#include <zup.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <errno.h>

#ifdef USE_READLINE
#include <readline/readline.h>
#include <readline/history.h>
#endif // USE_READLINE

typedef int (*repl_command)(int, const struct param*, int, char**);

static int
repl_read(int fd, const struct param *param, int argc, char **args)
{
    int err = 0;
    uint8_t buf[MAX_PACKET_SIZE];

    uint8_t bank;
    uint16_t address;
    uint16_t length;
    const char *pathname = NULL;

    if (argc != 3 && argc != 4)
        goto syntax_error;

    errno = 0;
    bank = strtoul(args[0], NULL, 16);
    err |= errno;

    errno = 0;
    address = strtoul(args[1], NULL, 16);
    err |= errno;

    errno = 0;
    length = strtoul(args[2], NULL, 16);
    err |= errno;

    if (argc == 4)
        pathname = args[3];

    if (err)
        goto syntax_error;

    if ((err = z_read(fd, bank, address, length, buf))) {
        print_error(err);
        return err;
    }

    hexdump(address, length, buf);

    if (pathname) {
        FILE *file;
        if (!(file = fopen(pathname, "w"))) {
            perror("File could not be opened");
            return -1;
        }
        fwrite(buf, sizeof(uint8_t), length, file);
        fclose(file);
    }

    return err;

syntax_error:
    fputs("Usage: read <bank> <address> <length> [pathname]\n", stderr);
    return 1;
}

static int
repl_write(int fd, const struct param *param, int argc, char **args)
{
    int err;
    char line[512];
    uint8_t buf[MAX_PACKET_SIZE];

    char *p;

    uint8_t bank;
    uint16_t address;
    uint16_t length = 0;

    do {
        // TODO: Handle fgets error
        fgets(line, LEN(line), stdin);
        if (line && !strcmp("\n", line))
            break;

        p = strtok(line, " \n");
        while (p && length < 10) {
            errno = 0;
            buf[length++] = strtoul(p, NULL, 16);
            p = strtok(NULL, " \n");
        }

        if (p) {
            fputs("WRITE: Input can't be longer than 256 bytes\n", stderr);
            return -1;
        }
    } while (1);

    if ((err = z_write(fd, bank, address, length, buf))) {
        print_error(err);
        return err;
    }

    return 0;
}

static int
repl_echo(int fd, const struct param *param, int argc, char **args)
{
    int err;
    char line[512];
    char buf[MAX_PACKET_SIZE];

    memset(line, 0, sizeof(line));
    memset(buf, 0, sizeof(buf));

    size_t length = 0;

    do {
        // TODO: Handle fgets error
        fgets(line, LEN(line), stdin);
        if (line && !strcmp("\n", line))
            break;

        size_t len = strlen(line);
        if (line[len - 1] == '\n')
            line[--len] = '\0';

        if (length + len >= MAX_PACKET_SIZE) {
            fputs("ECHO: Input can't be longer than 256 bytes\n", stderr);
            return -1;
        }

        strcat(buf, line);
        length += len;
    } while (1);

    if ((err = z_echo(fd, length, (uint8_t *)buf))) {
        print_error(err);
        return err;
    }

    fwrite(buf, sizeof(uint8_t), length, stdout);
    putchar('\n');
    fflush(stdout);

    return 0;
}

static int
repl_io_write(int fd, const struct param *param, int argc, char **args)
{
    return 0;
}

