Implement input component

It is required to redirect keyboard input (both physical or not) when
a GUI line edit is focused. This means other components cannot be
activated on key presses.

Therefore, this new component is meant as a higher-level abstraction
compared to the `keyboard`/`pad`/`mouse` components, which:

- Implements the same APIs provided by `keyboard`, `mouse` and `pad`.
- Returns the same results as the APIs above if no GUI element is
focused, no input otherwise.

Note: replacing calls to `keyboard`/`pad`/`mouse` with `input` will be
implemented in a future commit.

4 files changed, 237 insertions, 0 deletions

diff --git a/src/CMakeLists.txt b/src/CMakeLists.txt
index ba57b6f..da04812 100644
--- a/src/CMakeLists.txt
+++ b/src/CMakeLists.txt
@@ -10,6 +10,7 @@ set(components
     gfx
     gui
     header
+    input
     instance
     keyboard
     menu
diff --git a/src/input/CMakeLists.txt b/src/input/CMakeLists.txt
new file mode 100644
index 0000000..9de4843
--- /dev/null
+++ b/src/input/CMakeLists.txt
@@ -0,0 +1,5 @@
+add_library(input
+    "src/input.c"
+)
+target_include_directories(input PUBLIC "inc")
+target_link_libraries(input PUBLIC keyboard mouse pad peripheral)
diff --git a/src/input/inc/input.h b/src/input/inc/input.h
new file mode 100644
index 0000000..2dd401b
--- /dev/null
+++ b/src/input/inc/input.h
@@ -0,0 +1,56 @@
+#ifndef INPUT_H
+#define INPUT_H
+
+#include <keyboard.h>
+#include <mouse.h>
+#include <pad.h>
+#include <peripheral.h>
+#include <stdbool.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+typedef void (*input_ch)(char ch, void *user);
+typedef void (*input_erase)(void *user);
+
+struct input
+{
+    input_ch cb;
+    input_erase erase;
+    void *user;
+    unsigned char t;
+    bool repeat;
+    struct keyboard_combo prev;
+};
+
+void input_update(struct input *in, const union peripheral *p);
+int input_render(const struct input *in, const union peripheral *p);
+bool input_keyboard_justpressed(const struct input *in,
+    const struct keyboard *k,
+    const struct keyboard_combo *c);
+bool input_keyboard_pressed(const struct input *in,
+    const struct keyboard *k,
+    const struct keyboard_combo *c);
+bool input_keyboard_justreleased(const struct input *in,
+    const struct keyboard *k,
+    const struct keyboard_combo *c);
+bool input_pad_pressed(const struct input *in, const struct pad *p,
+    enum pad_key k);
+bool input_pad_justpressed(const struct input *in, const struct pad *p,
+    enum pad_key k);
+bool input_pad_released(const struct input *in, const struct pad *p,
+    enum pad_key k);
+bool input_mouse_pressed(const struct input *in, const struct mouse *m,
+    enum mouse_button b);
+bool input_mouse_justpressed(const struct input *in, const struct mouse *m,
+    enum mouse_button b);
+bool input_mouse_justreleased(const struct input *in, const struct mouse *m,
+    enum mouse_button b);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* INPUT_H */
diff --git a/src/input/src/input.c b/src/input/src/input.c
new file mode 100644
index 0000000..bb94424
--- /dev/null
+++ b/src/input/src/input.c
@@ -0,0 +1,175 @@
+#include <input.h>
+#include <keyboard.h>
+#include <mouse.h>
+#include <pad.h>
+#include <peripheral.h>
+#include <ctype.h>
+#include <stdbool.h>
+#include <stddef.h>
+#include <string.h>
+
+static void send_input(struct input *const in, const struct keyboard *const k,
+    const enum keyboard_key key)
+{
+    if (key != KEYBOARD_KEY_NONE)
+    {
+        switch (key)
+        {
+            case KEYBOARD_KEY_BACKSPACE:
+                in->erase(in->user);
+                break;
+
+            case KEYBOARD_KEY_ESC:
+                *in = (const struct input){0};
+                break;
+
