdraw(from, sline, sdist) {
+function can_unit_disengage_and_withdraw(who) {
+	let sline = friendly_unit_supply_line(who)
+	let sdist = friendly_unit_supply_distance(who)
+	let from = unit_hex(who)
 	let result = false
 	for_each_adjacent_hex(from, to => {
 		let side = to_side_id(from, to)
@@ -1996,6 +2008,15 @@ function can_disengage_and_withdraw(from, sline, sdist) {
 	return result
 }
 
+function can_all_disengage_and_withdraw(from) {
+	let result = true
+	for_each_undisrupted_friendly_unit_in_hex(from, u => {
+		if (result && !can_unit_disengage_and_withdraw(u))
+			result = false
+	})
+	return result
+}
+
 function can_disengage_and_move(from) {
 	let result = false
 	for_each_adjacent_hex(from, to => {
@@ -2006,40 +2027,39 @@ function can_disengage_and_move(from) {
 	return result
 }
 
-function can_retreat_with_group_move(from, sline, sdist) {
+function can_retreat_with_group_move(from) {
 	if (!is_battle_hex(from) || set_has(game.partial_retreats, from))
 		return false
-	if (game.turn_option === 'pass') {
-		// no partial retreats!
-		if (has_undisrupted_and_moved_friendly_unit_in_hex(from))
-			return false
-		return can_disengage_and_withdraw(from, sline, sdist)
-	} else {
+
+	if (game.turn_option === 'pass')
+		return can_all_disengage_and_withdraw(from)
+	else
 		return can_disengage_and_move(from)
-	}
+}
+
+function can_all_disengage_and_move_to(from) {
+	let result = true
+	for_each_undisrupted_friendly_unit_in_hex(from, u => {
+		if (result && !can_unit_disengage_and_withdraw(u))
+			result = false
+	})
+	return result
 }
 
 function can_retreat_with_regroup_move(from, to, rommel) {
 	if (!is_battle_hex(from) || set_has(game.partial_retreats, from))
 		return false
+
 	let speed = max_speed_of_undisrupted_and_unmoved_friendly_unit_in_hex(from)
 	if (game.turn_option === 'pass')
 		search_withdraw_retreat(from, speed + rommel)
 	else
 		search_move_retreat(from, speed + rommel)
 
-	let result = 0
-	for_each_undisrupted_friendly_unit_in_hex(from, u => {
-		if (can_move_to(to, unit_speed(u) + rommel) && !is_unit_moved(u))
-			result |= 1
-		else
-			result |= 2
-	})
-
 	if (game.turn_option === 'pass')
-		return result === 1
+		return can_all_disengage_and_move_to(from, to, rommel)
 	else
-		return result === 1 || result === 3
+		return can_any_disengage_and_move_to(from, to, rommel)
 }
 
 function can_select_retreat_hex() {
@@ -2050,11 +2070,11 @@ function can_select_retreat_hex() {
 	let rommel2 = (game.rommel === 2) ? 1 : 0
 
 	if (!game.to1 && game.from1)
-		if (can_retreat_with_group_move(game.from1, sline, sdist))
+		if (can_retreat_with_group_move(game.from1)
 			return true
 
 	if (!game.to2 && game.from2)
-		if (can_retreat_with_group_move(game.from2, sline, sdist))
+		if (can_retreat_with_group_move(game.from2)
 			return true
 
 	if (game.to1) {
@@ -2307,13 +2327,8 @@ states.refuse_battle = {
 	inactive: "refuse battle",
 	prompt() {
 		view.prompt = `You may Refuse Battle.`
-
-		update_supply_networks()
-		let sline = is_axis_player() ? game.axis_supply_line : game.allied_supply_line
-		let sdist = is_axis_player() ? distance_to[EL_AGHEILA] : distance_to[ALEXANDRIA]
-
 		for (let x of game.active_battles)
-			if (can_disengage_and_withdraw(x, sline, sdist))
+			if (can_all_disengage_and_withdraw(x))
 				gen_action_hex(x)
 		gen_action('next')
 	},
-- 
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