/**
 * \file
 * \brief shelly - a shell process
 */

#include <stdio.h>
#include <stdlib.h>

#include <drivers/lpuart.h>
#include <drivers/gic_dist.h>
#include <maps/imx8x_map.h>
#include <maps/qemu_map.h>
#include <aos/aos.h>
#include <aos/inthandler.h>
#include <aos/ump_binding.h>
#include <aos/ump_chan.h>
#include <aos/shelly_client.h>
#include <aos/aos_rpc.h>
#include <fs/fs.h>
#include <grading.h>

#include "shelly.h"

//state that is shared for all clients
static struct shelly_st_global * global_state;

#include "shelly_cmd.c"

static void init_fs_on_demand(void) {
    errval_t err;
    if (global_state->did_init_filesystem == false) {
        err = filesystem_init();
        if (err_is_fail(err)) shelly_write_str("Failed to init filesystem\n\r");
        global_state->did_init_filesystem = true;
        SHELLY_DEBUG("initialized filesystem\n");
    }
}


bool is_newline(char c) {
    return c == ASCII_NL || c == ASCII_EOF || c == ASCII_CR;
}

//prints a null terminated string
errval_t shelly_write_str(char * str) {
    errval_t err;
    for (size_t i = 0; str[i] != '\0'; ++i) {
        err = lpuart_putchar(global_state->uart_s, str[i]);
        if (err_is_fail(err)) return err_push(err, SHELLY_ERR_WRITE);
    }
    err = lpuart_putchar(global_state->uart_s, '\0');
    if (err_is_fail(err)) return err_push(err, SHELLY_ERR_WRITE);
    return SYS_ERR_OK;
}

void shelly_reset_buffer(void) {
    global_state->buffer_i = 0;
    memset(global_state->buf, 0, SHELLY_BUF_SIZE);
}

errval_t shelly_buffer_append(char c) {
    global_state->buf[global_state->buffer_i] = c;
    global_state->buffer_i += 1;

    if (global_state->buffer_i == SHELLY_BUF_SIZE) {
        shelly_reset_buffer();
        return SHELLY_ERR_BUFFER_OVERFLOW;
    }

    return SYS_ERR_OK;
}

__attribute__((__used__))
static void handle_lpuart_interrupt(void * arg) {
    errval_t err;
    assert(global_state);

    char input_char;
    while (true) {
        err = lpuart_getchar(global_state->uart_s, &input_char);
        if (err == LPUART_ERR_NO_DATA) {
            break;
        } else if (err_is_fail(err)) {
            USER_PANIC_ERR(err, "while trying to get character");
        }

        err = lpuart_putchar(global_state->uart_s, input_char);
        if (err_is_fail(err)) USER_PANIC_ERR(err, "while trying to put character");

        if (is_newline(input_char)) {
            err = lpuart_putchar(global_state->uart_s, ASCII_NL);
            if (err_is_fail(err)) USER_PANIC_ERR(err, "while trying to put character");
        }

        if (is_newline(input_char)) {
            global_state->buf[global_state->buffer_i] = '\0';
            global_state->buffer_i += 1;

            err = shelly_write_str("\n\r");
            if (err_is_fail(err)) USER_PANIC_ERR(err, "while trying to write string");

            if (global_state->current_getchar_request != NULL) {
                //send to client
                for (int i = 0; i < global_state->buffer_i; ++i) {
                    send_response(global_state->current_getchar_request, SYS_ERR_OK, global_state->buf[i], 0, NULL);
                }
                global_state->current_getchar_request = NULL;
                shelly_reset_buffer();
            } else {
                //treat as command
                err = handle_shelly_cmd(global_state->buf, global_state->buffer_i);
                if (err_is_fail(err)) shelly_write_str("failed to run command :(\n\r");

                shelly_reset_buffer();

                err = shelly_write_str("\n\ryou@windows me > ");
                if (err_is_fail(err)) USER_PANIC_ERR(err, "while trying to write string");
            }
        } else {
            err = shelly_buffer_append(input_char);
            if (err_is_fail(err)) {
                err = shelly_write_str("shelly buffer full! resetting...\n\r");
                if (err_is_fail(err)) USER_PANIC_ERR(err, "while trying to write string");
            }
        }
    }
}

static void handle_send_completed(void *arg, struct ump_send_queue_entry *entry) {
    free((void *)entry->header);
    free((void *)entry->payload);
    free(entry);
}

static void send_response(struct shelly_st_local * local_state, errval_t err, char c, size_t payload_size, void *payload) {
    assert(local_state);

    // SHELLY_DEBUG("[send_response]\n");
    struct shelly_header * header = malloc(sizeof(struct shelly_header));
    assert(header);
    header->type = SHELLY_MSG_RESPONSE;
    header->err = err;
    header->character = c;

    struct ump_send_queue_entry *entry = malloc(sizeof(struct ump_send_queue_entry));
    if (entry == NULL) USER_PANIC("Ran out of memory");

    ump_send(
        local_state->send_chan,
        entry,
        sizeof(struct shelly_header),
        header,
        payload_size,
        payload,
        handle_send_completed,
        NULL
    );
    // SHELLY_DEBUG("[send_response] done\n");
}

static void handle_payload(void *arg, size_t payload_size, void *payload) {
    struct shelly_st_local * local_state = arg;
    assert(local_state);
    assert(global_state);

    // listen for the next request on this channel
    ump_recv_header(local_state->recv_chan, handle_client_request, local_state);
}

static void handle_client_request(void *arg, size_t header_size, void *header_buf, size_t payload_size) {
    errval_t err;
    struct shelly_st_local * local_state = arg;
    assert(local_state);
    assert(global_state);

