+/* Size of rev graph with no "padding" columns */
+#define SIZEOF_REVITEMS (SIZEOF_REVGRAPH - (SIZEOF_REVGRAPH / 2))
+
+struct rev_stack {
+ struct rev_stack *prev, *next, *parents;
+ char rev[SIZEOF_REVITEMS][SIZEOF_REV];
+ size_t size;
+ struct commit *commit;
+ size_t pos;
+};
+
+/* Parents of the commit being visualized. */
+static struct rev_stack graph_parents[3];
+
+/* The current stack of revisions on the graph. */
+static struct rev_stack graph_stacks[3] = {
+ { &graph_stacks[2], &graph_stacks[1], &graph_parents[0] },
+ { &graph_stacks[0], &graph_stacks[2], &graph_parents[1] },
+ { &graph_stacks[1], &graph_stacks[0], &graph_parents[2] },
+};
+
+static inline bool
+graph_parent_is_merge(struct rev_stack *graph)
+{
+ return graph->parents->size > 1;
+}
+
+static inline void
+append_to_rev_graph(struct rev_stack *stack, chtype symbol)
+{
+ if (stack->commit->graph_size < ARRAY_SIZE(stack->commit->graph) - 1)
+ stack->commit->graph[stack->commit->graph_size++] = symbol;
+}
+
+static void
+done_rev_graph(struct rev_stack *graph)
+{
+ if (graph_parent_is_merge(graph) &&
+ graph->pos < graph->size - 1 &&
+ graph->next->size == graph->size + graph->parents->size - 1) {
+ size_t i = graph->pos + graph->parents->size - 1;
+
+ graph->commit->graph_size = i * 2;
+ while (i < graph->next->size - 1) {
+ append_to_rev_graph(graph, ' ');
+ append_to_rev_graph(graph, '\\');
+ i++;
+ }
+ }
+
+ graph->size = graph->pos = 0;
+ graph->commit = NULL;
+ memset(graph->parents, 0, sizeof(*graph->parents));
+}
+
+static void
+push_rev_stack(struct rev_stack *stack, char *parent)
+{
+ /* Combine duplicate parents lines. */
+ if (stack->size > 0 &&
+ !strncmp(stack->rev[stack->size - 1], parent, SIZEOF_REV))
+ return;
+
+ if (stack->size < SIZEOF_REVITEMS) {
+ string_ncopy(stack->rev[stack->size++], parent, SIZEOF_REV);
+ }
+}
+
+static void
+draw_rev_graph(struct rev_stack *graph)
+{
+ chtype symbol, separator, line;
+ size_t i;
+
+ /* Place the symbol for this commit. */
+ if (graph->parents->size == 0)
+ symbol = REVGRAPH_INIT;
+ else if (graph->parents->size > 1)
+ symbol = REVGRAPH_MERGE;
+ else if (graph->pos >= graph->size)
+ symbol = REVGRAPH_BRANCH;
+ else
+ symbol = REVGRAPH_COMMIT;
+
+ separator = ' ';
+ line = REVGRAPH_LINE;
+
+ for (i = 0; i < graph->pos; i++) {
+ append_to_rev_graph(graph, line);
+ if (graph_parent_is_merge(graph->prev) &&
+ graph->prev->pos == i) {
+ separator = '`';
+ line = '.';
+ }
+ append_to_rev_graph(graph, separator);
+ }
+
+ append_to_rev_graph(graph, symbol);
+
+ if (graph->prev->size > graph->size) {
+ separator = '\'';
+ line = ' ';
+ } else {
+ separator = ' ';
+ line = REVGRAPH_LINE;
+ }
+ i++;
+
+ for (; i < graph->size; i++) {
+ append_to_rev_graph(graph, separator);
+ append_to_rev_graph(graph, line);
+ if (graph_parent_is_merge(graph->prev)) {
+ if (i < graph->prev->pos + graph->parents->size) {
+ separator = '`';
+ line = '.';
+ }
+ }
+ if (graph->prev->size > graph->size) {
+ separator = '/';
+ line = ' ';
+ }
+ }
+
+ if (graph->prev->size > graph->size) {
+ append_to_rev_graph(graph, separator);
+ if (line != ' ')
+ append_to_rev_graph(graph, line);
+ }
+}
+
+void
+update_rev_graph(struct rev_stack *graph)
+{
+ size_t i;
+
+ /* First traverse all lines of revisions up to the active one. */
+ for (graph->pos = 0; graph->pos < graph->size; graph->pos++) {
+ if (!strcmp(graph->rev[graph->pos], graph->commit->id))
+ break;
+
+ push_rev_stack(graph->next, graph->rev[graph->pos]);
+ }
+
+ for (i = 0; i < graph->parents->size; i++)
+ push_rev_stack(graph->next, graph->parents->rev[i]);
+
+ /* FIXME: Moving branches left and right when collapsing a branch. */
+ for (i = graph->pos + 1; i < graph->size; i++)
+ push_rev_stack(graph->next, graph->rev[i]);
+
+ draw_rev_graph(graph);
+ done_rev_graph(graph->prev);
+}
+
+
+/*
+ * Main view backend
+ */
+