/**
 * @file oled.c
 * @brief SSD1315 OLED 128x64 I2C driver implementation
 */
#include <string.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2c.h"
#include "esp_log.h"
#include "oled.h"

static const char *TAG = "oled";

/* I2C configuration */
#define I2C_PORT        I2C_NUM_0
#define OLED_ADDR       0x3C
#define I2C_CLOCK_HZ    400000

/* Display buffer (128x64 / 8 = 1024 bytes) */
static uint8_t display_buffer[OLED_WIDTH * OLED_PAGES];

/* Simple 8x16 font (ASCII 0x20-0x7F) */
/* Using a basic 5x7 font doubled to 8x16 by row replication */
static const uint8_t font_8x8[][8] = {
    {0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00}, /* space */
    {0x00,0x00,0x5F,0x00,0x00,0x00,0x00,0x00}, /* ! */
    {0x00,0x07,0x00,0x07,0x00,0x00,0x00,0x00}, /* " */
    {0x14,0x7F,0x14,0x7F,0x14,0x00,0x00,0x00}, /* # */
    {0x24,0x2A,0x7F,0x2A,0x12,0x00,0x00,0x00}, /* $ */
    {0x23,0x13,0x08,0x64,0x62,0x00,0x00,0x00}, /* % */
    {0x36,0x49,0x55,0x22,0x50,0x00,0x00,0x00}, /* & */
    {0x00,0x05,0x03,0x00,0x00,0x00,0x00,0x00}, /* ' */
    {0x00,0x1C,0x22,0x41,0x00,0x00,0x00,0x00}, /* ( */
    {0x00,0x41,0x22,0x1C,0x00,0x00,0x00,0x00}, /* ) */
    {0x08,0x2A,0x1C,0x2A,0x08,0x00,0x00,0x00}, /* * */
    {0x08,0x08,0x3E,0x08,0x08,0x00,0x00,0x00}, /* + */
    {0x00,0x50,0x30,0x00,0x00,0x00,0x00,0x00}, /* , */
    {0x08,0x08,0x08,0x08,0x08,0x00,0x00,0x00}, /* - */
    {0x00,0x60,0x60,0x00,0x00,0x00,0x00,0x00}, /* . */
    {0x20,0x10,0x08,0x04,0x02,0x00,0x00,0x00}, /* / */
    {0x3E,0x51,0x49,0x45,0x3E,0x00,0x00,0x00}, /* 0 */
    {0x00,0x42,0x7F,0x40,0x00,0x00,0x00,0x00}, /* 1 */
    {0x42,0x61,0x51,0x49,0x46,0x00,0x00,0x00}, /* 2 */
    {0x21,0x41,0x45,0x4B,0x31,0x00,0x00,0x00}, /* 3 */
    {0x18,0x14,0x12,0x7F,0x10,0x00,0x00,0x00}, /* 4 */
    {0x27,0x45,0x45,0x45,0x39,0x00,0x00,0x00}, /* 5 */
    {0x3C,0x4A,0x49,0x49,0x30,0x00,0x00,0x00}, /* 6 */
    {0x01,0x71,0x09,0x05,0x03,0x00,0x00,0x00}, /* 7 */
    {0x36,0x49,0x49,0x49,0x36,0x00,0x00,0x00}, /* 8 */
    {0x06,0x49,0x49,0x29,0x1E,0x00,0x00,0x00}, /* 9 */
    {0x00,0x36,0x36,0x00,0x00,0x00,0x00,0x00}, /* : */
    {0x00,0x56,0x36,0x00,0x00,0x00,0x00,0x00}, /* ; */
    {0x00,0x08,0x14,0x22,0x41,0x00,0x00,0x00}, /* < */
    {0x14,0x14,0x14,0x14,0x14,0x00,0x00,0x00}, /* = */
    {0x41,0x22,0x14,0x08,0x00,0x00,0x00,0x00}, /* > */
    {0x02,0x01,0x51,0x09,0x06,0x00,0x00,0x00}, /* ? */
    {0x32,0x49,0x79,0x41,0x3E,0x00,0x00,0x00}, /* @ */
    {0x7E,0x11,0x11,0x11,0x7E,0x00,0x00,0x00}, /* A */
    {0x7F,0x49,0x49,0x49,0x36,0x00,0x00,0x00}, /* B */
    {0x3E,0x41,0x41,0x41,0x22,0x00,0x00,0x00}, /* C */
    {0x7F,0x41,0x41,0x22,0x1C,0x00,0x00,0x00}, /* D */
    {0x7F,0x49,0x49,0x49,0x41,0x00,0x00,0x00}, /* E */
    {0x7F,0x09,0x09,0x01,0x01,0x00,0x00,0x00}, /* F */
    {0x3E,0x41,0x41,0x51,0x32,0x00,0x00,0x00}, /* G */
    {0x7F,0x08,0x08,0x08,0x7F,0x00,0x00,0x00}, /* H */
    {0x00,0x41,0x7F,0x41,0x00,0x00,0x00,0x00}, /* I */
    {0x20,0x40,0x41,0x3F,0x01,0x00,0x00,0x00}, /* J */
    {0x7F,0x08,0x14,0x22,0x41,0x00,0x00,0x00}, /* K */
    {0x7F,0x40,0x40,0x40,0x40,0x00,0x00,0x00}, /* L */
    {0x7F,0x02,0x04,0x02,0x7F,0x00,0x00,0x00}, /* M */
    {0x7F,0x04,0x08,0x10,0x7F,0x00,0x00,0x00}, /* N */
    {0x3E,0x41,0x41,0x41,0x3E,0x00,0x00,0x00}, /* O */
    {0x7F,0x09,0x09,0x09,0x06,0x00,0x00,0x00}, /* P */
    {0x3E,0x41,0x51,0x21,0x5E,0x00,0x00,0x00}, /* Q */
    {0x7F,0x09,0x19,0x29,0x46,0x00,0x00,0x00}, /* R */
    {0x46,0x49,0x49,0x49,0x31,0x00,0x00,0x00}, /* S */
    {0x01,0x01,0x7F,0x01,0x01,0x00,0x00,0x00}, /* T */
    {0x3F,0x40,0x40,0x40,0x3F,0x00,0x00,0x00}, /* U */
    {0x1F,0x20,0x40,0x20,0x1F,0x00,0x00,0x00}, /* V */
    {0x7F,0x20,0x18,0x20,0x7F,0x00,0x00,0x00}, /* W */
    {0x63,0x14,0x08,0x14,0x63,0x00,0x00,0x00}, /* X */
    {0x03,0x04,0x78,0x04,0x03,0x00,0x00,0x00}, /* Y */
    {0x61,0x51,0x49,0x45,0x43,0x00,0x00,0x00}, /* Z */
};

