// Copyright 2019-2020 Espressif Systems (Shanghai) PTE LTD
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

#include <stdio.h>
#include <string.h>
#include <assert.h>
#include <sys/param.h>
#include "sdkconfig.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/semphr.h"
#include "esp_system.h"
#include "esp_intr_alloc.h"
#include "esp_private/usb_console.h"
#include "soc/periph_defs.h"
#include "soc/rtc_cntl_reg.h"
#include "soc/usb_struct.h"
#include "soc/usb_reg.h"
#include "soc/spinlock.h"
#include "hal/soc_hal.h"
#include "esp32s2/rom/uart.h"
#include "esp32s2/rom/usb/usb_dc.h"
#include "esp32s2/rom/usb/cdc_acm.h"
#include "esp32s2/rom/usb/usb_dfu.h"
#include "esp32s2/rom/usb/usb_device.h"
#include "esp32s2/rom/usb/usb_os_glue.h"
#include "esp32s2/rom/usb/usb_persist.h"
#include "esp32s2/rom/usb/chip_usb_dw_wrapper.h"


#define CDC_WORK_BUF_SIZE (CDC_ACM_WORK_BUF_MIN + CONFIG_ESP_CONSOLE_USB_CDC_RX_BUF_SIZE)

typedef enum {
    REBOOT_NONE,
    REBOOT_NORMAL,
    REBOOT_BOOTLOADER,
    REBOOT_BOOTLOADER_DFU,
} reboot_type_t;


static reboot_type_t s_queue_reboot = REBOOT_NONE;
static int s_prev_rts_state;
static intr_handle_t s_usb_int_handle;
static cdc_acm_device *s_cdc_acm_device;
static char s_usb_tx_buf[ACM_BYTES_PER_TX];
static size_t s_usb_tx_buf_pos;
static uint8_t cdcmem[CDC_WORK_BUF_SIZE];
static esp_usb_console_cb_t s_rx_cb;
static esp_usb_console_cb_t s_tx_cb;
static void *s_cb_arg;

#ifdef CONFIG_ESP_CONSOLE_USB_CDC_SUPPORT_ETS_PRINTF
static spinlock_t s_write_lock = SPINLOCK_INITIALIZER;
void esp_usb_console_write_char(char c);
#define ISR_FLAG  ESP_INTR_FLAG_IRAM
#else
#define ISR_FLAG  0
#endif // CONFIG_ESP_CONSOLE_USB_CDC_SUPPORT_ETS_PRINTF


/* Optional write lock routines; used only if ets_printf output via CDC is enabled */
static inline void write_lock_acquire(void);
static inline void write_lock_release(void);

/* The two functions below need to be revisited in the multicore case */
_Static_assert(SOC_CPU_CORES_NUM == 1, "usb_osglue_*_int is not multicore capable");

/* Called by ROM to disable the interrupts
 * Non-static to allow placement into IRAM by ldgen.
 */
void esp_usb_console_osglue_dis_int(void)
{
    if (s_usb_int_handle) {
        esp_intr_disable(s_usb_int_handle);
    }
}

/* Called by ROM to enable the interrupts
 * Non-static to allow placement into IRAM by ldgen.
 */
void esp_usb_console_osglue_ena_int(void)
{
    if (s_usb_int_handle) {
        esp_intr_enable(s_usb_int_handle);
    }
}

/* Delay function called by ROM USB driver.
 * Non-static to allow placement into IRAM by ldgen.
 */
int esp_usb_console_osglue_wait_proc(int delay_us)
{
    if (xTaskGetSchedulerState() != taskSCHEDULER_RUNNING ||
            !xPortCanYield()) {
        ets_delay_us(delay_us);
        return delay_us;
    }
    if (delay_us == 0) {
        /* We should effectively yield */
        vPortYield();
        return 1;
    } else {
        /* Just delay */
        int ticks = MAX(delay_us / (portTICK_PERIOD_MS * 1000), 1);
        vTaskDelay(ticks);
        return ticks * portTICK_PERIOD_MS * 1000;
    }
}

