Add HTTP server

README.md

@@ -2,6 +2,19 @@
 
 This repository contains the sources required to run the Inkpot frontend on a Lilygo T5, an ESP32 equipped with an e-ink display. It allows you to create Lua sketches that draw on the e-ink screen.
 
+You need to give it a 2.4Ghz Wifi SSID and password by adjusting `main/settings.h`. After that it will start an HTTP server that you can use to interact with the device. The HTTP server has two endpoints:
+
+- `GET /` -- Hello world page to confirm that things are working
+- `POST /draw` -- Accepts a Lua POST body and will execute the script
+
+You can send scripts like this:
+
+``` bash
+cat foo.lua | curl -X POST --data-binary @- 10.0.0.100/draw
+```
+
+The IP address of the display is logged to its serial output and can be read via `idf.py monitor` (see below).
+
 ## Prerequisites
 
 There is a `flake.nix` at the root of this repository that defines a development environment with all required tools. If you are using `direnv`, `cd` into the repositorie's root directory after cloning it and run `direnv allow`. If you aren't using direnv the enviroment can be activated using `nix develop .`.

assets/epaper.lua

@@ -13,12 +13,43 @@ print(
   'height: ' .. height
 )
 
-for i = 1, 50 do
-  x = math.random() * width
-  y = math.random() * height
-  r = 24 + math.ceil(math.random() * 12)
+-- easing functions taken from https://easings.net/
 
-  paper.fill_circle(x, y, r, math.floor(math.random() * 0xFF))
+function ease_in_sine(x)
+  return 1 - math.cos(x * math.pi / 2)
+end
+
+function ease_in_out_sine(x)
+  return -(math.cos(math.pi * x) - 1) / 2
+end
+
+--
+-- actual sketch follows below
+--
+
+local x = width / 2
+local max_radius = 128
+local min_radius = max_radius / 6
+local padding = max_radius
+local max_color = 0xDD
+local min_color = 0x33
+local steps = 72
+
+-- background
+paper.fill_rect(0, 0, width, height, 0x22)
+
+-- sketch
+for i = 1, steps do
+  local n = i / steps
+  local e1 = ease_in_sine(n)
+  local e2 = 1 - ease_in_out_sine(ease_in_sine(n))
+  local color = math.floor(max_color - (max_color - min_color) * e2)
+  paper.fill_circle(
+    x + math.sin((math.pi * 2) / n) * 32 * e1,
+    padding + (height - max_radius - padding * 2) * e1,
+    min_radius + (max_radius - min_radius) * e1,
+    color
+  )
 end
 
 paper.update()

main/CMakeLists.txt

@@ -2,5 +2,6 @@ idf_component_register(
   SRCS
     "inkpot.c"
     "paper.c"
+    "server.c"
   INCLUDE_DIRS "."
 )

main/inkpot.c

@@ -15,6 +15,7 @@
 #include <dirent.h>
 
 #include "paper.h"
+#include "server.h"
 
 #define WIFI_SCAN_LIST_SIZE 10
 #define LUA_FILE_PATH "/assets"
@@ -96,7 +97,7 @@ void run_lua_file(const char *file_name, const char *test_name) {
 }
 
 // Function to run an embedded Lua script
-void run_embedded_lua_test(const char *lua_script, const char *test_name) {
+void run_lua_string(const char *lua_script, const char *test_name) {
     ESP_LOGI(TAG, "Starting Lua test: %s", test_name);
 
     log_memory_usage("Start of test");
@@ -176,19 +177,96 @@ void scan_wifi_networks(void) {
     ESP_LOGI(TAG, "Wi-Fi scan completed.");
 }
 
-void app_main(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);
+    return ESP_OK;
+}
 
+esp_err_t http_draw(httpd_req_t* req) {
+    // READING STREAM
+    int req_size = req->content_len;
+    char* content = (char*)heap_caps_malloc(req_size, MALLOC_CAP_SPIRAM);
+    if (content == NULL) {
+        char msg[50];
+        sprintf(msg, "Failed to allocate %d chars\n", req_size);
+        httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, msg);
+        return ESP_ERR_INVALID_ARG;
     }
+    int current_pos = 0;
+    int amount_recieved;
+    while ((amount_recieved = httpd_req_recv(req, (content + current_pos), req_size)) > 0) {
+        ESP_LOGI(__FUNCTION__, "Read %d bytes\n", amount_recieved);
+        current_pos += amount_recieved;
+    }
+    if (amount_recieved < 0) {
+        char msg[50];
+        heap_caps_free(content);
+        ESP_LOGE(msg, "Failed to read bytes. Error code %d\n", amount_recieved);
+        httpd_resp_send_err(req, HTTPD_500_INTERNAL_SERVER_ERROR, msg);
+        return ESP_ERR_INVALID_ARG;
+    }
+    ESP_LOGI(__FUNCTION__, "Done reading %d bytes out of %d\n", current_pos, req_size);
 