    // SHELLY_DEBUG("[handle_client_request] client_id=%d\n", local_state->client_id);

    struct shelly_header * header = (struct shelly_header *) header_buf;

    if (header->type == SHELLY_MSG_GETCHAR) {
        grading_rpc_handler_serial_getchar();
        shelly_reset_buffer();
        global_state->current_getchar_request = local_state;
    } else if (header->type == SHELLY_MSG_PUTCHAR) {
        grading_rpc_handler_serial_putchar(header->character);
        err = lpuart_putchar(global_state->uart_s, header->character);
        if (err_is_fail(err)) USER_PANIC_ERR(err, "while trying to put character");
        if (is_newline(header->character)) {
            err = lpuart_putchar(global_state->uart_s, ASCII_CR);
            if (err_is_fail(err)) USER_PANIC_ERR(err, "while trying to put character");
        }
    }

    // skip payload
    ump_recv_payload(local_state->recv_chan, NULL, handle_payload, local_state);
}

__attribute__((__used__))
static errval_t connection_callback(void *arg, struct capref cap) {
    errval_t err;

    SHELLY_DEBUG("incoming connection\n");
    assert(global_state);

    //create a new local state
    struct shelly_st_local * local_state = calloc(sizeof(struct shelly_st_local), 1);
    assert(local_state);

    local_state->client_id = global_state->num_clients;
    global_state->num_clients += 1;

    // we can run the server on the default waitset since we are dispatching on
    // it for listening to connections anyways
    err = ump_chan_init(UMP_ROLE_SERVER, &local_state->send_chan, &local_state->recv_chan, sizeof(struct shelly_header), cap, global_state->ws);
    if (err_is_fail(err)) return err;
    // SHELLY_DEBUG("[connection_callback] local_state=%p\n", local_state);

    ump_recv_header(local_state->recv_chan, handle_client_request, local_state);

    SHELLY_DEBUG("connection ready to receive requests\n");

    return SYS_ERR_OK;
}


int main(int argc, char *argv[])
{
    errval_t err;

    global_state = calloc(sizeof(struct shelly_st_global), 1);
    assert(global_state);

    global_state->num_clients = 0;
    global_state->buffer_i = 0;
    global_state->ws = get_default_waitset();
    global_state->current_getchar_request = NULL;
    global_state->did_init_filesystem = false;

    //afeer: map lpuart registers
    struct capref cap_arg0 = {
        .cnode = cnode_arg,
        .slot  = 0
    };
    err = paging_map_frame_attr(get_current_paging_state(),
                                (void **) &global_state->lpuart_base, IMX8X_UART_SIZE,
                                cap_arg0, VREGION_FLAGS_READ_WRITE_NOCACHE);
    if (err_is_fail(err)) USER_PANIC_ERR(err, "while mapping lpuart registers");

    SHELLY_DEBUG("mapped lpuart\n");

    //afeer: map gic registers
    struct capref cap_arg1 = {
        .cnode = cnode_arg,
        .slot  = 1
    };
    err = paging_map_frame_attr(get_current_paging_state(),
                                (void**) &global_state->gic_base, IMX8X_GIC_DIST_SIZE,
                                cap_arg1, VREGION_FLAGS_READ_WRITE_NOCACHE);
    if (err_is_fail(err)) USER_PANIC_ERR(err, "while mapping gic registers");

    SHELLY_DEBUG("mapped gic\n");

    //afeer: init gic driver
    err = gic_dist_init(&global_state->gic_s, global_state->gic_base);
    if (err_is_fail(err)) USER_PANIC_ERR(err, "couln't init gic_dist interrupts");

    SHELLY_DEBUG("initialized gic driver\n");

    //afeer: init lpuart driver
    err = lpuart_init(&global_state->uart_s, global_state->lpuart_base);
    if (err_is_fail(err)) {
        USER_PANIC_ERR(err, "couldn't init lpuart");
    }

    SHELLY_DEBUG("initialized lpuart driver\n");

    struct capref inter_cap;
    err = inthandler_alloc_dest_irq_cap(IMX8X_UART3_INT, &inter_cap);
    if (err_is_fail(err)) USER_PANIC_ERR(err, "couln't alloc dest cap");

    SHELLY_DEBUG("created interrupt cap\n");

    err = inthandler_setup(inter_cap, global_state->ws, MKCLOSURE(handle_lpuart_interrupt, NULL));
    if (err_is_fail(err)) USER_PANIC_ERR(err, "couln't setup interrupt handler");

    SHELLY_DEBUG("setup interrupt handler\n");

    err = gic_dist_enable_interrupt(global_state->gic_s, IMX8X_UART3_INT, 0b11111111, 0);
    if (err_is_fail(err)) USER_PANIC_ERR(err, "couln't enable gic interrupts");

    SHELLY_DEBUG("enabled gic interrupt\n");

    err = lpuart_enable_interrupt(global_state->uart_s);
    if (err_is_fail(err)) USER_PANIC_ERR(err, "couln't enable lpuart interrupts");

    SHELLY_DEBUG("enabled lpuart interrupt\n");

    struct ump_binding_server server;
    err = ump_binding_register(&server, UMP_SERVER_SHELLY, connection_callback, NULL);
    if (err_is_fail(err)) USER_PANIC_ERR(err, "Failed to register UMP server");

    SHELLY_DEBUG("registered as shelly server\n");

    err = shelly_write_str("Welcome to Shelly(TM)(TM)!\n\r");
    if (err_is_fail(err)) USER_PANIC_ERR(err, "while trying to write welcome message");

    while (true) {
        err = event_dispatch(global_state->ws);
        if (err_is_fail(err)) {
            USER_PANIC_ERR(err, "in event_dispatch");
        }
    }
}