/* Called by ROM CDC ACM driver from interrupt context./
 * Non-static to allow placement into IRAM by ldgen.
 */
void esp_usb_console_cdc_acm_cb(cdc_acm_device *dev, int status)
{
    if (status == USB_DC_RESET || status == USB_DC_CONNECTED) {
        s_prev_rts_state = 0;
    } else if (status == ACM_STATUS_LINESTATE_CHANGED) {
        uint32_t rts, dtr;
        cdc_acm_line_ctrl_get(dev, LINE_CTRL_RTS, &rts);
        cdc_acm_line_ctrl_get(dev, LINE_CTRL_DTR, &dtr);
        if (!rts && s_prev_rts_state) {
            if (dtr) {
                s_queue_reboot = REBOOT_BOOTLOADER;
            } else {
                s_queue_reboot = REBOOT_NORMAL;
            }
        }
        s_prev_rts_state = rts;
    } else if (status == ACM_STATUS_RX && s_rx_cb) {
        (*s_rx_cb)(s_cb_arg);
    } else if (status == ACM_STATUS_TX && s_tx_cb) {
        (*s_tx_cb)(s_cb_arg);
    }
}

/* Non-static to allow placement into IRAM by ldgen. */
void esp_usb_console_dfu_detach_cb(int timeout)
{
    s_queue_reboot = REBOOT_BOOTLOADER_DFU;
}

/* USB interrupt handler, forward the call to the ROM driver.
 * Non-static to allow placement into IRAM by ldgen.
 */
void esp_usb_console_interrupt(void *arg)
{
    usb_dc_check_poll_for_interrupts();
    /* Restart can be requested from esp_usb_console_cdc_acm_cb or esp_usb_console_dfu_detach_cb */
    if (s_queue_reboot != REBOOT_NONE) {
        esp_restart();
    }
}

/* Call the USB interrupt handler while any interrupts are pending,
 * but not more than a few times.
 * Non-static to allow placement into IRAM by ldgen.
 */
void esp_usb_console_poll_interrupts(void)
{
    const int max_poll_count = 10;
    for (int i = 0; (USB0.gintsts & USB0.gintmsk) != 0 && i < max_poll_count; i++) {
        usb_dc_check_poll_for_interrupts();
    }
}

/* This function gets registered as a restart handler.
 * Prepares USB peripheral for restart and sets up persistence.
 * Non-static to allow placement into IRAM by ldgen.
 */
void esp_usb_console_before_restart(void)
{
    esp_usb_console_poll_interrupts();
    usb_dc_prepare_persist();
    if (s_queue_reboot == REBOOT_BOOTLOADER) {
        chip_usb_set_persist_flags(USBDC_PERSIST_ENA);
        REG_WRITE(RTC_CNTL_OPTION1_REG, RTC_CNTL_FORCE_DOWNLOAD_BOOT);
    } else if (s_queue_reboot == REBOOT_BOOTLOADER_DFU) {
        chip_usb_set_persist_flags(USBDC_BOOT_DFU);
        REG_WRITE(RTC_CNTL_OPTION1_REG, RTC_CNTL_FORCE_DOWNLOAD_BOOT);
    } else {
        chip_usb_set_persist_flags(USBDC_PERSIST_ENA);
        esp_usb_console_poll_interrupts();
    }
}

/* Reset some static state in ROM, which survives when going from the
 * 2nd stage bootloader into the app. This cleans some variables which
 * indicates that the driver is already initialized, allowing us to
 * initialize it again, in the app.
 */
static void esp_usb_console_rom_cleanup(void)
{
    extern char rom_usb_dev, rom_usb_dev_end;
    extern char rom_usb_dw_ctrl, rom_usb_dw_ctrl_end;

    uart_acm_dev = NULL;
    memset((void *) &rom_usb_dev, 0, &rom_usb_dev_end - &rom_usb_dev);
    memset((void *) &rom_usb_dw_ctrl, 0, &rom_usb_dw_ctrl_end - &rom_usb_dw_ctrl);
}

esp_err_t esp_usb_console_init(void)
{
    esp_err_t err;
    err = esp_register_shutdown_handler(esp_usb_console_before_restart);
    if (err != ESP_OK) {
        return err;
    }

    esp_usb_console_rom_cleanup();

