#include "epaper_manager.h"
#include "wifi_manager.h"
#include "pico/stdlib.h"
#include "pico/multicore.h"
#include <stdlib.h>
#include <string.h>
#include <stdio.h>

// e-Paper library includes
extern "C" {
    #include "DEV_Config.h"
    #include "EPD_7in5b_V2.h"
    #include "GUI_Paint.h"
}

// e-Paper display buffers
static UBYTE *g_epd_image = NULL;  // Black image buffer
static UBYTE *g_epd_red = NULL;    // Red image buffer

// Entry list for display
#define MAX_ENTRIES 15
#define ENTRY_LENGTH 64
typedef struct {
    char entries[MAX_ENTRIES][ENTRY_LENGTH];
    int count;
} EntryList;

static EntryList g_entry_list = {{}, 0};
static bool g_force_full_refresh = false;  // Flag to force full refresh when list is full

// Synchronization flag for multicore initialization
static volatile bool g_display_ready = false;

// Display update message structure for inter-core communication
typedef struct {
    EntryList entries;
    bool use_partial;  // Use partial refresh instead of full refresh
    UWORD xstart;      // Partial refresh region
    UWORD ystart;
    UWORD xend;
    UWORD yend;
} DisplayMessage;

static void init_epaper_display() {
    printf("Initializing 7.5\" e-Paper display (B V2)...\r\n");
    
    // Initialize the hardware
    if (DEV_Module_Init() != 0) {
        printf("Failed to initialize e-Paper hardware!\r\n");
        return;
    }
    
    // Initialize the display
    printf("EPD_7IN5B_V2_Init()\r\n");
    EPD_7IN5B_V2_Init_Fast();
    printf("EPD_7IN5B_V2_Clear()\r\n");
    
    // Create image buffers for black and red content
    // 7.5" display: 800x480, 8 pixels per byte, so (800/8) * 480 = 48000 bytes each
    UWORD imagesize = (EPD_7IN5B_V2_WIDTH / 8) * EPD_7IN5B_V2_HEIGHT;
    
    g_epd_image = (UBYTE *)malloc(imagesize);
    g_epd_red = (UBYTE *)malloc(imagesize);
    
    if (g_epd_image == NULL || g_epd_red == NULL) {
        printf("Failed to allocate memory for e-Paper image buffers!\r\n");
        return;
    }
    
    // Initialize red buffer to all white (0xFF = no red pixels)
    for (UWORD i = 0; i < imagesize; i++) {
        g_epd_red[i] = 0xFF;
    }
    
    // Setup paint buffer for black content
    printf("White background\r\n");
    Paint_NewImage(g_epd_image, EPD_7IN5B_V2_WIDTH, EPD_7IN5B_V2_HEIGHT, 0, WHITE);
    Paint_SelectImage(g_epd_image);
    Paint_Clear(WHITE);
    
    // Draw header
    EPD_7IN5B_V2_Init_Part();
    EPD_7IN5B_V2_Display_Partial(g_epd_image, 0, 0, EPD_7IN5B_V2_WIDTH, EPD_7IN5B_V2_HEIGHT);
    EPD_7IN5B_V2_Display_Partial(g_epd_image, 0, 0, EPD_7IN5B_V2_WIDTH, EPD_7IN5B_V2_HEIGHT);
    EPD_7IN5B_V2_Display_Partial(g_epd_image, 0, 0, EPD_7IN5B_V2_WIDTH, EPD_7IN5B_V2_HEIGHT);

    Paint_SelectImage(g_epd_red);
    printf("Drawing header\r\n");
    Paint_DrawString_EN(10, 10, "What's new today:", &Font24, WHITE, RED);
    
    // Display the image with both black and red buffers
    EPD_7IN5B_V2_Display_Partial(g_epd_red, 0, 0, EPD_7IN5B_V2_WIDTH, EPD_7IN5B_V2_HEIGHT);
    
    printf("e-Paper display ready!\r\n");
}

/**
 * Core 1 function: Runs display initialization and update handling
 */
static void core1_display_init() {
    // Initialize WiFi on Core 1 so IRQs are handled here
    wifi_init();

    init_epaper_display();
    g_display_ready = true;
    
    printf("[Core 1] Display ready, waiting for update messages...\n");
    
    // Initialize for partial refresh on second call
    EPD_7IN5B_V2_Init_Part();
    
    // Core 1 main loop: handle display updates via FIFO
    while (true) {
        // Check if there's a message from core 0
        if (multicore_fifo_rvalid()) {
            // Read the message pointer
            uint32_t msg_addr = multicore_fifo_pop_blocking();
            DisplayMessage *msg = (DisplayMessage *)msg_addr;