+    // TODO: Error handling
+    run_lua_string(content, "E-Paper Script via HTTP");
+    heap_caps_free(content);
 
+    // Done reading
+    char response[100];
+    sprintf(
+        response, "script drawn!"
+    );
+    httpd_resp_set_type(req, "text/plain");
+    httpd_resp_set_status(req, "200");
+    httpd_resp_send(req, response, HTTPD_RESP_USE_STRLEN);
+    return ESP_OK;
+}
+
+void register_http_routes(httpd_handle_t server) {
+    {
+        httpd_uri_t uri
+            = { .uri = "/", .method = HTTP_GET, .handler = http_index, .user_ctx = NULL };
+        httpd_register_uri_handler(server, &uri);
+    }
+    {
+        httpd_uri_t uri
+            = { .uri = "/draw", .method = HTTP_POST, .handler = http_draw, .user_ctx = NULL };
+        httpd_register_uri_handler(server, &uri);
+    }
+}
+
+// init
+
+void app_main(void) {
     // Initialize and mount the filesystem
     init_filesystem();
 
+    // Initialize NVS, needed for wifi
+    esp_err_t ret = nvs_flash_init();
+    if (ret == ESP_ERR_NVS_NO_FREE_PAGES || ret == ESP_ERR_NVS_NEW_VERSION_FOUND) {
+        ESP_ERROR_CHECK(nvs_flash_erase());
+        ret = nvs_flash_init();
+    }
+    ESP_ERROR_CHECK(ret);
+
+    // Set up HTTP server
+    httpd_handle_t server = get_server();
+    if (server != NULL) {
+        register_http_routes(server);
+    }
+
     // Run script in assets/epaper.lua
-    run_lua_file("epaper.lua", "E-Paper Script");
+    run_lua_file("epaper.lua", "E-Paper Startup Script");
 
     ESP_LOGI(TAG, "End of testing application.");
 

main/server.c

@@ -0,0 +1,49 @@
+#include "server.h"
+#include "settings.h"
+
+httpd_handle_t get_server(void);
+
+static void wifi_init_sta(void) {
+    // Initialize the ESP-NETIF
+    esp_netif_init();
+    esp_event_loop_create_default();
+
+    // Create default event loop
+    esp_netif_create_default_wifi_sta();
+
+    // Initialize the Wi-Fi driver
+    wifi_init_config_t cfg = WIFI_INIT_CONFIG_DEFAULT();
+    ESP_ERROR_CHECK(esp_wifi_init(&cfg));
+
+    // Set Wi-Fi mode to station
+    ESP_ERROR_CHECK(esp_wifi_set_mode(WIFI_MODE_STA));
+
+    // Configure Wi-Fi connection
+    wifi_config_t wifi_config = {
+        // TODO: Allow setting SSID at boot or build time
+        // For some reason I could not get https://cmake.org/cmake/help/latest/command/add_compile_definitions.html#command:add_compile_definitions to work
+        .sta = {
+            .ssid = WIFI_SSID,
+            .password = WIFI_PASS,
+        },
+    };
+
+    // Set the Wi-Fi configuration
+    ESP_ERROR_CHECK(esp_wifi_set_config(ESP_IF_WIFI_STA, &wifi_config));
+    ESP_ERROR_CHECK(esp_wifi_start());
+    ESP_ERROR_CHECK(esp_wifi_connect());
+}
+
+httpd_handle_t start_webserver(void) {
+    httpd_config_t config = HTTPD_DEFAULT_CONFIG();
+    config.lru_purge_enable = true;
+
+    httpd_handle_t server = NULL;
+    ESP_ERROR_CHECK(httpd_start(&server, &config));
+    return server;
+}
+
+httpd_handle_t get_server(void) {
+    wifi_init_sta();
+    return start_webserver();
+}

main/server.h

@@ -0,0 +1,19 @@
+#ifndef SERVER_H_
+#define SERVER_H_
+
+#include <stdio.h>
+#include <string.h>
+#include "freertos/FreeRTOS.h"
+#include "freertos/task.h"
+#include "esp_event.h"
+#include "esp_log.h"
+#include "nvs_flash.h"
+#include "esp_wifi.h"
+#include "esp_netif.h"
+#include "esp_http_server.h"
+
+// #include "settings.h"
+
+httpd_handle_t get_server(void);
+
+#endif // SERVER_H_

main/settings.h

@@ -0,0 +1,7 @@
+#ifndef SETTINGS_H_
+#define SETTINGS_H_
+
+#define WIFI_SSID ""
+#define WIFI_PASS ""
+
+#endif // SETTINGS_H_