Withdrawal path search.

1 files changed, 98 insertions, 1 deletions

diff --git a/rules.js b/rules.js
index ff66875..bf8832c 100644
--- a/rules.js
+++ b/rules.js
@@ -844,6 +844,99 @@ function search_move_bfs(from, cost, start, start_cost, road, max_cost) {
 	}
 }
 
+function search_withdraw(start, is_pass_move) {
+	// recon=4, forced march=+1, rommel bonus=+1
+	let limit = is_pass_move ? 6 : 4
+
+	path_enemy.fill(0)
+	for (let u = 0; u < units.length; ++u) {
+		if (is_enemy_unit(u)) {
+			let x = unit_hex(u)
+			if (x >= first_hex && x <= last_hex)
+				path_enemy[x] = 1
+		}
+	}
+
+	let sline = game.active === AXIS ? game.axis_supply_line : game.allied_supply_line
+	let sdist = game.active === AXIS ? distance_to[EL_AGHEILA] : distance_to[ALEXANDRIA]
+
+	search_withdraw_bfs(path_from[0], path_cost[0], start, 0, limit, sline, sdist)
+	search_withdraw_bfs(path_from[1], path_cost[1], start, 1, limit + 1, sline, sdist)
+	search_withdraw_bfs(path_from[2], path_cost[2], start, 2, limit + 2, sline, sdist)
+	search_withdraw_bfs(path_from[4], path_cost[4], start, 4, limit + 4, sline, sdist)
+
+	let grid = new Array(hexcount).fill('-')
+	for (let x = first_hex; x <= last_hex; ++x) {
+		for (let speed = 4; speed >= 1; --speed) {
+			if (path_cost[0][x] <= speed)
+				grid[x] = speed
+			if (path_cost[1][x] <= speed + 1)
+				grid[x] = speed
+			if (path_cost[2][x] <= speed + 2)
+				grid[x] = speed
+			if (path_cost[4][x] <= speed + 4)
+				grid[x] = speed
+		}
+	}
+	grid[start] = '@'
+
+	debug_hexes2("reach", path_cost[0])
+}
+
+// Breadth First Search
+function search_withdraw_bfs(from, cost, start, road, max_cost, sline, sdist) {
+	let queue = [ start << 4 ]
+
+	from.fill(0)
+	cost.fill(15)
+	cost[start] = 0
+
+	while (queue.length > 0) {
+		let item = queue.shift()
+		let here = item >> 4
+		let here_cost = item & 15
+		let next_cost = here_cost + 1
+
+		for (let s = 0; s < 6; ++s) {
+			let next = here + hexnext[s]
+
+			// can't go off-map
+			if (next < first_hex || next > last_hex || !hex_exists[next])
+				continue
+
+			// already seen
+			if (cost[next] < 15)
+				continue
+
+			let side = to_side(here, next, s)
+			let max_side = side_limit[side]
+
+			// must follow supply line
+			if (sline[side] === 0)
+				continue
+
+			// may not increase distance to supply source (except Bardia/Ft. Capuzzo)
+			if (sdist[next] > sdist[here] && side !== BARDIA_FT_CAPUZZO)
+				continue
+
+			// must stay on road for current bonus
+			if (side_road[side] < road)
+				continue
+
+			// cannot enter enemy hex
+			if (path_enemy[next])
+				continue
+
+			from[next] = here
+			cost[next] = next_cost
+
+			// enough movement allowance to keep going
+			if (next_cost < max_cost)
+				queue.push(next << 4 | next_cost)
+		}
+	}
+}
+
 function can_move_to(to, road, speed) {
 	// TODO: engagement & hexside limit
 	if (road >= 4 && path_cost[4][to] <= speed + 4)
@@ -1552,6 +1645,7 @@ states.refuse_battle_who = {
 	end_retreat() {
 		clear_undo()
 		release_hex_control(game.from1)
+		game.from1 = 0
 		game.state = 'refuse_battle'
 	}
 }
@@ -1561,7 +1655,10 @@ states.refuse_battle_to = {
 	prompt() {
 		view.prompt = `Withdraw: Select destination.`
 		let who = game.selected[0]
-		search_move(game.from1, 0, 4)
+
+		update_supply_networks()
+
+		search_withdraw(game.from1, false)
 		gen_withdraw_group_move(who, game.from1)
 		gen_action_unit(who)
 	},