#include <stdio.h>
#include <limits.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[RESULT_LENGTH-2] = "";

    stringObj(temp, &obj);
    snprintf(resulttext, RESULT_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 long_select_handler(ClickRecognizerRef recognizer, void *context){
    persist_write_string(current_code, temptext);
    window_stack_pop(true);
}

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_long_click_subscribe(BUTTON_ID_SELECT, 500, long_select_handler, NULL);
    window_single_click_subscribe(BUTTON_ID_BACK, back_handler);
}

static uint16_t get_num_rows_callback(MenuLayer *menu_layer,
                                      uint16_t section_index, void *context) {
    return NUM_ROWS;
}

static void draw_row_callback(GContext *ctx, const Layer *cell_layer,
                                        MenuIndex *cell_index, void *context) {
  static char s_buff[16];
  snprintf(s_buff, sizeof(s_buff), "Script %d", 1 + (int)cell_index->row);

  // Draw this row's index
  menu_cell_basic_draw(ctx, cell_layer, s_buff, NULL, NULL);
}

static int16_t get_cell_height_callback(struct MenuLayer *menu_layer,
                                        MenuIndex *cell_index, void *context) {
  const int16_t cell_height = 44;
  return cell_height;
}

void code_window_push() {
  if(!s_code_window) {
    s_code_window = window_create();
    WindowHandlers wh = {
        .load = code_window_load,
        .unload = code_window_unload };
    window_set_window_handlers(s_code_window, wh);
  }
  window_stack_push(s_code_window, true);
}

static void select_callback(struct MenuLayer *menu_layer,
                            MenuIndex *cell_index, void *context) 
{
    current_code = cell_index->row;
    code_window_push();
}

static void menu_load(Window *window)
{
  Layer *window_layer = window_get_root_layer(window);
  GRect bounds = layer_get_bounds(window_layer);

  s_menu_layer = menu_layer_create(bounds);
  menu_layer_set_click_config_onto_window(s_menu_layer, window);
#if defined(PBL_COLOR)
  menu_layer_set_normal_colors(s_menu_layer, GColorBlack, GColorWhite);
  menu_layer_set_highlight_colors(s_menu_layer, GColorDukeBlue, GColorWhite);
#endif
  menu_layer_set_callbacks(s_menu_layer, NULL, (MenuLayerCallbacks) {
      .get_num_rows = get_num_rows_callback,
      .draw_row = draw_row_callback,
      .get_cell_height = get_cell_height_callback,
      .select_click = select_callback,
  });
  layer_add_child(window_layer, menu_layer_get_layer(s_menu_layer));
}

static void menu_unload(Window *window)
{
    menu_layer_destroy(s_menu_layer);
}

void code_window_load(Window *window)
{
    Layer *window_layer = window_get_root_layer(window);
    GRect bounds = layer_get_bounds(window_layer);

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

    // Input text layer setup
    // GRect text_bounds = GRect(6, 6, 132, 127);
    s_input_text_layer = text_layer_create(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_code_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_18_BOLD));
    text_layer_set_text_alignment(s_result_text_layer, GTextAlignmentRight);
    layer_add_child(window_get_root_layer(s_code_window), text_layer_get_layer(s_result_text_layer));

    // Push the window, setting the window animation to 'true'
    window_stack_push(s_code_window, true);

    // If possible, load the previous code text
    // Object obj = parseEval("(def ad (fn (a) (* 3 a)))", &env);
    // Object obj2 = parseEval("(map ad (1 50 99))", &env);
    // printObj(&obj);
    // printObj(&obj2);
    // cleanObject(&obj);
    // cleanObject(&obj2);
    if(persist_exists(current_code)) {
        persist_read_string(current_code, mytext, SMAX_LENGTH);
        updateText();
    }
}

void code_window_unload(Window *window)
{
    // Save the current code text
    persist_write_string(current_code, temptext);

    text_layer_destroy(s_result_text_layer);
    text_layer_destroy(s_input_text_layer);

    window_destroy(window);
    s_code_window = NULL;
}

static void init(void) {
    env = defaultEnv();
    s_menu_window = window_create();
    window_set_window_handlers(s_menu_window, (WindowHandlers) {
        .load = menu_load,
        .unload = menu_unload
    });
    window_stack_push(s_menu_window, true);
}

static void deinit(void) {
    deleteEnv(&env);
    text_layer_destroy(s_input_text_layer);
    window_destroy(s_menu_window);
}

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