From d3de814d75dbe7f457eff1e9e8002913058797c3 Mon Sep 17 00:00:00 2001
From: arne <noreply@null.arnes.space>
Date: Mon, 6 Oct 2025 21:36:03 +0200
Subject: [PATCH] Send `index.html` to browser when visiting `/`

---
 main/inkpot.c | 71 +++++++++++++++++++++++++++++++++++++++++----------
 1 file changed, 57 insertions(+), 14 deletions(-)

diff --git a/main/inkpot.c b/main/inkpot.c
index b149c6f..3c70111 100644
--- a/main/inkpot.c
+++ b/main/inkpot.c
@@ -24,6 +24,14 @@
 #define MIN(a, b) (((a) < (b)) ? (a) : (b))
 #endif
 
+/* Scratch buffer size for sending files to HTTP clients */
+#define SCRATCH_BUFSIZE  8192
+
+struct file_server_data {
+    /* Scratch buffer for temporary storage during file transfer */
+    char scratch[SCRATCH_BUFSIZE];
+};
+
 static const char *TAG = "inkpot";
 
 // Function to log memory usage with the message at the end
@@ -184,16 +192,37 @@ void scan_wifi_networks(void) {
 
 // HTTP Server
 
-#define WRITE_HEADER(req, buffer, name, format, src) \
-    sprintf(buffer, format, src);                    \
-    ESP_ERROR_CHECK(httpd_resp_set_hdr(req, name, buffer));
-
 static esp_err_t http_index(httpd_req_t* req) {
-    // TODO: Serve HTML file with form POSTing to `/draw`
-    const char* response = "Hello world!\n";
-    httpd_resp_set_type(req, "text/plain");
-    httpd_resp_set_status(req, "200");
-    httpd_resp_send(req, response, HTTPD_RESP_USE_STRLEN);
+    char index_path[128];
+    strcpy(index_path, LFS_PATH);
+    strcat(index_path, "/http/index.html");
+
+    FILE *fd = fopen(index_path, "r");
+    char *chunk = ((struct file_server_data *)req->user_ctx)->scratch;
+    size_t chunksize;
+    do {
+        /* Read file in chunks into the scratch buffer */
+        chunksize = fread(chunk, 1, SCRATCH_BUFSIZE, fd);
+
+        if (chunksize > 0) {
+            /* Send the buffer contents as HTTP response chunk */
+            if (httpd_resp_send_chunk(req, chunk, chunksize) != ESP_OK) {
+                fclose(fd);
+                ESP_LOGE(TAG, "File sending failed!");
+                /* Abort sending file */
+                httpd_resp_sendstr_chunk(req, NULL);
+                /* Respond with 500 Internal Server Error */
+                httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, "Failed to send file");
+               return ESP_FAIL;
+           }
+        }
+
+        /* Keep looping till the whole file is sent */
+    } while (chunksize != 0);
+    fclose(fd);
+    httpd_resp_set_hdr(req, "Connection", "close");
+    httpd_resp_send_chunk(req, NULL, 0);
+    ESP_LOGI(TAG, "Sent index.html");
     return ESP_OK;
 }
 
@@ -252,17 +281,33 @@ esp_err_t http_draw(httpd_req_t* req) {
     return ESP_OK;
 }
 
-void register_http_routes(httpd_handle_t server) {
+esp_err_t register_http_routes(httpd_handle_t server) {
+    static struct file_server_data *server_data = NULL;
+
+    if (server_data) {
+        ESP_LOGE(TAG, "File server already started");
+        return ESP_ERR_INVALID_STATE;
+    }
+
+    // Allocate memory for server data
+    server_data = calloc(1, sizeof(struct file_server_data));
+    if (!server_data) {
+        ESP_LOGE(TAG, "Failed to allocate memory for server data");
+        return ESP_ERR_NO_MEM;
+    }
+
     {
         httpd_uri_t uri
-            = { .uri = "/", .method = HTTP_GET, .handler = http_index, .user_ctx = NULL };
+            = { .uri = "/", .method = HTTP_GET, .handler = http_index, .user_ctx = server_data };
         httpd_register_uri_handler(server, &uri);
     }
     {
         httpd_uri_t uri
-            = { .uri = "/draw", .method = HTTP_POST, .handler = http_draw, .user_ctx = NULL };
+            = { .uri = "/draw", .method = HTTP_POST, .handler = http_draw, .user_ctx = server_data };
         httpd_register_uri_handler(server, &uri);
     }
+
+    return ESP_OK;
 }
 
 // init
@@ -279,8 +324,6 @@ void app_main(void) {
     }
     ESP_ERROR_CHECK(ret);
 
-    // FIXME: Wifi server causes some crash, failing to yield to watchdog in time
-    // Set up HTTP server
     httpd_handle_t server = get_server();
     if (server != NULL) {
         register_http_routes(server);