# HG changeset patch
# User jbe
# Date 1381517416 -7200
# Node ID db863178d98b3581e562fbf0bb21cc4f9c8ee086
# Parent  806561cce3b172b6b1fa8db111db94f4a7def311
Algorithm to write "issue_order"."order_in_open_states"

diff -r 806561cce3b1 -r db863178d98b lf_update_issue_order.c
--- a/lf_update_issue_order.c	Fri Oct 11 20:07:41 2013 +0200
+++ b/lf_update_issue_order.c	Fri Oct 11 20:50:16 2013 +0200
@@ -88,6 +88,13 @@
   struct candidate **candidates;
 };
 
+// open issue to be assigned an "order_in_open_states":
+struct open_issue {
+  char *issue_id;
+  int minimum_position;
+  int position;
+};
+
 // determine candidate, which is assigned the next seat (starting with the worst rank):
 static struct candidate *loser(int round_number, struct ballot *ballots, int ballot_count) {
   int i, j;       // index variables for loops
@@ -173,7 +180,28 @@
   abort();
 }
 
-// write results to database:
+// calculate "order_in_open_states":
+static void calculate_order_in_open_states(struct open_issue *open_issues, int open_issue_count) {
+  int i, j, fallback_j = 0, fallback_minimum_position;
+  for (i=1; i<=open_issue_count; i++) {
+    fallback_minimum_position = -1;
+    for (j=0; j<open_issue_count; j++) {
+      if (open_issues[j].position) continue;
+      if (open_issues[j].minimum_position <= i) break;
+      if (
+        fallback_minimum_position < 0 ||
+        open_issues[j].minimum_position < fallback_minimum_position
+      ) {
+        fallback_j = j;
+        fallback_minimum_position = open_issues[j].minimum_position;
+      }
+    }
+    if (j==open_issue_count) j = fallback_j;
+    open_issues[j].position = i;
+  }
+}
+
+// write results to database (calls calculate_open_issue_order):
 static int write_ranks(PGconn *db, char *escaped_area_id) {
   PGresult *res;
   char *cmd;
@@ -204,7 +232,7 @@
       fprintf(stderr, "Could not escape literal in memory.\n");
       abort();
     }
-    if (asprintf(&cmd, "INSERT INTO \"issue_order\" (\"id\", \"order_in_admission_state\") VALUES (%i, %s)", candidates[i].seat, escaped_issue_id) < 0) {
+    if (asprintf(&cmd, "INSERT INTO \"issue_order\" (\"id\", \"order_in_admission_state\") VALUES (%s, %i)", escaped_issue_id, candidates[i].seat) < 0) {
       fprintf(stderr, "Could not prepare query string in memory.\n");
       abort();
     }
@@ -227,6 +255,85 @@
     if (res) PQclear(res);
     return 1;
   }
+  if (asprintf(&cmd, "SELECT \"issue_id\", \"minimum_position\" FROM \"open_issues_ordered_with_minimum_position\" WHERE \"area_id\" = %s", escaped_area_id) < 0) {
+    fprintf(stderr, "Could not prepare query string in memory.\n");
+    abort();
+  }
+  res = PQexec(db, cmd);
+  free(cmd);
+  if (!res) {
+    fprintf(stderr, "Error in pqlib while sending SQL command selecting ordered issues with minimum position.\n");
+    res = PQexec(db, "ROLLBACK");
+    if (res) PQclear(res);
+    return 1;
+  } else if (PQresultStatus(res) != PGRES_TUPLES_OK) {
+    fprintf(stderr, "Error while executing SQL command selecting ordered issues with minimum position:\n%s", PQresultErrorMessage(res));
+    PQclear(res);
+    res = PQexec(db, "ROLLBACK");
+    if (res) PQclear(res);
+    return 1;
+  } else if (PQnfields(res) < 2) {
+    fprintf(stderr, "Too few columns returned by SQL command selecting ordered issues with minimum position.\n");
+    PQclear(res);
+    res = PQexec(db, "ROLLBACK");
+    if (res) PQclear(res);
+    return 1;
+  } else {
+    int open_issue_count;
+    struct open_issue *open_issues;
+    open_issue_count = PQntuples(res);
+    open_issues = calloc(open_issue_count, sizeof(struct open_issue));
+    for (i=0; i<open_issue_count; i++) {
+      open_issues[i].issue_id = PQgetvalue(res, i, 0);
+      if (PQgetisnull(res, i, 1)) {
+        open_issues[i].minimum_position = 0;
+      } else {
+        open_issues[i].minimum_position = (int)strtol(PQgetvalue(res, i, 1), (char **)NULL, 10);
+        if (open_issues[i].minimum_position < 1) {
+          fprintf(stderr, "Unexpected minimum position value.\n");
+          PQclear(res);
+          free(open_issues);
+          res = PQexec(db, "ROLLBACK");
+          if (res) PQclear(res);
+          return 1;
+        }
+      }
+    }
+    PQclear(res);
+    calculate_order_in_open_states(open_issues, open_issue_count);
+    for (i=0; i<open_issue_count; i++) {
+      char *escaped_issue_id;
+      escaped_issue_id = escapeLiteral(db, open_issues[i].issue_id, strlen(open_issues[i].issue_id));
+      if (!escaped_issue_id) {
+        fprintf(stderr, "Could not escape literal in memory.\n");
+        abort();
+      }
+      if (asprintf(&cmd, "UPDATE \"issue_order\" SET \"order_in_open_states\" = %i WHERE \"id\" = %s)", open_issues[i].position, escaped_issue_id) < 0) {
+        fprintf(stderr, "Could not prepare query string in memory.\n");
+        abort();
+      }
+      freemem(escaped_issue_id);
+      res = PQexec(db, cmd);
+      free(cmd);
+      if (!res) {
+        fprintf(stderr, "Error in pqlib while sending SQL command to update issue order.\n");
+      } else if (
+        PQresultStatus(res) != PGRES_COMMAND_OK &&
+        PQresultStatus(res) != PGRES_TUPLES_OK
+      ) {
+        fprintf(stderr, "Error while executing SQL command to update issue order:\n%s", PQresultErrorMessage(res));
+        PQclear(res);
+      } else {
+        PQclear(res);
+        continue;
+      }
+      free(open_issues);
+      res = PQexec(db, "ROLLBACK");
+      if (res) PQclear(res);
+      return 1;
+    }
+    free(open_issues);
+  }
   res = PQexec(db, "COMMIT");
   if (!res) {
     fprintf(stderr, "Error in pqlib while sending SQL command to commit transaction.\n");
@@ -240,8 +347,8 @@
     return 1;
   } else {
     PQclear(res);
-    return 0;
   }
+  return 0;
 }
 
 // calculate ordering of issues in admission state for an area and call write_ranks() to write it to database: