Implement file reloading

When for examplue using formatters or doing vc updates, it is useful
if the file is reloaded from disk.

3 files changed, 86 insertions, 2 deletions

diff --git a/src/main/bindings.c b/src/main/bindings.c
index 10436d6..7ea75eb 100644
--- a/src/main/bindings.c
+++ b/src/main/bindings.c
@@ -35,11 +35,14 @@ void set_default_buffer_bindings(struct keymap *keymap) {
       BINDING(Ctrl, 'S', "find-next"),
       BINDING(Ctrl, 'R', "find-prev"),
 
+      BINDING(Meta, 'g', "goto-line"),
       BINDING(Meta, '<', "goto-beginning"),
       BINDING(Meta, '>', "goto-end"),
 
       BINDING(Ctrl, 'V', "scroll-down"),
       BINDING(Meta, 'v', "scroll-up"),
+      BINDING(Spec, '6', "scroll-down"),
+      BINDING(Spec, '5', "scroll-up"),
 
       BINDING(ENTER, "newline"),
       BINDING(TAB, "indent"),
@@ -204,4 +207,6 @@ void destroy_keymaps() {
       km->active = false;
     }
   }
+
+  VEC_DESTROY(&g_buffer_keymaps);
 }
diff --git a/src/main/cmds.c b/src/main/cmds.c
index 27b2a77..4cbb00f 100644
--- a/src/main/cmds.c
+++ b/src/main/cmds.c
@@ -47,8 +47,16 @@ int32_t find_file(struct command_ctx ctx, int argc, const char *argv[]) {
     return 1;
   }
 
-  window_set_buffer(ctx.active_window,
-                    buffers_add(ctx.buffers, buffer_from_file((char *)pth)));
+  const char *filename = realpath(pth, NULL);
+  struct buffer *b = buffers_find_by_filename(ctx.buffers, filename);
+  free((char *)filename);
+  if (b == NULL) {
+    b = buffers_add(ctx.buffers, buffer_from_file((char *)pth));
+  } else {
+    buffer_reload(b);
+  }
+
+  window_set_buffer(ctx.active_window, b);
   minibuffer_echo_timeout(4, "buffer \"%s\" loaded",
                           window_buffer(ctx.active_window)->name);
 
@@ -317,12 +325,14 @@ BUFFER_WRAPCMD_POS(buffer_paste_older);
 BUFFER_WRAPCMD_POS(buffer_goto_beginning);
 BUFFER_WRAPCMD_POS(buffer_goto_end);
 BUFFER_WRAPCMD_POS(buffer_undo);
+
 static int32_t buffer_view_scroll_up_cmd(struct command_ctx ctx, int argc,
                                          const char *argv[]) {
   buffer_view_scroll_up(window_buffer_view(ctx.active_window),
                         window_height(ctx.active_window));
   return 0;
 };
+
 static int32_t buffer_view_scroll_down_cmd(struct command_ctx ctx, int argc,
                                            const char *argv[]) {
   buffer_view_scroll_down(window_buffer_view(ctx.active_window),
@@ -330,6 +340,16 @@ static int32_t buffer_view_scroll_down_cmd(struct command_ctx ctx, int argc,
   return 0;
 };
 
+static int32_t buffer_goto_line(struct command_ctx ctx, int argc,
+                                const char *argv[]) {
+  if (argc == 0) {
+    return minibuffer_prompt(ctx, "line: ");
+  }
+
+  uint32_t line = atoi(argv[0]);
+  buffer_goto(window_buffer_view(ctx.active_window), line - 1, 0);
+}
+
 void register_buffer_commands(struct commands *commands) {
 
   static struct command buffer_commands[] = {
@@ -359,6 +379,7 @@ void register_buffer_commands(struct commands *commands) {
       {.name = "scroll-down", .fn = buffer_view_scroll_down_cmd},
       {.name = "scroll-up", .fn = buffer_view_scroll_up_cmd},
       {.name = "reload", .fn = buffer_reload_cmd},
+      {.name = "goto-line", .fn = buffer_goto_line},
   };
 
   register_commands(commands, buffer_commands,
diff --git a/src/main/main.c b/src/main/main.c
index f13e77e..cd36733 100644
--- a/src/main/main.c
+++ b/src/main/main.c
@@ -59,6 +59,59 @@ uint64_t calc_frame_time_ns(struct timespec *timers, uint32_t num_timer_pairs) {
 #define TIMED_SCOPE_BEGIN(timer) clock_gettime(CLOCK_MONOTONIC, &timer##_begin)
 #define TIMED_SCOPE_END(timer) clock_gettime(CLOCK_MONOTONIC, &timer##_end)
 
+struct watched_file {
+  uint32_t watch_id;
+  struct buffer *buffer;
+};
+
+VEC(struct watched_file) g_watched_files;
+
+void watch_file(struct buffer *buffer, void *userdata) {
+  if (buffer_is_backed(buffer)) {
+    struct reactor *reactor = (struct reactor *)userdata;
+    VEC_APPEND(&g_watched_files, struct watched_file * w);
+    w->buffer = buffer;
+    w->watch_id = reactor_watch_file(reactor, buffer->filename, FileWritten);
+  }
+}
+
+void reload_buffer(struct buffer *buffer) {
+  if (!buffer_is_modified(buffer)) {
+    buffer_reload(buffer);
+  } else {
+    minibuffer_echo("not updating buffer %s because it contains changes",
+                    buffer->name);
+  }
+}
+
+void update_file_watches(struct reactor *reactor) {
+  // first, find invalid file watches and try to update them
+  VEC_FOR_EACH(&g_watched_files, struct watched_file * w) {
+    if (w->watch_id == -1) {
+      w->watch_id =
+          reactor_watch_file(reactor, w->buffer->filename, FileWritten);
+      reload_buffer(w->buffer);
+    }
+  }
+
+  // then pick up any events we might have
+  struct file_event ev;
+  while (reactor_next_file_event(reactor, &ev)) {
+    // find the buffer we need to reload
+    VEC_FOR_EACH(&g_watched_files, struct watched_file * w) {
+      if (w->watch_id == ev.id) {
+        if (ev.mask & LastEvent != 0) {
+          w->watch_id = -1;
+          continue;
+        }
+
+        reload_buffer(w->buffer);
+        break;
+      }
+    }
+  }
+}
+
 void usage() { printf("TODO: print usage\n"); }
 
 int main(int argc, char *argv[]) {
@@ -127,8 +180,11 @@ int main(int argc, char *argv[]) {
   struct keymap *current_keymap = NULL;
   struct keymap *global_keymap = register_bindings();
 
+  VEC_INIT(&g_watched_files, 32);
+
   struct buffers buflist = {0};
   buffers_init(&buflist, 32);
+  buffers_add_add_hook(&buflist, watch_file, (void *)reactor);
   struct buffer initial_buffer = buffer_create("welcome");
   if (filename != NULL) {
     buffer_destroy(&initial_buffer);
@@ -270,6 +326,8 @@ int main(int argc, char *argv[]) {
     }
     TIMED_SCOPE_END(keyboard);
 
+    update_file_watches(reactor);
+
     // calculate frame time
     struct timespec timers[] = {buffer_begin, buffer_end,     display_begin,
                                 display_end,  keyboard_begin, keyboard_end};