/**************************************************************
 * demo_canvas_virtual_table_pages.c
 * LVGL 9.3 Canvas Virtual Table Pagination Demo (Fixed Buffer)
 * Screen: 1024x600
 * Visible Rows: 15
 * Total Rows: 200
 **************************************************************/

#include "lvgl.h"
#include <stdio.h>
#include <string.h>

#define SCREEN_W    1024
#define SCREEN_H    600
#define TOTAL_ROWS  200
#define VISIBLE_ROWS 15
#define HEADER_H    32
#define COL_CNT     6
#define ROW_H       36

/* ===== Dynamic Data for Row 7 ===== */
typedef struct {
    int vol;
    int temp;
    int res;
} row_data_t;

static row_data_t row7_data = {1,1,601};

/* Canvas Buffer - Pagination Buffer */
#define PAGE_ROWS 50   // Rows per page
#define CANVAS_HEIGHT (HEADER_H + PAGE_ROWS * ROW_H)
static lv_color_t cbuf[SCREEN_W * CANVAS_HEIGHT];

static lv_obj_t * canvas;
static lv_obj_t * scroll_cont;
static int current_page = 0;  // Current page number, starting from 0

static const float col_ratio[COL_CNT] = {0.06f, 0.12f, 0.14f, 0.14f, 0.12f, 0.42f};
static int col_w[COL_CNT];
static int col_x[COL_CNT];

/* ===== Calculate Column Widths and Start X Positions ===== */
static void calc_col_layout(void)
{
    int total_width = 0;
    for(int i=0; i<COL_CNT; i++){
        col_w[i] = (int)(SCREEN_W * col_ratio[i]);
        total_width += col_w[i];
    }
    if(total_width != SCREEN_W) col_w[COL_CNT-1] += SCREEN_W - total_width;

    col_x[0] = 0;
    for(int i=1;i<COL_CNT;i++) col_x[i] = col_x[i-1] + col_w[i-1];
}

/* ===== Simulated Data ===== */
static void get_row_text(int row, int col, char * buf, int len)
{
    if(row == 6) { // Row 7 dynamic data
        switch(col){
            case 0: lv_snprintf(buf,len,"7"); break;
            case 1: lv_snprintf(buf,len,"BT007"); break;
            case 2: lv_snprintf(buf,len,"12.%03d",row7_data.vol); break;
            case 3: lv_snprintf(buf,len,"20.%03d",row7_data.temp); break;
            case 4: lv_snprintf(buf,len,"%d",row7_data.res); break;
            case 5: lv_snprintf(buf,len,"2025-12-17 17:05"); break;
            default: buf[0]=0; break;
        }
        return;
    }

    switch(col){
        case 0: lv_snprintf(buf,len,"%d",row+1); break;
        case 1: lv_snprintf(buf,len,"BT%03d",row+1); break;
        case 2: lv_snprintf(buf,len,"12.%03d",row+1); break;
        case 3: lv_snprintf(buf,len,"20.%03d",row+1); break;
        case 4: lv_snprintf(buf,len,"%d",601+row); break;
        case 5: lv_snprintf(buf,len,"2025-12-17 17:05:%02d",row%60); break;
        default: buf[0]=0; break;
    }
}

/* ===== Draw Canvas Page ===== */
static void draw_canvas_page(lv_obj_t * canvas, int page)
{
    lv_draw_label_dsc_t label_dsc;
    lv_draw_label_dsc_init(&label_dsc);
    label_dsc.color = lv_color_black();
    label_dsc.font  = LV_FONT_DEFAULT;
    label_dsc.align = LV_TEXT_ALIGN_CENTER;
    label_dsc.text_local = true;

    lv_layer_t layer;
    lv_canvas_init_layer(canvas, &layer);

    /* Table Header */
    const char * titles[COL_CNT] = {"No","name","vol","temp","res","time"};
    for(int c=0; c<COL_CNT; c++){
        lv_area_t area = {col_x[c], 0, col_x[c]+col_w[c]-1, HEADER_H-1};
        label_dsc.text = titles[c];
        lv_draw_label(&layer, &label_dsc, &area);
    }

    /* Draw data for each page */
    int start_row = page * PAGE_ROWS;
    int end_row   = start_row + PAGE_ROWS;
    if(end_row > TOTAL_ROWS) end_row = TOTAL_ROWS;

    for(int r=start_row; r<end_row; r++){
        int y = HEADER_H + (r-start_row)*ROW_H;
        char buf[32];
        for(int c=0; c<COL_CNT; c++){
            get_row_text(r,c,buf,sizeof(buf));
            lv_area_t area = {col_x[c], y, col_x[c]+col_w[c]-1, y+ROW_H-1};
            label_dsc.text = buf;
            lv_draw_label(&layer, &label_dsc, &area);
        }
    }

    lv_canvas_finish_layer(canvas,&layer);
}

/* ===== Dynamically Update Row 7 ===== */
static void redraw_row7(void)
{
    int row = 6;
    int y = HEADER_H + (row - current_page*PAGE_ROWS)*ROW_H;