/* I2C write command */
static esp_err_t oled_write_cmd(uint8_t cmd)
{
    i2c_cmd_handle_t i2c_cmd = i2c_cmd_link_create();
    i2c_master_start(i2c_cmd);
    i2c_master_write_byte(i2c_cmd, (OLED_ADDR << 1) | I2C_MASTER_WRITE, true);
    i2c_master_write_byte(i2c_cmd, 0x00, true);  /* Co=0, D/C#=0 (command) */
    i2c_master_write_byte(i2c_cmd, cmd, true);
    i2c_master_stop(i2c_cmd);
    esp_err_t ret = i2c_master_cmd_begin(I2C_PORT, i2c_cmd, pdMS_TO_TICKS(100));
    i2c_cmd_link_delete(i2c_cmd);
    return ret;
}

/* I2C write data */
static esp_err_t oled_write_data(const uint8_t *data, size_t len)
{
    i2c_cmd_handle_t i2c_cmd = i2c_cmd_link_create();
    i2c_master_start(i2c_cmd);
    i2c_master_write_byte(i2c_cmd, (OLED_ADDR << 1) | I2C_MASTER_WRITE, true);
    i2c_master_write_byte(i2c_cmd, 0x40, true);  /* Co=0, D/C#=1 (data) */
    i2c_master_write(i2c_cmd, data, len, true);
    i2c_master_stop(i2c_cmd);
    esp_err_t ret = i2c_master_cmd_begin(I2C_PORT, i2c_cmd, pdMS_TO_TICKS(100));
    i2c_cmd_link_delete(i2c_cmd);
    return ret;
}

esp_err_t oled_init(int sda, int scl)
{
    /* Initialize I2C */
    i2c_config_t conf = {
        .mode = I2C_MODE_MASTER,
        .sda_io_num = sda,
        .scl_io_num = scl,
        .sda_pullup_en = GPIO_PULLUP_ENABLE,
        .scl_pullup_en = GPIO_PULLUP_ENABLE,
        .master.clk_speed = I2C_CLOCK_HZ,
    };
    
    ESP_ERROR_CHECK(i2c_param_config(I2C_PORT, &conf));
    ESP_ERROR_CHECK(i2c_driver_install(I2C_PORT, conf.mode, 0, 0, 0));
    
    vTaskDelay(pdMS_TO_TICKS(100));
    
