#include <stdio.h>
#include <limits.h>
//#include "fixed.h"
#include "calc.h"

static inline int8_t tokenCount() {
    return sizeof(tokens) / sizeof(tokens[0]);
}

static inline char* getToken(int8_t n) {
    return tokens[n % tokenCount()];
}

// Currently selected button, starts on '('
static int8_t selected_token = 1;

// Update the current code text with the contents of `mytext`,
// and add the current selected_token to the end
static void updateText()
{
    strcpy(temptext, mytext);

    const char *token = getToken(selected_token);
    if(token[0] == ' ') {
        strcat(temptext, "_");
    } else if(token[0] == '\n') {
        strcat(temptext, "\\n");
    } else {
        strcat(temptext, token);
    }

    text_layer_set_text(s_input_text_layer, temptext);
}

// Button handler
static void up_down_handler(ClickRecognizerRef recognizer, void *context){
    // Change current token
    if(click_recognizer_get_button_id(recognizer) == BUTTON_ID_DOWN)
        selected_token++;
    else
        selected_token--;

    // If selected token is outside of range, wrap around
    if(selected_token < 0)
        selected_token = tokenCount() - 1;
    else if(selected_token >= tokenCount())
        selected_token = 0;

    updateText();
}

// Backspace if possible, otherwise close the app
static void back_handler(ClickRecognizerRef recognizer, void *context) {
    if(mytext[0] == '\0') {
        window_stack_remove(window_stack_get_top_window(), true);
    } else {
        int8_t i = 0;
        while(mytext[++i] != '\0') { ; }
        mytext[i-1] = '\0';
        updateText();
    }
}

// Adds the current string to the main string
static void enter(){
    strcat(mytext, getToken(selected_token));
    selected_token = 0;
    updateText();
}

// Calculate result, display it and reset
static void calculate(){
    Object obj = parseEval(mytext, &env);
    char temp[MAX_LENGTH-2] = "";

    stringObj(temp, &obj);
    snprintf(resulttext, MAX_LENGTH, "R:%s", temp);
    selected_token = 0;
    text_layer_set_text(s_result_text_layer, resulttext);
}

// Button press handler
static void select_handler(ClickRecognizerRef recognizer, void *context){
    if(selected_token == sizeof(tokens) / sizeof(tokens[0]) - 1)
        calculate();
    else
        enter();
}

static void click_config_provider(void *context) {
    // Register click handlers
    window_single_repeating_click_subscribe(BUTTON_ID_UP, 100, up_down_handler);
    window_single_repeating_click_subscribe(BUTTON_ID_DOWN, 100, up_down_handler);
    window_single_click_subscribe(BUTTON_ID_SELECT, select_handler);
    window_single_click_subscribe(BUTTON_ID_BACK, back_handler);
}

static void init(void) {
    // Create a window and get information about the window
    s_window = window_create();

    // Register click config provider
    window_set_click_config_provider(s_window, click_config_provider);

    // Input text layer setup
    GRect text_bounds = GRect(6, 6, 132, 127);
    s_input_text_layer = text_layer_create(text_bounds);
    text_layer_set_text(s_input_text_layer, getToken(1));
    text_layer_set_font(s_input_text_layer, fonts_get_system_font(FONT_KEY_GOTHIC_28_BOLD));
    layer_add_child(window_get_root_layer(s_window), text_layer_get_layer(s_input_text_layer));

    // Result text layer setup
    GRect result_bounds = GRect(6, 128, 132, 132);
    s_result_text_layer = text_layer_create(result_bounds);
    text_layer_set_text(s_result_text_layer, "R: ");
    text_layer_set_font(s_result_text_layer, fonts_get_system_font(FONT_KEY_GOTHIC_28_BOLD));
    text_layer_set_text_alignment(s_result_text_layer, GTextAlignmentRight);
    layer_add_child(window_get_root_layer(s_window), text_layer_get_layer(s_result_text_layer));

    // Push the window, setting the window animation to 'true'
    window_stack_push(s_window, true);
    env = defaultEnv();

    // If possible, load the previous code text
    if(persist_exists(CODE_PKEY)) {
        persist_read_string(CODE_PKEY, mytext, SMAX_LENGTH);
        updateText();
    }
}

static void deinit(void) {
    // Save the current code text
    persist_write_string(CODE_PKEY, temptext);

    deleteEnv(&env);
    text_layer_destroy(s_input_text_layer);
    window_destroy(s_window);
}

int main(void) {
    init();
    app_event_loop();
    deinit();
}