From 71cf5a598192fd1bbc715cb90498011a609a78cf Mon Sep 17 00:00:00 2001
From: Chewing_Bever <roosensjef@gmail.com>
Date: Thu, 22 Feb 2024 11:42:56 +0100
Subject: [PATCH] feat: initial trie routing structure

---
 include/lnm/common.h                    |  2 +
 src/_include/lnm/http/router_internal.h | 36 ++++++++++++
 src/http/lnm_http_router.c              | 73 +++++++++++++++++++++++++
 3 files changed, 111 insertions(+)
 create mode 100644 src/_include/lnm/http/router_internal.h
 create mode 100644 src/http/lnm_http_router.c

diff --git a/include/lnm/common.h b/include/lnm/common.h
index 8cc982e..3ada2a4 100644
--- a/include/lnm/common.h
+++ b/include/lnm/common.h
@@ -32,6 +32,8 @@ typedef enum lnm_err {
   lnm_err_not_setup,
   lnm_err_bad_regex,
   lnm_err_not_found,
+  lnm_err_invalid_route,
+  lnm_err_overlapping_route,
 } lnm_err;
 
 typedef struct lnm_loop lnm_http_loop;
diff --git a/src/_include/lnm/http/router_internal.h b/src/_include/lnm/http/router_internal.h
new file mode 100644
index 0000000..e4f6bda
--- /dev/null
+++ b/src/_include/lnm/http/router_internal.h
@@ -0,0 +1,36 @@
+#ifndef LNM_HTTP_ROUTER_INTERNAL
+#define LNM_HTTP_ROUTER_INTERNAL
+
+#include "lnm/common.h"
+
+typedef struct lnm_http_route {
+} lnm_http_route;
+
+typedef struct lnm_http_router {
+  struct lnm_http_router *exact_children[128];
+  struct lnm_http_router *single_segment_child;
+  lnm_http_route *route;
+} lnm_http_router;
+
+/**
+ * Allocate and initialize a new http_router.
+ */
+lnm_err lnm_http_router_init(lnm_http_router **out);
+
+void lnm_http_router_free(lnm_http_router *router);
+
+lnm_err lnm_http_route_init(lnm_http_route **out);
+
+void lnm_http_route_free(lnm_http_route *route);
+
+lnm_err lnm_http_router_add(lnm_http_route **out, lnm_http_router *http_router,
+                            const char *path);
+
+/**
+ * Add all of the child router's routes to the parent router, under the given
+ * route prefix.
+ */
+lnm_err lnm_http_router_nest(lnm_http_router *parent,
+                             const lnm_http_router *child, const char *prefix);
+
+#endif
diff --git a/src/http/lnm_http_router.c b/src/http/lnm_http_router.c
new file mode 100644
index 0000000..f5001f8
--- /dev/null
+++ b/src/http/lnm_http_router.c
@@ -0,0 +1,73 @@
+#include <string.h>
+
+#include "lnm/common.h"
+#include "lnm/http/router_internal.h"
+
+lnm_err lnm_http_router_init(lnm_http_router **out) {
+  lnm_http_router *router = calloc(1, sizeof(lnm_http_router));
+
+  if (router == NULL) {
+    return lnm_err_failed_alloc;
+  }
+
+  *out = router;
+
+  return lnm_err_ok;
+}
+
+lnm_err lnm_http_route_init(lnm_http_route **out) {
+  lnm_http_route *route = calloc(1, sizeof(lnm_http_route));
+
+  if (route == NULL) {
+    return lnm_err_failed_alloc;
+  }
+
+  *out = route;
+
+  return lnm_err_ok;
+}
+
+static bool is_ascii(const char *s) {
+  while (*s != '0') {
+    if (*s > 127) {
+      return false;
+    }
+
+    s++;
+  }
+
+  return true;
+}
+
+lnm_err lnm_http_router_add(lnm_http_route **out, lnm_http_router *http_router,
+                            const char *path) {
+  if (path[0] != '/' || !is_ascii(path)) {
+    return lnm_err_invalid_route;
+  }
+
+  while (*path != '\0') {
+    unsigned char c = *path;
+
+    switch (c) {
+    case ':':
+      LNM_RES(lnm_http_router_init(&http_router->single_segment_child));
+
+      // All other characters in the segment are ignored
+      const char *next_slash_ptr = strchr(path, '/');
+      path = next_slash_ptr == NULL ? strchr(path, '\0') : next_slash_ptr;
+      break;
+    case '*':
+      // TODO multi-segment wildcard
+      break;
+    default:
+      LNM_RES(lnm_http_router_init(&http_router->exact_children[c]));
+      http_router = http_router->exact_children[c];
+      path++;
+      break;
+    }
+  }
+
+  LNM_RES(lnm_http_route_init(out));
+
+  return lnm_err_ok;
+}