+            default:
+            {
+                const char ch = keyboard_to_char(k, key);
+
+                if (isprint(ch))
+                    in->cb(ch, in->user);
+            }
+                break;
+        }
+    }
+}
+
+static void update_keyboard(struct input *const in,
+    const struct keyboard *const k)
+{
+    struct keyboard_combo c;
+
+    if (keyboard_any_justpressed(k, &c))
+        for (size_t i = 0; i < sizeof c.keys / sizeof *c.keys; i++)
+            send_input(in, k, c.keys[i]);
+    else if (keyboard_any_pressed(k, &c))
+    {
+        if (memcmp(&c, &in->prev, sizeof c))
+        {
+            in->repeat = false;
+            in->t = 0;
+        }
+        else
+        {
+            enum {LONG_INTERVAL = 25, SHORT_INTERVAL = 2};
+
+            if (!in->repeat)
+            {
+                if (++in->t >= LONG_INTERVAL)
+                    in->repeat = true;
+            }
+            else if (++in->t >= SHORT_INTERVAL)
+            {
+                for (size_t i = 0;
+                    i < sizeof c.keys / sizeof *c.keys; i++)
+                    send_input(in, k, c.keys[i]);
+
+                in->t = 0;
+            }
+        }
+
+        in->prev = c;
+    }
+    else
+    {
+        in->repeat = false;
+        in->t = 0;
+    }
+}
+
+void input_update(struct input *const in, const union peripheral *const p)
+{
+    switch (p->common.type)
+    {
+        case PERIPHERAL_TYPE_KEYBOARD_MOUSE:
+            if (in->cb && in->erase)
+                update_keyboard(in, &p->kbm.keyboard);
+
+            break;
+
+        case PERIPHERAL_TYPE_TOUCH:
+            /* Fall through. */
+        case PERIPHERAL_TYPE_PAD:
+            break;
+    }
+}
+
+int input_render(const struct input *const in, const union peripheral *const p)
+{
+    switch (p->common.type)
+    {
+        case PERIPHERAL_TYPE_KEYBOARD_MOUSE:
+            return 0;
+
+        case PERIPHERAL_TYPE_TOUCH:
+            /* Fall through. */
+        case PERIPHERAL_TYPE_PAD:
+            break;
+    }
+
+    return -1;
+}
+
+bool input_keyboard_justpressed(const struct input *const in,
+    const struct keyboard *const k,
+    const struct keyboard_combo *const c)
+{
+    return in->cb ? false : keyboard_justpressed(k, c);
+}
+
+bool input_keyboard_pressed(const struct input *const in,
+    const struct keyboard *const k,
+    const struct keyboard_combo *const c)
+{
+    return in->cb ? false : keyboard_pressed(k, c);
+}
+
+bool input_keyboard_justreleased(const struct input *const in,
+    const struct keyboard *const k,
+    const struct keyboard_combo *const c)
+{
+    return in->cb ? false : keyboard_justreleased(k, c);
+}
+
+bool input_pad_pressed(const struct input *const in,
+    const struct pad *const p,
+    const enum pad_key k)
+{
+    return in->cb ? false : pad_pressed(p, k);
+}
+
+bool input_pad_justpressed(const struct input *const in,
+    const struct pad *const p,
+    const enum pad_key k)
+{
+    return in->cb ? false : pad_justpressed(p, k);
+}
+
+bool input_pad_released(const struct input *const in,
+    const struct pad *const p,
+    const enum pad_key k)
+{
+    return in->cb ? false : pad_released(p, k);
+}
+
+bool input_mouse_pressed(const struct input *const in,
+    const struct mouse *const m,
+    const enum mouse_button b)
+{
+    return in->cb ? false : mouse_pressed(m, b);
+}
+
+bool input_mouse_justpressed(const struct input *const in,
+    const struct mouse *const m,
+    const enum mouse_button b)
+{
+    return in->cb ? false : mouse_justpressed(m, b);
+}
+
+bool input_mouse_justreleased(const struct input *const in,
+    const struct mouse *const m,
+    const enum mouse_button b)
+{
+    return in->cb ? false : mouse_justreleased(m, b);
+}