From f08957b513e4957857a1e03cd2e4f327a4a43b86 Mon Sep 17 00:00:00 2001
From: Enno Rehling <enno.rehling@gmail.com>
Date: Fri, 10 Jun 2016 18:24:18 +0200
Subject: [PATCH] test target selection rules for drifting ships.

---
 src/move.c      | 32 +++++++++++++++++++-------------
 src/move.h      |  1 +
 src/move.test.c | 19 +++++++++++++++++++
 src/tests.c     |  5 +++--
 4 files changed, 42 insertions(+), 15 deletions(-)

diff --git a/src/move.c b/src/move.c
index 98ed138fb..34490b9f6 100644
--- a/src/move.c
+++ b/src/move.c
@@ -783,9 +783,26 @@ static void msg_to_ship_inmates(ship *sh, unit **firstu, unit **lastu, message *
     msg_release(msg);
 }
 
+region * drift_target(ship *sh) {
+    int d, d_offset = rng_int() % MAXDIRECTIONS;
+    region *rnext = NULL;
+    for (d = 0; d != MAXDIRECTIONS; ++d) {
+        region *rn;
+        direction_t dir = (direction_t)((d + d_offset) % MAXDIRECTIONS);
+        rn = rconnect(sh->region, dir);
+        if (rn != NULL && fval(rn->terrain, SAIL_INTO) && check_ship_allowed(sh, rn) >= 0) {
+            rnext = rn;
+            if (!fval(rnext->terrain, SEA_REGION)) {
+                // prefer drifting towards non-ocean regions
+                break;
+            }
+        }
+    }
+    return rnext;
+}
+
 static void drifting_ships(region * r)
 {
-    direction_t d;
     bool drift = config_get_int("rules.ship.drifting", 1) != 0;
     double damage_drift = config_get_flt("rules.ship.damage_drift", 0.02);
 
@@ -796,7 +813,6 @@ static void drifting_ships(region * r)
             region *rnext = NULL;
             region_list *route = NULL;
             unit *firstu = r->units, *lastu = NULL, *captain;
-            int d_offset;
             direction_t dir = 0;
             double ovl;
 
@@ -831,17 +847,7 @@ static void drifting_ships(region * r)
             } else {
                 /* Auswahl einer Richtung: Zuerst auf Land, dann
                  * zufällig. Falls unmögliches Resultat: vergiß es. */
-                d_offset = rng_int () % MAXDIRECTIONS;
-                for (d = 0; d != MAXDIRECTIONS; ++d) {
-                    region *rn;
-                    dir = (direction_t)((d + d_offset) % MAXDIRECTIONS);
-                    rn = rconnect(r, dir);
-                    if (rn != NULL && fval(rn->terrain, SAIL_INTO) && check_ship_allowed(sh, rn) >= 0) {
-                        rnext = rn;
-                        if (!fval(rnext->terrain, SEA_REGION))
-                            break;
-                    }
-                }
+                rnext = drift_target(sh);
             }
 
             if (rnext != NULL) {
diff --git a/src/move.h b/src/move.h
index bdb4f61c7..9c5893629 100644
--- a/src/move.h
+++ b/src/move.h
@@ -83,6 +83,7 @@ extern "C" {
 #define SA_NO_COAST -2
 
     int check_ship_allowed(struct ship *sh, const struct region * r);
+    struct region * drift_target(struct ship *sh);
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/move.test.c b/src/move.test.c
index 4c0a07bc5..df12778f3 100644
--- a/src/move.test.c
+++ b/src/move.test.c
@@ -498,6 +498,24 @@ static void test_follow_ship_msg(CuTest * tc) {
     test_cleanup();
 }
 
+static void test_drifting_ships(CuTest *tc) {
+    ship *sh;
+    region *r1, *r2, *r3;
+    terrain_type *t_ocean, *t_plain;
+    ship_type *st_boat;
+    test_cleanup();
+    t_ocean = test_create_terrain("ocean", SEA_REGION|SAIL_INTO);
+    t_plain = test_create_terrain("plain", LAND_REGION|SAIL_INTO);
+    r1 = test_create_region(0, 0, t_ocean);
+    r2 = test_create_region(1, 0, t_ocean);
+    st_boat = test_create_shiptype("boat");
+    sh = test_create_ship(r1, st_boat);
+    CuAssertPtrEquals(tc, r2, drift_target(sh));
+    r3 = test_create_region(-1, 0, t_plain);
+    CuAssertPtrEquals(tc, r3, drift_target(sh));
+    test_cleanup();
+}
+
 CuSuite *get_move_suite(void)
 {
     CuSuite *suite = CuSuiteNew();
@@ -521,5 +539,6 @@ CuSuite *get_move_suite(void)
     SUITE_ADD_TEST(suite, test_ship_ridiculous_overload_no_captain);
     SUITE_ADD_TEST(suite, test_ship_damage_overload);
     SUITE_ADD_TEST(suite, test_follow_ship_msg);
+    SUITE_ADD_TEST(suite, test_drifting_ships);
     return suite;
 }
diff --git a/src/tests.c b/src/tests.c
index a0d54a4cc..25e82d578 100644
--- a/src/tests.c
+++ b/src/tests.c
@@ -196,9 +196,10 @@ ship_type * test_create_shiptype(const char * name)
         free(stype->coasts);
     }
     stype->coasts =
-        (terrain_type **)malloc(sizeof(terrain_type *) * 2);
+        (terrain_type **)malloc(sizeof(terrain_type *) * 3);
     stype->coasts[0] = test_create_terrain("plain", LAND_REGION | FOREST_REGION | WALK_INTO | CAVALRY_REGION | SAIL_INTO | FLY_INTO);
-    stype->coasts[1] = NULL;
+    stype->coasts[1] = test_create_terrain("ocean", SEA_REGION | SWIM_INTO | SAIL_INTO | FLY_INTO);
+    stype->coasts[2] = NULL;
     if (default_locale) {
         locale_setstring(default_locale, name, name);
     }