/*
static volatile sig_atomic_t quit = 0;

void
interrupt_handler(int signal)
{
    puts("Bye!");
    quit = 1;
    // fclose(stdin);
}
*/

enum args_type {
    A_END,
    A_BYTE,
    A_DBYTE,
    A_QBYTE,
    A_OBYTE,
    A_STRING,
    A_OPTIONAL = 16
};

struct command;

typedef int (*fptr)(int, const struct command *, struct param *, int, char **);

struct command {
    char alias;
    const char *name;
    int *args_spec;
    const char *usage;
    fptr fptr;
    int quit;
};

static int
parse_args(const struct command *cmd, int argc, char **args, ...)
{
    int i = 0;
    int opt = 0;
    int err = 0;
    va_list ap;
    va_start(ap, args);

    void *ptr = NULL;
    int *p = cmd->args_spec;

    for ( ; *p != A_END; ++p) {
        // Avoid runaway p
        assert(i < MAX_ARGS);

        if (*p == A_OPTIONAL) {
            opt = 1;
            continue;
        }

        if (i == argc && !opt)
            goto syntax_error;

        ptr = va_arg(ap, void *);
        errno = 0;
        char *end = NULL;

        switch (*p) {
        case A_BYTE:
            *((uint8_t *)ptr) = strtoul(args[i], &end, 16);
            break;

        case A_DBYTE:
            *((uint16_t *)ptr) = strtoul(args[i], &end, 16);
            break;

        case A_STRING:
            *((const char **)ptr) = args[i];
            break;
        }

        if (errno || args[i] == end) {
            fprintf(stderr, "Invalid argument: %s\n", args[i]);
            goto syntax_error;
        }

        ++i;
    }

    va_end(ap);
    return i;

syntax_error:
    va_end(ap);
    fputs(cmd->usage, stderr);
    return -1;
}

#define ARGS(...) (int []){__VA_ARGS__}

static int
repl_io_read(int fd, const struct param *param, int argc, char **args)
{
    uint8_t bank;
    uint16_t address;
    const char *filename = NULL;

    struct command cmd = {
        .alias = 'i',
        .name = "io_read",
        .usage = "",
        .fptr = NULL,
        .quit = 0,
        .args_spec = ARGS(A_BYTE, A_DBYTE, A_OPTIONAL, A_STRING, A_END),
        .usage = "Usage: read <bank> <address> <length> [pathname]\n"
    };

    parse_args(&cmd, argc, args, &bank, &address, &filename);
    printf("result: %hhx %hx %s\n", bank, address, filename);
    return 0;
}

// TODO: Handle signals (CTRL-C)
// TODO: Print errors when in repl and crash if from terminal
void
repl(int fd, struct param *param)
{
    struct command {
        const char *name;
        repl_command fptr;
        int quit;
    };

    const struct command cmd_table[] = {
        {"read",     repl_read,     0},
        {"write",    repl_write,    0},
        {"echo",     repl_echo,     0},
        {"io_read",  repl_io_read,  0},
        {"io_write", repl_io_write, 0},
        {"quit",     NULL,          1}
    };

    int quit = 0;

#ifdef USE_READLINE
    using_history();
#endif

    while (!quit) {
#ifdef USE_READLINE
        char *line = readline("* ");

        if (!line)
            break;

        add_history(line);
#else
        size_t len = 0;
        char line[512];
        fputs("* ", stdout);

        if (!fgets(line, sizeof(line), stdin))
            break;

        len = strlen(line);
        if (line[len - 1] == '\n')
            line[len - 1] = '\0';
#endif
        int argc = 1;
        char *args[MAX_ARGS] = { NULL };

        // Parse command
        args[0] = strtok(line, " ");
        if (!args[0])
            goto skip;
        while(argc < MAX_ARGS && (args[argc] = strtok(NULL, " ")))
            ++argc;

        // Match action
        int cmdi;
        for (cmdi = 0; cmdi < LEN(cmd_table); ++cmdi) {
            if (!strcmp(args[0], cmd_table[cmdi].name))
                break;
        }

        // Call action
        if (cmdi == LEN(cmd_table)) {
            fprintf(stdout, "Unknown command %s\n", args[0]);
        } else {
            repl_command fptr = cmd_table[cmdi].fptr;
            if (fptr)
                fptr(fd, param, argc - 1, &args[1]);
            quit = cmd_table[cmdi].quit;
        }
    skip:
#ifdef USE_READLINE
        free(line);
#endif
    }
}