    /* SSD1315 initialization sequence */
    oled_write_cmd(0xAE);  /* Display off */
    oled_write_cmd(0xD5);  /* Set display clock divide ratio */
    oled_write_cmd(0x80);
    oled_write_cmd(0xA8);  /* Set multiplex ratio */
    oled_write_cmd(0x3F);  /* 64 lines */
    oled_write_cmd(0xD3);  /* Set display offset */
    oled_write_cmd(0x00);
    oled_write_cmd(0x40);  /* Set display start line */
    oled_write_cmd(0x8D);  /* Charge pump setting */
    oled_write_cmd(0x14);  /* Enable */
    oled_write_cmd(0x20);  /* Memory addressing mode */
    oled_write_cmd(0x00);  /* Horizontal */
    oled_write_cmd(0xA1);  /* Segment remap (column 127 mapped to SEG0) */
    oled_write_cmd(0xC8);  /* COM output scan direction */
    oled_write_cmd(0xDA);  /* COM pins hardware configuration */
    oled_write_cmd(0x12);  /* Alternative pin configuration */
    oled_write_cmd(0x81);  /* Set contrast */
    oled_write_cmd(0x7F);
    oled_write_cmd(0xD9);  /* Set pre-charge period */
    oled_write_cmd(0xF1);
    oled_write_cmd(0xDB);  /* Set VCOMH deselect level */
    oled_write_cmd(0x40);
    oled_write_cmd(0xA4);  /* Display on (resume) */
    oled_write_cmd(0xA6);  /* Normal display (not inverted) */
    oled_write_cmd(0xAF);  /* Display on */
    
    /* Clear display buffer */
    memset(display_buffer, 0, sizeof(display_buffer));
    oled_update();
    
    ESP_LOGI(TAG, "OLED initialized");
    return ESP_OK;
}

void oled_clear(void)
{
    memset(display_buffer, 0, sizeof(display_buffer));
}

void oled_clear_area(uint8_t x, uint8_t y, uint8_t w, uint8_t h)
{
    for (uint8_t i = y; i < y + h; i++) {
        for (uint8_t j = x; j < x + w; j++) {
            if (j < OLED_WIDTH && i < OLED_HEIGHT) {
                uint16_t idx = (i / 8) * OLED_WIDTH + j;
                if (idx < sizeof(display_buffer)) {
                    display_buffer[idx] &= ~(1 << (i % 8));
                }
            }
        }
    }
}

void oled_draw_pixel(uint8_t x, uint8_t y, uint8_t color)
{
    if (x >= OLED_WIDTH || y >= OLED_HEIGHT) return;
    
    uint16_t idx = (y / 8) * OLED_WIDTH + x;
    if (idx >= sizeof(display_buffer)) return;
    
    if (color) {
        display_buffer[idx] |= (1 << (y % 8));
    } else {
        display_buffer[idx] &= ~(1 << (y % 8));
    }
}

void oled_draw_char(uint8_t x, uint8_t y, char c, uint8_t color)
{
    if (c < 0x20 || c > 0x5A) c = 0x20;  /* Space for non-printable */
    c -= 0x20;
    
    for (uint8_t i = 0; i < 8; i++) {
        uint8_t line = font_8x8[(uint8_t)c][i];
        for (uint8_t j = 0; j < 8; j++) {
            if (line & (0x80 >> j)) {
                oled_draw_pixel(x + j, y + i, color);
            } else {
                oled_draw_pixel(x + j, y + i, !color);
            }
        }
    }
}

void oled_draw_string(uint8_t x, uint8_t y, const char *str, uint8_t color)
{
    while (*str) {
        oled_draw_char(x, y, *str, color);
        x += 8;
        if (x + 8 > OLED_WIDTH) {
            x = 0;
            y += 8;
        }
        str++;
    }
}

void oled_draw_top_string(const char *str, uint8_t color)
{
    oled_draw_string(0, 0, str, color);
}

void oled_draw_hline(uint8_t x, uint8_t y, uint8_t w, uint8_t color)
{
    for (uint8_t i = 0; i < w; i++) {
        oled_draw_pixel(x + i, y, color);
    }
}

void oled_draw_vline(uint8_t x, uint8_t y, uint8_t h, uint8_t color)
{
    for (uint8_t i = 0; i < h; i++) {
        oled_draw_pixel(x, y + i, color);
    }
}

void oled_fill_rect(uint8_t x, uint8_t y, uint8_t w, uint8_t h, uint8_t color)
{
    for (uint8_t i = y; i < y + h; i++) {
        for (uint8_t j = x; j < x + w; j++) {
            oled_draw_pixel(j, i, color);
        }
    }
}

void oled_update(void)
{
    /* Set column address range */
    oled_write_cmd(0x21);
    oled_write_cmd(0);
    oled_write_cmd(127);
    
    /* Set page address range */
    oled_write_cmd(0x22);
    oled_write_cmd(0);
    oled_write_cmd(7);
    
    /* Write buffer */
    oled_write_data(display_buffer, sizeof(display_buffer));
}

void oled_display_on(void)
{
    oled_write_cmd(0xAF);
}

void oled_display_off(void)
{
    oled_write_cmd(0xAE);
}

void oled_set_contrast(uint8_t value)
{
    oled_write_cmd(0x81);
    oled_write_cmd(value);
}