    // Don't draw if row is not in current page
    if(row < current_page*PAGE_ROWS || row >= (current_page+1)*PAGE_ROWS) return;

    lv_layer_t layer;
    lv_canvas_init_layer(canvas,&layer);

    lv_draw_rect_dsc_t rect_dsc;
    lv_draw_rect_dsc_init(&rect_dsc);
    rect_dsc.bg_color = lv_color_white();
    rect_dsc.bg_opa   = LV_OPA_COVER;
    rect_dsc.border_width = 0;

    lv_area_t clear_area = {0, y, SCREEN_W-1, y+ROW_H-1};
    lv_draw_rect(&layer, &rect_dsc, &clear_area);

    lv_draw_label_dsc_t label_dsc;
    lv_draw_label_dsc_init(&label_dsc);
    label_dsc.color = lv_color_black();
    label_dsc.font  = LV_FONT_DEFAULT;
    label_dsc.align = LV_TEXT_ALIGN_CENTER;
    label_dsc.text_local = true;

    char buf[32];
    for(int c=0;c<COL_CNT;c++){
        get_row_text(row,c,buf,sizeof(buf));
        lv_area_t area = {col_x[c],y,col_x[c]+col_w[c]-1,y+ROW_H-1};
        label_dsc.text = buf;
        lv_draw_label(&layer,&label_dsc,&area);
    }

    lv_canvas_finish_layer(canvas,&layer);
}

/* ===== Timer to Update Row 7 ===== */
static void row7_timer_cb(lv_timer_t * t)
{
    LV_UNUSED(t);
    row7_data.vol++;
    row7_data.temp++;
    row7_data.res++;
    redraw_row7();
}

/* ===== Scroll Pagination ===== */
int y = 0;
static void scroll_event_cb(lv_event_t * e)
{
    lv_obj_t * cont = lv_event_get_target(e);
    y = lv_obj_get_scroll_y(cont);
    
    int new_page = current_page;
    bool is_scroll_up = false;  // Flag for scroll direction
    
    /* Page Change Conditions: Scroll to boundaries */
    if(y < -50) {
        // Scroll up beyond top: Go to previous page
        if(current_page > 0) {
            new_page = current_page - 1;
            is_scroll_up = true;  // This is scrolling up
        }
    } 
    else if(y > ((PAGE_ROWS - VISIBLE_ROWS) * ROW_H) + 50) {
        // Scroll down beyond bottom: Go to next page
        int max_page = (TOTAL_ROWS + PAGE_ROWS - 1) / PAGE_ROWS - 1;
        if(current_page < max_page) {
            new_page = current_page + 1;
            is_scroll_up = false;  // This is scrolling down
        }
    }
    
    if(new_page != current_page) {
        current_page = new_page;
        lv_canvas_fill_bg(canvas, lv_color_white(), LV_OPA_COVER);
        draw_canvas_page(canvas, current_page);
        
        // Set different scroll positions based on page direction
        if(is_scroll_up) {
            // Scroll up: Show bottom of new page (last few rows)
            lv_obj_set_y(canvas, 0);  // Reset canvas position
            lv_obj_scroll_to(cont, 0, (PAGE_ROWS - VISIBLE_ROWS) * ROW_H, LV_ANIM_OFF);
        } else {
            // Scroll down: Show top of new page (first few rows)
            lv_obj_set_y(canvas, 0);  // Reset canvas position
            lv_obj_scroll_to(cont, 0, 0, LV_ANIM_OFF);
        }
    }
}

/* ===== Main Demo ===== */
void demo_virtual_canvas_pages(void)
{
    calc_col_layout();

    lv_obj_t * scr = lv_scr_act();
    lv_obj_clean(scr);

    scroll_cont = lv_obj_create(scr);
    lv_obj_set_size(scroll_cont, SCREEN_W, SCREEN_H);
    lv_obj_set_scroll_dir(scroll_cont, LV_DIR_VER);
    lv_obj_set_scrollbar_mode(scroll_cont, LV_SCROLLBAR_MODE_AUTO);

    // Scroll callback
    lv_obj_add_event_cb(scroll_cont, scroll_event_cb, LV_EVENT_SCROLL, NULL);

    canvas = lv_canvas_create(scroll_cont);
    lv_canvas_set_buffer(canvas, cbuf, SCREEN_W, CANVAS_HEIGHT, LV_COLOR_FORMAT_RGB565);
    lv_canvas_fill_bg(canvas, lv_color_white(), LV_OPA_COVER);

    // Initial page
    current_page = 0;
    draw_canvas_page(canvas,current_page);

    lv_obj_set_pos(canvas,0,0);

    lv_timer_create(row7_timer_cb,500,NULL);
}