            // Drain FIFO to get the latest message
            while (multicore_fifo_rvalid()) {
                 printf("[Core 1] Skipping intermediate update\n");
                 free(msg); // Free the stale message
                 msg_addr = multicore_fifo_pop_blocking();
                 msg = (DisplayMessage *)msg_addr;
            }
            
            printf("[Core 1] Updating display with %d entries\n", msg->entries.count);
            
            // Update the e-Paper display
            if (g_epd_image != NULL && g_epd_red != NULL) {
                // For partial refresh, only clear the text area
                UWORD y_start = msg->ystart;
                UWORD y_end = msg->yend;
                
                Paint_SelectImage(g_epd_image);
                Paint_Clear(WHITE);
                
                // Calculate offset for partial refresh
                UBYTE *image_ptr = g_epd_image + (msg->ystart * (EPD_7IN5B_V2_WIDTH / 8));

                if(!msg->use_partial){
                    // for loop 5 times display white partial
                    int i = 0;
                    for(i = 0; i < 1; i++){
                        EPD_7IN5B_V2_Display_Partial(image_ptr, msg->xstart, msg->ystart, msg->xend, msg->yend);
                    }
                }
                
                // Draw all entries starting below header
                UWORD y_pos = 0;
                // paint only the last 10 entries
                int start_index = msg->entries.count > 10 ? msg->entries.count - 10 : 0;
                for (int i = start_index; i < msg->entries.count; i++) {
                    if (y_pos + 25 < 480) {  //Don't draw beyond screen
                        Paint_DrawString_EN(20, 50 + i*25, msg->entries.entries[i], &Font16, WHITE, BLACK);
                        y_pos += 25;  // Space between entries
                    } else {
                        printf("Skipping entry to avoid overflow\n");
                    }
                }
                // Use partial or full refresh
                printf("[Core 1] Using partial refresh\n");
                EPD_7IN5B_V2_Display_Partial(image_ptr, msg->xstart, msg->ystart, msg->xend, msg->yend);
            }
            
            // Free the message (it was allocated by core 0)
            free(msg);
        }
        
        sleep_ms(10);
    }
}

void epaper_start_background_thread() {
    printf("Launching e-Paper display init on core 1...\n");
    multicore_launch_core1(core1_display_init);
}

void epaper_send_update(const char *entry, bool finish_line) {
    if (!g_display_ready) return;  // Don't send if display isn't ready
    
    // Check if list is at capacity
    if (g_entry_list.count >= MAX_ENTRIES) {
        // List is full - clear all entries and start fresh
        printf("[Core 0] List is FULL - clearing all entries and starting fresh\n");
        g_entry_list.count = 0;
        g_force_full_refresh = true;
    }
    
    // Update the current entry (at g_entry_list.count)
    strncpy(g_entry_list.entries[g_entry_list.count], entry, ENTRY_LENGTH - 1);
    g_entry_list.entries[g_entry_list.count][ENTRY_LENGTH - 1] = '\0';
    
    // Allocate message structure
    DisplayMessage *msg = (DisplayMessage *)malloc(sizeof(DisplayMessage));
    if (msg == NULL) {
        printf("Failed to allocate display message!\n");
        return;
    }
    
    // Copy entry list to message
    msg->entries = g_entry_list;
    // We want to show the current line being edited, so we treat count as count + 1 for display purposes
    msg->entries.count = g_entry_list.count + 1;
    
    // Decide whether to use partial or full refresh
    msg->use_partial = !g_force_full_refresh;
    
    if (g_force_full_refresh) {
        printf("[Core 0] Forcing full refresh this update\n");
        g_force_full_refresh = false;  // Reset flag after setting it in message
        
        // Full text area refresh
        msg->xstart = 0;
        msg->ystart = 50;      // Start below the header
        msg->xend = 800;       // Full width
        msg->yend = 480;       // Full height from header onwards
    } else {
        // Partial refresh of ONLY the current line
        msg->xstart = 0;
        msg->ystart = 50 + (g_entry_list.count * 25);
        msg->xend = 800;
        msg->yend = msg->ystart + 25;
    }
    
    // Send message pointer to core 1 if FIFO has space
    if (multicore_fifo_wready()) {
        multicore_fifo_push_blocking((uint32_t)msg);
    } else {
        printf("[Core 0] FIFO full, skipping display update\n");
        free(msg);
    }
    
    // If finishing the line, increment count for next time
    if (finish_line) {
        g_entry_list.count++;
    }
}

void epaper_clear() {
    g_entry_list.count = 0;
    memset(g_entry_list.entries, 0, sizeof(g_entry_list.entries));
    g_force_full_refresh = true;
    epaper_send_update("", false);
}

void epaper_force_refresh() {
    g_force_full_refresh = true;
    epaper_send_update("", false);
}