#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

struct command;

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

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

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

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

// FIXME: Assert ranges for integers
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) {
            if (!opt)
                goto syntax_error;
            break;
        }

        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;
}

static int
cmd_boot(int fd, const struct command *cmd, const struct param *param,
         int argc, char **args)
{
    int err;
    uint8_t bank;
    uint16_t address;

    if ((err = parse_args(cmd, argc, args, &bank, &address) < 0))
        return err;


    return z_boot(fd, bank, address);
}

static int
cmd_read(int fd, const struct command *cmd, 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;

    err = parse_args(cmd, argc, args, &bank, &address, &length, &pathname);
    if (err < 0)
        return -1;

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

    if (param->human_readable) {
        hexdump(address, length, buf);
    } else if (pathname) {
        FILE *fp;
        if (!(fp = fopen(pathname, "w"))) {
            perror("File could not be opened");
            return -1;
        }
        fwrite(buf, sizeof(uint8_t), length, fp);
        fclose(fp);
    } else {
        fwrite(buf, sizeof(uint8_t), length, stdout);
        fflush(stdout);
    }

    return 0;
}

static int
cmd_write(int fd, const struct command *cmd,  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;
    const char *pathname = NULL;

    err = parse_args(cmd, argc, args, &bank, &address, &pathname);
    if (err < 0)
        return -1;

    if (param->human_readable) {
        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;
        }
    } else {
        FILE *fp = pathname ? fopen(pathname, "r") : stdin;

        if (!fp) {
            perror("File could not be opened");
            return -1;
        }

        // FIXME: fread MAX_PACKET_SIZE insted of 8
        // Split file into packets
        while ((length = fread(buf, sizeof(uint8_t), 8, fp))) {
            if ((err = z_write(fd, bank, address, length, buf)))
                break;
            address += length;
        }

        if (fp != stdin)
            fclose(fp);
    }

    return err;
}

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

    if (!param->human_readable) {
        fputs("Echo is a interactive command only", stderr);
        return -1;
    }

    parse_args(cmd, argc, args);

    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 command *cmd, const struct param *param,
              int argc, char **args)
{
    return 0;
}

static int
repl_io_read(int fd, const struct command *cmd, 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);
}
*/

const struct command cmd_table[] = {
    {
        .alias = 'b',
        .name = "boot",
        .fptr = cmd_boot,
        .quit = 0,
        .args_spec = ARGS(A_BYTE, A_DBYTE, A_END),
        .usage = "Usage: boot <bank> <address>\n"
    },
    {
        .alias = 'r',
        .name = "read",
        .fptr = cmd_read,
        .quit = 0,
        .args_spec = ARGS(A_BYTE, A_DBYTE, A_DBYTE, A_OPTIONAL, A_STRING, A_END),
        .usage = "Usage: read <bank> <address> <length> [pathname]\n"
    },
    {
        .alias = 'w',
        .name = "write",
        .fptr = cmd_write,
        .quit = 0,
        .args_spec = ARGS(A_BYTE, A_DBYTE, A_OPTIONAL, A_STRING, A_END),
        .usage = "Usage: write <bank> <address> [pathname]\n"
    },
    {
        .alias = 'i',
        .name = "io_read",
        .fptr = NULL,
        .quit = 0,
        .args_spec = ARGS(A_DBYTE, A_DBYTE, A_END),
        .usage = "Usage: io_read <address> <length>\n"
    },
    {
        .alias = 'o',
        .name = "io_write",
        .fptr = NULL,
        .quit = 0,
        .args_spec = ARGS(A_DBYTE, A_END),
        .usage = "Usage: io_write <address>\n"
    },
    {
        .alias = 'e',
        .name = "echo",
        .fptr = cmd_echo,
        .quit = 0,
        .args_spec = ARGS(A_END),
        .usage = ""
    },
    {
        .alias = 'q',
        .name = "quit",
        .fptr = NULL,
        .quit = 1,
        .args_spec = ARGS(A_END),
        .usage = ""
    }
};

int
run_line(int fd, struct param *param, char *line, const char *sep)
{
    int err;
    int argc = 1;
    char *args[MAX_ARGS + 1] = { NULL };
    fptr p;

    // Tokenize command
    args[0] = strtok(line, sep);
    if (!args[0])
        return 0;
    while(argc < LEN(args) && (args[argc] = strtok(NULL, sep)))
        ++argc;

    // Match action
    int cmdi;
    for (cmdi = 0; cmdi < LEN(cmd_table); ++cmdi) {
        if ((!args[0][1] && args[0][0] == cmd_table[cmdi].alias)
            || !strcmp(args[0], cmd_table[cmdi].name))
            break;
    }

    // Call action
    if (cmdi == LEN(cmd_table)) {
        fprintf(stdout, "Unknown command %s\n", args[0]);
        return -1;
    }

    if ((p = cmd_table[cmdi].fptr)
        && (err = p(fd, &cmd_table[cmdi], param, argc - 1, &args[1]))) {
        print_error(err);
        return err;
    }

    return cmd_table[cmdi].quit;
}

// TODO: Handle signals (CTRL-C)
void
repl(int fd, struct param *param)
{
    int quit = 0;

#ifdef USE_READLINE
    using_history();
#endif

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

        if (!line)
            break;

        add_history(line);
        quit = run_line(fd, param, line, " ");
        free(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';

        quit = run_line(fd, param, line, " ");
#endif
    }
}