    /* Install OS hooks */
    rom_usb_osglue.int_dis_proc = esp_usb_console_osglue_dis_int;
    rom_usb_osglue.int_ena_proc = esp_usb_console_osglue_ena_int;
    rom_usb_osglue.wait_proc = esp_usb_console_osglue_wait_proc;

    /* Install interrupt.
     * In case of ESP_CONSOLE_USB_CDC_SUPPORT_ETS_PRINTF:
     *   Note that this the interrupt handler has to be placed into IRAM because
     *   the interrupt handler can also be called in polling mode, when
     *   interrupts are disabled, and a write to USB is performed with cache disabled.
     *   Since the handler function is in IRAM, we can register the interrupt as IRAM capable.
     *   It is not because we actually need the interrupt to work with cache disabled!
     */
    err = esp_intr_alloc(ETS_USB_INTR_SOURCE, ISR_FLAG | ESP_INTR_FLAG_INTRDISABLED,
            esp_usb_console_interrupt, NULL, &s_usb_int_handle);
    if (err != ESP_OK) {
        esp_unregister_shutdown_handler(esp_usb_console_before_restart);
        return err;
    }

    /* Initialize USB / CDC */
    s_cdc_acm_device = cdc_acm_init(cdcmem, CDC_WORK_BUF_SIZE);
    usb_dc_check_poll_for_interrupts();

    /* Set callback for handling DTR/RTS lines and TX/RX events */
    cdc_acm_irq_callback_set(s_cdc_acm_device, esp_usb_console_cdc_acm_cb);
    cdc_acm_irq_state_enable(s_cdc_acm_device);

    /* Set callback for handling DFU detach */
    usb_dfu_set_detach_cb(esp_usb_console_dfu_detach_cb);

    /* Enable interrupts on USB peripheral side */
    USB0.gahbcfg |= USB_GLBLLNTRMSK_M;

    /* Enable the interrupt handler */
    esp_intr_enable(s_usb_int_handle);

#ifdef CONFIG_ESP_CONSOLE_USB_CDC_SUPPORT_ETS_PRINTF
    /* Install ets_printf handler */
    ets_install_putc1(&esp_usb_console_write_char);
#endif // CONFIG_ESP_CONSOLE_USB_CDC_SUPPORT_ETS_PRINTF

    return ESP_OK;
}

/* Non-static to allow placement into IRAM by ldgen.
 * Must be called with the write lock held.
 */
ssize_t esp_usb_console_flush_internal(size_t last_write_size)
{
    if (s_usb_tx_buf_pos == 0) {
        return 0;
    }
    assert(s_usb_tx_buf_pos >= last_write_size);
    ssize_t ret;
    size_t tx_buf_pos_before = s_usb_tx_buf_pos - last_write_size;
    int sent = cdc_acm_fifo_fill(s_cdc_acm_device, (const uint8_t*) s_usb_tx_buf, s_usb_tx_buf_pos);
    if (sent == last_write_size) {
        /* everything was sent */
        ret = last_write_size;
        s_usb_tx_buf_pos = 0;
    } else if (sent == 0) {
        /* nothing was sent, roll back to the original state */
        ret = 0;
        s_usb_tx_buf_pos = tx_buf_pos_before;
    } else {
        /* Some data was sent, but not all of the buffer.
         * We can still tell the caller that all the new data
         * was "sent" since it is in the buffer now.
         */
        ret = last_write_size;
        memmove(s_usb_tx_buf, s_usb_tx_buf + sent, s_usb_tx_buf_pos - sent);
        s_usb_tx_buf_pos = s_usb_tx_buf_pos - sent;
    }
    return ret;
}

ssize_t esp_usb_console_flush(void)
{
    if (s_cdc_acm_device == NULL) {
        return -1;
    }
    write_lock_acquire();
    int ret = esp_usb_console_flush_internal(0);
    write_lock_release();
    return ret;
}

ssize_t esp_usb_console_write_buf(const char* buf, size_t size)
{
    if (s_cdc_acm_device == NULL) {
        return -1;
    }
    if (size == 0) {
        return 0;
    }
    write_lock_acquire();
    ssize_t tx_buf_available = ACM_BYTES_PER_TX - s_usb_tx_buf_pos;
    ssize_t will_write = MIN(size, tx_buf_available);
    memcpy(s_usb_tx_buf + s_usb_tx_buf_pos, buf, will_write);
    s_usb_tx_buf_pos += will_write;

    ssize_t ret;
    if (s_usb_tx_buf_pos == ACM_BYTES_PER_TX || buf[size - 1] == '\n') {
        /* Buffer is full, or a newline is found.
         * For binary streams, we probably shouldn't do line buffering,
         * but text streams are likely going to be the most common case.
         */
        ret = esp_usb_console_flush_internal(will_write);
    } else {
        /* nothing sent out yet, but all the new data is in the buffer now */
        ret = will_write;
    }
    write_lock_release();
    return ret;
}

ssize_t esp_usb_console_read_buf(char *buf, size_t buf_size)
{
    if (s_cdc_acm_device == NULL) {
        return -1;
    }
    if (!esp_usb_console_read_available()) {
        return 0;
    }
    int bytes_read = cdc_acm_fifo_read(s_cdc_acm_device, (uint8_t*) buf, buf_size);
    return bytes_read;
}

esp_err_t esp_usb_console_set_cb(esp_usb_console_cb_t rx_cb, esp_usb_console_cb_t tx_cb, void *arg)
{
    if (s_cdc_acm_device == NULL) {
        return ESP_ERR_INVALID_STATE;
    }
    s_rx_cb = rx_cb;
    if (s_rx_cb) {
        cdc_acm_irq_rx_enable(s_cdc_acm_device);
    } else {
        cdc_acm_irq_rx_disable(s_cdc_acm_device);
    }
    s_tx_cb = tx_cb;
    if (s_tx_cb) {
        cdc_acm_irq_tx_enable(s_cdc_acm_device);
    } else {
        cdc_acm_irq_tx_disable(s_cdc_acm_device);
    }
    s_cb_arg = arg;
    return ESP_OK;
}

bool esp_usb_console_read_available(void)
{
    if (s_cdc_acm_device == NULL) {
        return false;
    }
    return cdc_acm_rx_fifo_cnt(s_cdc_acm_device) > 0;
}

bool esp_usb_console_write_available(void)
{
    if (s_cdc_acm_device == NULL) {
        return false;
    }
    return cdc_acm_irq_tx_ready(s_cdc_acm_device) != 0;
}


#ifdef CONFIG_ESP_CONSOLE_USB_CDC_SUPPORT_ETS_PRINTF
/* Used as an output function by ets_printf.
 * The LF->CRLF replacement logic replicates the one in ets_write_char_uart.
 * Not static to allow placement into IRAM by ldgen.
 */
void esp_usb_console_write_char(char c)
{
    char cr = '\r';
    char lf = '\n';

    if (c == lf) {
        esp_usb_console_write_buf(&cr, 1);
        esp_usb_console_write_buf(&lf, 1);
    } else if (c == '\r') {
    } else {
        esp_usb_console_write_buf(&c, 1);
    }
}
static inline void write_lock_acquire(void)
{
    spinlock_acquire(&s_write_lock, SPINLOCK_WAIT_FOREVER);
}
static inline void write_lock_release(void)
{
    spinlock_release(&s_write_lock);
}

#else // CONFIG_ESP_CONSOLE_USB_CDC_SUPPORT_ETS_PRINTF

static inline void write_lock_acquire(void)
{
}

static inline void write_lock_release(void)
{
}
#endif // CONFIG_ESP_CONSOLE_USB_CDC_SUPPORT_ETS_PRINTF